Hemimasticatory spasm misdiagnosed as other mimickers: Report of two cases

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. Neurology Asia 2015; 20(1) : 73 – 77 Address correspondence to: Beom Seok Jeon, MD, PhD, Department of Neurology, Seoul National University Hospital, Seoul, 110-744, Korea. Tel: 82-2-2072-2876, Fax: 82-2-3672-7553, e-mail: [email protected] INTRODUCTION Hemimasticatory spasm (HMS), which is characterized by unilateral, paroxysmal, involuntary contractions of one or more masticatory muscles, is a rare disorder of the trigeminal nerve motor branch. Gowers first described HMS in 1897, and only a few cases have been reported since then. Because of its rarity, HMS may be confused with other facial movement disorders, such as hemifacial spasm (HFS), temporomandibular joint disorder (TMD), oromandibular dystonia (OMD), facial myoclonus, facial tics, or other causes of abnormal facial movements. To alert clinicians of this disorder, we present here two Korean patients with HMS that were initially misdiagnosed as HFS and OMD.