What is hemifacial spasm?

Updated: Sep 16, 2019
  • Author: Steven Gulevich, MD; Chief Editor: Nicholas Lorenzo, MD, MHA, CPE  more...
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First described by Gowers in 1884, hemifacial spasm represents a segmental myoclonus of muscles innervated by the facial nerve. Hemifacial spasm presents in the fifth or sixth decade of life, almost always unilaterally, although bilateral involvement may occur rarely in severe cases. Hemifacial spasm generally begins with brief clonic movements of the orbicularis oculi and spreads over years to other facial muscles (corrugator, frontalis, orbicularis oris, platysma, zygomaticus). [1, 2]

Clonic movements progress to sustained tonic contractions of involved musculature. Chronic irritation of the facial nerve or nucleus, the near-universal cause of hemifacial spasm, may arise from numerous underlying conditions.

Facial musculature is subject to the same movement disorders as muscles of the limbs or trunk. Myoclonus, dystonia, and other movement disorders present with specific syndromes in the facial musculature. An understanding of the underlying mechanism leads to appropriate diagnostic evaluation and potential treatment.

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