TICS OF THE ARM AND OF THE SHOULDER
In the upper extremity tics may affect the various muscles of the shoulder, arm, or forearm. Shoulder tics are of frequent occurrence, and often owe their origin to the discomfort of a tight sleeve or of a badly fitting collar. They are generally a concomitant of neck tics, in particular of mental torticollis.
In this connection we may recall the case of O., and supplement it by a description of another—viz. young J.
This boy J. had always been "nervous," and affected with "nervous movements" of face or limbs. At the age of thirteen years, when playing in the house one day, he knocked himself against an open door and bruised the shoulder near the outer end of the left clavicle. Three or four days later all pain and discolouration had vanished, and the child's movements were perfectly unimpeded again. His tics continued as before.
Two months after this little accident was over and forgotten, it was remarked that at the seat of the contusion there was a slight swelling, quite painless and scarcely even uncomfortable, but disquieting enough to the parents and thought to require applications of neapolitan ointment and the actual cautery. This line of treatment effected no alteration in the local condition, but it had other far-reaching consequences, for the boy noticed the anxious interest aroused by the singular exostosis, and began to devote attention to it himself. From the moment that his parents manifested their apprehension by words of pity and by solicitous examination, his tics developed a preference for the left shoulder, though continuing to exhibit themselves in the face and the right arm. He would unexpectedly elevate or depress his shoulder, would shrug it forwards or brace it back, accompanying the performance with inclination of the head or abduction of the upper extremity. He was very positive as to the painless nature of his affection; his sole complaint was of a certain stiffness in the joint, and at the thought of it came an impulse to move the shoulder which there was no resisting. The twitching would disappear for a time for no fathomable reason, and reappear again. By the exercise of a little circumspection he could temporarily overcome it, and during sleep it subsided entirely.
The facts—duly controlled and confirmed by the parents—that involuntary shoulder movements preceded not merely the application of the counter-irritants, but the accident itself, and that the unique difference lay in the similarity of his shoulder tic to all his other tics before the trauma, and in its marked preponderance in degree and frequency after, especially subsequent to the treatment, are of weighty diagnostic significance. Plainly the injury and its sequelæ did not exert any causative influence on the tic, and while it is conceivable that the clavicle may have been cracked and an exostosis ensued, we must repeat that the pre-existence of the movements in question negatives the possibility of their being attributable to nerve irritation from a periosteal overgrowth. The only effect which the accident and its consequences had was to intensify the patient's preoccupation and to determine the incidence of the tic.
By the month of October, 1900, the latter was at its height, and had reached a state where differentiation of the movements and of their muscular counterparts was attended with no little difficulty. They could be resolved into four principal groups, whereby the shoulder was raised, lowered, advanced, or drawn back, respectively. The first of these presented no unusual feature except that with it the head was commonly inclined to the same side; but the act of depression was rather peculiar, inasmuch as it was achieved by a sudden contraction of the inferior muscles of the scapula, together with the pectoralis, which drew the humeral head downwards, elongated the capsule, and stretched the deltoid fasciculi over it. The space thus left between the separated articular surfaces was partly filled in by the neighbouring ligamentous and muscular structures. Anterior or posterior projection of the shoulder took place at the expense of an actual subluxation, the head of the humerus bulging under the pectoral or the scapular muscles. Each and every movement was accompanied by articular cracking, sometimes so insignificant as scarcely to be pathological, to which, nevertheless, the boy attached extravagant importance and devoted methodical investigation.
Ordinary arm movements were, without exception, unimpaired, nor was any bony malformation discoverable. The two shoulders were practically symmetrical, though the upper border of the trapezius on the left side was, if anything, thickened and more prominent than its fellow, and the same applied to the left scapular muscles. Horizontal extension of the left arm revealed a slight tremulousness, quite distinguishable from pathological tremor and from fibrillary twitching, and wholly comparable to what is seen when, by reason of a fracture or otherwise, a limb is for a certain length of time prevented from executing movements of extension.
[Beating or striking tics (the patient using his own fist against himself) arise from the attempt to alleviate some insignificant pain or irritation; but tics of this kind are in their turn the exciting cause of local discomfort, and so of fresh tics. In spite of the obviousness of this, it is often difficult to convince the patient that his movements are prior, not consecutive, to the unpleasant sensations.[99]]
Finally, tonic tics of the upper extremity find expression in attitudes that vary with the localisation of the contraction. We have already had occasion to observe this, which is an almost constant phenomenon in mental torticollis, in the case of young J., in Madame T., and in N., where, it will be remembered, the all but permanent elevation of the right shoulder seemed traceable to the habit of cutting stuffs with a pair of large scissors.