Brainstem auditory evoked potential monitoring and neuro-endoscopy: two tools to ensure hearing preservation and surgical success during microvascular decompression.
BACKGROUND
The effectiveness of microvascular decompression (MVD) has made trigeminal neuralgia (TN), hemifacial spasm (HFS), glossopharyngeal neuralgia, and other cranial nerve rhizopathy diseases treatable by surgery. To ensure hearing preservation and surgical success, we have presented our experience in the application of brainstem auditory evoked potential (BAEP) monitoring and neuro-endoscopy during MVD.


METHODS
From July 2007 to October 2012, a total of 93 patients in our institution received MVD for cranial nerve rhizopathies. Among these patients, 43 had both BAEP monitoring and endoscope-assisted microsurgery for their MVD. None of the patients had undergone previous surgical treatment. Postoperative outcomes were assessed based on the medical records and clinical follow-up.


RESULTS
This study included 32 women and 11 men. There were 36 HFS cases and seven TN cases, and the median patient age at the time of MVD was 48 years. The median duration of symptoms before MVD was 4.2 years, and the median follow-up duration was 3.5 years (range 1.5 months-5 years). All of the patients had either immediate or delayed complete relief from the symptoms after MVD. One TN patient underwent gamma knife radiosurgery 3 years after MVD, and two HFS cases had recurrent slight spasms, which warranted no further treatment. There was no surgical mortality. The major complications included one HFS patient with delayed and permanent hearing loss and facial palsy, which occurred 1 week after MVD. The surgical success rate was 100%, and the hearing complication rate was 2%.


CONCLUSIONS
The results of this retrospective study emphasized the importance of BAEP monitoring and neuro-endoscopy during MVD. It is well known that BAEP monitoring can preserve hearing function, and the endoscope offers neurosurgeons a second look to identify the nerve root entry zone and confirms the position of the Teflon felt. These two tools are especially useful in difficult cases.
Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan, ROC; Department of Neurosurgery, Hsinchu Branch, Taipei Veterans General Hospital, Hsinchu, Taiwan, ROC; National Yang-Ming University School of Medicine, Taipei, Taiwan, ROC.
Cheng-Chia
CC
Lee
Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan, ROC; National Yang-Ming University School of Medicine, Taipei, Taiwan, ROC.
Chih-Hsiang
CH
Liao
Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan, ROC; National Yang-Ming University School of Medicine, Taipei, Taiwan, ROC.
Chun-Fu
CF
Lin
National Yang-Ming University School of Medicine, Taipei, Taiwan, ROC; Department of Rehabilitation, Taipei Veterans General Hospital, Taipei, Taiwan, ROC.
Tsui-Fen
TF
Yang
Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan, ROC; National Yang-Ming University School of Medicine, Taipei, Taiwan, ROC.
Sanford P C
SP
Hsu
Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan, ROC; National Yang-Ming University School of Medicine, Taipei, Taiwan, ROC. Electronic address: yushuyen@gmail.com.
Yu-Shu
YS
Yen
Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan, ROC; National Yang-Ming University School of Medicine, Taipei, Taiwan, ROC.
Yang-Hsin
YH
Shih
D004724:Endoscopy; D016057:Evoked Potentials, Auditory, Brain Stem; D005156:Facial Neuralgia; D005260:Female; D006309:Hearing / Q000502:physiology*; D006801:Humans; D008297:Male; D061145:Microvascular Decompression Surgery / Q000379:methods*; D008875:Middle Aged; D064926:Neurophysiological Monitoring; D014277:Trigeminal Neuralgia / Q000601:surgery
brainstem auditory evoked potential; endoscope; hemifacial spasm; microvascular decompression; trigeminal neuralgia