Amyotrophic lateral sclerosis (ALS) is a progressive neurological disease that causes dysfunction of the nerves that control muscle movement. (The word “amyotrophic” comes from Greek roots that mean “without nourishment to muscles” and refers to the loss of signals nerve cells normally send to muscle cells. “Lateral” means “to the side” and refers to the location of the damage in the spinal cord. “Sclerosis” means “hardened” and refers to the hardened nature of the spinal cord in advanced ALS.) Over time, this leads to muscle weakness, gradually affecting how the body functions. In the late stages of ALS, the condition affects nerves that control breathing and other vital bodily functions, resulting in death.
There is no known cause or cure for ALS. A medication called Riluzole may extend life expectancy by about two to three months. Non-invasive ventilation may result in both improved quality and length of life. ALS is the most common type of motor neuron disease (MND); in the US, most people use the term ALS to mean MND. ALS is sometimes also referred to as Lou Gehrig's disease, after the famous baseball player who had the condition.
Descriptions of the disease date back to at least 1824 by Charles Bell. In 1869, the connection between the symptoms and the underlying neurological problems were first described by Jean-Martin Charcot, who in 1874 began using the term amyotrophic lateral sclerosis. It became well known in the United States in the 20th century when it affected the baseball player Lou Gehrig, and later when Stephen Hawking gained fame for his scientific achievements.