Intraoperative facial electromyography and brainstem auditory evoked potential findings in microvascular decompression for hemifacial spasm: correlation with postoperative delayed facial palsy.
BACKGROUND
Delayed facial palsy (DFP) after microvascular decompression (MVD) in patients with hemifacial spasm (HFS) is not uncommon, but the cause remains unknown.


OBJECTIVE
To assess whether intraoperative electromyography (EMG) and brainstem auditory evoked potential (BAEP) can predict DFP after MVD.


METHODS
Between September 2009 and February 2011 we examined 86 patients, 9 of whom (10.4%) developed DFP after MVD on the same side. All patients underwent MVD and were followed-up for a median period of 13 months (range 6-22). We retrospectively examined intraoperative facial EMG and BAEP findings using our MVD patients' registry. We excluded secondary HFS and immediate postoperative facial palsy after MVD in this study. We assessed the prevalence and clinical characteristics of DFP and compared EMG and BAEP findings between DFP and non-DFP groups.


RESULTS
All patients recovered completely, with a mean time to recovery of 37.8 days (range 22-57). There were no significant differences between DFP and non-DFP patients in terms of the amplitude and latency of intraoperative EMG and BAEP.


CONCLUSIONS
The usefulness of intraoperative facial EMG and BAEP is limited and cannot predict DFP after MVD for HFS. We speculate that DFP after MVD is not associated with permanent nerve damage according to the EMG findings.
Department of Neurosurgery, Bundang CHA Medical Center, CHA University, Seongnam, South Korea.
Hee Jin
HJ
Kim
Young Seok
YS
Park
Ju Seok
JS
Ryu
Ryoong
R
Huh
Inbo
I
Han
Dong Ah
DA
Shin
Tae Gon
TG
Kim
Kyung Gi
KG
Cho
Sang-Sup
SS
Chung
D000328:Adult; D004576:Electromyography / Q000379:methods*; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D005158:Facial Paralysis / Q000209:etiology* / Q000517:prevention & control; D005260:Female; D005500:Follow-Up Studies; D019569:Hemifacial Spasm / Q000601:surgery*; D006801:Humans; D008297:Male; D061145:Microvascular Decompression Surgery / Q000009:adverse effects* / Q000379:methods; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D011184:Postoperative Period; D011379:Prognosis; D012189:Retrospective Studies; D016896:Treatment Outcome