Here is a quote from the site on about the disease:
ALS Association - Jim "Catfish" Hunter Chapter | ALS Association - Jim "Catfish" Hunter Chapter
Amyotrophic lateral sclerosis (ALS), often referred to as "Lou Gehrig's disease," is a progressive motor neuron disease (MND) that attacks nerve cells in the brain and the spinal cord, damaging both upper and lower motor neurons. Motor neurons reach from the brain to the spinal cord and from the spinal cord to the muscles throughout the body. When the motor neurons die, the ability of the brain to initiate and control muscle movement is lost. With voluntary muscle action progressively affected, patients in the later stages of the disease may become totally paralyzed. Yet, through it all, the vast majority of people maintain sharp, unaffected minds.
A-myo-trophic comes from the Greek language. "A" means no or negative. "Myo" refers to muscle, and "Trophic" means nourishment. Literally, the word means "no muscle nourishment." When a muscle has no nourishment, it "atrophies" or wastes away. "Lateral" identifies the areas in a person's spinal cord where portions of the nerve cells that signal and control the muscles are located. As this area degenerates it leads to scarring or hardening ("sclerosis") in the region.
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. When muscles no longer receive the messages from the motor neurons that they require to function, the muscles begin to atrophy, or become smaller. Limbs begin to look "thinner" as muscle tissue atrophies.
Although the cause of ALS is not completely understood, the recent years have brought a wealth of new scientific understanding regarding the physiology of this disease.
