RESUMEN
Hemimasticatory spasm is a rare neurologic disorder characterized by unilateral, paroxysmal involuntary contraction of the masticatory muscles. It can be confused with other unilateral facial spasms. In this report, we present two patients with hemimasticatory spasm who were initially misdiagnosed with other disorders. The first patient was a 54-year-old man with a 9-year history of right facial spasm. He underwent microvascular decompression, without benefit, at another hospital with the diagnosis of hemifacial spasm two years prior to presenting at our hospital.On examination, right masseter and temporalis muscles had irregular contractions with twitches and prolonged spasms. His brain magnetic resonance imaging was normal.He showed a good response to carbamazepine. The second case was a 60-year-old man presented with a 10-year history of jaw-closing movement. Previous treatment for temporomandibular joint disorder was ineffective. He was previously diagnosed as oromandibular dystonia at another hospital, and biperiden and diazepam treatment resulted in slight improvement. There was tonic contraction and hypertrophy of the left masseter. He improved with carbamazepine. These cases illustrate the importance of hemimasticatory spasm as differential diagnosis, and the good response to carbamazepine.