TICS AND CHOREAS
A. Sydenham's Chorea
It would be difficult to find a better description of chorea minor than that given originally by Sydenham himself:
The dance of Saint Guy, chorea Sancti Viti in Latin, is a sort of convulsion whose incidence is greatest, in both sexes, between the age of ten and puberty. Its onset is characterised by weakness of one limb, which the patient drags behind him, and soon the arm of the same side is affected in the same way. He finds it impossible to maintain the same position of the arm for two consecutive moments, however great be his efforts to attain this object. Before he can bring a full glass to his lips he makes innumerable gestures and antics, as the convulsive moments of the limb deviate it from one side to the other, until at length he has piloted the glass opposite his mouth, when he empties it at a gulp.
If we were to confine ourselves to this description by Sydenham, which so far as typical cases of the disease are concerned is perfectly accurate, differentiation between tic and chorea would not be a matter of any complexity. Unfortunately, however, the varieties of this form of chorea are legion, and in practice one constantly meets with conditions suggesting alike the gesticulations of chorea and the convulsive reactions of tic. Moreover, it has been pointed out by Oddo[177] that the fact of the habitual exaggeration of tic during the very years when chorea is liable to appear is calculated to confuse the issue.
He has attempted, however, to specify certain factors in the differential diagnosis. In the first instance, the form of the movements is of significance: there is no co-ordination in the muscular play of the choreic; it is amorphous, indefinable, and erratic, whereas the gestures of tic are purposive, and may be said to have a shape. One never sees in chorea a succession of similar movements, but though a patient be suffering from several tics, each of them is reproduced always in the same fashion. Unilaterality of distribution is more common in chorea than in tic; in other words, chorea, more or less, follows anatomical lines in the regions it affects, whereas the incidence of tic is physiological.
Both are arhythmic in their manifestation; nevertheless the repetition of tic is noteworthy for its regularity as compared with the changing mode and rate of the other. Noir emphasises the diagnostic value of its frequency, abruptness, and reiteration of identical movements. In a majority of cases the interference of the will is futile as far as chorea is concerned, while the victim to tic is usually capable of restraining his muscular activity at least for a space. The choreic exhibits his movements in public, but the tiqueur seeks the seclusion of his own room. The association of tic with obsessional ideas is frequently encountered, but there is no similar connection between obsessions and chorea. In addition, the myasthenia, pains, and alterations in the reflexes that often characterise chorea are awanting in the other affection.
It cannot be gainsaid, however, that the frequency with which atypical varieties of chorea occur is inimical to a ready diagnosis, and the onerous nature of the task is not lessened by the circumstance that many choreics are the offspring of neuropathic parents and reveal psychical anomalies comparable to those of the subjects of tic.
In a disease such as variable chorea, which has features in common both with tic and with chorea properly so called, the problem of diagnosis is still more complicated, though excellent hints for its solution have been furnished by Brissaud.[178]
However frequently and warmly the theory of the origin of chorea in a neuropathic predisposition was advocated by Charcot, the fact of its usual evolution consecutive to some toxic or infective process is no less certain. Its incidence is greatest in children and the adolescent; it runs a regular course of increase and decrease; and the circumstances which cause the symptoms to vary during this cycle are never sufficiently potent to bring about even transitory suppression of them.
It is true that changes in the intensity of the symptoms seem to confer a remittent character on the affection, but there is nothing at all comparable to the sudden and unexpected waxing and waning of the form of chorea at present under consideration. None of the pathological attributes just mentioned concerns variable chorea, which, in addition, differs from Sydenham's chorea in two points—the multiplicity of the types of movement, and the fact that the patient can voluntarily check his involuntary actions. For these reasons, assimilation of the two clinical varieties is impossible, and the confusion of the two in practice need never occur.
A form of chorea entitled "habit spasm" by Gowers, and "habit chorea" by Weir Mitchell, has been the subject of further study by Sinkler,[179] but in all probability the cases of this description reported are instances of the variable chorea of Brissaud.
B. Huntington's Chorea
In spite of the preponderating etiological significance of heredity and the constancy of psychical imperfections in the chronic chorea of Huntington, its confusion with tic is not at all likely to occur. Difficulties might arise in distinguishing chorea major from variable chorea, however, and here we have the views of Brissaud to help us.
True chronic chorea is an incurable neurosis, of life-long duration. We have no trouble in pronouncing a diagnosis of chronic chorea if the symptoms date back five, ten, or twenty years, but they must have had a commencement, and the whole problem is to foretell the course of a chorea as yet only a few weeks or months old.
The involuntary movements of chronic chorea, like those of Sydenham's chorea, are illogical, but they are combined in a co-ordinate manner—that is to say, certain functionally associated muscular groups act simultaneously as for a particular end: the patient shrugs his shoulders, closes his fists, cracks his fingers, utters cries, he swallows, sniffs, sucks in his breath, makes the sound of kissing, etc, in all of which actions orderly participation of the musculature in a foreordained way is evident. Slight twitching of individual muscles and parts of muscles also occurs.
There is no limitation of the movements to a special division of the body; on the contrary, they spread from one muscle to another, and from one segment to another, rapidly and arhythmically. The gait is by turns skipping, dancing, or stumbling, interrupted by falls or by abrupt jerks of the loins. Speech is uncertain or monotonous; writing is incorrect and badly formed, sometimes illegible. A fact of the utmost importance is that all these involuntary movements may be modified, abated, relieved, so to speak, by voluntary movements in an inverse direction. In some cases the power of willing is still sufficiently developed to permit of the patient's following his occupation.
The steadily progressing increase in the seriousness of the motor trouble, paralleled by progressing mental deterioration, is one of the most significant factors in the differential diagnosis. It is precisely the variability of the symptoms that distinguishes variable chorea.
C. Hysterical Chorea
The conditions to which the name of hysterical chorea is applied may assume two forms, the commoner being known as rhythmical chorea, the other as arhythmical chorea. In the former case the convulsive movements are usually unilateral, being confined sometimes to a single limb, and reproducing, for instance, the actions of dancing (saltatory chorea), or of swimming (natatory chorea), or such professional movements as those of the blacksmith (chorée malléatoire). Occasionally there is a more or less faithful reproduction of deliberate and purposive acts in the form of attacks of varying duration, recurring, moreover—and this is their cardinal feature—at equal intervals.
Under the title of disease of the tics two cases have been published by Nonne,[180] the first consisting of rhythmical twitches in a man of forty years, secondary to a head injury, the other presenting similar appearances, but concerning a young girl of eighteen years who had sustained a shock. In neither was there any sign of hysteria. The reporter animadverts on the designation "rhythmical chorea," and protests that the systematisation and co-ordination of the movements are very different from the clinical picture of Sydenham's chorea, while their rhythmical nature does not allow of their being classified as tic.
Sometimes hysterical chorea is arhythmical—that is to say, the movements are irregular and contradictory, as in ordinary chorea. True chorea in cases of hysteria comes under this heading, as well as those cases where hysterical patients imitate the movements of chorea. The presence of the distinctive characters of hysteria makes a diagnosis of tic improbable.
The separation of hysterical from variable chorea may be peculiarly perplexing, as in one of Brissaud's cases, where the patient's extraordinary mental instability was such as is encountered only in advanced hysteria, while her disorders of motility were highly characteristic of what is known as variable chorea.
The condition described as chorea gravidarum may be placed at one time in the category of hysterical chorea, at another in that of ordinary chorea. In it there is intense motor restlessness, and accompanying mental symptoms are not awanting in a majority of instances.
D. Electric Chorea, Bergeron's Chorea, Dubini's Chorea, Fibrillary Chorea of Morvan
To render the study complete, we may remind ourselves of those still imperfectly differentiated forms known as electric chorea (Hénoch-Bergeron) and Dubini's chorea.
Bergeron's chorea affects children chiefly, and is characterised by the suddenness of its onset and the rapidity with which it attains its maximum. The movements are abrupt and brief, as though produced by an electric discharge at regular intervals, but their intensity does not hinder the execution of voluntary acts. They are sometimes confined to the head and limbs, most commonly they are generalised, and during sleep they disappear.
In the opinion of many, Bergeron's chorea is secondary to gastric disturbance. A cure may be regarded as certain, and indeed frequently follows the administration of an emetic. Sometimes the effect of the latter seems to be purely psychical.
Pitres thinks that this condition, as well as the electrolepsy of Tordeus, is simply a manifestation of infantile hysteria. According to Noir, there is an affinity between tic and electric chorea, and Ricklin is inclined to consider the two identical, but further study of the question is desirable.
Dubini's chorea is ushered in by pains and aches in the region of the head, neck, and sometimes the loins, and these are succeeded by electric-like twitches in the segment of a limb, which quickly become general. Severe convulsive attacks also occur, without loss of consciousness, entailing actual paresis of the limbs. The duration of the disease may be days or months, and 90 per cent. of the cases have a fatal issue. Confusion with tic is impossible.
We need not concern ourselves with so-called paralytic chorea, or with the fibrillary chorea of Morvan, which is a disease of adolescence, characterised by fibrillary contractions in the calves and thighs, passing thence to the trunk muscles and even to the arms; the face and neck, however, are spared, and during voluntary movement the fibrillation vanishes. Probably it is merely a variety of the paramyoclonus of Friedreich.