Charcot's disease, amyotrophic lateral sclerosis.This disease, also called ALS, is due to degeneration of the motor neurons. Motor neurons are nerve cells located in the brain, brainstem and spinal cord, which serve as control units and links of vital communication between the nervous system and the voluntary muscles of the body. Messages transmitted by the motor neurons located in the brain (called upper motor neurons) are transmitted to the motor neurons of the spinal cord (called lower motor neurons) as well as to their particular muscles. In Charcot's disease, the upper motor neurons (bulbar form) and the lower motor neurons (spinal form) degenerate or die, ceasing to send messages to the muscles. Being unable to function, the muscles gradually weaken and perish (atrophy).