ALS, or amyotrophic lateral sclerosis, is a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord. There is no cure for ALS yet. 

Motor neurons reach from the brain to the spinal cord and from the spinal cord to the muscles throughout the body. They govern voluntary movements and muscle control. ALS causes progressive degeneration of these motor neurons leading to their death. When the motor neurons die, the brain can no longer initiate and control muscle movement. With voluntary muscle action progressively affected, people may lose the ability to speak, eat, move and breathe. 

The disease was identified in 1869 by the French neurologist, Jean-Martin Charcot but became more widely known internationally in 1939 when it ended the career of one of baseball’s most beloved players, Lou Gehrig. For many years following, ALS was commonly known as Lou Gehrig’s Disease. 

‘Amyotrophic’ comes from the Greek language. "A" means no. "Myo" refers to muscle, and "Trophic" means nourishment – "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.