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Amyotrophic Lateral Sclerosis and Other Motor Neuron Diseases

by Michael Rubin, MDCM

Amyotrophic lateral sclerosis (ALS) and other motor neuron diseases (MNDs) are characterized by steady, relentless, progressive degeneration of corticospinal tracts, anterior horn cells, bulbar motor nuclei, or a combination. Symptoms vary in severity and may include muscle weakness and atrophy, fasciculations, emotional lability, and respiratory muscle weakness. Diagnosis involves nerve conduction studies, electromyography, and exclusion of other disorders via MRI and laboratory tests. Treatment is supportive.

ALS (Lou Gehrig disease, Charcot syndrome) is the most common MND. MNDs may involve the CNS as well as the peripheral nervous system. Usually, etiology is unknown. Nomenclature and symptoms vary according to the part of the motor system most affected. Myopathies have similar features but are disorders of the muscle membrane, contractile apparatus, or organelles (see Congenital Myopathies).

MNDs can be classified as upper and lower; some disorders (eg, ALS) have features of both. MNDs are more common among men, most often appearing during their 50s.

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