[Hemimasticatory muscle spasm: an electromyogram analysis].
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.
Wang
Yu-wei
YW
Department of Temporomandibular Joint Disorder and Orofacial Pain, Peking University School of Stomatology, Beijing 100081, China.
Ma
Xu-chen
XC
Zhang
Zhen-kang
ZK
Shen
Ding-guo
DG
Su
Feng-xia
FX
Fu
Kai-yuan
KY
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*