2 Cyclopædia of the Practice of Medicine, vol. xiv. p. 416.
In our own country there have been many epidemics of the same disorder on a small scale, and we may regard the Shakers as representing a type of the dancing mania. Weir Mitchell reports3 an outbreak which occurred quite recently In a children's asylum in Philadelphia. Prompt measures and separation of those affected from the well children checked the disorder, which at one time threatened to spread through the entire institution.
3 Lectures on Nervous Diseases, p. 69.
These epidemics were quite different from what we now call chorea, and the individuals suffering were clearly affected by a psychical disorder of an hysterical form. In time, however, the name has come to be applied to a systematic disease characterized by irregular spasmodic movements of the limbs and other parts of the body.
The disease has been divided by some writers into chorea magna and chorea minor. The former, however, as described, is only an aggravated variety of hysteria, and need not be considered in connection with this subject.
Although the name chorea does not correctly describe the disease under consideration, it has been used for so many years that it is more convenient to retain it.
DEFINITION.—Chorea, as we now understand it, is a spasmodic neurosis, characterized by constant involuntary and irregular jerkings and twitchings of muscles or groups of muscles, which, in the majority of cases, cease during sleep, and are accompanied by more or less psychical disturbance in most instances.
ETIOLOGY.—Hereditary influence in the production of chorea is more or less marked. In some cases the connection seems to be remote, but in many instances it will be found that one of the parents has suffered from some form of nervous disease or has inherited a nervous diathesis.
George Huntington of Pomeroy, Ohio,4 has recorded some remarkable instances of hereditary chorea. The affection, as he describes it, differs in many features from chorea as ordinarily met with, but it is apparently the same disease. It is found in the eastern end of Long Island, and has been studied in several generations by Huntington, his father, and grandfather. This part of Long Island is remarkably free from the usual type of chorea, none of these physicians having ever met with an example of it. The hereditary chorea is confined to a few families. It occurs more frequently in males than in females, and never attacks the patient until after middle life. It comes on gradually and takes years to develop, but when once established it yields to no form of treatment. In most cases there is a marked tendency to insanity and suicide in the later stages of the disease.