Tics and Their Treatment. Feindel Eugène

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СКАЧАТЬ 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.

      In all phenomena characterised as instinctive we cannot deny the existence of a certain congenital aptitude, the result possibly of ancestral education, owing to which some individuals learn infinitely more quickly than others, and in their case a period of preliminary education may seemingly be awanting. Probably the truth is, however, that this stage has been a very brief one. In man there is a gradual transformation of voluntary into automatic acts. Though no teacher be necessary, teaching is requisite. The infant learning to walk is really independent of his parents, and might, for that matter, be entirely self-taught; but the point remains, however automatic his walking subsequently become, that he begins by voluntarily co-ordinating the movements of his lower limbs and trunk towards a definite end.

      Another advance is still to be made.

      With increasing cortical development the individual is able, on stimulation no longer peripheral but central in origin, spontaneously to execute movements which frequent repetition has endowed with all the features of functional acts. Of these ideomotor phenomena physical exercises, games, manual trades, readily furnish instances. Swimming, for an instance, requires the rhythmical co-ordination of arm and leg, to attain which perseverance, retentiveness, and above all repetition are essential. At length the time arrives when the swimmer is surprised at the absence of any necessity for voluntary co-ordinating effort on his part. In fact, to reintroduce volition into this acquired automatism would be to court disaster. "What I do naturally," said Montaigne, "I can no longer perform if I attempt it expressly."

      From these physiological considerations we are led to make the following classification of motor reactions:

      1. Simple spinal reflexes, innocent of co-ordination or functional systematisation, on whose production or inhibition the will has no influence. To this division belong the movements known as spasms.

      2. Functional motor acts. Among these we may distinguish:

      a. Essential movements, e. g. respiration, suction, etc., appearing at birth, and co-ordinated in view of some definite function.

      b. Acts such as locomotion, mastication, etc., whose acquisition is subsequent to a more or less prolonged period of education.

       c. Non-essential ideomotor acts, acquired later in life, which soon assume all the characters of functional acts.

      The movements belonging to the first group in this latter category may manifest themselves without any exertion on the part of the will, but its activity is essential to the perfecting of the second, and the originating of the third.

      In this last division are placed the motor phenomena known as tics.

      TIC AND CO-ORDINATION

      We have thus come to see that a tic is a co-ordinated, systematised, purposive act. The majority of observers are satisfied on this point, although there exist various differences of opinion, more apparent than real, the inevitable result of disagreement as to the interpretation of certain expressions. It is imperative to obviate misunderstanding once and for all.

      In his first contribution to the study of the disease which bears his name, Gilles de la Tourette gave the general description of motor inco-ordination to the convulsive movements of his patients. It has been argued by Guinon, on the contrary, that they are really systematised, and that they reproduce, in an involuntary manner, the co-ordinated movements of everyday life. That this is sometimes the case Tourette subsequently admitted, but he still professed their frequent actual inco-ordination.

      This divergence of opinion is entirely attributable to difference of interpretation. Littré's definition of muscular inco-ordination is, "A condition occurring in various diseases of the nervous system, in which the patient cannot co-ordinate the necessary muscular movements for walking, grasping an object, etc." In this sense the term is applicable indiscriminately to the gesticulations of choreic, athetotic, or tic patients; to the ataxia of tabetics and others; to the tremor of disseminated sclerosis or paralysis agitans, etc. An expression so general is not merely of no diagnostic value; it leads to positive confusion.

      It is precisely in the type of inco-ordination that the difference lies. As rigorous a distinction must be drawn between the gestures of chorea and the gesticulations of the sufferer from tic as between the tremor of insular sclerosis and of Parkinson's disease.

      In assigning an exact meaning to the term muscular inco-ordination, we cannot do better than quote the remarks of Guinon:

      The tabetic who throws his legs to right and left, who as he sits at table cannot carry his spoon to his mouth, furnishes an instance of true motor inco-ordination. On the other hand, the subject of tic performs his voluntary actions with perfect assurance; though his infirmity occasion all sorts of ridiculous involuntary arm movements, he never brings his fork against his ear or his cheek, nor does he spill a drop from his glass; his walk may be interrupted by a sudden halt to bend his knees and kneel, or to strike his foot violently on the ground, but he never trips one leg over the other and never falls.

      In his article in the Dictionnaire Jaccoud, Letulle distinguishes two kinds of tics:

      The convulsive tic consists of a series of partial convulsions, while the co-ordinated tic is the expression of some complex act by a sequence of muscular contractions for that purpose. In the former case the СКАЧАТЬ