LOCALISATION OF THE MOTOR REACTION—VARIABLE TICS—FIXED TICS
The localisation of the motor reaction in cases of tic is essentially physiological. In rare instances its sphere may be limited to a single muscle, if one muscle only be requisitioned for the performance of a functional act; but it is very much more usual to find several muscles contributing, whose synergic contractions fashion the movement of which the tic is a caricature. If the same effect is yielded by the action of either of two different muscles or groups of muscles, as in rotation of the head, and if one be hindered from fulfilling its function, the incidence of a tic originally located in it will promptly be transferred to the other. This is the explanation of the persistence of rotatory tics after exclusion of the sternomastoids by surgical means.
Two symmetrical muscles may be affected, as in tics of blinking and of affirmation, or a median muscle, such as the orbicularis oris. Much more frequently the tic is unilateral in its distribution, as, for instance, when it involves the face; in this respect its figuration as a functional disturbance is well exemplified, for expressional movements of the face are normally bilateral. A tic may settle itself on two mutually antagonistic muscles, and manifest its presence in the immobilisation of a limb or segment of a limb; or only a portion of a muscle may contract, as in the case of the deltoid or trapezius, which are composed of bundles anatomically associated but physiologically independent, and so capable of being functionally differentiated by voluntary education. Fibrillary contraction and tic have nothing in common.
Inasmuch as the muscles concerned are under voluntary control, and their contractions such as the will can effect, it follows that with adequate practice the movement of a tic can always be imitated, and in predisposed soil imitation tics may thus take root; it is not always feasible, on the other hand, to counterfeit a spasm.
Several functional muscular territories may be simultaneously affected, and several tics may follow one another in quick succession, the duration of any one tic on any one site being a more or less varying quantity.
We have already noted the occurrence of variable tics. They appear one day to disappear a few days later, and reappear again after another space. Weeks or months may elapse without any vestige of them, until they suddenly break forth again unheralded. As a general though not absolute rule, the younger the patient, the less stable his tics. Occasionally they are isolated, limited, and stationary, one of the most frequent of this kind being a tic of blinking, but the intimate alliance between the motor troubles and the mental level of the subject helps to explain why these tics of children are so changeable.
In the case of young J., for instance, it was shortly after attaining his tenth year and entering school that first he began to tic, and thenceforward, at unequal intervals, trunk, arms, shoulders, legs, became in turn the seat of "movements of the nerves," while other more definite tics were not slow in developing.
When only six years old B. exhibited a respiratory tic, which changed a year later to one of the tongue, and after another year to one of the leg; at the age of twelve he used to nod his head in affirmation, and this was eventually succeeded by movements of negation, etc. He has since started a salaam tic, and finally a torticollis with deviation of the eyes.
We may cite an analogous case from Grasset:
A young girl, who had had eye and mouth tics in childhood, commenced at the age of fifteen to advance her right leg involuntarily—a sort of tic which lasted several months and gave place to paralysis of the same limb; for this affection was next substituted a whistling tic, and then for a whole year she used from time to time to give vent to a loud "Ah!" When she came under observation she was suffering from a tic of salutation, with retrocollic jerking of the head and shrugging of the right shoulder.
One of our own patients furnished us with the following story:
The disease made its debut by a blinking tic of both eyes, whose origin in the absence of any visual defect remained undetermined; grimacing and distortion of the mouth were the next to appear, as well as wrinkling of the nose and forehead, twitching of the eyebrows and contraction of one platysma, sometimes even of the ear muscles and the entire scalp. Then ensued up-and-down tossing of the head, or rotation of it from right to left, and, later, elevation and advancement of the shoulders, with restless agitation of hands and arms. A former trick of his of biting his nails is quite in abeyance at present; instead, he catches hold of his under lip every moment and abrades its mucous membrane with his nails, so much so that the lip is swollen and cracked like those of children with nibbling tics. Some months ago he acquired the habit of giving utterance to a soft little cry not unlike the sound made by a guinea-pig.
One tic has succeeded another in an unbroken series. The facial tics were more of the nature of grimaces, which the child amused itself in repeating; no doubt the scratching of the lip was a sequel to the desire of experiencing a new sensation, while the movements of hands, arms, and shoulders were very variable and different enough from the accompanying phenomena. No one of the tics was at all of protracted duration; on the contrary, each was fugitive and changeable, and therein presented a resemblance to the child's mental status. In sleep they completely disappeared; in the presence of strangers or if his interest was in any way aroused, they quieted down, while they increased on holidays, during games, or with physical fatigue.
It is clear that determination of the tic's localisation and mode can come only with the mental evolution of the patient, and that the transformation from the psychical inconsistency of childhood to the stability of the adult is paralleled by the change in the tic's manifestations as the scale of age is ascended. Any individual, whatever his years, who is in the stage of mental infantilism, will tic after the manner of a child, for the characters of a tic are dependent on the state of mind of its subject.