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. With voluntary muscle action progressively affected, patients in the later stages of the disease may become totally paralyzed.

Importantly, there are significant devices and therapies that can manage the symptoms of ALS that help people maintain as much independence as possible and prolong survival.

ALS is amyotrophic lateral sclerosis, also called Lou Gehrig disease or motor neuron disease. Nerve cells (neurons) in the brain and spinal cord which are responsible for transmitting nerve signal to the body's muscles degenerate and die. Signals from the brain can no longer reach the muscles, which themselves begin to atrophy. Eventually, the muscles which control breathing are affected, and the patient usually dies of respiratory failure.

ALS is virtually 100% fatal. Most patients die within five years of the onset of symptoms, although about 10% survive for over 10 years. Noted physicist Stephen Hawking has had ALS since the early 1960s and has survived for more than 45 years. There is no cure for ALS. One medication (riluzole) has been shown to slow the degenerative process by several months, but treatment is otherwise restricted to relief of symptoms, including assistance with respiration and communication.