Tics and Their Treatment

The manifestation of each and every tic – be it a flicker of the eyelid, a turn of the head, a cry, a cough – is through the medium of a muscular contraction. On the very nature of this contraction opinion is divided.

To its distinctive features of abruptness and momentariness is due the epithet "convulsive" habitually assigned it, but the qualification is not secure. Since the time of Willis the word convulsion has been employed in a double sense, to signify clonic muscular contractions (the "convulsion" of popular parlance) and tonic muscular contractions (a meaning attached to the term only by the scientist).

For our part, we can raise no valid objection to the specification of tics as convulsive, provided always that the existence of clonic convulsive tics and of tonic convulsive tics be recognised. As a matter of fact, clinical observation supplies instances of both sorts.

Nevertheless, attention has been confined by a majority of authors to the consideration of the former variety only, so much so that a whole order of facts which in derivation, essence, and external characteristics ought to be identified with the tics has been passed over in silence. Even on the assumption that the proposal to recognise the two classes cannot be entertained, at the least it is advisable to predetermine the import of the word convulsion, and to speak of clonic convulsive tics. This is the formula of Ferrand and Widal in their article "Convulsion" in the Encyclopædic Dictionary of the Medical Sciences. Similarly, Troisier[6 - TROISIER, Dictionnaire Dechambre, art. "Face."] says that the convulsive tic properly so called is characterised by clonic movements, in which opinion Erb and most German observers concur. Tonic tic appears to have been forgotten, and we have thought it our duty to resuscitate it.

Cruchet has quite recently approached the subject in a critical fashion:

To extend the term tic to tonic spasms such as mental torticollis, mental trismus, or permanent blepharospasm, is singularly to outstep the limits of its significance. We believe Erb, Troisier, and Oppenheim are warranted in restricting convulsive tic to clonic convulsions, and the consequent simplification and elucidation of the question lead us to adopt the same view.

If it be solely a matter of terminology, and if universal consent reserve tic for convulsions whose expression is clonic, we shall be the first to withdraw the phrase "tonic tic," making the single proviso that some other designation be found for a condition which differs from the clonic tic only in its external features, and not in origin, pathogeny, or treatment.

What is this other name to be? Are these tonic muscular contractions to be regarded as synonymous with contractures? If so, do we mean myotetanic contracture – to utilise the excellent division imagined by Pitres – as in hysteria, or myotonic contracture, as in Parkinson's disease? The state of muscular contraction in tonic tic does not correspond accurately to either, though it is certainly more akin to the myotonic form; but myotonia is a sort of caput mortuum for the too facile classification of cases in reality difficult to place, and we are afraid the term is not calculated to ensure precision of ideas.

Should we be reproached with straining the primary meaning of the word tic by applying it to a contraction of a certain duration, we find ample justification ready at hand in the pages of Cruchet himself. "It was probably in 1656," he says, "that tique appeared in the French language, in the works of Jean Jourdin." Now, in the quaint description of the horse's tique given by that writer, the signs of the disease are said to be cocking of the ears, rolling of the eyes, clenching and gnashing of the jaws, stiffening of the tail, nibbling at the bit, etc. What else are these than persistent contractions or tonic tics, alternating or co-existing with jerking movements or clonic tics?

We have no desire, of course, to over-estimate the argumentative value of this passage, the interest of which is mainly historical; but we find ourselves wholly in accord with Cruchet when he remarks of the scientific distinction formulated by Willis, and again by Michael Etmüller, between continuous, permanent tonic convulsions, and intermittent, momentary clonic convulsions, that it is uninvolved, practical, and of universal applicability.

In 1768 certain tics were classified among the tonic convulsions by Boissier de Sauvages. Marshal Hall[7 - HALL, On the Disease and Derangement of the Nervous System, London, 1841.] gave an account of various tonic facial convulsions to which Valleix refers as non-dolorous tics or idiopathic convulsions of the face. Coming nearer to our own times, we find the distinction of which we have been speaking again elaborated by Jaccoud,[8 - JACCOUD, Pathologie interne, t. i. 1879, pp. 595-8.] in 1870, and accepted also by Rosenthal.

Doubtless physiologists and pathologists are not invariably at one as regards the proper characters of the two, and subdivisions into continuous tonic contractions as opposed to intermittent tonic contractions have been deemed necessary; but without burdening the subject with a plethora of detail, we think it simple, suggestive, and clinically satisfactory to uphold Willis's generalisations and to enlist their help in the exposition of the tics. Hence, unless under special circumstances, we consider recourse to the epithet "convulsive" superfluous, and we shall employ the word tic by itself, except when there may be occasion to indicate the form of muscular contraction. The gain in conciseness is not likely to be neutralised by any loss of precision.

From our rapid survey of the vicissitudes through which the tic has passed, we may profitably gather one or two lessons.

In so far as is compatible with its nature, the schematisation of tic is indispensable. The inevitable variability of the personal factor and the absence of a real breach of continuity between any two essentially differing morbid affections ought not to deter us from the attempt to project a line of demarcation between them. Natural science is pledged to the labour of differentiation. It is the glory of Charcot's alternately synthetic and analytic work to have demonstrated the value of this method in the sphere of neuropathology. At the same time, the wisdom of attaching only a provisional importance to any scheme and of welcoming possible modification is of course self-evident. Inexact and undiscriminating inference may be a stumbling-block in the path of progress and inimical to the cultivation of the faculty of observation. Further, inaccuracy of definition not only exaggerates the liability to misunderstanding, but has sometimes also the disadvantage of promoting an illusory belief in the possession of the truth.

CHAPTER III

THE PATHOGENY OF TIC

TIC AND SPASM

Our study of tic can be approached only after a preliminary understanding as to the meaning of two words too frequently confounded even in scientific literature —tic and spasm. Let us explain, then, once for all, exactly what we intend by the latter.

Etymologically (σπασμὁς, σπἁω, I draw) the word signifies a twitch, but as it is unfortunately considered a synonym for convulsion, the two expressions are used indifferently in medical parlance, though the desirability of restricting the application of the former has more than once been indicated. Littré's definition – "an involuntary contraction of muscles, more particularly of those not under voluntary control" – may appear somewhat idle, as the contraction of muscles not under the influence of the will can scarcely be other than involuntary. His intention was, no doubt, to reserve spasm for convulsive phenomena in non-striped muscle fibres; but in this limited sense the term has not met with acceptance, and it remains equivalent to "involuntary muscular contraction," whatever that may mean. Thus interpreted, it is applicable to any and every involuntary muscular movement, physiological and pathological, to the inco-ordination of tabes, to chorea, athetosis, tremor, etc.

Rather than imagine a new substantive to characterise certain of these muscle contractions, we may retain the word in a somewhat wider though equally precise sense, and follow the distinction drawn by Brissaud[9 - BRISSAUD, Leçons sur la maladies nerveuses, 1st series, chap. xxiv. p. 506.] in 1893: "a spasm is the result of sudden transitory irritation of any point in a reflex arc; … it is a reflex act of purely spinal or bulbo-spinal origin."

By definition, then, a spasm is the motor reaction consequent on stimulation of some point in a reflex spinal or bulbo-spinal arc. To differentiate between the reflex, which is physiological, and the spasm, which is pathological, we may add as a corollary: the irritation provocative of the spasm is itself of pathological origin, and no spasm can occur without it. The anatomo-pathological substratum of a spasm is, then, some focus of irritation on a spinal or bulbo-spinal reflex arc, which may be situated in peripheral end organ, in centripetal path, in medullary centre, or in centrifugal fibre. Whatever be its localisation, it will determine a spasm in our sense of the word.

Cortical or subcortical excitation, however, as well as peripheral stimuli, may provoke these bulbar and spinal centres to activity. Irritation of a point on the rolandic cortex, or on the cortico-spinal centripetal paths, is followed by a motor reaction exactly as with afferent impulses; the sole change is in the route taken by the centripetal stimulus; the reflex centre remains bulbo-spinal, and the efferent limb of the arc is as before.

The application of the word spasm to these motor responses to cortical or subcortical stimulation is quite justifiable. Developmentally the grey matter of the cerebral convolutions is ectodermic, as is the skin, and capable of functioning as a sensory surface; it may be considered the end organ of an afferent path that conducts to medullary reflex centres. According to our definition, then, provided the centre of the reflex arc be bulbo-spinal and the irritation pathological, the consequent motor phenomenon is a spasm.

A distinction most nevertheless be drawn between the two cases, inasmuch as in the one the afferent path is peripheral, in the other it is cortico-spinal, and there is a corresponding difference in the clinical picture. Jacksonian convulsions, consecutive to cortical stimulation, do not seem to bear much resemblance to spasmodic movements indicative of peripheral —i. e. sensory nerve – irritation. As a matter of fact, it is not always easy to differentiate the two, except by the aid of concomitant phenomena. The characteristic evolution of the Jacksonian convulsion is of course readily recognisable. We can similarly diagnose an irritative lesion of the internal capsule not so much from the objective features of the convulsive movements as from accompanying indications. In short, there need never be any occasion for confusion. Convulsive conditions attributable to irritation of cortico-spinal centripetal paths have long been described and analysed: they constitute well-recognised morbid entities, among which may be enumerated Jacksonian epilepsy, hemichorea, hemiathetosis, pre-and post-hemiplegic hemitremor, etc.

These clinical denominations for the affections under consideration it is at present desirable to retain. We shall not call them spasms; above all, we must not call them tics, else we shall end by confounding conditions absolutely distinct. The case recorded by Lewin,[10 - LEWIN, Arch. d. phys. diat. Therapie, 1900, p. 281.] under the title of "convulsive tic," of a three-year-old infant still unable to walk, who has daily attacks in which "all the muscles" twitch for about a minute at a time, is indeed a most singular tic. We were under the impression that such an attack is usually known as an epileptiform convulsion. Is the term "convulsive tic" quite a happy synonym?

Again, in the recent thesis of Cruchet the attempt has been made to base the pathological physiology of tic on researches of von Monakow and Muratow apropos of the occurrence of choreic, epileptoid, or athetotic movements after certain lesions of the cerebro-spinal axis, and to find an analogy in the action of various convulsion-producing substances (Richet and Langlois). Cruchet's conclusion is that convulsive tic is as often cortical or subcortical as spinal in origin; that it is, in short, a mere symptom, common to many cerebro-spinal conditions.

The same regrettable confusion is discernible in various treatises on neuropathology the work of German and other foreign authors.

As far as we are concerned, the outcome of the whole matter is simply this: if tic is doomed to be used indifferently for convulsion, its retention in scientific terminology is unjustifiable. Rather, then, than widen its application, we prefer to restrict it; we shall employ the term convulsion in its most general sense of "any anomaly due to excess of muscular contraction," of whatever variety or origin; and we shall limit the use of the word spasm to phenomena the result of irritation at any point on afferent or efferent reflex paths, or in reflex bulbo-spinal centres.

In thus indicating our position, we find ourselves once more in accord with generally received opinion since the days of Charcot. These views have been excellently expressed by Guinon:

Convulsive movements differ widely in kind. Some consist of localised spasms in the domain of a motor or mixed nerve, most frequently one of the cranial series – in especial the seventh – consecutive to some anatomical lesion, central or peripheral. The great majority of observers, French and foreign alike, are in the habit of designating such movements "tics." … But they are only partial convulsions limited to the area of some one nerve, not true convulsive tics, differing alike in essential features and concomitant symptoms. From the anatomo-pathological standpoint, moreover, lesions are as constantly present in the one as absent in the other.

The opinion of Brissaud on the subject coincides with our own.

If we suppose now that the cortex ceases to act as a surface of peripheral excitation, and becomes itself a reflex centre, we note at once a complete change. The modification effected by the cortex on afferent impressions is obvious in altered motor reactions, which appear with the stamp of cortical intervention, herein differing from bulbo-spinal phenomena. To this category belong the tics; we shall soon see why and how.

Conformably, then, to convention sanctioned by usage, and especially by the teaching of Charcot and Brissaud, we have given a precise definition to the word spasm, and we can only solicit its general adoption.

To resume briefly the argument we have advanced in the foregoing paragraphs, we maintain:

If in a given motor phenomenon there is no evidence of actual or previous cortical intervention, it is not a tic.

If the motor reaction is consecutive to pathological irritation at any point on a bulbo-spinal reflex arc, it is a spasm.

If the cortex is or has been involved in its production, it is not a spasm.

Should it present, in addition to the fact of cortical participation, certain distinctive pathological features, it is a tic.

It is precisely these distinguishing characteristics that we shall now proceed to examine, preluding our study of them with one or two physiological considerations.

TIC AND MOTOR REACTIONS; REFLEX, CO-ORDINATED, FUNCTIONAL, AUTOMATIC, AND VOLUNTARY ACTS

The instantaneous muscular contraction that follows the application of a drop of sulphuric acid to the limb of a decerebrate frog is an example of a pure spinal reflex. With the persistence of the irritation contraction of the other limb and of the whole body ensues; the simple spinal reflex has become generalised. Observe the frog a little longer. Soon the sound foot approaches the affected limb and attempts by rubbing to remove the point of irritation. A movement of attack has succeeded the simple movement of defence, and indicates a complete change in the nature of the motor reaction. In the first case the limb is withdrawn briskly from the painful stimulus; in the second the animal performs a series of co-ordinated purposive movements. The first reflex is automatic, and so no doubt is the second, since the frog is decerebrate. But a co-ordinated movement is not of necessity automatic from the outset; its automatism may be the sequel to voluntary education. Co-ordination is often a manifestation of cortical activity.

Take, next, the case of the infant. His earliest muscular movements are pure spinal reflexes. Pinch his leg, and he withdraws it; continue the stimulus, and he moves the other leg, his arms, his whole body; he starts to cry. The original reflex is becoming generalised, yet he makes no attempt to remove the source of irritation. Should a particle get into his eye, his lids will blink so long as the pain persists, but he never rubs them to expel the foreign body. In Virchow's phrase, the newborn infant is a spinal animal, endowed with spinal reflexes only; his responses to stimuli are beyond voluntary control.

More complex motor phenomena, however, equally independent of cortical influence, characterise the early days of the infant's life. The contact of his lips with the breast at once elicits a reflex in the shape of sucking movements. These are obviously co-ordinated and adapted for a particular end; suction is a functional act. Yet the cortex plays no part therein; the act is automatic from the beginning. Peripheral excitation from tactile impression of nipple, teat, or finger is sufficient to provoke this reflex response.

Similarly with the functions of respiration and nictitation – their establishment follows the stimulation by air of the respiratory or conjunctival mucosa. The appropriate movements constitute the spontaneous reaction to afferent impulses; they are simple bulbar reflexes. Co-ordinated and purposive though they be, they do not come within the sphere of the will. The newborn child cannot voluntarily accelerate or retard his respiratory rhythm.

But a day comes when the formation of cortico-bulbar or cortico-spinal anastomoses renders possible the interaction of higher and lower centres; respiration may be made quicker or slower; the eyelid may be closed less rapidly, more often. In a word, cortical modification of function becomes a reality.

A further step in advance is soon taken.

Under the "law of least effort" the inhibitory power of the will reduces motor reaction for the attainment of a given object to a minimum. The infant begins to make more complicated movements, attempting the removal of a source of annoyance by direct attack, learning to scratch itself, to spit instead of swallow, etc.

The essential difference between these acts – a thousand other examples might be chosen – and the reflexes of the first group, is that the precise and regular execution of the former demands more or less prolonged education, repetition, and voluntary co-ordination.

It is true these co-ordinated acts are eventually performed with all the spontaneity of the simplest reflexes; voluntary co-operation is no longer indispensable; scratching, spitting, walking, can be effected without any actual intervention of the will. But we must not forget such muscular automatism entails a preliminary training in the shape of frequent repetition of purposive movements – a training which varies in duration with the individual and the nature of the particular movement. It is only after several years of volitional effort that such acts as locomotion or the expulsion from the throat of an irritant particle become really automatic.

The fact that the newly hatched chick is capable of walking has been advanced as an argument for the existence of congenital automatism. It is true that the chick's movements are very imperfect – it stumbles and falls, as does the infant, on the slightest provocation, and even without any apparent cause; but the rapidity with which certain animals acquire the faculty is so surprising that the latter almost appears to have been innate.