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.

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

In about 10% of cases, ALS is caused by a genetic defect. In other 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 1 out of every 100,000 people.

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

Symptoms usually do not develop until after age 50. Persons with ALS have a loss of muscle strength and coordination that eventually gets worse. This eventually makes one unable to do routine tasks such as going up steps, getting out of a chair, or swallowing.

Breathing or swallowing muscles may be the first muscles affected. As the disease gets worse, more muscle groups develop problems.

ALS does not affect the senses (sight, smell, taste, hearing, touch), bladder or bowel function, or a person's ability to think or reason.

Symptoms include:

• Difficulty breathing
• Difficulty swallowing
  • Gagging
  • Chokes easily
• Head drop due to weak spinal and neck muscles
• Muscle cramps
• Muscle weakness that slowly gets worse
  • Commonly involves one part of the body first, such as the arm or hand
  • Eventually leads to difficulty lifting, climbing stairs, and walking
• Paralysis
• Speech problems, such as a slow or abnormal speech pattern
• Voice changes, hoarseness

Additional symptoms that may be associated with this disease:

• Drooling
• Muscle contractions
• Muscle spasms
• Ankle, feet, and leg swelling
• Weight loss