Within the spectrum of the idiopathic or primary tic disorders (Table 1) certain trends become apparent. As it passes from single to multiple tics the pattern of movements tends to become more complex and extends from the head to involve other parts of the body. There is also increased likelihood of vocal tics and decreased chance of spontaneous resolution. Studies of Gilles de la Tourette pedigrees reveal that in addition to patients with the full-blown disorder there are many relatives who suffer from lesser degrees of chronic tic and probably represent partial expression of the condition. Most of these seem to have multiple tics without vocalizations (Corbett et al. 1969, Eldridge et al. 1977, Golden 1978, Nee et al. 1980, Lees et al. 1984, Kurlan et al. 1986, Randolph et al. 1993). The justification for separating multiple tics from Gilles de la Tourette's syndrome is thus not strong. On the other hand, however, the simple and frequently single tics, occurring transiently in children, seem likely to represent a different problem, although the movements themselves are identical. The fact that they occur commonly, resolve spontaneously, and have no known pathological significance seems to separate them as a different entity. Some authors, however, have postulated that simple tics of childhood are a mild expression of the same condition that causes Gilles de la Tourette's syndrome (Kurlan 1994) and the exact relationship has yet to be determined.
Marsden's Book of Movement Disorders
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