It is obvious that the course of chorea is very much influenced by the complicating rheumatism, or endo- or pericarditis. or other rheumatic disease, such as pleurisy, which, as we know, are quite frequent. They furnish an explanation for the fact that chorea, in spite of its generally favorable prognosis, may, like any other infectious disease, occasionally present septic phenomena and a fatal termination.
Death from chorea is a rare eVellt and occurs only in from two to three per cent. of the CASTS. In some of these death is directly due to the cardiac disease and its consequences; other fatal eases, however, am so-called pure uncomplicated cases of chorea. The latter chiefly deserve attention, although they are rarer in childhood than at a later period, up to the age of about twenty years. Only one or two fatal cases under the age of seven years have been reported (Riehon), and practically none of boys at any age.
The danger of sudden death, e., within a few hours or days, ap pears to be greater in those patients in whom the psychic symptoms, such as great h•ritability, violent temper, etc., are most prominent, a phenomenon which recalls the well-known fact that in nervous indi viduals the danger of sudden and unexpected death must always be reckoned with, even when they are suffering only frotn a comparatively mild organic disease.
Unfavorable symptoms in the course of chorea are: Sudden eleva tion of temperature that eannot be explained by any obvious complication, disturbance of the respiration, a small frequent pulse, pallor, and cyan osis. Such prodromal symptoms, which usually coincide with a great change for the worse in the choreic movements (6tat de mal chorelque, Charcot), are generally followed in a short time by coma and death.
The pathologic findings, aside from the changes in the mitral valve, do not suffice to explain the rapid death and consist in serous meningitis, such as occurs in a great variety of infections and intoxications. It seems justifiable to attribute death to this serous meningitis, particularly as the manner of death bears a close resemblance to that which is ob served in "apoplexia sero8a." The age at which chorea first makes its appearance varies between 4 and 20 years, the period between the it h and 13th years of life furnish ing the largest number of eases. The reason why ehorea is most fre quent during this period of life is not easy to find.
Heubner, who regards the choreic movements as mimic movements, attempts to explain the comparative immunity of the first three or four years of life by- pointing out that chorea cannot occur in a child that has not yet learned to speak in pantomine in whom, therefore, the corresponding nerve centres are not capable of function and cannot be placed in a state of infection by the toxic or morbid process which is the foundation of chorea.
In regard to sex, girls, according to our statistics, appear to be affected more than boys. The proportion is greater in statistics based on clinical material from private practice (one male to 25 females), and smaller when dispensary material is utilized (one male to 1.3-1.6 females). As Wollenberg points out, this indicates that girls are more often attacked by the severe forms, which require hospital treatment, than are boys.
The time of year probably has some influence on the frequency of the choreic diseases. It is greater in the cold, wet months, and less in dry, warm weather, a peculiarity which is also common to many diseases that are certainly not infectious and cannot therefore be made the basis of any further conclusions.
Direct homologous heredity [the identical disease] does not play an important part in chorea. Wollenberg states that, according to a number of statistics, heredity is present in about 2 per cent. of the cases, of which about 1.5 per cent. show inheritance from the mother alone. On the other hand, the occurrence of chorea in one member of the family and rheumatism in another is not infrequent.
A general nervous disposition is observed somewhat more frequently. Judging from the literature, the percentage of choreic patients with a neuropathic diathesis varies between 20 and 36; but these figures must be considered as representing the lowest limit, since a negative history is obtained in many families that are undoubtedly neurotic. The relations between neuropathia and chorea are by no means clear. If, with Heubner, we regard chorea as a "rheumatic equivalent" as the localization of the rheumatic infection in the nervous system, the question whether rheumatic patients of a nervous type are more apt to develop chorea than those who are not nervous becomes doubly interesting. This question cannot be answered off-hand in the affirmative, at least so far as our experience has gone. On the other hand, it is not to be denied that febrile diseases, or chronic nutritional disturbances which lower the resistance of the entire organism, and therefore of the nervous system also, produce a certain predisposition to the intoxication or infection which manifests itself as chorea.