Hemi Masticatory Spasm: Series of 7 Cases and Review of Literature

Hemi masticatory spasm (HMS) is a rare movement disorder affecting muscles of mastication attributed to dysfunction of motor branch of trigeminal nerve and is characterized by painful spasm of masticatory muscles. Microvascular compression leading to focal demyelination of motor branch of trigeminal nerve is the most speculated on mechanism of HMS. Treatment options range from medical to surgical approaches, but botulinm toxin (BTX) has now become the preferred treatment.

We report a retrospective review of 7 cases of HMS, supported by electrophysiological and clinical findings. All the cases had excellent response to BTX therapy.

In this article, we highlight the delay in diagnosis of HMS attributed to rarity, long course of illness, association with hemiatrophy, "Lichen Sclerosus et Atrophicus," and scleroderma/morphea. Considering the favorable outcome to BTXs, surgical treatment can be avoided or delayed in majority except secondary cases.