What Is Motor Neuron Disease?
Reviewed: Dr. Gromatzky
3. Lower Motor Neuron Disease
Lower motor neuron (LMN) disease occurs when a lesion affects nerve fibers that are traveling from the anterior gray column of the spinal cord to the target muscle. One of the main characteristics seen in LMN disease is the paralysis or flaccidity (loss of muscle tone).
This contrasts with UMN disease where the paralysis is accompanied by excessive muscle tone. Other associated symptoms include fasciculations, fibrillations, hyporeflexia, and hypotonia. It is often accompanied by muscle atrophy, especially in chronic cases. The most common causes of LMN disease are trauma to the peripheral nerves, polio, Guillain Barre syndrome, cauda equina syndrome, and in some cases amyotrophic lateral sclerosis.
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