2 The clinical approach

Some neurological disorders such as stroke are so common and serious that reducing their burden features in the public health goals of many countries. Others are similarly common, and treatable, but often are regarded as having less public health importance for instance epilepsy or migraine. Some common conditions remain unpreventable and incurable such as Alzheimer’s disease. The most frequent cause of disability in young adults, multiple sclerosis, is thankfully not all that common. Less common disorders are myriad, of which many are hopelessly incurable, for instance motor neurone disease. Vigilance is required to detect few very rare diseases which are completely treatable, for example Wilson’s disease or tetanus. Perhaps the rarest of all, variant Creutzfeldt–Jakob disease, has attracted disproportionate political, economic, and public health concern, at least in the United Kingdom. So, neurologists have to be familiar with a huge range of disorders and balance the challenge of large numbers of patients with common disorders against vigilance for the once-in-a-lifetime patient with a treatable disease who slips in to the end of a busy clinic (MacDonald et al. 2000). Some contemporary neurologists need to sub-specialize, so as to provide optimal diagnosis and management of rare disorders such as myasthenia, and also the difficult end of the spectrum of more common disorders such as refractory epilepsy or treatable neuromuscular disease. But it is vital for most neurologists to nurture their general neurological skills, so as to maintain a broad diagnostic perspective, and to teach students and trainees.

The three traditional measures of disease frequency are mortality, incidence, and prevalence. Choosing which to use depends on the frequency of the disease in question, whether it is likely to be fatal, whether it is an acute one-off event or chronic, and also on logistic and methodological issues to do with recording and coding the disease itself. Because the frequency of most diseases varies by age, and sometimes by sex too, age- and sex-specific rates should be given. Frequencies of disease based on hospital data tend to be hopelessly flawed because one has no idea of the size of the denominator population, or of why some patients were referred to hospital and others not.

Mortality data, the number of deaths from a particular disease per annum in a population of known size, are routinely collected in developed countries from death certificates. However, there are many problems of erratic classification of disease and poor coding practice. Even more problematic is that some diseases like migraine are not fatal; others may be fatal but linger in such a chronic fashion that the patient’s death is due to, and is coded as, something quite different; multiple sclerosis patients may die of bronchopneumonia or cancer; and some disease entities have mild forms which are seldom fatal, for instance lacunar stroke. However, mortality data are based on large numbers usually and are likely to be precise as a result. Nonetheless, mortality only crudely approximates to disease frequency and is unhelpful when asking rather specific questions, such as how often do patients with epilepsy die suddenly and to what are their deaths due?

Incidence is the number of new cases of a disease appearing in a defined population of known size per annum. To measure it one must therefore have good census data to define the population denominator, multiple and overlapping case-finding methods to identify all the patients, a clear definition of when the disease actually starts which is easy for stroke but more difficult for gradually progressive disorders such as motor neurone disease, and a large enough number of patients with the disease to calculate precise estimates of frequency over a defined time period. All this is hardly possible outside prospective community-based studies although, if all the community is getting health care in one place and the records system is well organized and funded, such as in Rochester, Minnesota, then retrospective estimates of incidence are reasonably accurate, and probably the only sensible method for rare diseases. Any method relying on scrutiny of patient records would be threatened if society insists that researchers must first obtain the explicit consent of every patient.

Table 2.1 provides some estimates of the incidence of various neurological disorders in the conventional way of number of new cases per 100 000 population per annum, but not stratified by sex. In addition, it emphasizes that even the common neurological disorders such as multiple sclerosis are not all that common in primary care where physicians have to be extraordinarily alert to recognize and diagnose disorders they may never have seen since medical school. In educating students in neurology we should concentrate on the common disorders and on the general principles of recognizing that a patient has a neurological disorder so they can be referred to neurologists for precise diagnosis (Donaghy 2005).

The prevalence of a disease is the number of patients with that disease at a particular point in time, usually expressed per 100 000 population. Again this requires good census data or some other method of measuring the population denominator, such as a United Kingdom family practice computerized age–sex register, and then finding all the patients with the disease of interest in that population and confirming they actually have the disease. This is surprisingly difficult to do, and tedious, particularly when the disease is rare. Of course, prevalence will tell one nothing about fatalities. Furthermore, for episodic diseases such as transient ischaemic attacks, an episode many years before may well have been forgotten and, even if not, it may be difficult to diagnose in retrospect. Nonetheless, for some chronic and persisting disorders, estimates of prevalence can be illuminating (Table 2.2). This table again shows just how rare many neurological disorders are, even in a family practice of five doctors looking after 10 000 people. If one knows the incidence and the proportion of patients who die, then prevalence can be calculated and does not have to be measured directly.

Just under 10 per cent of the population consult their general practitioner about a neurological symptom each year in the United Kingdom. About 10 per cent of these are referred for a specialist opinion, usually to a neurologist. The commonest diseases or clinical problems encountered in a general neurological out-patient clinic are shown in Table 2.3. Together these nine conditions account for roughly 75 per cent of general neurological referrals and are diagnosed initially on purely clinical grounds and frequently managed purely in an out-patient setting (Perkin 1989; Stevens 1989). The remaining 25 per cent of neurological consultations concern the huge range of other neurological disorders, many rare. Such disorders are particularly likely to require highly specialist investigation and treatment, to need in-patient care, and continuing follow-up care. Naturally these broad statistics will vary in different healthcare settings which may not be based upon general practice, and as the demand for, and availability of, neurological services changes.

This section is concerned with a practical, everyday approach to diagnosing neurological disorders. It does not aim for the exhaustive completeness familiar in traditional accounts of the neurological examination. However there are times at which a more detailed approach to clinical assessment is necessary, for instance in elucidating the neuroanatomical site of the lesion responsible for muscle weakness (Section 2.4) or a somatosensory disturbance (Section 2.5). Also it is important to document the different reflexes which can be elicited, giving some indication of their usefulness (Section 2.3). These more traditional clinical approaches to such problems are presented separately, later in this chapter.

History taking is fundamental to neurological diagnosis. For instance, epilepsy or migraine are diagnosed solely on the basis of the history, with the examination merely ensuring there is no evidence of associated underlying structural disorders of the brain. The history is usually much more informative than examination, which generally is either reassuringly normal or merely confirms features anticipated from the history. However, sometimes examination is crucially helpful. For instance, in localizing the cause of muscle weakness, specific physical signs will reveal whether the lesion affects the upper motor neurone, the lower motor neurone, or the muscle. An unanticipated physical sign such as an extensor plantar response, signifying pyramidal tract damage, or papilloedema, signifying raised intracranial pressure, will alter one’s diagnostic view fundamentally if the history has pointed to diagnoses such as psychologically determined weakness or benign tension headache.

A good history provides a story whose internal direction points intuitively towards a diagnosis. It is much more revealing to treat the history as story telling than to take the utilitarian approach of simply listing symptoms with the expectation that a diagnosis will appear miraculously. Experience reveals that patients often describe the symptoms of certain disorders in a very distinctive way. Intuitive recognition of a characteristic history plays a large part in diagnosis. There is no particular list of questions to ask. It is best to invite the patient to describe their symptoms in the order in which they occurred, with approximate dates. Important detail can be clarified by specific questioning during or after the patient’s account. It is helpful to determine whether the patient’s symptoms are so ‘disabling’ as to prevent crucial everyday activities or work, or whether they merely constitute a ‘nuisance’. This will guide the decision as to whether a symptom such as headache needs treatment.

Some features of the history provide important clues to the neurological diagnosis. Questions about them should be phrased in open terms which do not influence the patient’s response:

Time course. Symptoms of abrupt or instantaneous onset usually indicate epilepsy, with sudden loss of consciousness, or cerebrovascular disease, the instantaneous headache of subarachnoid haemorrhage, or a sudden hemiparesis due to middle cerebral artery embolus. Symptoms that deteriorate subacutely, over hours, days, or even a few weeks are generally caused by inflammatory or demyelinating disorders. Slowly deteriorating symptoms over some weeks, months, or years point to the growth of a tumour, or a neurodegenerative process. Relapsing and remitting symptoms which come and go over weeks are typical of multiple sclerosis whilst recurrent headaches, each lasting 3 h to 3 days, are typical of migraine.

Negative symptoms. These indicate loss of normal neurological functions and are the commonest symptoms of damage to the nervous system. Examples include the hemiparesis due to cerebral hemisphere infarction, memory loss due to Alzheimer’s disease, muscle weakness due to motor neurone degeneration, or the loss of micturition control due to a cauda equina tumour.

Positive symptoms. These are novel phenomena which often suggest specific diagnoses. A ‘pill-rolling’ tremor of the fingers and thumb at rest is characteristic of Parkinson’s disease. Flashing lights, photopsia, or zig-zag lines, fortification spectra, preceding a headache are diagnostic of classical migraine. Repetitive twitching of the fingers or the corner of the mouth occurs in focal motor seizures. A hallucination of an odd smell, often like burning rubber, is typical of an epileptic discharge in the temporal lobe. Tingling in the toes and fingers is typical of acquired, rather than inherited, peripheral neuropathy.

Neuroanatomical localization. Sometimes enquiry about other specific symptoms is necessary to anatomically localize the disease process. For example a patient with suspected motor neurone disease should be asked whether there are sensory or sphincter symptoms which might point to the alternative diagnoses of generalized peripheral neuropathy or to spinal cord compression respectively. A patient with sensory symptoms in the legs should be asked whether their hands are also affected; this would be a pointer to a polyneuropathy or cervical myelopathy rather than a focal lesion of the cauda equina or thoracic spinal cord. Determine whether a patient with dysphasia also has impaired spatial abilities, such as a dressing apraxia or getting lost in familiar places; this would point to a generalized dementing process involving both cerebral hemispheres rather than a focal lesion of the left hemisphere causing pure dysphasia. Question a patient with gait unsteadiness about vertigo or double vision, which would imply damage to the brainstem rather than to the cerebellum or somatosensory pathways.

Eye witness descriptions. Patients with blackouts are unaware of what they did whilst unconscious and may not recollect the onset of the blackout. Thus, an eye witness description of a convulsion or automatic behaviour is diagnostic of epilepsy. In a patient with early dementia, it is often the spouse who provides the evidence for loss of intellectual function: forgetting the grandchildren’s names, inability to do the usual crossword, or personality change. Patients with motor neurone diseases are often unaware of their limb muscle fasciculations, yet their spouse may have noticed their occurrence whilst in bed.

Previous neurological history. This is vital for establishing the diagnosis of multiple sclerosis, a neurological disorder which is disseminated in space and time. Thus, a history of temporary unilateral visual loss due to optic neuritis a decade previously suggests multiple sclerosis in a 30-year-old woman with unsteady gait and urgency of micturition due to an incomplete spinal cord lesion.

Familial disorders. Many neurological disorders are genetic, although each of these is usually rare. Examination of the relatives of a patient with longstanding muscle wasting and weakness below the knees, and with high foot arches, pes cavus, may reveal autosomal dominant inheritance of a similar disorder so allowing diagnosis of hereditary motor and sensory neuropathy, otherwise known as Charcot–Marie–Tooth disease. First cousin marriage between the parents may be a clue to autosomal recessive disorders in offspring with neurological disease. Sex-linked recessive disorders, transmitted on the X chromosome and occurring in males, will not manifest in the mother, but may be present in the males of earlier or parallel generations.

Contributory general medical disorders. Progressively deteriorating neurological symptoms should prompt questions about possible underlying cancer affecting the nervous system: smoking, weight loss, haemoptysis, bowel symptoms, and recent breast and gynaecological check-ups. In a patient with stroke, a previous history of ischaemic or valvar heart disease, hypertension, diabetes, oral contraceptive usage, migraine, or cocaine abuse may be relevant. Unusual neurological disorders, such as opportunistic infections or lymphoma of the central nervous system, are particularly likely in the increasing numbers of immunosuppressed patients who are HIV infected, or have received organ transplants. Typical neurological side-effects of medicines are headache, giddiness, tremulousness, tinglings, and peripheral neuropathy; a patient’s drugs should be checked in a pharmacopeia for side-effects, and the onset of the symptoms related to the introduction of the drug. The travel history may raise the likelihood that a patient’s symptoms are due to an underlying infection such as leprosy, schistosomiasis, malaria, diphtheria, or borreliosis. Patients addicted to alcohol or recreational drugs are notorious for underestimating or denying consumption which may be directly relevant to disorders such as ataxia and stroke respectively.

Present day neurology has acquired a reputation for being both complicated and arcane because of the huge diversity of examination techniques which have been described. This has led in turn to the notion that there is an excessively lengthy entity called ‘a full neurological examination’ which utilizes this vast panoply of examination manoeuvres. Also, there is a commonly held belief that if one religiously executes all those manoeuvres, a diagnosis will miraculously appear. In reality the diagnostic process is one of intuition which involves devising a selective examination to answer diagnostic hypotheses posed by the symptoms of the particular patient in question. For instance, it is usually pointless to undertake cognitive testing in a patient who has given a cogent history of paraesthesiae in an arm, or to undertake detailed muscle power examination in a patient presenting with cognitive decline.

Many of the described examination manoeuvres are simply alternative methods of detecting the same pathological signature. Therefore to use more than one of them introduces unnecessary redundancy and repetition to the examination. For instance, a cerebellar lesion affecting the arm can be detected by the finger–nose test, by dysdiadochokinesis, by demonstrating ‘cerebellar hypotonia’, or by showing ‘underdamping’ when the outstretched arm is displaced with the eyes closed. Experienced neurologists develop sensitive and critical, yet economical, examination skills. They may recognize that a properly conducted finger–nose test is the only test that need be performed to demonstrate a cerebellar disorder of the arm. Valuable physical signs offer proof that an abnormality is present. Less valuable signs merely suggest one. The worth of trying to elicit different signs varies accordingly.

Often tests are of limited usefulness because they do not provide objective evidence of abnormality. Examples include the patient’s subjective responses to visual or somatosensory testing, or the influence of psychological factors on exertion of muscle power. Consequently a useful neurological examination will be rich in manoeuvres which can provide unequivocal evidence of pathology. These include inspection for papilloedema, testing pupil-light reflexes and eye movements, examining for cogwheel rigidity, noting muscle wasting and detecting absent tendon reflexes, extensor plantar responses, or sustained ankle clonus. For this reason it is recommended that physicians develop a brief basic neurological examination for routine use which is rich in testing for such unequivocal physical signs (Donaghy 2005). It avoids manoeuvres which are simply repetitive or imprecise ways of detecting the same pathology.

Such basic neurological examinations take only a few minutes. The ensuing example of a quick screening examination includes practical advice such as how to phrase instructions, where to place the hands for best effect, and how to interpret fundamentals such as abnormal reflexes. This basic examination is quite adequate for examining a patient with uncomplicated headache or epilepsy, or as part of a general medical examination for a patient without neurological symptoms. Other tests should be added on to this examination if the patient’s symptoms suggest a particular disease, or if abnormalities requiring further assessment are encountered during the basic examination.

It is practical to perform this basic examination in four stages: first during history taking, second whilst the patient is walking, third whilst the patient is sitting facing you, and fourth whilst the patient is lying down (Table 2.4) (Donaghy 2005).

Speech and cognition. Abnormalities of speech, thought, or memory raise questions of dysphasia or generalized dementia. Dysarthric speech is slurred. Dysphonic speech is quiet.

Facial expression. An impassive face suggests Parkinson’s disease, or occasionally a bilateral facial palsy. A melancholy facial expression occurs in depression. Dementia reduces the use of facial expression and gesture for non-verbal communication.

Involuntary movements. Pill-rolling tremor of the fingers at rest is characteristic of Parkinson’s disease. Sudden choreiform movements of the hands, which may look like fidgets, occur in Huntingdon’s disease and are often disguised as mannerisms. Unilateral spasms of eye closure occur in hemifacial spasm. Fixed or spasmodic head rotation to the side occurs in torticollis.

Walking. In the wide-based gait of ataxia the feet cross more than the usual 0–5 cm apart, and the stride length is irregular. Uniformly small strides occur in the gait apraxia of frontal lobe disease. Difficulty in starting, shuffling, and then progressively lengthening strides occur in Parkinsonism. Arm swing is lost in Parkinson’s disease, usually unilaterally early on. Floppy foot drops occur in peripheral nerve or nerve root disease. Stiff foot drops occur in spastic upper motor neurone lesions, or occasionally in dystonia. A waddling gait, with drop of the pelvis on the striding side, occurs in proximal muscle weakness due to myopathy.

Heel-to-toe walking. This is a sensitive screen for cerebellar disease, or sensorimotor abnormalities affecting the limbs. It is best tested by instructing ‘Please walk heel-to-toe, like this’ whilst the

examiner demonstrates two or three such steps (Fig. 2.1). Patients will stumble to the side if they have ataxia due to cerebellar disease, or loss of leg proprioception due to peripheral neuropathy or dorsal column disease.

Romberg test. This is an excellent test for loss of proprioceptive feedback from the legs in peripheral neuropathy or dorsal column disease. In patients with abnormal heel–toe walking, it differentiates those with ataxia due to loss of proprioceptive feedback from those with ataxia due to cerebellar disease. It is best tested by the examiner instructing ‘stand with your feet together like this [whilst demonstrating], get your bearings, and now close your eyes—I won’t let you fall’ whilst preparing to steady the patient’s shoulders with their hands if the patient begins to topple (Fig. 2.2). Romberg test is positive if the patient falls, or is unable to maintain balance without corrective movements of the feet. It is important to realize that a correctly performed Romberg test does not merely test balance with the eyes closed, but is a comparison of stability with and without vision. A truly positive Romberg test takes some moments to develop, with an increasing amplitude of slow swaying until a critical degree of lean occurs, beyond which the patient can no longer remain upright. Not uncommonly one encounters patients who promptly fall in one direction immediately upon closing their eyes; this usually results from lack of confidence or is otherwise

psychologically determined, and rarely indicates structural disease of the nervous system.

Ophthalmoscopy. Inspect the optic nerve head, also called the optic disc. It is important to understand the location of the optic nerve head, which corresponds to the blind spot, within the visual field and its corresponding position in the eye. This enables the patient’s direction of gaze to be aligned so that the examiner can look into their eye confident of looking directly at, or very near to, the optic disc. The blind spot, which represents the optic disc, lies about 20° of visual angle lateral to the point of fixation in each eye. Also it lies just below the horizontal. This determines the ‘line of attack’ (Fig. 2.3). Therefore the patient should be asked to fixate on a point behind the examiner chosen for height so that he is able to look into their eye comfortably from just below its horizontal meridian. The particular fixation point chosen will depend upon the relative heights of the examiner’s and the patient’s heads. The ophthalmoscope should be used with one’s right eye to examine the patient’s right eye, and vice versa for the left, looking into the eye from about 20° lateral to the line of fixation, and from just below the line of sight.

Examine whether the edge of the optic disc is sharply defined as is normal, or has blurred edges suggesting disc swelling due to papilloedema due to raised intracranial pressure. A pale or white disc is due to optic atrophy. Having inspected the optic disc, the vessels and more peripheral parts of the retina can be scrutinized, for instance if diabetic retinopathy is suspected; this is easier if the pupils are dilated. The foveal pit, or macula, can be inspected whilst the patient stares directly at an ophthalmoscope beam adjusted to the small spot.

Visual fields. It is time-consuming and rarely rewarding to carry out detailed examination of the peripheral and central portions of the visual fields of each eye separately unless the patient has symptoms of visual or pituitary disease. The following quick manoeuvre is a simple screen for homonymous hemianopia, an identical visual field deficit in both eyes due to cerebral hemisphere disease, and for sensory inattention due to parietal lobe lesions. The patient is asked to ‘keep looking at my nose and point to whichever of my index fingers moves’. The examiner’s arms are raised so as to position the index fingers at about 80° peripheral in each visual field. After a moment the tip of one index finger should be moved once whilst keeping the rest of the arm still; the patient should point immediately. If the patient has sensory inattention or a homonymous hemianopia, they will only see movement on one side despite simultaneous movement of the fingers on both sides and further analysis of the deficit can be undertaken. A red pinhead, or perimetry techniques, are often required for accurate detection and delineation of more subtle visual field defects. These include red desaturation monocularly in the temporal field in optic chiasm lesions, or the monocular partial central scotoma so common in optic neuritis.

Sensory inattention may be detected by moving your finger on both sides simultaneously, but the patient will only detect movement on one side. Of course sensory inattention, which reflects a parietal lobe lesion, can only be diagnosed if each visual field is normal when tested separately.

Eye movements. Inspection of the patient’s face when gazing straight ahead will show the drooping eyelid of ptosis. Mild to moderate ptosis can be difficult to detect if bilateral. In definite ptosis, the eyelid will overlap the edge of the pupil when looking straight ahead.

To test eye movements ask the patient ‘to hold your chin with one hand [in order to prevent head movements] and then follow my finger with your eyes’. A finger or a stick is held vertically and moved laterally to about 50 or 60°. After holding it still for a moment, ask the patient whether he sees it as single or double. Simultaneously inspect the eyes carefully to detect nystagmus or any paralysis of

ocular movement. Vertical eye movements can be tested similarly by holding a finger horizontally and moving it up and then down by about 45°. Many elderly patients develop clinically insignificant loss of upgaze.

Pupils. To test the pupil-light reflex, the patient should be asked to fixate the examiner’s nose whilst he notes the size of the pupils before light stimulation. If it is very difficult to see the pupil because of dim illumination, or a darkly pigmented iris, it helps to shine the torch beam at the bridge of the nose so that light scatter is enough to make the pupil visible, without stimulating the pupil-light response by directly shining the light into the eye (Fig. 2.4). Second, shine the torch directly into the left eye and observe that both pupils constrict equally; this elicits the direct pupil-light response on the left and the indirect, or consensual, response on the right. Third, swing the torch beam quickly across to the right eye and check that there is no further dilatation or constriction of either pupil. This swinging torch test compares the amplitude of the direct and consensual pupil responses of each eye. If there were an optic nerve lesion on the right, both pupils would dilate slightly when the torch was shone in the right eye, compared to their normal constriction following left eye stimulation. This method of comparing the pupil responses has the sensitivity to detect relative, rather than absolute, afferent pupillary defects due to partial optic nerve lesions, as may occur in optic neuritis.

A unilaterally small pupil is most usually due to a cervical sympathetic pathway lesion causing Horner’s syndrome, which will be associated with no more than a slight degree of eyelid drooping, ptosis (Fig. 2.5).

A unilaterally, fixedly dilated pupil is typical of an oculomotor nerve lesion (III cranial nerve) (Fig. 2.6), in which also there will be impairment of adduction and vertical eye movement, and the ptosis will be usually much more marked than in Horner’s syndrome.

Facial sensation. The fingertips of both the examiner’s hands are lightly drawn on both sides simultaneously across the patient’s forehead, to the cheek and nose, and then onto the chin. Whilst doing so, he should ask ‘do my fingers feel normal and the same on each side?’ whilst covering all three territories of the trigeminal nerve, frontal (V₁), maxillary (V₂), and mandibular (V₃) (Fig. 2.7). Any area of altered sensation can be tested in more detail and mapped out using a pin or a wisp of cotton wool.

Testing the corneal reflex with a wisp of cotton wool is not necessary as a routine. The following method is recommended if you do need to test the corneal reflex, for instance, if you suspect potentially harmful loss of corneal sensation or a subtle facial nerve lesion. Make a fine wisp of cotton wool and ask the patient to look upwards whilst warning them that ‘I’m going to touch the corner of your eye with this cotton wool’. Introduce this cotton wisp from below and to the side and brush the junction between the cornea and sclera (Fig. 2.8). Normally a unilateral stimulus provokes bilateral blinking, another example of a ‘unilateral afferent-bilateral efferent’ reflex. Contact lenses are the commonest cause of seemingly absent corneal reflexes.

Facial movements. Subtle degrees of facial weakness, such as unilateral slowing of movement, are best seen if the examiner steps back a couple of paces so as to see both sides of the patient’s mouth simultaneously within their central vision. Voluntary movement of the mouth can be produced by instructing ‘show me your teeth like this’ or ‘give me a smile’. An even better demonstration is provoked by smiling at the patient who usually responds with an involuntary grin which demonstrates facial movements perfectly. Observe whether both sides of the mouth move equally quickly, and produce similar elevation and deepening of the nasolabial skin creases. If the mouth movement is asymmetrical, indicating unilateral weakness, ask the patient to ‘raise your eyebrows’ to see whether both sides of the frontalis muscle in the forehead contract equally (Fig. 2.9). Lower motor neurone lesions of the seventh nerve will affect movements of both the forehead and the mouth. Unilateral upper motor neurone facial paralysis affects only the mouth and lower face, but not the forehead.

Hearing. To test hearing in the right ear, the patient is instructed ‘Could you repeat this number’ whilst the examiner lightly rubs the tip of their finger in the other ear to create a masking noise and whispers a number from about 2 ft, and vice versa to test the left ear.

Unilateral or bilateral deafness should be assessed further by Weber’s and Rinne’s tests (Section 2.2.3) to distinguish between conductive and sensorineural deafness, and by auroscopic examination of the eardrum.

Palatal movements. These are best tested by asking the patient to open their mouth and say ‘ah’ whilst illuminating the throat with a torch. If the elevation of the palate and uvula is normal and symmetrical, and there is no swallowing difficulty or dysphonia, there is no need for the discomfort of eliciting the gag reflex as a routine. When necessary the gag reflex is elicited by stimulating one side of the soft palate with a stick and watching the resultant rise of both sides of the palate.

Tongue movement. It is best to inspect the tongue for wasting or fasciculations while it is relaxed on the floor of the mouth during examination of the palatal movements. It is misleading to look for fasciculations whilst the tongue is being actively protruded since most normal tongues show ripples and flickers under such circumstances. Tongue movements can be tested by asking the patient to ‘stick out your tongue and move it from side to side like this’ and demonstrate this movement. A lower motor neurone lesion affecting a hypoglossal nerve causes the tongue to be wasted on, and deviate towards the same side as the lesion. If an upper motor neurone lesion is bilateral, the tongue becomes spastic and square in profile and its movements limited and slow. Tongue power is best tested by asking the patient to push their tongue into the corner of their cheek whilst the examiner palpates. In a cerebellar lesion, alternating tongue movements will be slowed and irregular.

Inspection. The profile of the upper arms should be inspected for muscle wasting or fasciculations with the patient sitting facing towards the examiner. Then the hands should be inspected for muscle wasting by looking particularly at the first dorsal interosseous muscles on the dorsum of the hand between the thumb and forefinger, innervated by the ulnar nerve, and the abductor pollicis brevis in the lateral part of the thenar eminence, innervated by the median nerve.

Tone. Either the extrapyramidal rigidity of Parkinson’s disease, or the spasticity of an upper motor neurone lesion can be detected reliably in the arms. Different techniques are used to test for these tone changes. Which one is chosen should be determined by which of these conditions is suspected. Spasticity should be sought by holding the patient’s hand with the elbow flexed, and abruptly supinating the forearm to detect a sudden jerk of spastic resistance known as a ‘pronator catch’ (Fig. 2.10).

The ‘cogwheel rigidity’ of Parkinson’s disease is best detected by holding the patient’s wrist with one hand, and repeatedly flexing and extending the fingers and wrist by gripping the tips of the fingers with the other hand (Fig. 2.11). If mild, sometimes the abnormality can be brought out by the patient simultaneously waving the other arm in the air. The term ‘cogwheel rigidity’ merely describes leadpipe rigidity with superimposed tremor.

Power. For general screening purposes it is sufficient to test one proximal and one distal muscle in each arm. The best proximal muscle to test is shoulder abduction to 90° by deltoid (C5 root, axillary nerve). A good distal muscle to test is the first dorsal interosseous (TI root, ulnar nerve), which spreads the fingers apart. Its power can be compared with the examiner’s own first dorsal interosseous muscle (Fig. 2.12). Additional muscles should be tested if a lesion of a particular peripheral nerve or root is suspected.

Coordination. The finger–nose test is the most reliable but is only sensitive if the patient is required to stretch their arm out fully from the shoulder to touch the examiner’s target finger (Fig. 2.13). The examiner should stand well behind their own outstretched target finger so as to detect the randomly distributed inaccuracies in the patient’s pointing known as ataxia or dysmetria. Dysmetria on this test usually indicates cerebellar disease, cerebellar ataxia, or loss of proprioceptive feedback, sensory ataxia, but can occur in proximal muscle weakness. If ataxia is detected, pseudoathetosis indicative of loss of sensory feedback can be sought by asking the patient to hold out the arms horizontally with the eyes closed, with the fingers extended and spread apart; if pseudoathetosis is present, the fingers wander and fail to remain in position (Fig. 21.47).

Arm tendon reflexes. The biceps reflexes (musculocutaneous nerve; 5th and 6th cervical roots) should be tested from the patient’s right side. The examiner’s thumb should be used to transmit a firm blow from the tendon hammer to the biceps tendon within the cramped space of the antecubital fossa so as to elicit a visible or palpable contraction of the biceps muscle (Fig. 2.14).

When testing the triceps reflex (radial nerve; 7th and 8th cervical roots), the hammerhead should hit the tendon at right angles just above the elbow because the triceps muscle has an extremely short tendon (Fig. 2.15). The brachioradialis reflex (radial nerve; 6th cervical root) is difficult to elicit reliably and rarely adds extra information unless a C6 root lesion is suspected, or the examiner is trying to localize or detect a radial nerve lesion. Tendon reflexes are brisk in upper motor neurone lesions. An absent tendon reflex will be due to a peripheral nerve or nerve root lesion. Before concluding that a reflex is absent reinforcement should be undertaken

by asking the patient to ‘bite your teeth together when I say “bite”’ whilst you try simultaneously to elicit the reflex.

Inspection. The bulk of the vastus medialis component of quadriceps just above and medial to the kneecap can be observed by asking the patient to ‘tighten your kneecaps’. The bulk of more distal muscles can be demonstrated by asking the patient to ‘cock your toes up towards you’ whilst checking that the tibialis anterior muscle bulges in front of the anterior border of the tibial bone. The leg muscles should be inspected for fasciculations which are visible flickering contractions within the muscle belly, insufficient to produce movement around the joint, and which signify disease of the lower motor neurone, for instance in motor neurone disease. Sometimes fasciculations are visible in otherwise normal calf muscles of healthy individuals, particular after exercise. Skin ulcers, burns, or disrupted joints, known as Charcot joints, may be trophic changes resulting from loss of protective pain sensation.

Tone. The spasticity of an upper motor neurone lesion, observed as sustained clonus, is the most reliable objective tone change detectable in the legs. Ankle clonus is elicited by externally rotating the foot and holding the knee slightly flexed with one hand, whilst sharply jerking the sole of the foot upwards with the other hand (Fig. 2.16). For a few seconds the foot should be held firmly in sustained dorsiflexion since the rhythmic downward beatings of clonus may take a moment or two to become evident. Sustained clonus, or unsustained clonus of more than 6 beats, is generally regarded as definite evidence of an upper motor neurone lesion.

Power. Testing of one proximal and one distal muscle in each leg is sufficient to screen for the weakness of unexpected myopathies (proximal), peripheral neuropathy (distal), or upper motor neurone lesions (both proximal and distal). Proximal leg power is reflected by hip flexion (iliopsoas muscle, 1st and 2nd lumbar roots) best tested by instructing the patient to ‘push your leg up to 45 degrees’ and then for the examiner to press downwards just above the knee (Fig. 2.28). A distal muscle, tibialis anterior (peroneal nerve, 5th lumbar root) is tested by asking the patient to ‘cock your foot up towards you’ whilst the examiner tries to overcome this dorsiflexion at the ankle (Fig. 2.17). Tibialis anterior is a particularly valuable muscle to test, since it will be weakened by upper motor neurone lesions, polyneuropathy, common peroneal nerve lesions, and in L5/S1 root lesions due to prolapsed intervertebral disc. Some leg muscles are so naturally powerful that milder degrees of weakness cannot be detected reliably by bedside testing. For instance, mild weakness of knee extension by quadriceps (femoral nerve; 3rd and 4th lumbar roots) may be revealed best by asking a patient to stand up from a chair without using their arms. Ankle plantar flexion by gastrocnaemius (posterior tibial nerve; 1st and 2nd sacral roots) is best tested by asking a patient to stand on tiptoe or even to hop.

Tendon reflexes. The knee jerk or quadriceps tendon reflex (femoral nerve; L3/4) is elicited by lifting and flexing both knees over the

examiner’s left arm by 60–90°, and then striking the two patellar tendons in turn to compare the reflex on both sides (Fig. 2.18).

The ankle jerk or gastrocnaemius or Achilles tendon reflex (posterior tibial nerve; S1/S2) is best tested by externally rotating the foot with the knee slightly bent, gently dorsiflexing the knee, and then striking the Achilles tendon firmly with the hammer (Fig. 2.19). Poor technique is often responsible for the ankle jerks appearing to be absent; the examiner may not have struck the Achilles tendon sufficiently firmly, or the patient may be ‘helping’ by holding the foot rigidly in dorsiflexion. Brisk tendon reflexes point to an upper motor neurone lesion in which case sustained ankle clonus and/or an extensor plantar response would be expected too. Slightly brisk reflexes may occur in anxious, tense patients. The reflexes are absent in peripheral nerve or root lesions. The ankle jerks are absent in many people over the age of 70. As with the arm reflexes, reinforcement should be undertaken before finally declaring a reflex absent.

Plantar responses. An extensor plantar or Babinski response (Fig. 2.20) is a definite sign of an upper motor neurone lesion. It is present from the onset of the upper motor neurone lesion, well before sufficient spasticity has developed to allow clonus or hypereflexia.

Technique is all-important for eliciting the plantar response reliably (Fig. 2.21). The patient should be lying down unable to see their toes. The examiner should passively move the great toe up and down beforehand, both to ensure relaxation, and also to detect hallux rigidis which would mask the toe movement. Then, lightly holding the leg just above the ankle with the left hand, a thin stick, or a key is held in the right hand and slowly but firmly drawn up the outer aspect of the sole and across the ball of the foot. During this the examiner should watch the great toe from the side so as to detect whether its first movement is downwards (flexor and normal) or upwards (extensor and abnormal).

Sensory examination. In a patient without sensory symptoms, such as deadness or tinglings, and whose Romberg test is normal, sensory examination is rarely abnormal. Generally it is not worth performing as a routine if disease of the sensory pathways is not suspected.

The following examples show how other examination manoeuvres can be added to the general neurological examination (Section 2.2.2) if the patient’s symptoms suggest a specific disorder, or if the basic examination has revealed abnormalities requiring further evaluation. Further details and other examples are given in other chapters.

The general neurological examination outlined in Section 2.2.2 does not test every cranial nerve in detail. The following main functions of each cranial nerve are easily testable, should the clinical situation require it:

Commonly patients complain of neurological symptoms affecting a single limb. In such cases, or if abnormalities are found on general neurological examination, a wide range of muscles and sensory territories must be examined using a strategy to distinguish between polyneuropathy, root lesions, mononeuropathy, and myopathy. For example, if a patient has weakness of the first dorsal interosseous muscle (ulnar nerve, T1 root), but abductor pollicis brevis (median nerve, T1) is normally strong, it is clear that there is an ulnar nerve lesion rather than a polyneuropathy or a T1 root lesion. Muscle strength can be assessed particularly sensitively in the arms by testing the strength of individual muscles, such as biceps or finger flexors and extensors, using the identical muscle in the examiner. Full details of muscles innervated by individual peripheral nerves are given in Chapter 22.

Frequently tested muscles in the arm are:

Useful muscles to test in the leg include:

Dementia is a diffuse loss of cognitive function, particularly involving memory, due to generalized disease of both cerebral hemispheres. Diagnosing early dementia can be difficult and the spouse’s observations are all-important. Initially minor symptoms may have been attributed to absent-mindedness. Then patients are noted to develop uncharacteristic errors of judgement, inability to perform their customary intellectual tasks such as puzzles or games, loss of interest in hobbies and recreations, and inability to remember the names of friends and family. As the disease becomes more advanced, the personality is lost and patients may become disinhibited about the usual social codes of excretion or sexuality. Ultimately the patient becomes mute and unresponsive, wanders aimlessly, is incontinent, and dependent on feeding.

Demented patients are vague or rambling during history taking although this is sometimes masked by preserved social skills. Simple bedside clues to dementia involve checking the orientation for date and place; orientation for person usually being preserved except in psychiatric disease or simulated dementia. Calculation ability is usefully tested by serial subtraction of 7 from 100. General knowledge of everyday and historical events should be assessed to judge whether it is consistent with the patient’s educational and social background. Memory loss may be indicated by impaired immediate and 5-min recall of a simple three-line address or of three objects. Cognitive estimates such as ‘Roughly how long is a man’s spine?’ or ‘How many camels are there in Holland?’ may be abnormal in frontal lobe disease. If the patient’s demeanour is flat or gloomy it suggests depression, which may be a clue to potentially treatable pseudodementia. Self-neglect may be evident, as may be failure to use facial expression and gesture for non-verbal communication. Right parietal lobe spatial functions can be tested by asking the patient to draw or copy a three-dimensional cube. If a dysphasic component prevents understanding of such instructions, impaired spatial functioning may be revealed by dressing apraxia in which the patient is unable to put on a dressing gown or shirt correctly when one of the sleeves has been pulled through the wrong way.

In a patient with hesitancy or urgency of micturition, or retention or incontinence of urine, the following aspects of examination are crucial. Extensor plantar responses point to a spinal cord lesion affecting the upper motor neurones. Absent ankle jerks point to

cauda equina compression or peripheral neuropathy. Blunted perianal pinprick sensation occurs in cauda equina lesions. The anal reflex can be tested by stroking the anal verge firmly with an orange stick, and looking for a reflex contraction which crinkles the anal skin (Section 2.3.3). This reflex is lost in cauda equina lesions but is difficult to elicit reliably, with the response being particularly uncertain in older patients or those with a patulous anus.

Cardiovascular examination is usually more informative than neurological examination to elucidate the underlying cause of stroke or transient ischaemic attacks. Cardiac arrhythmia, particularly atrial fibrillation, or hypertension may be significant. Auscultation may reveal possible sources of cerebral emboli; cardiac murmurs indicative of valvar disease, or the bruit of an internal carotid artery stenosis audible just below the angle of the jaw. When listening for carotid bruits, it is important to ask the patient to hold their breath so that breath sounds are not confused with a bruit. Cranial bruits, for instance due to a vascular malformation, are best heard by applying the stethoscope bell over the closed eyelid, and listening when the patient has opened the other eye and is fixating. This avoids distraction due to eye movement noises. Atrial septal defects, potentially admitting paradoxical emboli from the venous circulation, are suggested by the subtle finding of fixed splitting of the second heart sound during respiration.

Any progressive focal neurological abnormalities of the brain, spinal cord, or nerve roots raises the question of compression or infiltration by tumour. In such cases, the search for a primary systemic tumour should include examination of all lymph node groups, the breasts, testicles, chest including chest X-ray, abdomen, rectum, and prostate or vagina.

Straight leg raising will be limited by pain to less than the normal 80–90° on the side of a prolapsed intervertebral disc affecting the L5 or S1 nerve roots. Muscles innervated by the different nerve roots under suspicion should be tested, particularly ankle dorsiflexion (L5). The briskness of the ankle jerks should be compared carefully on the two sides, if necessary from behind with the patient kneeling on a chair. Pinprick sensation in the L5 dermatome on the dorsum of the foot and lateral leg below the knee, and in the S1 dermatome on the sole of the foot and back of the calf, should be compared on the two sides. The lumbar spine should be examined for focal tenderness or deformity which might indicate a tumour deposit or infection in a vertebra.

During history taking the patient may exhibit a paucity of facial expression or a characteristic pill-rolling tremor of the finger and thumb at rest. Observe walking for a slow and shuffling start, or loss of arm swing. Unilateral loss of arm swing whilst walking may be the earliest sign of Parkinson’s disease. Cogwheel rigidity of the arms is a valuable objective test and is often more pronounced when the patient waves the other arm in the air (Fig. 2.11). Test writing for micrographia (Fig. 2.32) in which the letters get smaller during the writing of a word, but note that some patients have learned to compensate for this by writing long words in segments of a few letters at a time, momentarily stopping or lifting the pen from the paper between these groups of letters.

A completely different strategy is required to examine unconscious patients because of their inability to carry out instructions. The general medical examination may reveal head trauma, cardiovascular shock, arrhythmia, respiratory failure, pyrexia, alcohol intoxication, or the pinpoint pupils of opiate overdose. Blood sugar testing with Dextrostix will reveal hypo- or hyperglycaemia, and blood should be sent for toxicological analysis and creatinine measurement. Neck stiffness due to meningism is usually found in subarachnoid haemorrhage or meningitis, careful technique will detect mild neck rigidity (Fig. 2.33). Regular or spontaneous breathing may be disrupted by damage to brainstem respiratory nuclei; Cheyne–Stokes respiration with irregular waxing and waning of respiration is typical of cerebral hemisphere lesions. The depth of unconsciousness is reflected by the extent of any withdrawal response to painful squeezing of the fingernails or toenails. If withdrawal is particularly reduced on one side, it points to a contralateral cerebral lesion. The plantar responses are usually bilaterally extensor in unconscious patients and have little specific diagnostic or localizing value. Decerebrate posturing, in which the limbs become stiffly extended, usually indicates a brainstem lesion. Generalized or focal seizures may be evident in status epilepticus or

encephalitis, and can particularly affect the corner of the mouth, with repetitive twitching. Brainstem function can be tested by eliciting the vesibulocular reflex of compensatory eye movement induced by head rotation, or by irrigation of the ears with cold water, the so-called caloric response. Brainstem integrity is also reflected by the corneal reflex of bilateral eye closure when one cornea is stimulated with a wisp of cotton wool, and by the cough and gag responses to laryngeal or pharyngeal stimulation with a sucker or stick.

Although most neurological signs directly reflect pathology affecting the corresponding pathway within the nervous system, some reflect secondary pathology at a site remote from the main pathological abnormality. These are known as false localizing signs. They mainly result from raised intracranial pressure, or from spinal cord lesions (Larner 2003).

False localizing signs as a result of raised intracranial pressure were first noted by Collier (1904). A sixth nerve palsy is the commonest false localizing sign of raised intracranial pressure, be it due to intracranial mass, benign intracranial hypertension, or cerebral venous sinus thrombosis. Two pathological anatomical explanations for such sixth nerve palsies have been proposed: first stretching of the nerve by downward or backward displacement of the brainstem and second, angulation or compression of the nerve as it passes over the ridge of the petrous temporal bone (Fig. 2.34). Less frequently the trigeminal or facial nerves can be affected by raised intracranial pressure with either positive or negative symptoms. When a supratentorial swelling causes herniation of the medial temporal lobe through the tentorium cerebelli, a third nerve palsy can result. Unilateral pupil dilatation, known as Hutchinson’s pupil is usually the first sign, and attributed to the centrifugal location of pupil constrictor axons within the nerve. Usually the dilated pupil is ipsilateral to the cerebral mass lesion but contralateral occurrence also occurs (Larner 2003). Third nerve palsy due to transtentorial herniation of the temporal lobe may be followed by a contralateral hemiparesis attributed to compression of the cerebral peduncle. A less frequent alternative is that of an ipsilateral hemiparesis, attributed to compression of the cerebral peduncle contralateral to the lesion, as a result of lateral displacement of the midbrain against the free edge of the tentorium. This false localizing ipsilateral hemiparesis is known as the Kernohan notch phenomenon and typically results from acute subdural haematoma.

A large proportion of those presenting with neurological disorders are the elderly. Stroke, Parkinson’s disease, dementia, and cervical spondylotic myelopathy are common disabling neurological conditions in this age group. Furthermore, troublesome neurological symptoms which evade formal diagnosis are common in patients in their seventh decade and beyond. Examples include mild degrees of memory difficulty, dizziness and dysequilibrium, falls (Section 2.6.5), or unwitnessed blackouts. High-level gait disorders (Section 2.6.4), without a demonstrable frontal lobe abnormality on scanning, are a common problem for the very old. These may be difficult to distinguish from the mild gait deterioration which is almost universal by the age of 80. In elderly patients with neurological

disorders particular effort should be made to pursue diagnoses which may lead to improvement or stabilization of the disorder during the patient’s natural lifespan. Examples include detection and treatment of subdural haematoma, meningioma, Parkinson’s disease, herpes encephalitis, hydrocephalus, idiopathic demyelinating polyneuropathy, lumbar canal stenosis, and myasthenia gravis.

The neurological examination becomes less discriminating in elderly patients. Absent ankle tendon jerks, loss of vibration sense from the feet, mild weakness of ankle dorsiflexion, and general loss of muscle bulk are frequent age-related findings. These only assume clear pathogenic significance if unilateral, or if they emerge at an unexpectedly rapid rate during sequential examinations. Steadily diminishing pupil size, and loss of upgaze or convergence are frequent asymptomatic ocular signs in the elderly. Hearing, smell, and taste all deteriorate with ageing. Gait in the elderly often shows small strides, uncertainty, a widened base, use of a stick, and a tendency to walk carefully around corners. Romberg’s test is frequently positive. Heel–toe walking is often impossible for elderly patients yet without any clear relationship to an identifiable and deteriorating disease process.

Traditionally, the clinical approach of neurology has been to detect a particular constellation of physical signs allowing localization of a lesion to a particular site. Examples of such syndromes include:

Increasingly nowadays patients seek medical advice before they have progressed to the ‘full-house’ of symptoms and signs diagnostic of a particular syndrome or disorder, such as those above. The ready availability of high definition imaging allows definitive investigation of such patients at an earlier stage when clinical assessment alone may be unable to provide precise localization. Thus, the clinical approach of modern neurology needs to investigate the possible diseases which could be the cause of such incomplete, early syndromes. For in many instances this will allow treatment of the underlying disorder before irreversible neurological damage has occurred, particularly in the case of spinal cord and cauda equina compression.

A reflex is the simplest form of involuntary response to a stimulus. The anatomical basis of a reflex arc consists of: (1) a receptor organ; (2) an afferent path running from the periphery to the brainstem or spinal cord; (3) in some reflexes one or more intercalated neurones in the central nervous system link the afferent path to the (4), efferent path which leaves the neuraxis by the lower motor neurone axons to reach (5), the effector organ. Reflexes are elicited by afferent sensory stimuli such as touch, pain, sudden muscle stretch, light, or noise. The efferent response consists of muscular contraction, a modification in muscle tone, or glandular secretion. Important though visceral reflexes are, the neurologist investigating the state of the nervous system is mainly concerned with reflexes that excite responses in the somatic musculature.

Reflexes play an important role in diagnostic neurology because they reflect the integrity of, or alterations in, the neural structures responsible for their arc. Loss of a reflex may be due to interruption of the afferent path by a lesion involving the first sensory neurone in the peripheral nerves, plexuses, spinal nerves, or dorsal roots, by damage to the central paths of the arc in the brainstem or spinal cord, by lesions of the lower motor neurone at any point between the anterior horn cells and the muscles, of the muscles themselves, or by the neural depression produced by neural shock. In clinical practice, the most useful and oft-elicited reflexes are the tendon reflexes of the limbs, the jaw jerk, the plantar response, the superficial abdominal reflexes, the pupil-light response, and in infants, the Moro reflex. The place of these particular reflexes in the routine neurological examination is outlined in Section 2.2.2. This section describes the elicitation and significance of these reflexes and of a wide variety of others which are used occasionally.

The physiological basis of the tendon reflex is the myotatic reflex, which is the reflex contraction of a muscle or part of a muscle in response to stretch. It is monosynaptic; mediated by a reflex arc consisting of two neurones with one synapse between them (Lloyd 1952). The afferent input of the tendon reflex is transmitted by large myelinated sensory peripheral nerve fibres which innervate the muscle spindles. These in turn are connected in parallel with the main contractile extrafusal muscle fibres. Their nuclear chain fibres signal the actual length of the spindle whilst the nuclear bag fibres detect the velocity of change of length (Fig. 2.35). The overall sensitivity of the muscle spindle is determined by its efferent supply from γ-motor neurones which control contraction of its intrafusal muscle fibres (Fig. 2.35). Tendon reflexes must be distinguished from the tonic stretch reflex which results from slow or prolonged stretch of a muscle and which is a polysynaptic response, probably involving cortical pathways (Marsden et al. 1973). The activity of many bulbar and spinal reflexes is profoundly influenced by the state of the muscle spindles and of the gamma efferent system of motor nerve fibres. In conditions causing hypotonia cerebellar lesions the tendon reflexes are depressed. By contrast the hypertonia associated with increased gamma efferent discharge exaggerates reflexes; such enhancement is greater in spasticity than in extrapyramidal rigidity. Anxiety, tensing, and painful conditions may also cause some increase in the deep tendon reflexes. Paradoxically in severe long-standing spinal cord lesions or spastic diplegia, the spasticity is so severe that sometimes the tendon reflexes in the lower limbs may be difficult to elicit. This is due to irreversible muscular contractions resulting from to chronic spasticity, or a dominant flexor withdrawal reflex which inhibits the tendon jerks.

A tendon reflex or jerk is a sharp muscular contraction evoked by suddenly stretching the muscle. The sudden stretch may be brought about by tapping the tendon, or by suddenly displacing the segment of a limb into which the muscle is inserted (Fig. 2.36). The response, a muscular contraction, is most evident in the muscle stretched, but may not be confined to this muscle. A tendon reflex is diminished or abolished by a lesion interrupting either the afferent, central, or efferent paths of the reflex arc, or by a disorder which makes the muscle incapable of responding to the nervous impulse.

If initially absent, reinforcement of tendon jerks may be achieved by simultaneous voluntary muscle contraction elsewhere in the body such as biting the teeth together, clenching a fist, or by pulling the flexed fingers of the two hands against each other, Jendrassik’s manoeuvre. This increases activity in the gamma efferent system. Reflex activity in the legs may be studied electrically by recording the ‘H’ reflex, a contraction in the calf muscles which can be elicited by stimulating electrically the medial popliteal nerve. The H response, which is a monosynaptic reflex evoked by stimulation of group I afferent fibres in the nerve, follows the so-called M response evoked in the muscle by the direct effect of the nerve stimulus upon alpha efferent fibres. In early polyneuropathy the tendon reflexes may be lost before sensory loss is detectable clinically, although abnormalities of conduction usually are detectable electrically. Rarely, the tendon reflexes are congenitally absent. Some or all of the tendon reflexes may be well-nigh impossible to elicit, despite reinforcement, in well-muscled young men who are completely healthy. Table 2.5 gives the principal tendon reflexes, their mode of elicitation, and their innervation. Additional reflexes are sometimes elicited to localize the level of a spinal cord lesion: deltoid, pectoralis, long finger flexor, thigh adductor, or hamstrings.

Clinical interpretation of tendon reflexes involves two separate considerations; interpretation of an individual reflex relative to the other reflexes, and an absolute judgement as to whether an individual reflex is abnormal. An individual reflex can be regarded as abnormal only if it is absent despite reinforcement, or if its elicitation produces a clonic contraction of the muscle. The varying shades of sluggishness and briskness between these two extremes are not in themselves definitively abnormal. In contrast, comparison of tendon reflexes between different body regions may be helpful in localizing pathology, without any of the reflexes being individually abnormal. Examples include the slightly brisker reflexes unilaterally in a patient with mild hemiparesis, or the brisker reflexes in the legs than in arms in a patient with thoracic spinal cord compression. To document these variations in reflex intensity, various grading systems have been recommended (Dick 2003). None of these grading systems is fully satisfactory, and it is recommended that the observations are recorded as: absent despite reinforcement; present only with reinforcement; reduced; normal; brisk without clonus; clonus.

Clonus is a rhythmical series of contractions evoked by maintaining stretch and tension in a muscle. It is associated with increased gamma efferent discharge, and is often elicitable when the tendon reflexes are exaggerated after a corticospinal lesion. Ankle clonus is obtained by sharply dorsiflexing the ankle (Fig. 2.16). Clonus of the quadriceps, patellar clonus, is best elicited by a sudden sharp downward displacement of the patella. Clonus in the finger flexors can sometimes be elicited by suddenly extending the fingers.

Hoffmann’s reflex. The patient’s hand is pronated and the observer grasps the terminal phalanx of the middle finger between their forefinger and thumb. With a sharp flick the phalanx is passively flexed and suddenly released. A positive response consists of a sharp twitch of adduction and flexion of the thumb and flexion of the fingers. This reflex is physiologically identical with the flexor finger-jerk, which is elicited by tapping the palmar surface of the slightly flexed fingers. It is an index of muscular hypertonia rather than proof of a corticospinal lesion as such. It is not always positive in the presence of such a lesion, and may be elicitable in a nervous individual with no organic disease; if present only unilaterally it is likely to be significant.

Reflex spread. In states of muscular hypertonia a reflex response may spread beyond the muscles stretched, as when a tap on the styloid process of the radius elicits a contraction not only of the brachioradialis, but also of the long flexors of the fingers.

Inverted reflexes. In the upper limbs, so-called ‘inverted reflexes’ may be a useful sign of lesions of the cervical spinal cord. For instance, a lesion at C5-6 may both interrupt the arc for reflexes innervated by that segment, and also compress the corticospinal tracts to give exaggeration of reflexes subserved by lower segments. Thus tapping the biceps tendon may fail to elicit the biceps jerk but gives contraction of triceps, the ‘inverted biceps jerk’. Similarly, the brachioradial jerk may be absent but the attempts to elicit it cause finger flexion, the ‘inverted radial jerk’. An inverted knee jerk, with contraction of the hamstrings with knee flexion when the quadriceps tendon is tapped, may also be a sign of a spinal-cord lesion at L2-4 (Boyle et al. 1979) but is much less common.

The palmomental reflex. To elicit this reflex, an orange stick is firmly scratched across the base of the thenar eminence. A positive response consists of involuntary contraction of the ipsilateral mentalis muscle giving a dimpling of the chin (Owen and Mulley 2002). The reflex may be present bilaterally in normal individuals but exhausts after a few trials. If persistently elicitable, or occurring in response to stimuli outwith the palm, it is likely to indicate cerebral damage.

The superficial abdominal reflexes. These are cutaneous reflexes consisting of a brisk unilateral contraction of the adjacent part of the abdominal wall in response to a corresponding cutaneous stimulus, such as a light stroke with an orange stick (Dick 2003). It is convenient to elicit them at three levels on each side—just below the costal margin (T8), at the level of the umbilicus (T10), and just above the inguinal ligament (T12) using stimuli which run medially along the territory of the dermatome. The abdominal and erector spinae reflexes are polysynaptic, and are reactions of the trunk to potential injury. They are plurisegmental, and lead to a local withdrawal from the stimulus. These reflexes may be absent in normal people, especially older women, in the aged, the obese, those with abdominal scars, and the multiparous.

They are normally dependent upon the integrity of the corticospinal tract for reasons not fully understood. Hence a corticospinal lesion is usually associated with diminution or loss of the superficial abdominal reflexes upon the same side. Loss of the abdominal reflexes is not always proportional to the severity of the lesion. In multiple sclerosis, for example, they may be lost early, at a stage of the disease when other signs of corticospinal tract dysfunction are slight. In spastic diplegia and motor neurone disease, on the other hand, they are often retained, despite frank spasticity of the legs.

The reflex arcs of the superficial abdominal reflexes are localized in the spinal cord from the seventh to the twelfth dorsal segments. Lesions involving the arcs themselves may produce diminution or loss of the reflexes, for instance a structural lesion of the spinal cord at those segmental levels, or damage to the lower motor neurone by poliomyelitis.

The cremasteric reflex. The cremasteric reflex is a cutaneous reflex closely related to the abdominal reflexes. The stimulus is a light scratch along the inner aspect of the upper part of one thigh. The response is a contraction of the cremaster muscle, with elevation of the testicle on that side. This reflex, mediated by the first lumbar spinal segment, is diminished or abolished by a corticospinal tract lesion or a lesion of the reflex arc. It is usually extremely brisk in children, in whom it may sometimes be elicited by a stimulus applied to any part of the lower limb. It is often diminished or absent on the affected side in a patient with a varicocele.

The gluteal reflex. The gluteal reflex is physiologically akin to the abdominal reflexes. A scratch on the buttock evokes contraction of the glutei. The spinal segments concerned are L4 and 5.

The plantar reflex. The plantar reflex is one of the most important of all reflexes to the neurologist, because, if extensor, it provides unequivocal evidence of an upper motor neurone lesion. The plantar reflex normally remains extensor for the first year of life. After that the normal flexion withdrawal reflexes throughout the leg must be overridden for standing and walking. This plantar reflex is stimulated by a slow, firm, longitudinal scratch up the lateral aspect of the sole of the foot from the heel towards the toes (Fig. 2.21). The normal response is plantar flexion of the toes, sometimes associated with dorsiflexion of the foot at the ankle, contraction of the tensor fasciae latae muscle, and other variable muscular contractions. It is a spinal segmental reflex mediated by the first sacral segment of the cord. As a superficial reflex it is akin to the abdominal cremasteric reflexes (Lance 2002).

The extensor plantar response or Babinski response occurs in the presence of a corticospinal tract lesion. The normal reflex response of the great toe is replaced by an upward, extensor movement (Fig. 2.20). Extension of the great toe is not an isolated phenomenon of the abnormal plantar reflex, but is part of a general reflex flexion of the whole lower limb. This relates to the primitive flexor withdrawal reflex in response to a nociceptive stimulus to the lower limb seen in animals after division of the spinal cord. Both the flexor and extensor plantar responses are nociceptive reflexes, but ‘the unique feature of the pathological extensor response is the recruitment of extensor hallucis longus into contraction with tibialis anterior and extensor digitorum longus’ (Kugelberg and Hagbarth 1958). The afferent focus, or region from which it is easiest to elicit this reflex, is the outer border of the sole and the transverse arch of the foot but may extend to the leg or thigh in corticospinal tract lesions. The motor focus, or minimal response, is a contraction of the inner hamstring muscles which may be present even when the great toe fails to move. When fully developed, the extensor plantar reflex consists of flexion at all joints of the lower limb with dorsiflexion of the great toe and abduction or fanning of the other toes.

There are several points of practical importance in eliciting the plantar reflex, some of which are discussed in Section 2.2.2. The stimulus should always be applied first along the outer border of the sole; an extensor response may sometimes be obtained here when the inner border of the sole yields a flexor response. The response is more consistently obtained if the stimulus is then continued medially across the anterior arch of the sole of the foot. Oppenheim’s reflex, dorsiflexion of the great toe, evoked by firm moving pressure on the skin over the tibia, is physiologically the same as Babinski’s reflex, differing only in the site of the stimulus. The same is true of Chaddock’s and Gordon’s reflexes. Chaddock’s, also called the external malleolar sign, is an extensor plantar response elicited by scratching the skin in the region of the external malleolus. In Gordon’s, also called the paradoxical flexor reflex, the stimulus consists of squeezing the calf muscles. The extensor plantar reflex is not an all-or-none reaction: minor degrees of corticospinal tract damage lead to an incomplete flexor response or a failure of the great toe to move either up or down, an ‘equivocal’ response. In experienced hands such equivocal responses carry reasonably reliable diagnostic implication if clearly unilateral.

Bilateral extensor plantar reflexes are often observed during sleep and deep coma from any cause, and for a short time after an epileptic convulsion. They are usually extensor in the first year of life, when the corticospinal fibres are incompletely developed. An extensor plantar response has been noted sometimes in patients in whom no anatomical lesion of the corticospinal tract was subsequently discovered. Occasionally the plantar response remains clearly flexor despite the presence of such a lesion (Van Gijn 1978). It may occur transiently as a result of physical fatigue. In the presence of a corticospinal tract lesion, the Babinski response may be lost if an associated lower motor neurone lesion paralyses the extensor hallucis muscle. This is a common problem in amyotrophic lateral sclerosis where denervation of the distal leg musculature can obscure the presence of the associated upper motor neurone lesion.

The bulbocavernosus reflex. The bulbocavernosus reflex consists of contraction of the bulbocavernosus muscle, which can be detected by palpation, in response to squeezing the glans penis. The spinal segments concerned are sacral 2, 3, and 4. This reflex is abolished in lesions of the cauda equina.

The anal reflex. The anal reflex consists of contraction of the external sphincter ani in response to a firm scratch on the skin of the anal verge. It tends to be absent in the elderly and those with a patulous anus. The spinal segments concerned are sacral 4 and 5.

Some of the most clinically significant cranial reflexes are unilateral afferent-bilateral efferent reflexes in type. In these, a unilateral sensory stimulus evokes a bilateral motor response. Interpretation of the effects of lesions affecting either the afferent or efferent pathways, or the brainstem nucleus is based upon the circuitry (Fig. 2.37 and Table 2.6). The pupil-light reflex circuitry is discussed in Section 13.3.1.

The corneal reflex. The stimulus that evokes the corneal reflex is a light touch upon one cornea with a wisp of cotton wool. The normal response is bilateral blinking. The afferent path is through the first division of the fifth cranial nerve. The central path consists of fibres uniting the spinal nucleus of the fifth nerve with both facial nuclei. The efferent path passes through the facial nerves to both orbiculares oculi muscles. A lesion involving the fifth nerve or its spinal nucleus, since it interrupts the afferent path, causes bilateral loss of blinking in response to stimulation of the cornea on the side of the lesion. A lesion involving the nucleus or fibres of one seventh nerve interrupts the efferent path and hence causes loss of the reflex on the side of the lesion only, whilst the blink response remains on the other side. Loss of the corneal reflex is often an early sign of a lesion of the fifth nerve and may occur before any cutaneous anaesthesia can be detected. Apart from lesions involving the reflex arc, the corneal reflex is lost in states of deep coma.

The palatal reflex. The palatal or gag reflex consists of bilateral elevation of the soft palate in response to touching it on one side. The afferent path is by the glossopharyngeal nerve; the efferent by the vagus. The prominence of the palatal reflex varies between normal individuals. It is abolished by glossopharyngeal nerve lesions causing anaesthesia of the palate, and by lesions of the vagus nuclei. In lesions of a single vagus nerve, the response is unilateral, irrespective of the side of the stimulus, and the uvula is displaced towards the normal side.

The glabellar tap. A brisk tap on the glabella above the bridge of the nose causes bilateral blinking. In the normal individual, on repeated tapping the blinking ceases after two or three taps, known as the glabellar tap sign, nasopalpebral reflex or blinking reflex (Schott and Rossor 2003). Electrophysiological recordings from the orbicularis oculi have shown that there is an initial low amplitude monosynaptic reflex response, followed by a larger response of longer latency which is clearly polysynaptic. This habituates in normal individuals. In many with Parkinsonism blinks occur continuously in time with the taps, a ‘positive glabellar tap sign’. However it is not specific and occurs also in diffuse frontal lobe damage and some normals.

The vestibulo-ocular reflex. This is also known as the oculocephalic reflex. The term ‘Doll’s head phenomenon’ is ambiguous because the eyes of some dolls are fixed, whilst those of others counter-rotate. When the eyelids are held open and the head is

rotated sharply from side to side, the eyes initially show conjugate deviation away from the side to which the head is moved. On flexion of the neck they move upwards; after each such movement they return slowly to the mid position even if the head remains rotated or flexed. The reflex persists in blind individuals and after occipital lobectomy (Plum and Posner 1980). It is impaired when there are lesions of the oculomotor nerves. Its absence usually indicates a brainstem lesion.

The caloric or oculovestibular reflex. This has much in common with the vestibulo-ocular reflex. Irrigation of an external auditory meatus with warm or cold water causes nystagmus in normal individuals. As this reflex depends upon the integrity of the vestibular nuclei, its absence may be a valuable sign of pontine damage if there is no reason to suspect a labyrinthine or eighth nerve lesion. Repeated absence of the caloric reflex is an important criterion in diagnosing brainstem death (Section 33.7.2).

The jaw jerk. In response to a tap upon the chin, so as to depress the lower jaw, there is a bilateral contraction of the elevators of the jaw. The jaw jerk is best elicited with the mouth half open, with the examiner resting a finger on the central mandible to cushion the blow of the tendon hammer. Both afferent and efferent paths pass through the trigeminal nerve. This reflex is a muscle stretch reflex, and, like other such reflexes, becomes exaggerated as a result of bilateral corticospinal tract lesions. It is often weakly present in normal individuals, and is only clearly enhanced if notably brisk and of large amplitude, or if it provokes jaw clonus.

Primitive oral reflexes. In the infant the contact of an object with the lips evokes sucking movement of the lips, tongue, and jaw. This sucking reflex is lost after infancy but may reappear in states of severe cerebral degeneration, such as senile dementia (Paulson and Gottlieb 1968). It may be unilateral, and associated with a grasp reflex on the same side. The snout reflex consists of lip puckering in response to pressure over the base of the nose (Schott and Rossor 2003). The slower rooting reflex involves the lips following and seeking out a gentle tactile stimulus on the adjacent cheek, or in response to a visual object, and involves head turning. These sucking, snout, and rooting reflexes are normal in infants, and re-emerge in frontal lobe lesions. It is most accurate to consider the pout reflex as a separate entity from the snout reflex, although the two terms are often used interchangeably. The pout reflex is evoked by a brisk tap upon a spatula placed on the closed lips, and if positive produces an immediate pouting response. This represents an enhanced myotatic reflex of the orbicularis oris muscle which appears in bilateral corticospinal tract lesions at or above the upper brainstem.

The pharyngeal reflex. This consists of constriction of the pharynx in response to a touch upon the posterior pharyngeal wall. Its afferent path runs in the glossopharyngeal nerve, its efferent path in the vagus. It is abolished by lesions causing pharyngeal anaesthesia and by lesions of the vagus nuclei. In cases of unilateral paralysis of the vagus musculature, the response is confined to the opposite half of the pharynx. Compared to the palatal reflex it is more difficult to elicit and interpret and does not offer additional localizing value.

These are reflexes in which the response consists not of a brief muscular contraction but of a sustained modification in the posture of one or more sections of the body.

Tonic neck reflexes. In the decerebrate animal changes in the position of the head relative to the body cause reflex modifications of limb tone and posture. These reflexes, which are excited from the proprioceptors of the cervical spine, are known as tonic neck reflexes and may sometimes be observed in severe cerebral diplegia. Passive turning of the head to one side evokes extension of the arm and leg on the side to which the head is turned; the contralateral limbs flex.

Associated reactions. Associated reactions or associated movements, are automatic modifications of the posture of parts of the body when vigorous voluntary or reflex movement of some other part occurs. They are best observed in the paralysed upper limb in hemiplegia, following a vigorous grasping movement with the sound hand. Other patterns of associated movement occur. Such semi-voluntary activities as yawning, stretching, and coughing often evoke associated movements in the paralysed limbs in hemiplegia, and may arouse false hopes that recovery is occurring.

The Moro reflex. This is normally present at birth and disappears by 20 weeks of age; persistence suggests a diffuse central nervous system disorder. It is elicited by holding the infant supine with the head slightly flexed, and then dropping the head through about 30°. The normal response is of symmetrical abduction, extension, and rotation of the arms. An asymmetrical Moro response occurs in brachial plexus injury or hemiparesis.

The Landau reflex. This reflex should be present by 10 months of age and will be absent in diplegia or tetraplegia. The infant is held prone supported by the examiner’s hand. The normal response is extension of the neck, trunk, and legs. If abnormal, the infant tends to collapse into flexion around the examiner’s hand.

These are primitive reflexes of the limbs similar to the primitive oral reflexes (Section 2.3.4). Normally present in early development, their later inhibition may be released by frontal lobe damage. Two aspects of the stimulus are required to elicit a grasp reflex (Schott and Rossor 2003). Initially deep pressure over the palm evokes a brief catching movement of the fingers. This only develops into the firm holding phase if the object is then gently pulled away. Grasping reflexes may coexist with utilization behaviour.

Grasp reflex of the hand. Contact of an object such as the examiner’s finger with the palmar surface of the fingers, especially in the region between the thumb and the index finger, causes reflex flexion of the fingers and thumb so that the patient’s hand involuntarily grasps. The patient is unable to relax this grasp voluntarily, and efforts to pull the object away only cause it to be held more firmly. The patient may even notice that when he is holding an object he is unable to relinquish hold of it. Even an object presented visually may be groped for. Forced grasping and groping, which have been considered a regression to the infantile stage of the function of grasping, usually indicate a lesion involving the upper part of the opposite frontal lobe. A unilateral grasp reflex in a fully conscious patient is of some localizing value. Its localizing value is much less when the reflex is bilateral or the patient semi-comatose.

The grasp reflex of the foot. A similar grasp reflex is sometimes seen in the foot. Light pressure or a stroking movement applied to the distal half of the sole and plantar surface of the toes evokes tonic flexion and adduction of the toes without other associated movements. Like the fingers, the toes may grasp and hold an object. This reflex is present in the normal infant up to the end of the first year, and in 50 per cent of children with Down’s syndrome. It may occur either with or without the hand-grasp reflex, and it results from similar lesions.

Utilization behaviour. Patients with frontal lobe lesions may grasp and use everyday implements placed in front of them, without the behaviour being purposeful (Lhermitte 1983). Similar behaviour can also occur when incidental objects are encountered during other activities (Shallice et al. 1989). Utilization behaviour typically follows damage to the inferior frontal lobes.

Anatomical localization of the lesion responsible for muscle weakness is a common aim of neurological examination.

Surprisingly often patients do not complain of weakness itself, but rather of difficulty in using a limb for certain manoeuvres, or to walk. Particularly for the hand, an integrated motor–sensory organ, the early symptoms of difficulty in manipulating buttons or pens, or dropping things, can be remarkably similar in pure motor and pure sensory disorders. Furthermore, a patient who complains of weakness may be suffering in reality from numbness, disinclination to use a painful limb, incoordination, or even the aesthenic effects of cardiorespiratory disease. Patients may use the term ‘weakness’ when referring to other motor disorders which do not involve loss of raw muscle power, such as the bradykinesia of Parkinsonism (Section 40.3.1), or apraxia (Section 34.4.3) which is an inability to formulate and execute a complex movement despite intact functioning of the upper and lower motor neurones and muscles. Weakness accompanied by exhaustion may be a complaint of patients with chronic fatigue syndrome. However such patients are capable usually of exerting normal muscle strength, at least momentarily, if adequately encouraged.

Weakness of certain muscles often produces distinctive complaints. Proximal arm muscle weakness usually causes difficulty in doing the hair, hanging out washing, or lifting objects from high shelves. Patients rarely notice isolated weakness of small hand muscles, but sometimes complain of loss of grip, for instance in trying to unscrew bottle tops. Weakness of individual arm muscles can be distinctively symptomatic, such as difficulty in sliding the hand into a pocket with weakness of finger extension due to posterior interosseous nerve lesions, or difficulty in pushing the car gear lever forward with focal triceps weakness. Proximal leg muscle weakness, particularly if it affects quadriceps, leads to difficulty in climbing or descending stairs, standing out of the bath, or arising from sitting without using the arms. Distal leg muscle shows as ankle instability or foot drop, inability to scrunch up the toes into plantar flexion so as to keep loose shoes on, or to grip the edge of a swimming bath so as to dive.

The pattern of the weakness and the presence of other symptoms have considerable implications for localizing the lesion and determining the pathology:

Although patients are usually conscious that their proximal muscles, such as biceps or quadriceps, have wasted, often they are oblivious of advanced atrophy of distal muscles, such as the dorsal interossei.

Concurrent alteration of sphincter control should provoke prompt attempts to diagnose and treat the cause of associated limb weakness. Urgency of micturition with frequent voiding of small quantities, and sometimes incontinence, reflects the small, spastic irritable bladder typical of bilateral upper motor neurone lesions, particularly those affecting the spinal cord. Retention of urine, or sometimes dribbling incontinence, occurs in cauda equina disease. Erectile impotence is an early feature of either spinal cord or cauda equina disease. It is rare for anal sphincter control to be impaired in a manner that is characteristically diagnostic before obvious abnormalities of micturition or potency. Rapidly developing impairment of sphincter control implies compression of the spinal cord or cauda equina and requires emergency investigation.

If examination reveals muscle weakness, it is necessary to differentiate between lesions of the upper or lower motor neurones, the neuromuscular junction, or primary muscle disease. Also one should recognize that distinctive patterns of fluctuating weakness may be due to psychological factors, loss of kinaesthetic feedback, or pain. The key features to this differential diagnosis are the presence of wasting or fasciculations, the pattern of muscle power loss, changes in tone, tendon reflex abnormalities, plantar responses, and the topography of any associated sensory loss.

Wasting. This is typical of a denervated muscle, or one affected by primary muscle disease. Other causes are much rarer (Section 22.1.4). In polyneuropathy the wasting will be predominantly distal, in myopathy it is predominantly proximal. The wasting follows the distribution dictated by the innervation in individual peripheral nerve lesions (Sections 22.9 and 22.10) or spinal root lesions (Section 29.2). Wasting develops in any muscle which has been significantly denervated for 4–6 weeks. Muscle atrophy is not a feature of myasthenia.

Disuse atrophy. Disuse atrophy of muscles occurs in patients who have been recumbent for general medical reasons. It may affect muscles acting at a diseased joint, such as quadriceps with knee arthritis. Disuse atrophy can be distinguished from the wasting due to lower motor neurone or muscle diseases because the reflexes and tone are normal, and no fasciculations occur. But, most importantly, strength is relatively well-preserved in a disuse-atrophied muscle, whereas a pathologically wasted muscle will be profoundly weakened.

Pseudohypertrophy. It is an unusual physical sign in which a pathologically weakened muscle is hypertrophied. It is a particular sign in the calves in Duchenne muscular dystrophy (Section 24.2.1) and is a rare feature of polyneuropathies such as hereditary motor and sensory neuropathy (Section 21.4) and multifocal motor neuropathy (Section 21.11.3).

Fasciculations. These occur during subacute partial denervation of muscles, and are a particularly common feature of motor neurone disease. A fasciculation is a flickering contraction visible for a moment within the belly of a muscle. It represents simultaneous contraction of all the muscle fibres in the motor unit innervated by a single motor neurone (Fig. 2.38). Fasciculations are most easily visualized in those muscles with large motor units containing hundreds of muscle fibres, such as powerful proximal limb muscles, rather than in those muscles with small motor units that are used for fine motor control, such as the small hand muscles. However, electromyography will detect fasciculation discharges in such muscles even though they may be invisible to the naked eye. Fasciculations are only definitely pathological if associated with wasting or weakness of the muscle.

Tone. The tone of a muscle is the response it shows to passive stretching. A completely relaxed and resting muscle is not in a state of continuous partial contraction and is electrically silent; it has elasticity, but no tone. Therefore tone can be assessed only when the muscle is stretched or when it is maintaining posture against an applied force such as gravity. Postural tone is the state of partial contraction of certain muscles needed to maintain the posture of body parts.

In neurological practice, tone is usually assessed by moving a limb and observing the reaction which occurs in the muscles that are being stretched. The moment stretch begins, the muscle spindles give out afferent stimuli and reflex partial contraction results. The responses to momentary and to more prolonged stretching are different, the former being responsible for the tendon jerks, the latter eliciting more complex responses, often in the form of tonic contraction. Variations in the sensitivity of these reflexes account for the alterations in tone which occur as a result of nervous disease. Forceful continued contraction of a group of muscles, produced by biting or clenching one fist or pulling firmly with the flexed fingers of both hands, temporarily causes an increased flow of afferent impulses in the sensory fibres from the spindles. In turn this increases the rate of discharge in gamma motor neurones throughout the body, thus causing a generalized slight increase in sensitivity of the spindles to stretch. The tendon reflexes become brisker as the state of contraction of its intrafusal fibres is increased. This phenomenon, also known as reinforcement, or Jendrassik’s manoeuvre, is often used to elicit tendon reflexes which at first seem absent. In spasticity and in extrapyramidal rigidity, the ‘set’ of the spindles is continuously increased.

On stretching, the tone of a muscle may feel to be increased, termed spasticity or rigidity or hypertonia, or reduced, that is flaccidity or hypotonia. These alterations are of great value in neurological diagnosis. Muscle tone is normally regulated by reticulospinal fibres which accompany the pyramidal tract and exert an inhibitory effect upon the stretch reflex. This inhibition balances the background facilitatory impulses conveyed by the pontine reticulospinal and lateral vestibulospinal pathways. In turn these are influenced by multisynaptic reflex arcs traversing the cerebellum, basal ganglia, and brainstem. Dorsal reticulospinal fibres appear specifically to inhibit flexor lower limb reflexes. When lesions of the pyramidal and reticulospinal tracts release stretch reflexes from inhibition, the resultant increase in tone is initially associated with hyperactivity of dynamic fusimotor neurones. If such increased tone persists, termed spasticity, increased alpha-neurone discharge develops so that spasticity may be associated with increases in both gamma, dynamic fusimotor, and alpha-motor neurone activity.

Spasticity. This results from lesions of the pyramidal and often of the reticulospinal pathways. The stretch reflexes become hyperactive because of increased excitability of dynamic fusimotor neurones and alpha neurones which have been released from descending inhibitory influences. If the dorsal reticulospinal system is also damaged, there is disinhibition of afferent flexor reflex pathways. Release of such flexor reflexes may give flexor spasms in the lower limbs in response to stimulation of the legs, bladder, bowels, or skin. The ‘extensor’ plantar or Babinski reflex (Section 2.3.3) is one component of the primitive flexor withdrawal reflex. Usually in spasticity the affected limb shows increased resistance to passive stretching. This is particularly severe initially, but then ‘gives’ suddenly as the movement is continued. This sign is seen particularly well in the legs of a patient with a spastic paraplegia due to bilateral pyramidal tract disease and is known as ‘clasp-knife’ rigidity. Hyperactivity of tendon reflexes is often accompanied by clonus (Section 2.3.2) in which sustained stretch of muscle evokes repetitive contraction and relaxation due to reverberating activity in the hyperexcitable fusimotor system. Spasticity, in the form of sustained ankle clonus, or a pronator catch in the forearm is an incontrovertible sign of pyramidal tract disease.

Extrapyramidal rigidity. This differs from spasticity. It occurs in patients with disease of the basal ganglia such as Parkinsonism. The rigidity is uniform in degree throughout the entire range of passive movement, known as ‘plastic’ or ‘leadpipe’ rigidity. If tremor is superimposed it is referred to as ‘cogwheel’ rigidity. In dystonia there is simultaneous contraction of agonists and antagonists so that the reciprocal inhibition of antagonists is impaired and there is increased alpha-neurone discharge. As a consequence parts of the body become virtually fixed in an abnormal posture.

Decerebrate rigidity. This occurs in animals when a transverse lesion across the midbrain at about the level of the superior colliculus or red nucleus releases the brainstem, cerebellum, and spinal cord from cerebral control. Strong continuous contraction in extensor groups of muscles occurs so that an animal placed upright with support will remain standing, but if pushed over cannot rise. This contraction may occur intermittently, leading to episodes of decerebrate posturing. This predominance of extensor activity is mediated by the reticulospinal and vestibulospinal pathways, and is aroused by a further lesion induced at the level of the vestibular nuclei. In man, a similar state may accompany severe midbrain lesions which usually cause loss of consciousness also. In such a case all four limbs are rigidly extended, the back is arched, and there may be neck retraction. Thus the patient, if lying supine, is virtually supported by the back of the head and the heels, a posture known as opisthotonos. The arching of the back can be increased by any sensory stimulus and there is striking resistance to any attempt at flexing the limbs passively. Tonic neck reflexes can usually be elicited; turning the head to one side gives extension of the limbs on that side and flexion on the other.

Decorticate rigidity. This usually occurs with lesions of the cerebral white matter, or thalamus and internal capsule. The arm is flexed and adducted whilst the leg is stiffly extended, a posture similar to that of chronic spastic hemiplegia.

Flaccidity. Flaccidity, or hypotonia, is a reduction in tone. It may be due to cerebral or spinal shock resulting from acute and extensive brain or spinal cord lesions which transiently suppress all motor reflex activity. It is a common manifestation of cerebellar disease, associated with diminished gamma efferent activity. It also occurs whenever a lesion of the afferent or efferent pathway interrupts the spinal reflex arc. In severe hypotonia, as in patients with total flaccid paralysis, all resistance to passive stretch is lost and the limbs are limp and flail-like. Lesser degrees of hypotonia in the upper limbs can be elicited by asking the patient to hold out their arms horizontally. The forearms are then tapped briskly. When one limb is hypotonic, the recoil is slowed and the arm oscillates through a wider range as though ‘underdamped’. If a hypotonic patient is asked to raise their arms above their head with the palms facing forwards, the palm of a hypotonic limb is seen to be externally rotated. In practice hypotonia has limited diagnostic usefulness, being overshadowed by more prominent features of cerebellar disease, such as dysmetria, or of spinal reflex arc disease, such as areflexia.

Pattern of weakness. Severe upper motor neurone lesions cause complete paralysis of the limb. Less severe upper motor neurone lesions cause distinctive patterns of weakness. In the arm, extensor muscles are most markedly affected: deltoid, triceps, finger, and wrist extensors, and the dorsal interossei. In the leg, hip flexion due to iliopsoas is usually affected earliest, and hamstring and ankle dorsiflexion weakness is often pronounced. As a general rule, weakness is symmetrically distributed distally in polyneuropathy and proximally in myopathies. In mononeuropathy or spinal nerve root lesions, the pattern of weakness follows the innervation pattern.

Tendon reflexes. Tendon reflexes (Section 2.3.2) are crucial to differentiating between upper and lower motor neurone disorders, being brisk in the former, and often absent or hypoactive in the latter. Although areflexia is common in lesions affecting the lower motor neurone reflex arc, this is mainly due to coexisting involvement of the muscle spindle sensory afferent fibres within peripheral nerves or roots. For example, the tendon reflexes are preserved even with quite advanced muscle denervation in motor neurone disease, because the sensory afferent pathways are not affected. Tendon reflexes are preserved in primary muscle disease, except when chronic fibrosis of the muscle or damage to the muscle spindle have occurred. Areflexia occurs in the rare disorder of Eaton–Lambert myasthenic syndrome.

There are only three objective conclusions with clear pathological implications that can be made about any individual tendon reflex viewed alone. Either it is normal, or it is absent despite reinforcement, or it is pathologically brisk in that one or more clonic beats occur during elicitation (Section 2.3.2). A normal reflex may vary from being only obtainable with reinforcement, to being quite brisk in anxious individuals. It is often valuable to compare the briskness of reflexes in different regions of the body. For instance upper motor neurone lesions will produce brisker tendon reflexes on the side of a hemiplegia, or in the legs compared to the arms in thoracic spinal cord lesions. A focally hypoactive reflex occurs in the territory of a diseased spinal nerve root or peripheral nerve. The ankle jerks may be markedly hypoactive compared to the knee and arm reflexes in polyneuropathy.

An extensor plantar reflex or Babinski response (Section 2.3.3) represents incontrovertible evidence of an upper motor neurone lesion. Circumstantial evidence of an upper motor neurone lesion may be provided by absent superficial abdominal reflexes (Section 2.3.3).

Unilateral cerebral hemisphere lesions cause contralateral hemiparesis, often including the lower facial musculature. The forehead, tongue, and bulbar musculature will be spared unless an upper motor neurone lesion is bilateral. Focal lesions affecting only a portion of the motor cortex produce paralysis of the body part represented by that point of the homunculus (Fig. 2.39). An example is the ‘cortical hand’ in which weakness affects all movement of the hand, including finger extension, flexion, and abduction. Complete hemiplegia commonly results from small lesions in the internal capsule, where the corticospinal tract fibres are crowded together. Focal motor, or Jacksonian epileptic attacks often picking out only one side of the mouth, or the finger and thumb, or the great toe, are typical of irritative lesions of the motor cortex. Predominantly proximal or limb girdle patterns of hemiparesis result from high motor cortex lesions and often result from ischaemia in the watershed between middle and anterior cerebral artery territories. Cortical or subcortical lesions often cause an associated cognitive deficit.

By contrast a lesion deep in the white matter, particularly one affecting the internal capsule, usually produces dense hemiplegia without cognitive loss. Milder hemiparesis with prominent dysarthria or ataxia points to lacunar infarction in the posterior limb of the internal capsule. If a hemiparesis is associated with a cranial nerve lesion on the opposite side, this so-called ‘alternating hemiplegia’ signifies a brainstem location for the lesion.

The clue to a brainstem lesion causing weakness is an associated disorder of a cranial nerve (Fig. 2.40), or of the intrinsic pathways of the brainstem such as the cerebellar or vestibular connections. The majority of lesions of the brainstem are due to ischaemia, with demyelination, haemorrhage, or tumour deposits also occurring. They are often patchy and unstereotyped in their location and effects. Pyramidal tract damage in the brainstem can be either unilateral or bilateral depending upon the topography of the lesion; asymmetric bilateral lesions are commonest. Because the pyramidal tract decussates in the lower medulla, all brainstem lesions above this level will produce contralateral weakness. Lesions of the cerebellum or its peduncles are often associated with damage to the adjacent brainstem. Cerebellar hemisphere damage causes ipsilateral dysmetria or ataxia, and hypotonicity. Midline damage to the cerebellar vermis causes gait ataxia, truncal ataxia, dysarthria, and slowed and irregular tongue movements. Lesions of the flocculonodular lobe, or vestibulocerebellum produce various eye movement abnormalities, including skew deviation and head tilt, inaccurate saccades, square-wave jerks, loss of smooth pursuit, and opsoclonus.

. These cause various syndromes associated with weakness if the cerebral peduncles are involved (Liu et al. 1992; Bogousslavsky et al. 1994; Silverman et al. 1995). Posterior cerebral artery penetrating branch ischaemic vascular lesions are the commonest cause:

Lesions of the central and posterior midbrain produce various eye movement abnormalities especially affecting vertical eye movements, pupil reactions, and altered eyelid movements.

. These are notably variable in their effects. These include dysarthria, contralateral ataxia, trigeminal (V), abducens (VI), facial (VII), or auditory (VIII) nerve lesions (Fig. 2.42). Complex eye movement disorders are common too; ipsilateral gaze palsy, internuclear ophthalmoplegia, one-and-a-half syndrome, and skew deviation (Section 13.2.2). Owing to the higher decussation of the corticofacial fibres, a unilateral corticospinal lesion in the pons does not cause weakness of the opposite side of the face, but only of the opposite limbs. But the lesion may also involve the facial nucleus or the intrapontine fibres of the facial nerve on the same side, thus causing one form of ‘crossed hemiplegia’. Different forms of this have been described (Silverman et al. 1995):

. These are more likely to cause weakness if medially situated. The lower the medullary lesion the more likely is the involvement of pyramidal decussation. A medial medullary lesion produces an ipsilateral hypoglossal (XII) nerve palsy and contralateral hemiparesis and sensory loss affecting vibration sense and joint position (Fig. 2.43). More lateral medullary lesions cause the Wallenberg syndrome of ataxia, vertigo, nystagmus, ipsilateral trigeminal (V) territory sensory loss, Horner’s syndrome, nystagmus, dysphagia loss of gag reflex (IX and X cranial nerves), and contralateral spinothalamic tract damage with pain and temperature loss below the face (Sacco et al. 1993).

The distinctive clinical features of a spinal cord lesion are paralysis below the level of the lesion with signs of upper motor neurone damage, impaired sphincter control, and a sensory level. It should be noted that the spinal cord is shorter than the vertebral column and thus the segmental localization of a lesion will correspond to a higher vertebral level (Fig. 2.44). If the dorsal columns are substantially affected, there will be gait ataxia, Rombergism, and altered joint position and vibration sensations in the feet. At the level of the lesion, the tendon reflex arc may be interrupted at the level of the lesion and muscle wasting and weakness may reflect anterior horn cell destruction.

Lower motor neurone lesions produce patterns of weakness which reflect pathology localized to the anterior horn cells, a spinal nerve root, or an individual peripheral nerve.

. The myotomal pattern of weakness occurring with spinal nerve root lesion is usually accompanied by dermatomally distributed sensory disturbance and loss of the tendon reflex subserved by that segment. In reality most muscles receive spinal root innervation from at least two segments, and single nerve root lesions usually produce relatively mild degrees of weakness (Table 2.8). Furthermore there is some variation in the exact spinal segment which makes the major contribution to a muscle, depending upon whether the brachial or lumbosacral plexus is pre-fixed or post-fixed (Section 22.5.1).

. A detailed account of the muscles innervated by each peripheral nerve of the arm (Section 22.9) and leg (Section 22.10) is given elsewhere. Polyneuropathy produces weakness which is symmetrical and predominantly distally located. Additional weakness of proximal muscles may occur in acquired demyelinating polyneuropathies affecting proximal nerve segments and roots. Lesions of the brachial or lumbosacral plexus produce patterns of weakness, and sensory and reflex loss, which cannot be accounted for by lesions either of an individual spinal nerve root or an individual peripheral nerve (Sections 22.5 and 22.6).

. This disease characteristically affects the proximal limb muscles symmetrically. Various forms of muscular dystrophy (Section 24.2) pick out specific muscle groups, facioscapulolumeral, and oculopharyngeal dystrophies being examples. Myasthenia gravis (Section 24.10.1) may present with proximal limb muscle weakness, with pharyngeal and palatal weakness, or with ptosis and eye movement abnormalities; characteristically muscle bulk will be preserved, reflexes are normal, and fatigability is demonstrable. Proximal muscle weakness also occurs in the Lambert–Eaton myasthenic syndrome (Section 24.10.2), but there are associated autonomic features such as dry mouth. Furthermore, the tendon reflexes, although initially absent, show post-tetanic potentiation in which a reflex reappears when retested after sustained maximal contraction of its muscle. Neck extensor muscle weakness is uncommon and occurs in myasthenia, motor neurone diseases, myotonic dystrophy, and some myopathies. Muscle and neuromuscular junction diseases do not produce sensory disturbance.

Not uncommonly patients demonstrate momentarily fluctuating, inconsistent, or collapsing patterns of weakness. There are three possible causes of this: loss of sensory feedback, pain or, most usually, psychological factors. Fluctuating weakness due to loss of kinaesthetic feedback usually affects the hand, and is often associated with pseudoathetosis. Normality of underlying muscle power can be demonstrated by asking the patient to look at their hand so as to provide feedback whilst making a simple elementary movement such as abducting the index finger. This will reverse weakness which had been apparent during a more complex movement such as spreading all the fingers apart. Collapsing weakness due to pain in a joint may be accompanied by complaints of discomfort; the raw power of the muscles can be assessed by instructing the patient to ‘push as hard as you can just for a moment when I count to three’. Psychologically determined weakness (Section 4.8.1) fluctuates, is inconsistent, may be improved temporarily by firm encouragement, and is discordant with obviously better use of the limb during natural activities such as dressing. If due to malingering, it may be associated with theatrical grunting and sighing in a charade of effort, and the collapsing element may occur more from the trunk than from the limb itself.

Patients express their symptoms of somatosensory dysfunction in a multitude of ways and only careful enquiry by the neurologist will determine their likely pathophysiological relevance.

Numbness. This is a term that is used confusingly. Most doctors mean by it ‘a loss of sensation’, but many patients really mean weakness or clumsiness. It is less ambiguous to ask about ‘deadness [or loss] of skin sensation’. Polyneuropathy produces numbness in a glove and stocking distribution. When patients describe numbness and/or pins or needles extending on to the trunk, it is most commonly due to myelitis, an inflammation of the spinal cord, which may occur as part of multiple sclerosis. Some patients with numb feet describe a feeling of walking on cotton wool. Those with numb hands may feel as though they are touching things through a plastic bag.

Paraesthesiae. These are spontaneous abnormal sensations, most usually described as ‘pins and needles’. They may be physiological, especially during hyperventilation, but in such cases they are generalized, especially periorally, and only intermittent. Continuous paraesthesiae are an important indicator of acquired, rather than congenital disease of the nervous system. They are particularly likely in idiopathic demyelinating polyneuropathy, and less common in lesions of central sensory pathways. Attacks of focal paraesthesiae can occur in focal epilepsy of the sensory cortex. Focal paraesthesiae, occurring intermittently, are common in compressive mononeuropathy, a common example being the finger paraesthesiae at night and after hand usage in carpal tunnel syndrome.

Dysaesthesiae. These are unpleasant distorted sensations resulting from actual sensory stimuli. Usually they occur in focal peripheral nerve damage or polyneuropathies that involve axonal degeneration.

Spontaneous pain. This can occur in association with paraesthesiae in peripheral nerve disorders. It is a particular and early feature in the sensory territory of a nerve affected by vasculitis. Lancinating pain radiating in a dermatomal distribution down a limb, like an electric shock, suggests spinal nerve root compression by prolapsed intervertebral disc. Painful disorders of an internal viscus, joint, or muscle may be referred to an area of skin either overlying or remote to the abnormality. Spontaneous pain in the limbs, trunk, or face can arise from posterior thalamic lesions and has a particularly unpleasant burning character, often with ‘tearing’ or ‘grinding’ qualities. Similar sensations of continuous burning, warmth, or cold may result from a spinothalamic tract lesion, but are clearly localized to within an area of altered skin sensation. Spontaneous pain occurs in causalgia and complex regional pain syndrome (Section 17.5).

Analgesia and thermoanaesthesia. Reduced ability to feel pain and temperature sensations occurs in peripheral neuropathies affecting unmyelinated and small myelinated fibres and in lesions of the spinothalamic tract and posterior thalamus, including syringomyelia. Painless burns, or unfelt wounds may occur in the analgesic area.

Lhermitte’s symptom. It consists of an electric shock or strong paraesthesiae radiating down the trunk, and often into the limbs, on sudden flexion of the neck. It is particularly common in myelitis due to multiple sclerosis, and also occurs in cervical spondylitic myelopathy, vitamin B₁₂ deficiency, and some sensory neuropathies involving both the central and peripheral axons of the dorsal root ganglia.

Tight bands and size distortions. Tight bands and size distortions, such as feeling that the toes are swollen, are abnormal sensations occurring in the fingers and feet of patients with acquired demyelinating polyneuropathy and lesions of the dorsal columns in the spinal cord.

Clumsiness and Rombergism. These are due to loss of kinaesthetic feedback via large myelinated peripheral nerve sensory fibres or the dorsal column-medial lemniscus system. Hand clumsiness particularly affects the complex motor–sensory integration involved in activities such as doing up buttons or underwear clips, particularly when the eyes cannot monitor the action. ‘Dropping things’ may be an associated complaint, however this symptom in isolation rarely denotes disease. Loss of joint position sense from the legs causes gait unsteadiness. This is particularly noticeable when the patient tries to walk in the dark or close their eyes in the shower and is known as Rombergism.

Astereognosis. This occurs in patients with parietal lobe lesions. They may complain of being unable to identify coins manually in their pocket or with their eyes closed.

Many complex and time-consuming methods have been described for semiquantitative assessment of different sensory modalities. In most clinical situations these make little or no extra contribution to diagnosis over and above what can be achieved by simple testing of superficial skin sensation using the fingertips or a pin, by routine testing of vibration, and joint position sense, and by Romberg’s test. What is important is to examine each patient with a clear strategy for resolving the diagnostic hypotheses. The neurologist must instruct the patient clearly in how to respond to stimuli, and must present these stimuli unambiguously. In general, superficial sensation is assessed by taking the patients’ view as to whether the stimulus ‘feels normal’. By contrast, joint position and vibration sensations can be assessed more objectively by using the principles of blinding, in which the patients’ eyes are closed, of forced choice in which the patient has to respond ‘up’ or ‘down’ or of time-locked response in which the patient has to say ‘now’ immediately the tuning fork stops vibrating.

Superficial skin sensation. The boundary of an area of sensory loss is mapped best by starting within the numb area and working outwards until the normal area is reached. Traditionally, an unused pin or a wisp of cotton wool are recommended. However, neither patients nor doctors are familiar with the thresholds for such sensations on different parts of the body. This can make it difficult for the patient to report whether the quality of sensation is altered, unless there is a clear boundary; it is rare for skin sensation to be completely lost. However, everyone is familiar with the feeling of fingertips on every part of their body skin and patients can tell you instantly whether the ‘finger feels normal’ when you lightly stroke any patch of skin. Furthermore, the examiner can use both his forefingers to present simultaneously comparable stimuli to the two sides of the patient’s body. Thus the use of fingertip stroking is recommended for routine testing of superficial sensation and will reveal spinothalamic abnormalities affecting tickle or dorsal column pathway abnormalities impairing pressure sensation. Only rarely it is necessary to test temperature sensation; if so the cold metal of a tuning fork generally provides a sufficient stimulus. A tube of warm water can be used to test warm sensation in those rare occasions when it is necessary to test the unmyelinated thermal fibres in isolation. Occasionally superficial sensory testing produces hyperpathia, in which any background loss of sensation is overshadowed by an abnormal, and sometimes unpleasant, additional quality to the sensory experience. In such situations it can be difficult to determine which is the abnormal side, because of this apparent heightening of sensation.

Vibration sensation. This should be tested using a 128-Hz tuning fork struck in such a way that it does not produce audible high frequency harmonics that can be heard rather than felt by the patient. Place it on the patient’s sternum and ask ‘can you feel it buzzing?’ Then move it to the tip of the great toe, or a finger, and ask the patient to ‘close your eyes, and tell me as soon as it stops buzzing’. The patient should respond promptly when the examiner stops the buzzing prongs with the fingers of their other hand (Fig. 2.45).

If vibration sense is absent from the toes, testing should be repeated more proximally on the ankle malleolus, tibial bone, knee, anterior superior iliac crest, and finally the rib cage. Vibration sense abnormalities usually mean there is a polyneuropathy affecting large myelinated sensory fibres, or a spinal cord lesion. Vibration sense is not affected by a lesion restricted to the somatosensory cerebral cortex. Vibration sense is lost from the lower legs of many elderly people as a natural ageing phenomenon.

Joint position sensation. With the patient’s eyes open, move the great toe up and then down, showing to the patient ‘this is up and this is down’. Then ask the patient to close their eyes and identify small movements (Fig. 2.46). The distal interphalangeal joints of the fingers can be tested similarly. Usually joint position sensation is lost in similar conditions to vibration sensation. It is particularly likely to be abnormal in patients with sensory ataxia or Rombergism. But, unlike vibration sensation, joint position perception is also lost in lesions of the somatosensory cortex.

Romberg’s test and pseudoathetosis. These provide evidence of loss of kinaesthetic sensory feedback from the legs and hands respectively. They are abnormal in disorders of large myelinated sensory peripheral nerve fibres and of the dorsal column —medial lemniscus system. Romberg’s test has been described previously (Section 2.2.2). Pseudoathetosis is demonstrated by asking the patient to close their eyes and extend their hands and fingers in front of them. The fingers and wrist ‘wander’ slowly in random directions, of which the patient is unaware (Fig. 2.47).

Sensory inattention. This occurs with lesions of the parietal lobe insufficient to cause gross cortical sensory loss, but sufficient to cause perceptual rivalry between the two sides of the body. The patient is able to appreciate stimuli when applied simultaneously to both sides of the body. However, when two similar stimuli are applied simultaneously to the same skin area on each side, one side will be ignored. This finding implies a disturbance in function of the sensory area of the contralateral cerebral cortex. The phenomenon does not occur if the interval between the two contacts is more than 3 s (Critchley 1953).

Astereognosis. This is another sign which may occur in patients with lesions of the arm representation of the opposite sensory cortex. They are unable to appreciate the form and texture of objects placed in the hand with the eyes closed. Correctly this should be called stereoanaesthesia, but the term astereognosis is more often used. Strictly speaking, the latter term should be reserved for failure to recognize objects, such as coins, when the primary sensory modalities are intact. This is an agnosic defect, due to a disorder of sensory association and akin to the other more complex disorders of parietal lobe function.

Two-point discrimination abnormalities and graphaesthesia. These occur in patients with a lesion of the sensory cortex. The threshold for two-point discrimination is much greater on the abnormal than on the normal side, and there may be inability to recognize figures or letters drawn on the skin. Sensory stimuli are also incorrectly localized on the affected side.

Polyneuropathy. A distal stocking, and later glove, distribution of diminished skin sensation is typical of polyneuropathy (Fig. 2.48). Usually the border between normal and reduced sensation gradually changes over some centimetres rather than being abrupt.

Focal neuropathy. The pattern of superficial sensory loss corresponds to the territory of innervation of the affected peripheral nerve (Fig. 2.49). The border between normal and reduced sensation is reasonably well-defined although not abrupt. Usually the area of sensory loss for touch is larger than that for pain or temperature.

Spinal root lesions. These cause loss of superficial sensation in the corresponding dermatome (Fig. 2.50). In the earlier stages of a single root lesion, tingling or pain in the dermatome may occur without demonstrable superficial sensory loss, because there is some overlap of innervation from adjacent roots.

Spinal cord lesions. These produce patterns and modalities of sensory loss which depend upon the level of the lesion, the degree of damage to the spinothalamic tracts in the arterolateral cord, which carry pain and temperature sensations from the opposite side (Fig. 2.51A), and to the dorsal columns, which carry vibration and joint position sensations ipsilaterally (Fig. 2.51B).

Spinal cord compression. Spinal cord compression or transection causes reduction or loss of all modalities of sensation below the dermatomal level corresponding to the segment of the transection (Fig. 2.52). There may be a zone of hyperasthesia in the dermatome immediately above the lesion. External compression of the spinal cord often produces early loss of pain and temperature sensation in the sacral dermatomes, because the fibres subserving these lowest segments travel most superficially within the spinothalamic tracts.

Intramedullary spinal cord lesions. These initially affect the decussating spinothalamic tracts within the spinal cord at the level of the lesion (Fig. 2.53A). This produces a ‘cape-like’ pattern of suspended sensory loss affecting pain and temperature sensations, but not touch or kinaesthesia (Fig. 2.53B); a pattern typical of syringomyelia (Section 28.5.15). Expanding intramedullary lesions within the spinal cord usually spare pain sensation from the sacral dermatomes, because these fibres travel the most superficially in the spinothalamic tracts.

The Brown–Séquard syndrome. This syndrome follows damage to one half of the spinal cord (Fig. 2.54). Below the level of the lesion there is ipsilateral weakness and loss of vibration and joint position sensations and contralateral loss of pain and temperature sensations. Elements of light touch sensation may be preserved bilaterally since it is a composite sensation involving both spinothalamic and dorsal column pathways.

Myelitis. This can produce relatively restricted patterns of sensory loss which characteristically extend onto the trunk, may spare the hand or foot, and may be strictly unilateral (Fig. 2.55). Depending upon the location of the myelitis within the spinal cord, spinothalamic and dorsal column sensations may be differentially affected. Sometimes a Brown–Séquard syndrome is encountered if only one half of the spinal cord is involved. Severe forms of myelitis produce impairment of all modalities of sensation below the level of the lesion.

Foramen magnum. Foramen magnum and high cervical spinal cord compressive lesions can cause loss of vibration sense limited to the arms and upper ribcage if the lesion affects the decussation of the medial lemniscus. External compressive lesions at the foramen magnum may produce symptoms of ‘rotating sensory loss’ in which sensory symptoms start in one limb, for instance a foot, and later rotate to the other foot and the hand on the same side, before eventually reaching the remaining hand.

Brainstem lesions. These lesions produce sensory abnormalities interpretable on an anatomical basis. Dissociated sensory loss in the face can result from syringobulbia, due to involvement of the descending fibres from the trigeminal nerve. Lesions of the pons and medulla can give facial sensory impairment on one side, due to a lesion of the trigeminal nucleus, with hemianaesthesia and/or hemianalgesia of the trunk and limbs on the opposite side due to involvement of ascending sensory tracts. A lesion of the upper pons or midbrain can give complete contralateral sensory loss. An infarct in the midbrain involving the third nerve nucleus, red nucleus, and medial lemniscus may give a unilateral third nerve palsy with contralateral static tremor, hemianaesthesia known as Benedikt’s syndrome (Section 2.4.4), and hemianalgesia. More often such unilateral sensory loss is dissociated, involving only pain and temperature sensation, owing to selective involvement of ascending fibres of the spinothalamic tract, as in the lateral medullary Wallenberg’s syndrome due to vertebral or posterior inferior cerebellar artery thrombosis (Section 2.4.4). Occasionally in such cases there is a sensory level on the trunk on the affected side (Matsumoto et al. 1988).

Thalamic lesions. These lesions can produce patchy contralateral hemianaesthesia and hemianalgesia. Often there is also spontaneous pain of a peculiar, unpleasant, and disturbing nature on the partially anaesthetic side. Fortunately, this thalamic pain syndrome, usually resulting from infarction, is rare. The discomfort most often affects the face, arm, and foot. Surprisingly, extensive thalamic lesions such as neoplasms usually produce comparatively little sensory loss. Sometimes more anterior thalamic infarcts impair appreciation of posture, passive movement, light touch, and tactile discrimination with little effect upon pain and thermal sensibility. Sharply defined hemisensory loss is an unusual phenomenon, occurring only in lesions of the thalamus or immediately adjacent internal capsule.

Cortical sensory loss. Lesions restricted to the somatosensory cortex characteristically impair joint position sensation and two-point discrimination, whilst vibration sense is preserved (Gilman 2002). Graphaesthesia is common in cortical lesions and best tested by asking the patient, with closed eyes, to identify numbers inscribed with a stick on the palm of their hand.

Psychologically determined sensory loss. This type of loss (Section 4.8.2) often has implausibly sharply defined boundaries, which may shift in position, and which do not obey anatomical distributions.

When a patient complains of pain, the neurologist must determine whether it is a neuropathic pain, due to disease directly affecting the nervous system, rather than a musculoskeletal pain. Local tenderness, or discomfort on passively moving a joint, are signs suggestive of disease or strain injuries affecting bones, joints, tendon, muscles, or other organs. Localization of the painful area is diagnostically helpful in spinal root, and cranial or peripheral nerve lesions. However, pain may be imprecisely localized in complex regional pain syndrome or cerebral lesions.

Referred pain. Painful lesions of the muscles or viscera sometimes give pain perceived to be in the overlying skin, or in a remote cutaneous area. Such painful sensations seem not to be coming from the viscus involved but from the body surface. But this apparent error in localization, giving what is alternatively called pseudovisceral pain, is systematically related to the dermatomes innervated by those dorsal roots that supply the diseased viscus. Thus afferent pain fibres from the myocardium enter the T1-5 dorsal root ganglia and myocardial pain is referred to the anterior chest wall and down the inner aspect of the left or of both arms. Similarly, pain fibres from the diaphragm travel in the phrenic nerve (C3-4) so that diaphragmatic pain is often referred to the C3 and 4 dermatomes in the neck and shoulder.

Cutaneous nerve lesions. These lesions produce pain which is prickly, associated with paraesthesiae and often dysaesthetic to the extent that patients avoid contact or tight clothing. Despite this apparent increase in sensitivity, background thresholds for sensation will be impaired if, for instance, a wisp of cotton is used to compare the two sides.

Spinal nerve root. Spinal nerve root pain is worsened by stretching movements such as the straight leg-raising test in sciatica, by other movements, or by sneezing, all of which increase the degree of compression. The pain radiates in a dermatomal distribution and may be out of all proportion to the degree of demonstrable sensory or motor loss.

Spinal cord and brainstem. These lesions affecting the spinothalamic tracts (Section 17.2) occasionally produce a burning and poorly localized pain associated with demonstrable impairment of pain and temperature sensations.

Thalamic pain. Also known as the Dejerine–Roussy syndrome, this results from lesions within, or just behind, the posterior thalamamus. Appreciation of sensory stimuli is impaired on the contralateral body, but stimuli such as pain, cold, and touch induce marked pain (Section 17.2).

Cortical lesions. These produce pain only rarely. A pseudothalamic burning pain syndrome can result from damage to the deep part of the Sylvian cortex and may be associated with hemiplegia.

Walking is a complex motor performance which can be affected by a wide variety of different diseases, and which undergoes natural change with aging. Everybody’s gait differs in a characteristic way; one can normally recognize an acquaintance by her walk even when too far away to see her face. Yet mammals generate the rhythmic muscle activities necessary for gait by specialized spinal cord circuits, known as central pattern generators for locomotion (Duysens et al. 2000). These locomotor-generating circuits receive important feedback first concerning loading and unloading of limbs to control the onset of limb swinging, and second of hip position to initiate limb swing. Even when these circuits are disconnected from forebrain control, as in much spinal cord injury, robotic devices coupled with a treadmill can be used to retrain a degree of locomotor ability (Dietz et al. 2002).

Non-neurological disorders, such as hip joint disease are important in the differential diagnoses of gait abnormalities. Particularly in the elderly, gait disorders may be multifactorial, for instance involving both a neurological disease such as Parkinsonism, the mild gait apraxia of natural senescence, and degenerative arthritis of the hip joints. Gait disorders are conveniently classified hierarchically into low-, middle-, and high-level gait disorders, reflecting the level of the nervous system lesion (Nutt et al. 1993). Psychogenic gait disorders are immensely variable (Section 4.8.4) and usually do not result in injury if falls occur.

Normal walking requires equilibrium, so as to maintain a balanced upright posture, coupled with locomotion (Nutt et al. 1993). Equilibrium involves various righting reflexes for assumption of the upright posture, antigravity supporting reactions to maintain that posture, postural reflexes to maintain balance during weight transfers, rescue reactions to avoid falling if postural reflexes prove inadequate, and protective reactions if all else fails and falling starts. Locomotion involves gait ignition mechanisms followed by rhythmic stepping. Unsurprisingly, this complex motor task is controlled by many different brain regions. The brainstem appears to have a particular role in righting reflexes, synergizing proximal and trunk muscles to maintain balance, and in gait ignition. The basal ganglia are not involved in the rhythm of walking, but lesions impair postural responses and gait ignition. Chronic cerebellar lesions do not eliminate equilibrium reactions or alter their pattern, but do alter the scaling of responses, generally rendering them too large. The frontal cortex is important for postural responses, and cortical mechanisms are responsible for executive control of whether, when, where, and how fast to walk.

Bedside diagnosis of disordered gait requires analysis of how various features of the patient’s walking differ from normal:

Separation of the feet. Normally the feet cross within a few centimetres of each other during a stride leading to occasional scuffs on the inner heel of shoes. In normal efficient gait, the feet loop slightly round each other so that the footprints of the two feet lie almost in a straight line (Fig. 2.56A). A wide-based gait occurs in cerebellar and sensory ataxias (Fig. 2.56B), probably as a compensation to preserve balance and so the feet do not catch on one another when crossing on dysmetric strides. A slightly wide-based gait can occur too in apraxia (Fig. 2.56D) or Parkinson’s disease (Fig. 2.56C), but the stride length is short in those conditions. The feet cross in wide arcs in spastic gaits, because the stiffly extended leg and foot cannot be slightly flexed in the normal manner so as to clear the ground during a stride (Fig. 2.56F).

Stride length. People normally hit their standard stride length with their first step and it varies little thereafter (Fig. 2.56A). In ataxia the stride length varies, elongated strides may lead to overbalancing behind a foot which has landed too far ahead, or sometimes shortening causes a stumble over a foot which has gone down too soon (Fig. 2.56B). Shortened, shuffling strides occur in Parkinson’s disease. The gait ignition failure of more advanced Parkinson’s disease leads to a hesitant start to a walk, and acceleration associated with increasing stride length (Fig. 2.56C). Gait apraxias, or frontal gait disorders, cause short striding of constant length from the start, a marche à petits pas (Fig. 2.56D). Such patients have particular difficulty in turning corners, being unable to spin round at a single step, and sometimes getting their feet hopelessly tangled up, or having to walk around corners. (Fig. 2.56D).

Foot drop. Foot drop interferes with normal gait because it prevents the patient from swinging their striding leg through underneath their body without it catching on the ground. Stiffly held foot drops usually result from spasticity, less often from dystonia. Walking with a spastic leg requires laborious circumduction of the stiffly extended leg and foot in a wide lateral arc so as to avoid catching the toe (Fig. 2.56E), a compensatory manoeuvre required bilaterally in spastic paraparesis (Fig. 2.56F). This scissors gait is exhaustingly inefficient and throws unnatural stresses upon the low back and pelvic girdle which can result in further gait deterioration due to secondary degenerative arthritis. Circumduction of the striding leg is not so marked in dystonic foot drop because usually the patient retains the ability to lift the foot by flexing the leg at the hip and knee and raise the pelvis whilst striding. Floppy foot drops occur with lower motor neurone weakness of tibialis anterior due to motor neurone, spinal root, or peripheral nerve diseases. In order to swing the dangling foot through during a stride without catching it on the ground, the hip and knee are flexed exaggeratedly, with lifting of the pelvis, and the leg is kicked out in front at the end of the stride before being stamped down onto the ground.

Pelvic tilt. Normally the pelvis remains horizontal, or even elevates slightly, when the weight is taken by only one leg during a stride. This stabilization of pelvic height is achieved principally by gluteus medius contraction on the weight-bearing side. Gluteal muscle weakness will cause the pelvis to flop downwards towards the side on which the leg has been lifted to stride out, giving the gait a waddling appearance. This is the typical gait of proximal myopathy.

Arm swing. Normally balance is assisted by swinging the arm opposite to the striding leg, familiar in its most exaggerated form in military marching. Loss of arm swing is characteristic of Parkinson’s disease, occurring unilaterally in early disease. The physician should not make the patient aware that it is their arm swing which is of particular interest. However, later in the examination it should be ensured that the shoulder is not immobile simply due to joint disease. Arm swing of irregular amplitude, sometimes of a slightly wild nature, may occur in ataxia, in part as a balance compensatory mechanism.

Rising and standing. Rising and standing depend upon righting reflexes and supporting responses respectively. Withstanding pushed displacements demonstrates reactive postural responses. The response to larger displacement pushes, or spontaneous imbalances, demonstrates the integrity of rescue and protective reactions, but should be tested with care to avoid injury.

Central nervous system equilibrium reactions and locomotor generation are well able to compensate for the gait disorder resulting from disorders of the musculoskeletal or peripheral motor and sensory systems. The musculoskeletal gait disorders of limping due to arthritis, prosthetic limbs, waddling due to proximal muscle weakness, and foot drop due to lower motor neurone disorders are easy to recognize. Ataxia due to loss of proprioceptive, visual, or vestibular feedback usually lead to cautious locomotion with efficient compensatory maintenance of equilibrium. Such conditions produce a major threat to independent walking when associated with other middle- or high-level disorders of gait which impair these compensatory mechanisms.

The mechanisms for maintaining equilibrium and implementing locomotor control by the cerebral cortex are distorted by disorders of the pyramidal tract, cerebellum, and basal ganglia, and superimposed movement disorders such as chorea or dystonia. For instance cerebellar ataxia causes dysmetria of striding and postural adjustment mechanisms. Early Parkinson’s disease and pyramidal tract lesions impair postural responses. It is only when very severe, or conjoined with another gait disorder, that walking ability is completely abolished by middle-level disorders.

These are the least well-understood gait disorders and have attracted varying and confusing descriptive labels. They are defined as disorders of those high level processes, presumably cortical and subcortical in the frontal lobes, responsible for selecting postural responses and locomotor behaviour suitable for the particular circumstance of the patient at that time. By definition they cannot be explained by middle-level gait disorders. In general neurological practice they are often called gait apraxia, marche à petits pas, and sometimes atherosclerotic Parkinsonism, but the precise manifestations and disabilities clearly vary widely between patients. These disorders usually occur in the elderly, or in those with acquired bilateral disease of the frontal lobes, due to ischaemia or demyelination. Five useful clinical components have been described, usually some overlap of features is evident (Nutt et al. 1993):

Cautious gaits. These are common in the elderly who are often conscious of disequilibrium and a real risk of falling; they walk slowly with small steps, a slightly wide base, and walk carefully round corners. Cautious gait occurs in mild dementia (Jankovic et al. 2001).

Subcortical dysequilibrium. This is associated with poor or aberrant postural responses such as neck extension and backwards falling, and are often associated with oculomotor abnormalities, dysarthria, or extrapyramidal signs.

Frontal dysequilibrium. This impairs a patient’s ability to stand up, to remain standing or sitting independently, to organize their leg and trunk movements so as to bring their feet under their centre of gravity, or to avoid tangling their feet up when attempting to corner.

Gait ignition failure. This is familiar as part of Parkinsonism. It can be an isolated phenomenon with freezing attacks provoked by diversion of attention or narrow spaces, such as an open doorway. Walking is often easier if the patient concentrates on a rhythmically recurring feature, such as paving stone cracks, the tip of their walking stick, or simply by counting. Primary progressive freezing gait is a manifestation of various underlying neurodegenerative disorders and progresses within a few years to postural instability and eventual loss of walking (Factor et al. 2006).

Frontal gait disorders. These result from multiple forebrain lesions and involve varying combinations of a wide-based gait, short steps, shuffling, initiation hesitations, and dysequilibrium.

Thirty per cent of people aged over 65 fall each year, a quarter of whom are seriously injured. One in twenty fracture bones, particularly the hip (Tinetti et al. 1988). These injuries are an important cause of either temporary or permanent disability and sometimes death.

Gait disorders are a leading cause of such falls, particularly the high-level disorders which are particularly common in the elderly (Sudarsky 1990; Williams et al. 2006). Many such gait disorders are slowly progressive, often presumably due to non-specific neurodegenerative disease which merges with normal age-related changes in gait. Stepwise progression of a gait disorder points to cerebrovascular disease and interventions which may prevent further events should be considered. The gait disorder associated with Parkinson’s disease may improve with dopaminergic treatment although the associated impairment of postural adjustment mechanisms often responds poorly. Patients with signs of spinal cord disease should be investigated for potentially operable compressive lesions. Rapidly evolving high-level gait disorders should be investigated for potentially operable structural cerebral disease such as frontal tumours, subdural haematoma, obstructive hydrocephalus, or normal pressure hydrocephalus.

Drop attacks, postural hypotension, inadequate vision, poor illumination, and trips over environmental hazards are the other important cause of falls in the elderly (Sheldon 1960). The common complaint of unsteadiness is often associated with demonstrably impaired vestibular function (Fife and Baloh 1993). Suddenly occurring Tumarkin falls associated with vertiginous episodes can occur with or without the Menière syndrome (Ishiyama et al. 2003). Drop attacks are momentary losses of postural tone whilst standing, without loss of awareness or consciousness, and usually the patient is aware of the fall before hitting the ground. More than 80 per cent of such patients have become free of drop attacks at a mean follow-up of 6.5 years, whether or not there is an associated medical condition (Meissner et al. 1986). The average number of attacks experienced is 11 and they are not a predictor of stroke, suggesting that their pathogenesis is not vascular. Postural hypotension is another important cause of falls in the elderly, often being precipitated by antihypertensive and vasodilator drugs, and occasionally being due to peripheral or central autonomic failure.

Generally symptoms of autonomic nervous system disease develop insidiously and reflect loss of function, or failure of autonomic regulation. Occasionally paroxysms of autonomic hyperactivity occur in diseases such as Guillain–Barré syndrome (Section 21.10.1), causing wide fluctuations in blood pressure and heart rate which predispose to cardiac arrhythmias, episodic skin flushing, sweating disturbances, paralytic ileus, pupil abnormalities, and micturition disturbances. Autonomic dysreflexia occurs in high spinal cord lesions. Stimuli originating in the skin, muscles, or internal organs below the level of the lesion lead to hypertension, bradycardia, and sweating. Bladder distension is a noteworthy precipitant of autonomic dysreflexia.

The early symptoms of autonomic failure can be relatively unnoticed for years because of compensatory mechanisms. Persistent postural hypotension when standing leads to recurrent faintness, dizziness, episodes of vision draining away and blacking out, feelings of weakness, aching across the shoulders and posterior neck, or attacks of abrupt unconsciousness with falling. Food, alcohol, drugs, hot baths, or exercise can provoke these symptoms. These symptoms are reversed by lying down. Gastrointestinal autonomic dysfunction causes either nocturnal diarrhoeal attacks or pseudo-obstruction. Such obstruction may be generalized, or localized as in achalasia of the cardia or Hirschprung’s disease; commonly laparotomy has been performed to exclude mechanical bowel obstruction. Autonomic denervation of the bladder and genitalia impairs voiding, causes erectile impotence, and can allow retrograde ejaculation. Patients are usually unaware that they have lost sweating, but direct questioning can reveal that the palms no longer sweat and the finger skin has lost that moist adhesive quality required for effective gripping of paper. An autonomically denervated foot becomes warm and red due to loss of cutaneous vasoconstriction, and dry due to loss of sweating; the resultant lack of skin lubrication may contribute to cracking, fissuring, and ulcer formation.

Some autonomic disorders are focal, examples being Horner’s syndrome (Section 13.3.5), Adie’s pupil (Section 13.3.4), gustatory sweating, idiopathic palmar or axillary hyperhidrosis or surgical sympathectomy.

A wide variety of possible investigations of autonomic function have been described (Mathias and Bannister 1999). Most of these are too complex for routine clinical use. They include thermoregulatory and sweat testing, gastrointestinal function testing, sympathetic skin responses, measurement of noradrenaline and renin responses to head-up tilt, urodynamic studies and sphincter electrophysiology, and penile plethysmography.

Simple clinical tests for autonomic failure include:

Sweating. Lack of moistness may be noted on the palms and soles of patients with peripheral neuropathies involving autonomic fibres. Sweating can be provoked by putting a hand in a plastic bag to prevent evaporation and warming it under a light for a few minutes. Indicator dyes, such as Ponzo red, which turn red on becoming wet, can be dusted onto the skin, or placed under pieces of transparent tape stuck to the skin.

Lying and standing blood pressure. Normally on standing the blood pressure is unchanged or rises slightly and the pulse rate increases slightly. In autonomic failure the blood pressure falls and there may be no compensatory tachycardia (Fig. 2.57). Baseline blood pressure tends to fall slightly on repeated testing so it is advisable to measure blood pressure in the sequence lying–standing–lying and to compare the second pair of readings.

Sinus arrhythmia. Normally the heart rate rises during inspiration and falls during expiration. This sinus arrhythmia is mediated by the cardiac vagus nerves. Loss of variation in the R–R interval when the electrocardiogram is recorded during deep breathing occurs in autonomic neuropathy (Fig. 2.58).

Valsalva manoeuvre. When a normal subject attempts to exhale forcibly against a voluntarily closed glottis, the blood pressure drops, with loss of venous return to the heart, and the heart rate rises. When this intrathoracic pressure increase is released, the blood pressure overshoots because of continued sympathetic drive, and the heart rate drops below the basal level due to baroreflex activation (Fig. 2.59). Autonomic neuropathies abolish this second blood pressure overshoot and the associated reflex bradycardia (Fig. 2.59). If the baroreflex arc remains intact, as may be the case in high spinal cord lesions and some forms of central autonomic

failure, the cardiac rate rises during the initial phase of falling blood pressure. In formal quantitative testing the subject is asked to exhale against a standard resistance of 40 mm Hg.

A wide variety of disorders cause autonomic dysfunction, usually associated with other neurological or general medical disorders (Table 2.9). In everyday clinical practice the most common neurological diseases causing autonomic failure are diabetic polyneuropathy and Parkinson’s disease. It is usually relatively asymptomatic in both cases.

Intensive care may be required for patients critically ill either as a result of primary neurological disease, or in those in whom a neurological disorder is a component of, or secondary to, a general medical disorder. Those whose neurological condition is associated with a general medical disorder are generally suffering from hypoxic-ischaemic brain damage, or the complications of, or interactions between, metabolic disease, organ failure, critical illness, and sepsis.

The commonest primary neurological diseases requiring admission to a neurological intensive care unit are myasthenia gravis, Guillain–Barré syndrome, neurological infections, status epilepticus, and stroke (Howard et al. 2003). Many such patients will have been fully conscious of the steady decline in their respiratory or bulbar functioning, may remain conscious whilst receiving intensive care, and may remain in an intensive care unit for some weeks before recovery. This can place substantial emotional demands on the patients, relatives, and staff. A regular dialogue should be maintained. In particular, patients with respiratory failure moving inexorably towards assisted ventilation should be forewarned that this is an expected and planned aspect of their treatment. Likewise, avoidance of pain by sympathetic positioning, and its treatment by analgesics is essential.

Indications for admission to neurological intensive care have been defined (Howard et al. 2003): impaired consciousness, bulbar muscle failure, severe ventilatory respiratory failure, uncontrolled seizures, severely raised intracranial pressure, some monitoring and interventional treatments, and unforeseen general medical complications. Naturally specific treatments indicated for the particular diagnosis should be instituted along with general intensive care measures.

Particular dilemmas arise in patients with bulbar or ventilatory failure due to progression of an incurable degenerative disorder, such as amyotrophic lateral sclerosis. Patients and their relatives should receive a pre-emptive and frank discussion about the implications of ventilation under such circumstances, stressing the often limited and short-term resultant improvements in the quality of life. Some such patients do receive mechanical ventilation, either as a deliberate decision, or as an ill-considered emergency response when a medical crisis has arisen. Complex medical and legal considerations concern the patient’s rights to turn off ventilation by withdrawing consent to an invasive medical procedure, to planned withholding of treatments for pneumonia or other potentially terminal complications, and to the need to prevent the distress of terminal dyspnoea if a decision is taken to discontinue ventilation (Borasio and Voltz 1998; Bradley et al. 2002).

Ventilatory respiratory failure can result from a wide range of peripheral neuropathies, disorders of neuromuscular transmission, primary muscle diseases, and disordered central respiratory control (Polkey et al. 1999). The commonest and most familiar setting is of Guillain–Barré syndrome with progressive reduction of respiratory ventilation over days. Equally important is the risk of aspiration pneumonia or asphyxia by choking due to the development of bulbar muscle failure. Patients at risk of developing neuromuscular respiratory failure should be monitored with regular forced vital capacity measurement, sometimes with measurement of blood oxygenation, particularly if there is pre-existing pulmonary disease. Early warning signs of respiratory failure, such as the patient having to take frequent breaths whilst speaking, or exhibiting the paradoxical abdominal wall movements of diaphragm weakness, should be sought in at-risk patients. Artificial ventilation is generally required when the forced vital capacity falls below 12–15 ml/kg body weight, or there is evidence of significant bulbar muscle failure (Ropper et al. 1991). Artificial ventilation may be required for between two and five weeks in patients with Guillain–Barré syndrome. In general an endotracheal tube is regarded as satisfactory for ventilation durations up to two weeks. For more prolonged ventilation a tracheostomy becomes necessary, placed either surgically or percutaneously (Hughes et al. 2005). Weaning from ventilation is guided by evidence of recovering strength and respiratory movements, with the patient able to self-ventilate for increasing proportions of the day.

Deep venous thrombosis is a consequence of leg immobilization due to neuromuscular disease or paraplegia (Weingarden 1992; Henderson et al. 2003). This can lead to the potentially fatal consequence of pulmonary embolism. Deep venous thrombosis or pulmonary embolism occur in 16 per cent of patients with spinal cord injury (Weingarden 1992). Prophylaxis against deep venous thrombosis is necessary from the outset by analogy with post-operative surgical prophylaxis. A two-thirds reduction in the occurrence of deep venous thrombosis can be achieved by twelve-hourly subcutaneous heparin 5000 units or elasticated support stockings; both measures being recommended in the paralysed patient (Collins et al. 1988; Hughes et al. 2005).

Constipation may result from autonomic involvement, diet change, or opiate usage. In severe constipation, gastrointestinal feeding may need to be replaced by parenteral feeding, and nasogastric drainage placed. Adynamic ileus may respond to erythromycin or neostigmine. The immobility of patients in intensive care usually mandates bladder catheterization which should be maintained under strictly sterile conditions. Permanent loss of sphincter control can be anticipated in some conditions, such as traumatic paraplegia, and long-term approaches to sphincter care instituted as early as practicable.

Continuous vigilance is required to detect intercurrent infections such as pneumonia, or metabolic disorders. Decubitus ulcers should be avoided by a regular programme of turning. Contractures of paralysed limbs should be forestalled by regular physiotherapy and intervening limb positioning. A fluid replacement programme should be carefully designed and monitored, and adequately balanced and calorific nutrition provided by nasogastric or parenteral administration (Ropper et al. 1991).

Patients are naturally anxious whilst a potentially serious symptom such as muscle weakness is under investigation before a definite diagnosis has been made. It is rarely helpful to discuss an evocative diagnosis such as motor neurone disease while it is still only a possibility. However patients with morbid anxieties may draw their neurologist into detailed discussions of specific diagnoses even while these remain hypothetical. Once the doctor is sure of the diagnosis, most patients seem keen for it to be named so as to resolve the anxiety of uncertainty. In deciding how much to say about the diagnosis of a condition likely to be fatal, such as motor neurone disease, and its progression and complications, one treads a narrow dividing line between brutal honesty and humane economy of truth. Any particular problems likely to occur in an individual patient’s disease should be put in perspective before the patient becomes upset by the summary information so readily available from popular sources, such as journalism. Often it is valuable to discuss the diagnosis in stages with the patient, preferably in the presence of a close relative. Well-meaning relatives may try to prevent doctors from telling the patient that they have a fatal disease. But patients ultimately detect this conspiracy of secrecy at a time when death may loom, thereby undermining trust and confidence just when these qualities are of inestimable value.

Many patients become angry with their neurologist soon after hearing of a fatal or life changing disease. This is particularly the case in those too young to have become philosophical about their own mortality. Indeed doctors may bear the brunt of this anger as though they were somehow responsible for the disease’s occurrence. But anger should be understood sympathetically as a natural stage in patients’ adjustments to incurable or fatal illness. It usually follows an early phase of denial and isolation before being succeeded by bargaining, then depression, and ultimately by acceptance (Kubler-Ross 1969). During the stages of anger and bargaining, the doctor–patient relationship is vulnerable and can only be preserved by patience and understanding, thereby laying the foundations of confidence which enable patients to trust their doctor’s advice when miserable problems arise later in the disease.

Patients greatly appreciate the involvement of those who can provide advice and practical help to offset the various disabilities of their disorder. Consultants in neurological disability and rehabilitation should be involved at the first sign of a needy disability, together with care teams of speech therapists, occupational therapists, physiotherapists, and social workers. Charitable organizations, such as the Motor Neurone Disease Association can provide valuable equipment and devices with minimal delay, and often provide psychological support and practical advice to patients.