Читать книгу Tics and Their Treatment - Feindel Eugène - Страница 11

The view which regards tic as a "pathological muscular habit" provides emphatic illustration of the sinister influence of volitional infirmity.

This aspect of the question is of deep significance. If we define a habit, in the words of Littré, as a "disposition acquired by the repetition of the same acts," we can easily conceive how intimate is the relation between habit and automatism, and how constant rehearsal of the same movement in the same manner will create a mode of motor reaction independent of the function of the will. It has been made clear already that the phenomena of tic, regarded from the motor standpoint, reveal an identical process at work; but the fundamental difference between the habits of normal individuals and those of tic subjects is that the former can be checked or modified by voluntary effort, whereas the latter gradually acquire the pathological features of tenacity and irresistibility.

In a typical case of tic (says Dupré)14 the establishment of a reflex sensorimotor diastaltic arc, viâ the cortex, between peripheral stimuli of whatever nature and corresponding muscular reaction, is a sign that predisposition has changed the physiological to the pathological, and transformed a habit into a tic.

Guinon argues, however, that tic ought not to be cited in the catalogue of diseases, since it is ultimately a deep-rooted "bad habit" only, not a pathological fact.

We are not prepared to maintain, of course, that all motor "bad habits" are tics, for a whole host of familiar gestures, tricks, and mannerisms do not merit the name, superfluous and even detestable though they may be. It is true they are the product of education, and become, since the will has less and less to do with their appearing, at the last purely automatic; they may thus developmentally bear a close resemblance to tics. As Letulle says:

The infant who is constantly sucking its thumb, the individual who never ceases picking his teeth, or rubbing his eyes, or lips, or chin, or ear, who is for ever scratching his head or his beard – all have no doubt, originally, been driven to the repetition of the trick by some real necessity in the shape of dental caries, or ciliary blepharitis, or pityriasis capitis; but removal of the cause is not followed by cessation of the gesture. A man will learn the habit of perpetually smoothing his hair, and will not desist from his favourite trick though he become absolutely bald.

But such automatic habits and mannerisms are not genuine tics so long as the movement executed conserves in form the characters of a normal gesture. Be it never so inopportune or absurd, it is not a tic. It comes rather under the heading of stereotyped acts, whose kinship with, and difference from, the tics, have been well demonstrated by Séglas.

While the stereotyped act has all the appearance of a normal movement, the tic, on the contrary, is a "corrupt" muscular contraction; its subject is irresistibly impelled to its performance, and any attempt at repression is painful, sometimes even agonising. Victory is perhaps not entirely impossible, but any arrest is, as a rule, only temporary, and entails suffering which well deserves to be considered pathological.

On the other hand, the thousand illogical and absurd mannerisms of which we have been speaking betray no irresistible imperiousness in their execution, and require no agonising struggle for their repression. They are not tics. The crucial point in the differential diagnosis is the presence or absence of mental suffering.

The distinction may be further elaborated. Concentration of the attention may diminish the intensity or even inhibit the occurrence of a tic; inversely, a simple bad habit is manifested preferably during this very concentration. In the heat of physical or intellectual labour, we have all our favourite and characteristic tricks: we curl our moustache, we twist our beard, we scratch our forehead, we rub our chin, we nod our head, we fidget with our fingers in reading, speaking, reciting – in any mental or physical exercise requiring our attention we reveal innumerable little oddities of movement; but let our thoughts be directed for an instant to these gestures of distraction, and they disappear forthwith, to reappear afresh when we are absorbed in our work again. Charcot used to twist his hair round his index finger so intricately that to disentangle the finger one day a lock of hair had actually to be cut off. It was a trick of his, not a tic.

In the case of the latter, leisure of mind and body is the signal for the apparition of the inopportune movements. Any form of effort demanding the attention will, as a general rule, lessen their frequency or abolish them altogether.

Trousseau quotes the case of a young girl afflicted with severe tic who could play through any piece on the piano without the slightest interruption. Guinon similarly has known cases, one of whom could juggle accurately with knives, and another whose infirmity did not prevent her from taking a successful part in operatic ballet. Young L. is passionately fond of dancing, but he never tics in the ballroom. O. is an excellent amateur billiard player and never handicapped by his tic when playing, or, for that matter, when fishing or fencing; but if his attention be not thus absorbed, it is only with the utmost difficulty that he can master his tic.

We all have met the young man who cannot strike a ball at tennis without protruding his tongue at the same moment; his partner bites his lips at any difficult stroke. At other times neither betrays the slightest grimace; neither is conscious of any effort in maintaining repose. The occurrence of these movements during active concentration of the attention, and the absence of either difficulty or distress in checking them, justify their classification as stereotyped acts, in subjects psychically normal.

Tic is a pathological habit, to use Brissaud's phrase, and its description as a habit disease is in harmony with the facts. We must expect, of course, to meet every intermediate variety between the bad habit and the true tic, but this need not deter us from drawing the above-noted distinction, the application of which will be found not without value in the great majority of instances.