Medical Definition of Motor neuron disease

  • Medical Author:
    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Motor neuron disease: A group of related diseases of the nervous system that are characterized by steadily progressive deterioration of the motor neurons in the brain, brainstem, and spinal cord. Abbreviated MND. Motor neurons are the nerve cells along which the brain sends instructions, in the form of electrical impulses, to the muscles. The degeneration of motor neurons leads to weakness and wasting of muscles. MND usually first affects the arms or legs. Then shoulders and other muscles may be affected. Weakness and wasting in the muscles of the face and throat may cause problems with speech, chewing, and swallowing. MND does not affect touch, taste, sight, smell, or hearing, nor does it directly affect bladder, bowel, or sexual function. In the vast majority of cases, the intellect remains unchanged. Subtypes of MND are distinguished by the major site of degeneration of the motor neurons'for example, amyotrophic lateral sclerosis (Lou Gehrig's disease), progressive spinal muscular atrophy, progressive bulbar palsy, and primary lateral sclerosis. The prognosis is dependent upon the type of MND.

Reviewed on 12/11/2018

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