SECTION IV. 



GENERAL NEUROSES, OF UNKNOWN ANATOM 

 ICAL ORIGIN. 



CHAPTER I. 



CHOREA CHOREA ST. VITI ST. VITTJS'S DANCE. 



ETIOLOGY. St. Vitus's dance may be called a purely motor neu- 

 rosis, all of its symptoms being attributable to a morbid irritability of 

 the motor nerves, while no derangement, or, at least, no constant de- 

 rangement of the sensory or intellectual function can be detected. 



The pathogeny of chorea is obscure. None of the anatomical re- 

 searches hitherto made upon the subject, nor any study of its symp- 

 toms, give us any positive information as to the real point whence the 

 morbid irritation of the motor nerves proceeds. The results of the 

 somewhat rare autopsies which have been made upon subjects who 

 have died of chorea have been either negative, or else so discordant 

 that any lesion discovered in the central organs of the nervous system 

 cannot be referred to the chorea, but rather to some accidental com- 

 plication, or to the disease of which the patient died. The general 

 implication of nearly all the cerebro-spinal motor nerves altogether 

 contradicts the supposition that the origin of the disease lies in the 

 peripheral nerves. The complete integrity of the other cerebral 

 functions makes it improbable that the movements of chorea originate 

 in the brain. On the other hand, certain pauses in the muscular rest- 

 lessness which occur, particularly during sleep and during the action 

 of chloroform, would seem to imply that the motor influence is derived 

 from the brain rather than from the spinal marrow. There is no good 

 ground for the hypothesis that chorea is dependent upon a dispropor- 

 tion in size between the spinal canal and the spinal marrow, or upon 

 inflammation of the vertebrae, or upon spinal irritation, for we do not 

 even know that the seat of the malady really lies in the spinal 

 marrow. 



