What is amyotrophic lateral sclerosis (ALS)?

Updated: Jul 20, 2021
  • Author: Ryan Ghusayni, MD; Chief Editor: Andrew K Chang, MD, MS  more...
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Amyotrophic lateral sclerosis (ALS), also known as Charcot's disease and Lou Gehrig's disease, is a disease of unknown cause characterized by slowly progressive degeneration of upper motor neurons (UMNs) and lower motor neurons (LMNs). [1]

The UMN findings include hyperreflexia and spasticity. They result from degeneration of the lateral corticospinal tracts in the spinal cord. The LMN findings include weakness, atrophy, and fasciculations. They are a direct consequence of muscle denervation via destruction of the anterior horn cell. ALS is eventually fatal because of respiratory muscle weakness. Aspiration pneumonia and medical complications of immobility contribute to morbidity. [2] Although ALS is incurable, there are treatments that can prolong meaningful quality of life; therefore, diagnosis is important to patients and families.

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