amyotrophic lateral sclerosis

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amyotrophic lateral sclerosis

(ALS) (ā'mīətrōf`ik, sklĭrō`sĭs) or

motor neuron disease,

sometimes called Lou Gehrig's disease, degenerative disease that affects motor neurons in the brainbrain,
the supervisory center of the nervous system in all vertebrates. It also serves as the site of emotions, memory, self-awareness, and thought. Anatomy and Function
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 and spinal cordspinal cord,
the part of the nervous system occupying the hollow interior (vertebral canal) of the series of vertebrae that form the spinal column, technically known as the vertebral column.
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, preventing them from sending impulses to the muscles. The muscles atrophy quickly, causing weakness, paralysis, and eventual death, usually when the muscles that control respiration fail. The intellect, eye motion, and bladder control are not affected. ALS sometimes originates in the brain, causing initial symptoms such as difficulty in swallowing or talking; in other cases it originates in the spinal cord, causing initial symptoms such as weakness in the extremities. About a tenth of ALS cases are hereditary. ALS usually develops after age 40; more men are affected than women.

There appear to be several causes of ALS, and a number of genetic mutations have been linked to about a third of all ALS cases. In 1991 a research team led by Teepu Siddique and Robert H. Brown, Jr. located a gene for familial ALS on chromosome 21. A later discovery pinpointed a mutation in the gene that codes for an enzyme, superoxide dismutase (SOD), as responsible for a percentage of familial cases. These defects do not appear to be present in the more common nonfamilial, or "sporadic," form of the disease. Since then, however, two defective proteins have been found to be associated with both inherited and sporadic ALS, one involved in regulating RNA and the other involved in clearing defective or unneeded proteins. Scientists also have studied the buildup of the chemical glutamate that occurs in ALS patients. Glutamate normally acts as a neurotransmitterneurotransmitter,
chemical that transmits information across the junction (synapse) that separates one nerve cell (neuron) from another nerve cell or a muscle. Neurotransmitters are stored in the nerve cell's bulbous end (axon).
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 in the brain, with excess amounts being absorbed by the cells. In ALS patients the reabsorption process fails, and the buildup of glutamate selectively destroys motor neurons. Other possible causes of ALS include defects in the gene that makes the neurofilament proteins that support nerve cell axons, and antibodies that interfere with calcium channels in the cells and cause a toxic buildup of calcium in the neurons.

There is no cure for ALS. Devices such as wheelchairs and speech synthesizers can help patients maintain independence. Research into treatment has concentrated on neurotrophic factors (proteins that assist nerve growth and health) and glutamate blockers. Rilutek (formerly Riluzole), the first drug approved by the Food and Drug Administration for treatment of ALS (1995), adds a few months to the life expectancy of most patients but does not relieve symptoms. Another drug, myotrophin, seemed somewhat promising in early studies (1996), but its effectiveness was not confirmed and it has not been approved. Baseball star Lou GehrigGehrig, Lou
(Louis Gehrig) , 1903–41, American baseball player, b. New York City. He studied and played baseball at Columbia, where he was spotted by a scout for the New York Yankees.
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 died of ALS in 1941, bringing it national attention.

Amyotrophic Lateral Sclerosis

 

an organic disease of the central nervous system, with predominant affection of the spinal cord and medulla oblongata. First described in 1865 by the French neuropathologist J. Charcot.

About 3 percent of all organic lesions of the central nervous system are due to amyotrophic lateral sclerosis, which is observed mainly in the 30- to 50-year age group. The causes of the disease are unknown. The majority of scientists regard the condition as degenerative, but a theory of viral causation is being developed. The onset of amyotrophic lateral sclerosis is accompanied by gradually intensifying weakness of arms and legs. Swallowing and speech become impaired in proportion to the progress of the disease. As a result of weakness of the muscles of the tongue, soft palate, and vocal cords, choking occurs during eating, food enters the nose, and speech becomes nasalized and sometimes completely impossible. Tendon reflexes of the arms and legs are intensified, and pathological reflexes appear. Sensitivity disorder is occasionally present. Amyotrophic lateral sclerosis is chronic.

Treatment Medicinal preparations which benefit the central nervous system and the metabolism in damaged tissues (lipotserebrin, dibazol, proserine, vitamins B12, B1 and E), and physiotherapy. Constant and attentive care of the patient is necessary.

REFERENCE

Khondkarian, O. A. “Bokovoi amiotroficheskii skleroz.” In Mnogotomnoe rukovodstvo po nevrologii, vol. 3, book 1. Edited by S. N. Davidenkov. Moscow, 1962. (A bibliography is included.)

V. S. ROTENBERG

amyotrophic lateral sclerosis

[¦a′mī·ə¦träf·ik ′la·trəl sklə′rō·səs]
(medicine)
A progressive neurological disorder characterized by loss of connection and death of motor neurons in the cortex and spinal cord.
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