Amyotrophic Lateral Sclerosis

Alternative names:

ALS; Lou Gehrig's disease

Definition:

A disorder causing progressive loss of nervous control of voluntary muscles because of destruction of nerve cells in the brain and spinal cord.

Causes, incidence, and risk factors:

Amyotrophic Lateral Sclerosis is a disorder involving loss of the use and control of muscles. The nerves controlling these muscles shrink and disappear, which results in loss of muscle tissue due to the lack of nervous stimulation. Muscle strength and coordination decreases, beginning with the voluntary muscles (those under conscious control, such as the muscles of the arms and legs). The extent of loss of muscle control continues to progress, and more and more muscle groups become involved. There may be a loss of nervous stimulation to semi-voluntary muscles, such as the muscles that control breathing and swallowing. There is no effect on ability to think or reason. The cause is unknown.

ALS affects approximately 1 out of 100,000 people. It appears in some cases to run in families. The disorder affects men more often than women. Symptoms usually do not develop until adulthood, often not until after age 50.