Tics and Their Treatment Part 7

TIC AND POLYGON

The proposal has been made by Gra.s.set to apply his attractive hypothesis of the cortical polygon to the interpretation of the pathogenesis of tic. It is desirable, first of all, to recall briefly the significance of the word polygon in the sense adopted by that neurologist.[16]

At the central end of the physiological ladder is the superior or cortical system of perception neurons whose cells form the grey matter of the convolutions. Physiological and clinical research necessitates the subdivision of this system into two groups--the neurons of psychical automatism, and the neurons of superior (_i.e._ voluntary or free) cerebration. The former function is not of the same level as the ordinary reflex arc, since it is in relation to co-ordinated, intelligent, and in a sense conscious acts; at the same time it is to be distinguished a.s.siduously from the latter, in which we include our personality, moral consciousness, free will, and responsibility.

Activity on the part of the inferior psychical neurons is seen:

1. In normal individuals--during sleep, dreams, and acts of distraction.

2. In the nervous--in nightmares, oniric states, table turning, thought reading, the use of the divining rod, automatic writing, c.u.mberlandism, spiritualism.

3. In the diseased--in somnambulism, catalepsy, hysteria, certain phenomena of epilepsy, hypnotism, double personality; also in some cases of aphasia, and in such conditions as astasia-abasia. Every manifestation of this inferior psychism is characterised by spontaneity, herein differing from mere reflex acts, but not by freedom, which is the _propre_ of superior psychism.

The various neurons subserving the former or inferior function are cortical, and form the cortical polygon. Situated at a higher physiological level are those for the latter function, united in what I designate the centre O.

Gra.s.set's general conception of tic is accordingly as follows:

In contradistinction to a pure reflex, a tic is a complex or a.s.sociated act. There is, however, more than one centre for the elaboration of these complex or a.s.sociated acts, notably the bulbo-medullary axis, and the cerebral polygon, as we call it. The former serves as centre not merely for simple reflexes, but for true a.s.sociated acts also, such as conjugate deviation of the head and eyes, walking movements in the decerebrate animal, etc.

We can conceive, then, a first group of non-mental tics corresponding to and reproducing these movements of bulbo-medullary origin.[17]

Let us turn now to our polygon formed by the various centres of psychic automatism. Polygonal reactions, such as writing or speaking, exceed both simple reflexes and bulbo-medullary a.s.sociated acts in complexity; they are to all appearance spontaneous and in a certain measure intellectual, but they are neither free nor conscious--attributes that distinguish the functions of the centre O, the seat of the personal, conscious, voluntary, responsible ego. The polygon consists of receptive sensory centres for hearing, vision, and general sensibility, and of transmitting motor centres for speaking, writing, and various body movements. They all communicate with each other, with O, and with the periphery, so rendering possible voluntary modification of automatic action. In some cases, on the contrary, there may be a sort of dissociation between O. and the polygon, when the activity of the latter becomes supreme, as during sleep--we dream with our polygon--or in distraction.

In states intermediate between the physiological and the pathological, pure independent polygonal action may reveal itself in the remarkable phenomena of nightmare, the divining rod, table turning, automatic writing, etc., while certain aphasias and agraphias, somnambulism, catalepsy, and various hysterical conditions const.i.tute the pathology of the polygon.

The fact that all mental attributes and functions are situate in O definitely negatives, in my opinion, any cla.s.sification in the category of mental diseases of such conditions as hysteria, so many of whose manifestations are polygonal alone.

Our second group of tics--polygonal tics, we may style them--are correspondingly a.s.sociated, co-ordinated, and psychical, but not mental; they have nought to do with the superior psychism of O.

Finally, in direct and strict dependence on an actual idea is a third group of tics, the psychical tics properly so called.

We have reproduced Gra.s.set's theory in some detail since it is one of the two most recent contributions to the study of the tic's pathogenesis. The other is that of Brissaud.

An apparent lack of harmony between the rival hypotheses is, we shall see, due rather to a difference in the interpretation of certain terms than to a real opposition of ideas.

Brissaud's view that the tic is a co-ordinated automatic act and consequently cortical is objected to by Gra.s.set. Every automatic co-ordinated act is not of necessity cortical. Conjugate deviation of the head and eyes may be of bulbar origin; certain spinal movements even may be no less co-ordinated and automatic. The decerebrate animal's walk may be perfect in its co-ordination.

Careful a.n.a.lysis shows the divergence of opinion to arise merely from a differing significance attached to the word origin. Brissaud is considering the origin of the tic in time, at the moment of its appearance; Gra.s.set its origin in s.p.a.ce, at the seat of its production.

Once the tic is const.i.tuted, its repet.i.tion each moment is a manifestation of polygonal activity, but it is none the less true that the movement which has degenerated into a tic had its source in cortical, _i.e._ psychical, activity.

Any one who appreciates the import of Gra.s.set's ideas will readily understand his terminology; it is at the same time expedient that the possibility of ambiguity in the use of words etymologically synonymous should be avoided. Now, however judicious be the distinction he draws between psychical and mental, it is to be feared it is not always adequately grasped: we do not intend, therefore, to employ either mental or psychical tic in our vocabulary, still less "psycho-mental" tic (Cruchet). As for bulbo-medullary tic, it appears to us to be identical with spasm as we have defined it, unless indeed it is to be taken as signifying a tic begotten of a spasm, in which interpretation Gra.s.set and Brissaud both acquiesce.

TIC AND FUNCTION

We must now pa.s.s on to elaborate our conception of tic as a disordered functional act.

The term function is employed to denote various biological phenomena differing widely in manifestation and design. Vegetative functions such as digestion, circulation, urination, etc., are regulated by a special unstriped muscle system, the mechanism of which cannot be suspended by cortical interposition; hence under no circ.u.mstances can its derangement bring a tic into being.

Other functions, subserved by striped muscles, come within the range of voluntary activity. Some--_e.g._ respiration--are essential to the maintenance of life, and scarcely to be differentiated from those we have called vegetative. Others, such as nict.i.tation, mastication, locomotion, are no whit less important, since their cessation, in the absence of extraneous aid, would speedily have a detrimental effect on the organism. They too are in a sense vital.

Others, again, such as expectoration, are useful, though not indispensable. Some people labour under the disadvantage of being unable to expectorate, but it is not a fatal defect. The function is not universal.

Finally, let us take once more the case of the child.

As he grows up he pa.s.ses by easy transitions from the voluntary to the automatic stage. He is taught to swim, and swimming soon rivals walking in the unconcern with which the movements are executed; he learns to write, and no less rapidly does the act become one of unconscious familiarity; his games, his exercises, the labour of his hands--be it digging or typewriting--all reach the level of regular automatism; in short, they are functional acts as truly as locomotion or even respiration, with the qualification of being neither essential nor general.

Such examples serve to ill.u.s.trate the comprehensiveness of the term functional, and embody all the intermediate forms between what is inherently vital and what is purely acquired. When we have to deal in practice with a case of functional disease, discrimination is obligatory from the standpoint of prognosis. We are alarmed at our patient's respiratory embarra.s.sment, not at his impaired caligraphy.

A distinction has also been drawn between _functional_ and _professional_ affections, profession being conceived as a function of the individual in relation to society. But the latter term has the drawback of being too exclusive. As a matter of fact, scriveners' palsy is met with in people who, so far from being professional writers, do not use the pen much at all. Nor is it necessary to be a professional pianist to develop pianists' cramp. It would be more accurate to speak of disturbances in "occupation acts," it being understood that these have by dint of repet.i.tion acquired the automatic characters of true functional acts.

Let us consider for a moment the salient features and component elements in our conception of function.

First and foremost is repet.i.tion. It is an absolute law, this of the periodicity of function, and strikingly exemplified in the case of the circulation, digestion, urination, etc. Regularity of rhythm is no less obvious in the muscular activity of mastication, locomotion, and respiration, and its degree seems to be in direct proportion to the duration and vital importance of the particular function.

The characters of this rhythm may be influenced by various extraneous causes. A painful stimulus makes us blink or quickens our respiration.

The will may intervene, to accelerate or r.e.t.a.r.d. The personal factor accounts for individual differences, but for each individual a certain rhythm and amplitude of movement, suited exactly to the end in view and conforming to the natural law of least effort, may be regarded as normal. It is only in pathological cases that this law admits of exceptions, and these we shall now proceed to investigate.

Disobedience to the law in the shape of exaggeration or redundance of purposive movement indicates functional excess. For instance, the object of the function of nict.i.tation is to moisten the conjunctiva. In its evolution the child's unmethodical reaction gives place to the rhythmical automatism of the adult. Perfection is the fruit of education.

But the person whose impetuous and uninterrupted blinking far exceeds the demand of the eye for lubrication is plainly troubled with excess, with "hypertrophy" of function. Herein may consist a tic, and, in fact, a large number of tics are nothing more than functional derangements of this kind.

The execution of a functional act at an inopportune moment const.i.tutes another variety of functional disorder. A smile with no pleasant thought to correspond; a cry, a word, that betoken no precise idea; a gesture to relieve an irritation that does not exist; a chewing movement when the mouth is empty--all are examples of untimely, inappropriate functional acts, which merit the name of tics if in addition they are anomalous as regards rhythm, amplitude, and intensity.

Again, the performance of function is accompanied by antecedent desire and subsequent satisfaction. Authoritative proof of this law is furnished by the case of micturition and of defaecation, although momentary suspension of the function of nict.i.tation or of respiration is also a sufficiently convincing mode of demonstrating its truth. In the case of locomotion and other motor functions a preliminary feeling of need may not be so imperative, but it is none the less constant.

Now, it has been observed already that these are equally conspicuous features in our conception of tic. In so far, then, as the latter is preceded by irresistible impulsion and followed by inordinate content, it may be considered a functional affection.

We cannot, however, dispose of each and every tic as an anomaly of some normal universal function. We have already had occasion to notice a large number of functional acts that are not of general distribution, so-called professional movements, which of course are liable to derangement. Such functional disturbances may be styled professional cramps, spasms, or neuroses; but are they identical with tics?

To attach the majority of them to the tics is, in our opinion, justifiable. They are the clinical expression of abnormalities supervening in a function that has by repet.i.tion acquired the automatism of genuine functional acts: they are germane to the tics. In certain points, however, the a.n.a.logy is not absolute.

Professional cramps are motor phenomena distinguished by arrest of intended movement. Spasm signifies excess of motor reaction, cramp denotes its inhibition. It cannot, then, be said that they present the characteristic features of spasm as we have defined it: they are akin rather to a form of tonic tic of which we shall give instances later.

With this premise, we can identify the professional cramp as a functional anomaly recognisable by defective amplitude and force on the part of the motor reaction. Its most special character is its appearance exclusively during the exercise of the function of which it forms the anomaly. Writers' cramp manifests itself in the act of writing, dancers'

cramp during dancing, and so on. We are ready to admit the close affinity of professional cramp to tic, with which it has an additional element in common in its occurrence among the psychically unstable. But, regarded as a tic, it is unique in its dependence on the casual exhibition of the professional act; as long as the telegraphist has no occasion to transmit messages, his occupation cramp will not incommode him in the least.

The great majority of genuine tics, on the other hand, are roused into activity by anything or nothing, and this distinction is fundamental.

With all due recognition, therefore, of the marked resemblances between the two, we shall be well advised in not confounding them under one designation. For want of a better word, we shall use the phrase professional cramp to specify functional disturbances taking place solely during the discharge of professional acts.

One other cla.s.s remains to be dealt with, consisting of functional acts not merely superfluous but actually prejudicial to him who is at once their creator and their slave. The idea that induced them and the object they have in view are alike irrational.

An individual as he moves his arm one day becomes aware of a cracking feeling in his shoulder-joint, and from the unwonted nature of the sensation emanates the notion that he must have some form of arthritic lesion. Renewal of the gesture is attended with reproduction of the sound. The thought of a possible injury develops and extends until it is an object of constant preoccupation and becomes a fixed idea. Under its malign influence the movement is repeated a hundredfold and with growing violence until it pa.s.ses into the field of automatic action. It is typically functional in its repet.i.tion, in the a.s.sociation of desire and satisfaction; but it originates in an absurd idea, and is actuated by a meaningless motive: its range is exaggerated, its performance irresistible, and its reiteration pernicious. In fact, it is a tic.