What is ALS?

Amyotrophic lateral sclerosis (ALS), often referred to as "Lou Gehrig's Disease," is a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord. Motor neurons reach from the brain to the spinal cord and from the spinal cord to the muscles throughout the body. The progressive degeneration of the motor neurons in ALS eventually leads to their death. When the motor neurons die, the ability of the brain to initiate and control muscle movement is lost. "Myo" refers to muscle, and "Trophic" means nourishment–"No muscle nourishment." As motor neurons degenerate, they can no longer send impulses to the muscle fibers that normally result in muscle movement. Early symptoms of ALS often include increasing muscle weakness, especially involving the arms and legs, speech, swallowing or breathing. Limbs begin to look "thinner" as muscle tissue atrophies.
 
(from Living with ALS, Manual 1: What's It All About?)
The nerves that are affected when you have ALS are the motor neurons that provide voluntary movements and muscle power. There are medically documented cases of people in whom ALS ‘burns out,’ stops progressing or progresses at a very slow rate. As one man put it, “I’ve made ALS part of my life, not my whole life.”