The role of autonomic nervous system in the pathophysiology of hemifacial spasm.
OBJECTIVE
Despite the vascular compression of the seventh cranial nerve has been verified by the microvascular decompression surgery as the cause of hemifacial spasm (HFS), the mechanism of the disease is still unknown. We believe that the autonomic nervous system in adventitia of the offending artery may contribute to the HFS. To prove our hypothesis, we performed an experiment in SD rats.


METHODS
Moller's HFS model was adopted and the abnormal muscle response (AMR) wave was electrophysiologically monitored. With randomization, some HFS rats underwent exclusion of the offending artery or removal of the ipsilateral superior cervical ganglion. Some HFS rats with negative AMR following exclusion of the offending artery were dripped with norepinephrine onto the neurovascular conflict site.


RESULTS
With exclusion of the offending artery, AMR disappeared in 14 (70%) of the 20 HFS rats, while in three (30%) of the 10 from sham operation group (P<0·05). With ganglionectomy, AMR disappeared in 12 (75%) of the 16 HFS rats, while in two (25%) of the eight from the sham operation group (P<0·05). With norepinephrine drip, AMR reappeared in four (67%) of the six from those offending-artery-excluded HFS rats, while in zero of the six from normal-saline-dripped group (P<0·05).


CONCLUSIONS
The neurotransmitter releasing from the autonomic nervous endings in the worn adventitia of the offending artery may induce an ectopia action potential in those demyelinated facial nerve fibers expanding to the neuromuscular conjunction and trigger an attack of HFS.
Department of Neurosurgery, XinHua Hosptial, Shanghai JiaoTong University School of Medicine, China.
Qiu-Meng
QM
Zhou
Jun
J
Zhong
Wei
W
Jiao
Jin
J
Zhu
Xiao-Sheng
XS
Yang
Ting-Ting
TT
Ying
Xue-Sheng
XS
Zheng
Ning-Ning
NN
Dou
Yong-Nan
YN
Wang
Shi-Ting
ST
Li
D000818:Animals; D001341:Autonomic Nervous System / Q000098:blood supply / Q000502:physiology*; D005152:Facial Muscles / Q000098:blood supply / Q000294:innervation; D019569:Hemifacial Spasm / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013699:Temporal Arteries / Q000502:physiology