ALS is a condition in which nervous systems looses control over voluntary muscles. I won’t add more details about it, as you can find more information on MDA’s website, and definitely on Wikipedia:
From Wikipedia:
Amyotrophic Lateral Sclerosis (ALS, sometimes called Maladie de Charcot, or, in the United States, Lou Gehrig’s Disease) is a progressive, usually fatal, neurodegenerative disease caused by the degeneration of motor neurons, the nerve cells in the central nervous system that control voluntary muscle movement. As a motor neuron disease, the disorder causes muscle weakness and atrophy throughout the body as both the upper and lower motor neurons degenerate, ceasing to send messages to muscles. Unable to function, the muscles gradually weaken, develop fasciculations (twitches) because of denervation, and eventually atrophy because of that denervation. The patient may ultimately lose the ability to initiate and control all voluntary movement except for the eyes.
