A VAST number of disturbances of motility, distinguished as spasm, chorea, cramp, myoclonus, myotonia, etc., may be derived from the same pathological substratum as tic, and an equally vast number of psychical anomalies may spring from that psychopathic diathesis of which tic is merely the motor expression.
The frequency of these associations is confirmed by innumerable clinical observations, many instances of which have been given already.
That the relations between tic and other diseases of the nervous system are very intimate is patent from every-day experience; such and such a tic may be succeeded, in the same individual, by a much graver condition in the shape of mental disease, general paralysis, tabes dorsalis, etc. Inversely, some cases of chorea seem to terminate by leaving no trace of their occurrence beyond some little convulsive movement or tic. The position tic occupies is, then, a peculiarly interesting one, for it may be the starting-point of another affection, it may be an intercurrent phenomenon, or it may persist as the reminder of some previous disease. For this reason it well merits attentive study.
In this chapter we shall examine the connections of tic with hysteria, neurasthenia, epilepsy, mental disease, and idiocy respectively.
TICS AND HYSTERIA
Our response to the question whether tics are hysterical in origin is a direct negative. Without attaching pathognomonic significance to stigmata, we may remark how seldom they are encountered among those who suffer from tic, and how rarely the latter exhibit any of the paroxysmal manifestations of hysteria.
Modifications of general sensibility such as anæsthesia or hyperæsthesia are unknown; the special senses are intact; in particular, contraction of the visual fields is never met with. Though these signs are negative, their importance from the point of view of diagnosis is none the less real.
The mental condition of patients with tic is no doubt analogous to that of hysterical cases, but it is no less common in many others that present no sign of that neurosis. There is little or nothing in tic characteristic of hysteria, and one sometimes questions whether the soi-disant hysteria of certain subjects of tic is the real disease.
In the same way as all who are predisposed, the sufferer from hysteria may develop a tic or tics, and although tic was held by Briquet, Axenfeld, Bouchut, and others, to be merely an accessory symptom of hysteria and nervosism, these doctrines were propounded prior to the analytic researches of Charcot.
Pitres,[155] whose opinion is so weighty in matters neurological, considered a predisposition to tic as a sign of hysteria, for which neurosis the subjects of tic were candidates, and supported his contention by various clinical examples: