Amyotrophic lateral sclerosis (ALS), also called Lou Gehrig's disease after the baseball star who died of it, is the most common form of motor neuron disease that occurs in adults (see nervous system, diseases of the). It strikes an estimated 1 to 2 out of every 100,000 persons worldwide. Onset most commonly occurs between the ages of 50 and 60. ALS patients have increasing problems with muscle weakness, including the muscles of the arms or legs, as well as the speaking or swallowing muscles. Respiratory muscles are eventually involved, and death occurs when these muscles become too weak to support respiration, usually 3 to 10 years after onset.
ALS is characterized by the death of the motor neurons that determine muscle strength and control movement. As motor neurons die, muscles cannot receive the full impulses from the brain and spinal cord nerves. The muscles become progressively weaker and shrink (atrophy), and movements become slow and stiff (spastic). Muscle degeneration often starts in the hands and arms, spreading to other parts of the body, and finally to the respiration muscles.
About 10% of ALS patients have a family history of the disease. Gene analysis techniques have located an abnormal gene in about half of these families, but the cause in the remaining families with ALS is not known. Patients without a family history are considered to have sporadic ALS.
There is no effective treatment for ALS, but a number of drug trials are being conducted. The drug riluzole, which was approved for use in 1995, has been found to slow the nerve damage a little, providing a little more time for a person with ALS. Much can be done to help ALS patients as they lose muscle strength. Assistive devices, such as leg braces, walkers, and wheelchairs, can help maintain a certain level of independence. The ultimate issue for an ALS patient is whether to choose ventilator support when muscles of respiration fail.