CHOREA. 379 



In considering its etiology, in the first place, we are struck by the 

 prevalence of the .disease at the time of the second dentition and at 

 the period of puberty. It often happens that an individual suffers 

 from the disease at both these periods, and remains free from it during 

 the interval. This accounts for the belief of the laity, that the com- 

 plaint returns every seven years. Before the sixth year of life the 

 disease is rare ; and it is equally uncommon after the age of fifteen. 

 Even the most advanced old age, however, is not entirely secure from 

 it, and in such cases the affection exhibits a peculiar intractability. 

 The predisposition to the disease is far greater in the female sex than 

 hi the male ; and in certain cases an almost unmistakable hereditary 

 tendency to St. Vitus's dance has been observed. Moreover, hydraemia, 

 anaemia, and rheumatism seem to augment the tendency to this affection. 

 It undoubtedly is going too far to regard the connection between 

 chorea and rheumatism as constant ; but it cannot be denied that a 

 remarkable number of chorea patients have already suffered from acute 

 or chronic rheumatism, or else, during the disease or after it has sub- 

 sided, a rheumatic attack sets in. In like manner, inasmuch as false 

 heart-murmurs are very often heard in the hearts of chorea patients 

 (and although many of them may be considered as blood-murmurs, 

 and due to anaemia and to nervous derangement), yet the number 

 which are certainly dependent upon valvular disease is large enough 

 to enable us to judge how many of the patients have already suffered 

 from rheumatic pericarditis and endocarditis. One of the most severe 

 cases of chorea which I have ever witnessed was in a girl fifteen years 

 of age, each one of whose joints successively became swollen ; and 

 another was in a girl, twenty years old, who had bad disease of the 

 heart. Besides the mimic instinct, various mental emotions, especially 

 fear, have been assigned as causes of chorea, as have also the irritation 

 of worms in the intestines, onanism, pregnancy, and other agents. In 

 particular instances it of course is very difficult to determine the 

 causal connection between chorea and such influences, which so often 

 exist without perceptible effect upon the health. The effect of exam- 

 ple, which plays the principal r61e in the chorea major as well as in 

 chorea minor, is instanced in the epidemic appearance of the disease 

 sometimes observed in boarding-schools. The influence of pregnancy 

 is inferred from the fact that, among adult patients, very many of them 

 are pregnant women. Chorea rarely appears before the end of the 

 second month of pregnancy, and its appearance is equally rare in the 

 later half of the term. Once established, it usually lasts until after 

 delivery. 



SYMPTOMS AKD COURSE. St. Vitus's dance is characterized by 

 movements of the voluntary muscles, which, however, are not excited 



