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Facial Motor Evoked Potential Techniques and Functional Prediction during Cerebello-pontine Angle Surgery
Korean J Clin Lab Sci 2018;50:470-476  
Published on December 31, 2018
Copyright © 2018 Korean Society for Clinical Laboratory Science.

Jae-Seung Baek1, Sang-Ku Park1, Dong-Jun Kim1, Chan-Woo Park1, Sung-Hyuk Lim1, Jang Ho Lee2, Young-Kuk Cho3

1Department of Neurology, Samsung Medical Center, Seoul, Korea 2Department of Clinical Laboratory Science, Semyung University, Jecheon, Korea 3Department of Medical Laboratory Science, Seoyeong University, Gwangju, Korea
Correspondence to: Jae-Seung Baek
Department of Neurology, Samsung Medical Center, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea
Tel: 82-2-3410-2737 Fax: 82-2-3410-2759 E-mail:
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Facial motor evoked potential (FMEP) by multi-pulse transcranial electrical stimulation (mpTES) can complement free-running electromyography (EMG) and direct facial nerve stimulation to predict the functional integrity of the facial nerve during cerebello-pontine angle (CPA) tumor surgery. The purpose of this paper is to examine the standardized test methods and the usefulness of FMEP as a predictor of facial nerve function and to minimize the incidence of facial paralysis as an aftereffect of surgery. TES was delivered through electrode Mz (cathode) - M3/M4 (anode), and extracranially direct distal facial muscle excitation was excluded by the absence of single pulse response (SPR) and by longer onset latency (more than 10 ms). FMEP from the orbicularis oris (o.oris) and the mentalis muscle simultaneously can improve the accuracy and success rate compared with FMEP from the o.oris alone. Using the methods described, we can effectively predict facial nerve outcomes immediately after surgery with a reduction of more than 50% of FMEP amplitude as a warning criterion. In conclusion, along with free-running EMG and direct facial nerve stimulation, FMEP is a useful method to reduce the incidence of facial paralysis as a sequela during CPA tumor surgery.
Keywords : Cerebellopontine angle, Facial nerve, Intraoperative monitoring, Motor evoked potential, Transcranial electrical stimulation

December 2018, 50 (4)
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