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.
TIC AND PARAMYOCLONUS MULTIPLEX—TIC AND MYOCLONUS
It is not our intention here to seek to provide a differential diagnosis between tic and the various conditions usually classed as myoclonus, and that for two reasons: in the first place, we cannot admit that the latter form a distinct clinical or nosographical entity, since the term myoclonus seems simply to be an abbreviation for clonic muscular convulsion, and is a symptom rather than a clinical syndrome; secondly, the fact that the tics themselves have been incorporated with myoclonus involves the investigation of all the published cases with a view to their critical sifting. This task we have pursued for our own edification, but to enter on it here would serve no useful purpose, and we shall rest content with examining succinctly several recent cases described as myoclonus, in the hope that the prosecution of further research will introduce order into what is at present chaos.
Among the various forms of myoclonus there is one which presents a certain individuality, and which was described originally by Friedreich under the name of paramyoclonus multiplex.