A prewarning sign for hearing loss by brainstem auditory evoked potentials during microvascular decompression surgery for hemifacial spasm

Background: Permanent hearing loss after posterior fossa microvascular decompression (MVD) for typical trigeminal neuralgia (TTN) is one of the possible complications of this procedure. Intraoperative brainstem auditory evoked potentials (BAEPs) are used for monitoring the function of cochlear nerve during cerebellopontine angle (CPA) microsurgery. Level-specific (LS)-CE-Chirp® BAEPs are the most recent evolution of classical click BAEP, performed both in clinical studies and during intraoperative neuromonitoring (IONM) of acoustic pathways during several neurosurgical procedures. Methods: Since February 2016, we routinely use LS-CE-Chirp® BAEPs for monitoring the function of cochlear nerve during CPA surgery, including MVD for trigeminal neuralgia. From September 2011 to December 2018, 71 MVDs for TTN were performed in our department, 47 without IONM of acoustic pathways (Group A), and, from February 2016, 24 with LS-CE-Chirp BAEP (Group B). Results: Two patients of Group A developed a permanent ipsilateral anacusia after MVD. In Group B, we did not observe any permanent acoustic deficit after surgery. In one case of Group B, during arachnoid dissection, intraoperative LS-CE-Chirp BAEP showed a temporary lag of V wave, resolved in 5 min after application of intracisternal diluted papaverine (0.3% solution without excipients). Conclusion: MVD is widely considered a definitive surgical procedure in the management of TTN. Even though posterior fossa MVD is a safe procedure, serious complications might occur. In particular, the use of IONM of acoustic pathways during MVD for TTN might contribute to prevention of postoperative hearing loss.

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Real-time intraoperative monitoring of brainstem auditory evoked potentials during microvascular decompression for hemifacial spasm

Journal of Neurosurgery ◽

10.3171/2015.10.jns151224 ◽

2016 ◽

Vol 125 (5) ◽

pp. 1061-1067 ◽

Cited By ~ 14

Author(s):

Byung-Euk Joo ◽

Sang-Ku Park ◽

Kyung-Rae Cho ◽

Doo-Sik Kong ◽

Dae-Won Seo ◽

...

Keyword(s):

Evoked Potentials ◽

Hearing Impairment ◽

Hemifacial Spasm ◽

Microvascular Decompression ◽

Intraoperative Monitoring ◽

Auditory Evoked Potentials ◽

Brainstem Auditory Evoked Potentials ◽

Stimulation Rate ◽

Preliminary Study ◽

Warning Criteria

OBJECTIVE The aim of this study was to define a new protocol for intraoperative monitoring (IOM) of brainstem auditory evoked potentials (BAEPs) during microvascular decompression (MVD) surgery to treat hemifacial spasm (HFS) and to evaluate the usefulness of this new protocol to prevent hearing impairment. METHODS To define the optimal stimulation rate, estimate the number of trials to be averaged, and identify useful warning criteria in IOM of BAEPs, the authors performed a preliminary study of 13 patients with HFS in 2010. They increased the stimulation rate from 10.1 Hz/sec to 100.1 Hz/sec by 10-Hz increments, and they elevated the average time from 100 times to 1000 times by 100-unit increments at a fixed stimulus rate of 43.9 Hz. After defining the optimal stimulation rate and the number of trials that needed to be averaged for IOM of BAEPs, they also identified the useful warning criteria for this protocol for MVD surgery. From January to December 2013, 254 patients with HFS underwent MVD surgery following the new IOM of BAEPs protocol. Pure-tone audiometry and speech discrimination scoring were performed before surgery and 1 week after surgery. To evaluate the usefulness of the new protocol, the authors compared the incidence of postoperative hearing impairment with the results from the group that underwent MVD surgery prior to the new protocol. RESULTS Through a preliminary study, the authors confirmed that it was possible to obtain a reliable wave when using a stimulation rate of 43.9 Hz/sec and averaging 400 trials. Only a Wave V amplitude loss > 50% was useful as a warning criterion when using the new protocol. A reliable BAEP could be obtained in approximately 9.1 seconds. When the new protocol was used, 2 patients (0.8%) showed no recovery of Wave V amplitude loss > 50%, and only 1 of those 2 patients (0.39%) ultimately had postoperative hearing impairment. When compared with the outcomes in the pre-protocol group, hearing impairment incidence decreased significantly among patients who underwent surgery with the new protocol (0.39% vs 4.02%, p = 0.002). There were no significant differences between the 2 surgery groups regarding other complications, including facial palsy, sixth cranial nerve palsy, and vocal cord palsy. CONCLUSIONS There was a significant decrease in postoperative hearing impairment after MVD for HFS when the new protocol for IOM of BAEPs was used. Real-time IOM of BAEPs, which can obtain a reliable BAEP in less than 10 seconds, is a successful new procedure for preventing hearing impairment during MVD surgery for HFS.

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Does Intraoperative Monitoring of Auditory Evoked Potentials Reduce Incidence of Hearing Loss as a Complication of Microvascular Decompression of Cranial Nerves?

Neurosurgery ◽

10.1227/00006123-198902000-00017 ◽

1989 ◽

Vol 24 (2) ◽

pp. 257-263 ◽

Cited By ~ 70

Author(s):

Aage R. Møller ◽

Margareta B. Møller

Keyword(s):

Hearing Loss ◽

Evoked Potentials ◽

Hemifacial Spasm ◽

Microvascular Decompression ◽

Auditory Evoked Potentials ◽

Cranial Nerves ◽

Hearing Threshold ◽

Speech Discrimination ◽

Compound Action Potentials

Abstract During a 14-month period, 129 individuals underwent 140 operations for microvascular decompression to relieve hemifacial spasm, disabling positional vertigo, tinnitus, or trigeminal neuralgia at our institution. Seven patients were operated upon twice on the same side and 4 were operated upon on both sides at different times. In each case, the brainstem auditory evoked potentials were monitored intraoperatively by the same neurophysiologist. In 75 of these operations, compound action potentials were also recorded from the exposed 8th nerve. Comparison of speech discrimination scores before the operation and at the time fo discharge showed that at discharge, discrimination had decreased in 7 patients by 15% or more and increased in 4 patients by 15% or more, in 2 patients by as much as 52%. Essentially similar results were obtained when preoperative speech discrimination scores were compared with results obtained from the 87 patients who returned for a follow-up visit between 3 and 6 months after discharge. Only one patient lost hearing (during a second operation to relieve hemifacial spasm). Another patient (also operated upon to relieve hemifacial spasm) suffered noticeable hearing loss postoperatively, but had recovered nearly normal hearing by 4 months after the operation. Nine patients had an average elevation of the hearing threshold for pure tones in the speech frequency range (500 to 2000 Hz) of 11 dB or more at 4 to 5 days after the operation; 8 of these had fluid in their middle ears that most likely contributed to the hearing loss. Threshold elevations occurred at 4000 Hz and 8000 Hz in 19 and 29 ears, respectively.

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Reduction in high-frequency hearing loss following technical modifications to microvascular decompression for hemifacial spasm

Journal of Neurosurgery ◽

10.3171/2014.12.jns141699 ◽

2015 ◽

Vol 123 (4) ◽

pp. 1059-1064 ◽

Cited By ~ 12

Author(s):

Parthasarathy Thirumala ◽

Andrew M. Frederickson ◽

Jeffrey Balzer ◽

Donald Crammond ◽

Miguel E. Habeych ◽

...

Keyword(s):

Hearing Loss ◽

Hemifacial Spasm ◽

Microvascular Decompression ◽

High Frequency ◽

Auditory Evoked Potentials ◽

Pure Tone Audiometry ◽

Brainstem Auditory Evoked Potentials ◽

Vestibulocochlear Nerve ◽

High Frequency Hearing Loss ◽

Technical Modifications

OBJECT Microvascular decompression is a safe and effective procedure to treat hemifacial spasm, but the operation poses some risk to the patient’s hearing. While severe sensorineural hearing loss across all frequencies occurs at a low rate in experienced hands, a recent study suggests that as many as one-half of patients who undergo this procedure may experience ipsilateral high-frequency hearing loss (HFHL), and as many as one-quarter may experience contralateral HFHL. While it has been suggested that drill-related noise may account for this finding, this study was designed to examine the effect of a number of techniques designed to protect the vestibulocochlear nerve from operative manipulation on the incidence of HFHL. METHODS Pure-tone audiometry was performed both preoperatively and postoperatively on 67 patients who underwent microvascular decompression for hemifacial spasm during the study period. A change of greater than 10 dB at either 4 kHz or 8 kHz was considered to be HFHL. Additionally, the authors analyzed intraoperative brainstem auditory evoked potentials from this patient cohort. RESULTS The incidence of ipsilateral HFHL in this cohort was 7.4%, while the incidence of contralateral HFHL was 4.5%. One patient (1.5%; also included in the HFHL group) experienced an ipsilateral nonserviceable hearing loss. CONCLUSIONS The reduced incidence of HFHL in this study suggests that technical modifications including performing the procedure without the use of fixed retraction may greatly reduce, but not eliminate, the occurrence of HFHL following microvascular decompression for hemifacial spasm.

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