INTENSITY OF THE MOTOR REACTION
The muscular contraction varies considerably in intensity, in most cases exceeding that of the corresponding normal movement, and, especially in tonic tics, being often so powerful as to necessitate the exertion of great force to overcome it. Even though one's effort prove unavailing, however, it is only needful to distract the patient's attention to perform any and every passive movement with consummate ease.
In the case of S., any attempt to budge the head from its torticollic position on the left evokes strong muscular resistance; but engage him in conversation or otherwise divert his mind, and the difficulty soon vanishes. By similar means, the resistance awakened by sudden change of the direction of passive rotation will rapidly die down.
Occasionally the muscles brought into play surpass their fellows of the opposite side in size and power, this secondary hypertrophy being the natural sequel of repeated exercise. It was noted by Charcot that in rotatory tics the disused muscles atrophied, whereas the affected muscles hypertrophied, but they may do so only in appearance. The tonus of the muscles at the moment of examination may create differences inappreciable during relaxation. Sometimes one comes across such expressions as "paresis" or even "paralysis" of antagonistic muscles, and "contracture" of those in which the tic is localised. To draw a distinction between slight contracture of the latter and mild paresis of the former is a problem practically always insoluble. Opinion has been ever divided on this point; yet some, in their desire to harmonise the two, take up an eclectic position and do not hesitate to speak[53] of "paralytic contracture," or "mixed contracture, at once active and passive," a terminology by no means calculated to simplify the question, and one the discussion of which we do not care to pursue.
We should like, however, to allude to a matter of clinical observation that we frequently have had occasion to remark. What simulates muscular enfeeblement in the subject of tic is often nothing else than a want of accuracy and adresse in the performance of a given movement. For instance:
S. enjoys robust health; his only trouble is a lack of accurate control over his limbs. His execution of the most elementary movements is incorrect. There is no tremor, no jerkiness, simply a loss of the sense of position. He never knows whether he is holding himself straight, whether his arms are exactly horizontal or his shoulders symmetrical. Often he confuses right and left, and when requested to perform some act on one side, he declares he is tempted to perform it simultaneously on both. The order to fold his arms and rotate the upper part of his body to the right evokes an inconceivable display of contortions. In the attempt to bend his head and body backward, fear of losing his balance causes him to twist and turn about most strangely, and the remark that all this he might avoid by merely putting one foot further back seems to cause him infinite surprise.
Or again:
The absence of precision in Mademoiselle R.'s movements, her habit of arresting the action before attaining the desired end, are not to be ascribed to any feeling of discomfort, but to her ignorance of the amplitude of her efforts, and of the position of her limbs. Her acts are always feeble, hesitating, and curtailed, a curious mixture of muscular languor and vigilance, "as if she were afraid of breaking herself." She appears to be constantly seeking some new position for herself, and to be as constantly oblivious of her actual attitude. With eyes closed, however, she indicates the relation of her limbs exactly.
Another example is furnished by the case of L., to which reference is made on p. 135.
There is no call to multiply instances. Enough has been said to demonstrate the frequent occurrence, if not of motor inco-ordination, at least of faulty orientation in space and of defective estimation in regard to the range and intensity of voluntary movements, among the subjects of tic. The topic is a very interesting and fruitful one, on which considerable light may be thrown by the application to it of the results of Pierre Bonnier's[54] remarkable studies on the sense of attitudes, a subject that we intend to develop on another occasion.