title: [Hemimasticatory muscle spasm: an electromyogram analysis].
abstract: OBJECTIVE
  To investigate the usefulness of electromyogram (EMG) in the diagnosis of the patients with hemimasticatory spasm (HMS).
  
  
  METHODS
  Four cases with HMS were reported. All the 4 patients were undertaken needle and surface electrode EMG examination.
  
  
  RESULTS
  Needle electrode EMG of the 4 patients with HMS showed grouped potentials synchronously with the onset of the spasm, which indicated abnormal excitatory electrical activities of the trigeminal nerve resulting in involuntary masticatory muscle movements.
  
  
  CONCLUSIONS
  It is very important to use EMG for the diagnosis of HMS.
authors.affiliation: Department of Temporomandibular Joint Disorder and Orofacial Pain, Peking University School of Stomatology, Beijing 100081, China.
authors.forename: Yu-wei
authors.initials: YW
authors.lastname: Wang
authors.forename: Xu-chen
authors.initials: XC
authors.lastname: Ma
authors.forename: Zhen-kang
authors.initials: ZK
authors.lastname: Zhang
authors.forename: Ding-guo
authors.initials: DG
authors.lastname: Shen
authors.forename: Feng-xia
authors.initials: FX
authors.lastname: Su
authors.forename: Kai-yuan
authors.initials: KY
authors.lastname: Fu
mesh_terms: D000328:Adult; D003937:Diagnosis, Differential; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008410:Masticatory Muscles / Q000503:physiopathology*; D008875:Middle Aged; D013035:Spasm / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*