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.

Our earliest step was to confiscate the offending hat, and this had the instantaneous result of diminishing the violence and frequency of the tic, which the subsequent practice of appropriate exercises entirely dispelled.

If now we direct our attention to the psychical aspect of the case, we are struck with the goodness, devotion, and disinterestedness of our patient. Her one concern is for the welfare of others, and she is indifferent to the pleasures of literature, art, games, or even work. All that is required of her she performs with docility, but never with animation. The extent of her passiveness is seen in her childlike acceptance of her parents' wishes. Her temperament is neither gay nor sad, but merely dull. Indolence and maladroitness predominate in all her actions, and reveal themselves in the curious awkwardness and nonchalance that characterise the execution of even the simplest movement. She is essentially of a very unstable nature, but its torpidity is no less obvious than its instability. If there is no abruptness in her acts, it is equally true that she is never still. She cannot maintain any given attitude; she cannot fix her gaze on any particular object. Her restlessness is such that her position is changed from moment to moment, however slowly and imperceptibly. Her eyes are only half opened; as she speaks, her lips are scarcely seen to move.

It has been a laborious and protracted task to teach her to sit motionless with her hands in front of her, and no less unremitting effort has been required to make her open her mouth properly, or turn her head naturally from side to side.

In some ways the endless movements of her hands and fingers—she never ceases playing with her dress or her gloves or her handkerchief—are vaguely reminiscent of those of athetosis, and on the left side especially, if they become a little brisker, there is slight hyperextension of the phalanges. She reads aloud in a low, colourless, monotonous tone of voice, without punctuation or accent, articulating the syllables defectively and slurring the ends of the words. At the finish of each paragraph comes a halt, as if from fatigue, and on command a fresh start is made with the same careless indifference. As for the lower extremities, the tale is identical. Mademoiselle R. cannot stand upright. She rests on either one leg or the other. Her left foot is never flat on the ground, but sometimes on the inner border, sometimes on the outer. The faulty attitude is readily enough corrected, though she declares she is ignorant of it. It is a sort of half clonic, half tonic, tic of the foot, whose slowness is on a par with that of all her other acts.

It is because clonic tics are so easily recognised that they are the most familiar, but we must not ignore another variety—viz. the tonic tics, corresponding to the tonic form of convulsion.

Tonic tic is of common occurrence in cases of mental torticollis. In that disease rotation of the head may be sustained for a considerable length of time without interruption, showing the permanent nature of the muscular contraction. Strictly speaking, we are concerned not with a sudden gesture, but with an attitude. Abundant evidence is forthcoming to substantiate its mental origin, and it may therefore be described as an attitude tic. Among other instances of tonic tics may be specified the affection of the masseters known as mental trismus (Raymond and Janet), or that continuous contraction of the orbicularis which keeps the eye half closed, though it may momentarily disappear under the influence of the will—a tonic blinking tic. O. and young J. have already supplied examples of attitude tics, and reference may further be made to another of our patients[49]:

Sometimes the mouth is drawn directly and completely to the left, more usually to the right; at other times simultaneous contraction of the upper and lower lips takes place, constituting a sufficiently faithful reproduction of the grimace made by a child in the attempt to refrain from crying; at other times still, imperfect closure of the lids and upward deviation of the eyes bear a resemblance to children's imitation of a blind man. Displacement of the mouth to the right is the movement of longest duration, and while it persists the patient is capable of stuttering speech, without relaxing her lips. The other tics last but a few seconds, while all vanish if she laughs or opens her mouth wide to exhibit her tongue. They follow each other at irregular intervals, and during the moments of rest the face resumes its normal expression.

Cruchet, as has been already remarked, has criticised the use of the term attitude tic, on the ground that the adoption of an attitude, however vicious it be, need not be the outcome of a convulsion. Doubtless; but it is no less true that a tonic convulsion may "take shape"—e.g. the arc de cercle of hysteria, the phenomena of catatonia and catalepsy, etc. Of course if the word tic is to be synonymous with intermittent twitching, then it is inapplicable in this class of case; but if our connotation of the term be accepted, we must find an expression that will serve to differentiate between tonic and clonic varieties. We are not aware of any particular advantage in describing the condition as a permanent contraction, for the obvious result of a permanent contraction, whether it be clenching of the jaws, occlusion of the eyelids, or rotation of the head, is the production of an attitude, a "position in which the body is kept" (Littré). No other designation could therefore be more appropriate than attitude tic, or could indeed be imagined, seeing that Cruchet himself ranges mental torticollis among the tics, and describes it as "an attitude of defence and of repose."

It may sometimes happen that the manifestations of stereotyped acts consist in the assumption of attitudes, but in spite of their affinity to the tics we deem it preferable to reserve the term "stereotyped attitude" or "akinetic stereotyped act" for cases where the motor reaction is clothed in the form of a normal movement. As it is inaccurate to describe as a tic a repeated gesture whose execution is normal in degree and in rapidity, so the mere immobility of a limb, or the prolonged contraction of a muscle, ought not to be called an attitude tic if the muscular effort does not differ from that which a healthy person would make to preserve the same position. In such circumstances we say that it is a stereotyped gesture or attitude. For the diagnosis of tic it is insufficient to establish the existence of a transient or permanent muscular contraction, and to note the inopportuneness of the movement; the contraction must be abnormal in itself, its abruptness unwonted and its intensity excessive—in short, it must be a convulsion; and finally, its repetition must be continued and exaggerated.

We have felt that some such explanation as the foregoing is required to justify our use of the term tonic or attitude tic, to whose close intimacy and association with the better-known type pathogeny and clinical observation alike bear witness. In any case such terms as myotonus or myoclonus are too comprehensive, in view of our present-day knowledge, to specify the particular motor affection with which we are concerned.

As a general rule it is only one part or segment of the body that is immobilised by a tonic tic, but in regard to the possibility of a general involvement, the following instance[50] may be cited, although we do not think it can be considered decisive:

A man thirty-two years old, who had recovered from a first attack of mental torticollis, underwent a relapse in quite a different form. If when walking with his head perfectly straight he were asked to go round to the right, he instantly appeared to become rooted to the spot and could not turn even his head in the required direction; at the same time he felt a compression of his throat as if he were being strangled, and for a few seconds he experienced acute anguish. A moment later he was all right again, and his action unimpeded.

Without going so far as to classify this incident as a tic, and without venturing to assert the existence of a tic of immobility, one cannot but be struck with its analogy to the attitude tics of which we have been speaking, and to catatonic conditions met with in the insane, of which too the pathogeny presents more than one point of similarity with that of this species of tic.

[In this connection reference may be made to certain conditions occasionally noted among those who tic—viz. a curious tendency to maintain abnormal positions of the limbs or trunks, and difficulty in or impossibility of relaxing various muscles (catatonic aptitudes). Patients are sometimes given to the exaggerated repetition of the ordinary movements of their members (echokinesis), as well as to imitation of the actions of others (echomimia). Such catatonic and echopraxic phenomena[51] are not confined to sufferers from tic, for they are encountered among psychopathic subjects generally, and indicate defect of cortical control—what is called by Brissaud "passive activity." These catatonic aptitudes may be discovered by resort to clinical tests, such as letting the arm fall from the horizontal position.[52]]