Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, is a progressive wasting away of the nerve cells in the brain and spinal column that control the muscles that allow movement. Over a period of months or years, ALS causes increasing muscle weakness, inability to control movement, and problems with speaking, swallowing, and breathing.

The cause of ALS is unknown, and there is no cure. Treatment focuses on keeping the person as strong as possible and preventing complications of the disease. People with ALS may eventually require ventilator support, if they choose to have that treatment. Common causes of death in people with ALS are pneumonia, pulmonary embolism, lung failure, or heart failure, usually within a few years after symptoms begin. However, some people live with the disease for many years.