Objective: The primary aim of the study was to assess the sensitivity and specificity of intraoperative monitoring in predicting postoperative hearing loss during microvascular decompression (MVD).
Methods: The study was designed as an examination of the diagnostic accuracy of brainstem evoked potentials compared with reference standard for nonserviceable hearing loss (Class C/D), which is a change of more than 50 dB on pure tone threshold, and change of speech discrimination score of more than 50. All patients underwent surgery and audiograms at a University of Pittsburgh Medical Center facility in the study period 2005-2012. All participants received a pre- and postaudiogram within 90 days before or after the operation. During the operation, participants received intraoperative monitoring with a supervising physician. A total of 238 patients were selected. Brainstem auditory evoked potentials (BAEPs) were indexed into categories of change based on their maximum change and response at the end of surgery. Differences in hearing outcome by BAEP change were analyzed.
Results: Age and sex did not affect outcomes. Patient outcome was affected by condition. The BAEP categories significant changes, transient loss, and persistent loss show a sensitivity/specificity of 0.905/0.701, 0.667/0.903, and 0.429/0.972, respectively. The receiver operating characteristic curve has an area under the curve of 0.870 with a 95% confidence interval of 0.783 to 0.957.
Conclusions: Loss of wave V during MVD is a specific indicator of postoperative hearing loss. The current alarm criteria used to warn the surgeon is a sensitive indicator of impending postoperative hearing loss.
Classification of evidence: This study provides Class IV evidence that in patients undergoing MVD, intraoperative BAEPs accurately identifies those who will have postoperative hearing loss.
© 2014 American Academy of Neurology.