Motor Neuron Disorder


Lead Author(s): 

Jonathan S. Kirschner, MD, RMSK
Se Won Lee, MD

Supporting Author(s): 

Sylvia I. Watkins-Castillo, PhD

Motor neuron diseases (MNDs) are a group of rare disorders affecting motor neurons (nerve cells) that transmit signals from the brain to the muscles in the body. They present with muscle weakness and wasting, resulting in impaired walking, fine motor skills, limitations in activities of daily living, swallowing, speech, and eventually breathing. Motor neuron diseases can be classified into acquired (non-inherited) or inherited. There are no direct tests to identify MNDs, with diagnosis often the result of ruling out other conditions that early symptoms can mimic. In addition, there is no cure or standard treatment for MNDs. Generally, treatment consists of addressing symptoms, compensating for impairments, and providing palliative and supportive care. Some MNDs stabilize for long periods of time, while some rapidly progress to death in a few years.

Amyotrophic lateral sclerosis (ALS), often known as Lou Gehrig’s disease, is the most common type of motor neuron disease. It is usually rapidly progressive, has an unclear cause, and lacks a definite cure. According to the ALS registry, prevalence is 4 to 5 per 100,000 people, affecting more than 13,000 people1 Prevalence has been increasing over time due to better identification of cases. It is a fatal condition with short life expectancy after diagnosis.

  • 1. Mehta P, Kaye W, Bryan L, et al. Prevalence of amyotrophic lateral sclerosis - United States, 2012-2013. MMWR Surveill Summ 2016;65(8):1-12.


  • Fourth Edition

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