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Amyotrophic lateral sclerosis

  • Definition

    Amyotrophic lateral sclerosis, or ALS, is a disease of the nerve cells in the brain and spinal cord that control voluntary muscle movement.

    ALS is also known as Lou Gehrig's disease.


    Alternative Names

    Lou Gehrig's disease; ALS; Upper and lower motor neuron disease; Motor neuron disease


    Causes, incidence, and risk factors

    In about 10% of cases, ALS is caused by a genetic defect. In the remaining cases, the cause is unknown.

    In ALS, 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 on one's own.

    ALS affects approximately 5 out of every 100,000 people worldwide.

    There are no known risk factors, except for having a family member who has a hereditary form of the disease.