Background: Hemimasticatory spasm is a very rare movement disorder characterized by unilateral, involuntary, paroxysmal contractions of the jaw-closing muscles, causing clinically brief twitches and/or spasms.
Case report: A 62-year-old female consulted us with a 30-year history of unusual involuntary twitches in the preauricular region and spasms that hampered jaw opening. During these spasms, she could not open her mouth. On physical examination, we also observed hypertrophy of the masseter and temporalis muscles, which can be features of hemimasticatory spasm. She was treated with botulinum toxin type A, with excellent response. Here, we present her case and review the literature.
Discussion: Hemimasticatory spasm is a rare movement disorder. Given the excellent response to botulinum toxin type A treatment, it should be considered within the spectrum of facial spasms.
Keywords: Hemimasticatory spasm; botulinum toxin; jaw-closing spasm.