THE general characters of the motor reaction constituting the objective manifestation of tic form the subject of previous analysis in the chapter on pathological physiology. It is our present intention to approach them from the semiological point of view.

To give a description of the motor disturbance of universal applicability is evidently to attempt the impossible. The modifications of functional acts are legion, and in the case of tic anomalies of muscular contraction vary not merely with the individual, but in the individual. Each tics after his own fashion; and no two tics are ever exactly interchangeable. As Trousseau was wont to say, "the disease in a sense forms part of the constitution of the person affected."

THE TYPE OF MOTOR REACTION—CLONIC TIC AND TONIC TIC

The motor reaction may be either clonic or tonic in type. Clonic tics are distinguished by more or less abrupt contractions, separated by longer or shorter intervals of relaxation or repose. The duration of a clonic tic convulsion may be exceedingly brief, though perhaps not so brief as the instantaneous "electric" twitches of a spasm, which have the extreme rapidity of pure reflex phenomena. Exception ought to be made for the face, no doubt, seeing that the suddenness of the movements in facial tic is precisely what complicates the diagnosis between it and facial spasm, as we shall see. In the limbs, the variations appear to stand in close relation to the nature of the primary factor, the mental condition of the patient, and the mode of reaction peculiar to him. The quickness with which the reaction occurs increases in proportion to the length of time the tic has existed, although once it has become habitual, any further change is rather in the direction of additional complexity.

Sometimes a relative deliberateness of execution raises suspicions as to the accuracy of the diagnosis. In the case of a child with several tics, one affecting the mouth in particular, Guinon was struck by the slowness of the muscular contractions.

To begin with (he says), the mouth was opened gradually, but as soon at the limit of separation of the maxillæ was reached, it was immediately closed, without remaining even for a moment in the extended position, as one would have expected had there been a tonic contraction of the infrahyoid muscles.

Cases of this kind, however, are not really instances of the tonic variety.

One of us has had the opportunity of observing a young woman afflicted with a curious combination of motor disorders, akin no less to the clonic form of tic than to the gesticulations of chorea and the undulatory movements of athetosis. Their resemblance to the clinical type described by Brissaud under the name of variable chorea is noteworthy, a distinguishing feature, however, being the sluggishness of the muscular contractions, which may well be a reflex of the patient's mental inertness.

Mademoiselle R., a young woman twenty-six years old, is a small and delicate creature with slender limbs and tapering fingers. She is extremely myopic, but her general health is excellent, and there is nothing to suggest that she is suffering from organic disease of the nervous system. Apart from the fact that her parents are rather "nervous," the family history is negative.

Since the age of twelve she has been subject to various tics of the face and head. She wrinkles her forehead and moves her scalp to and fro, and sometimes she turns her head slowly and steadily towards the left side, raising her eyes up and to the left at the same moment. Head and eyes forthwith resume their normal position. The deliberateness of the act is altogether exceptional. If, however, she happens to be wearing her hat—which is remarkable for its size, weight, and unwieldiness—the gesture is repeated in a quick and jerky manner. Any diversion, such as reading, knitting, listening to a conversation, especially if she feels she is not being noticed, will augment the intensity of the movements, which the thought of being observed, or the awakening of her interest, or rest in bed, or sleep, has the effect of abbreviating or checking.