Intraoperative facial motor evoked potentials monitoring with transcranial electrical stimulation for preservation of facial nerve function in patients with large acoustic neuroma.
BACKGROUND
Although various monitoring techniques have been used routinely in the treatment of the lesions in the skull base, iatrogenic facial paresis or paralysis remains a significant clinical problem. The aim of this study was to investigate the effect of intraoperative facial motor evoked potentials monitoring with transcranial electrical stimulation on preservation of facial nerve function.


METHODS
From January to November 2005, 19 patients with large acoustic neuroma were treated using intraoperative facial motor evoked potentials monitoring with transcranial electrical stimulation (TCEMEP) for preservation of facial nerve function. The relationship between the decrease of MEP amplitude after tumor removal and the postoperative function of the facial nerve was analyzed.


RESULTS
MEP amplitude decreased more than 75% in 11 patients, of which 6 presented significant facial paralysis (H-B grade 3), and 5 had mild facial paralysis (H-B grade 2). In the other 8 patients, whose MEP amplitude decreased less than 75%, 1 experienced significant facial paralysis, 5 had mild facial paralysis, and 2 were normal.


CONCLUSIONS
Intraoperative TCEMEP can be used to predict postoperative function of the facial nerve. The decreased MEP amplitude above 75 % is an alarm point for possible severe facial paralysis.
Liu
Bai-yun
BY
Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China. liubaiyun1212@163.com
Tian
Yong-ji
YJ
Liu
Wen
W
Liu
Shu-ling
SL
Qiao
Hui
H
Zhang
Jun-ting
JT
Jia
Gui-jun
GJ
D000328:Adult; D000368:Aged; D004599:Electric Stimulation Therapy; D004576:Electromyography; D019054:Evoked Potentials, Motor; D005154:Facial Nerve / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D009464:Neuroma, Acoustic / Q000503:physiopathology*