Amyotrophic lateral sclerosis, or ALS, is a disease of the nerve cells in the brain, brain stem and spinal cord that control voluntary muscle movement.
ALS is also known as Lou Gehrig disease.
Lou Gehrig disease; ALS; Upper and lower motor neuron disease; Motor neuron disease
One out of 10 cases of ALS is due to a genetic defect. The cause is unknown in most other cases.
In ALS, motor nerve cells (neurons) waste away or die, and can no longer send messages to muscles. This eventually leads to muscle weakening, twitching, and an inability to move the arms, legs, and body. The condition slowly gets worse. When the muscles in the chest area stop working, it becomes hard or impossible to breathe.
ALS affects approximately 5 out of every 100,000 people worldwide.
Having a family member who has a hereditary form of the disease is a risk factor for ALS. Other risks include military service. Some risk factors are controversial.