title: Analysis of wave III of brain stem auditory evoked potential waveforms during microvascular decompression of cranial nerve VII for hemifacial spasm.
abstract: BACKGROUND
  Intraoperative monitoring of brain stem auditory evoked potential during microvascular decompression (MVD) prevent hearing loss (HL). Previous studies have shown that changes in wave III (wIII) are an early and sensitive sign of auditory nerve injury.
  
  
  OBJECTIVE
  To evaluate the changes of amplitude and latency of wIII of brain stem auditory evoked potential during MVD and its association with postoperative HL. Hearing loss was classified by American Academy of Otolaryngology - Head and Neck Surgery (AAO-HNS) criteria, based on changes in pure tone audiometry and speech discrimination score.
  
  
  METHODS
  Retrospective analysis of wIII in patients who underwent intraoperative monitoring with brain stem auditory evoked potential during MVD was performed. A univariate logistic regression analysis was performed on independent variables amplitude of wIII and latency of wIII at change max and On-Skin, or a final recording at the time of skin closure. A further analysis for the same variables was performed adjusting for the loss of wave.
  
  
  RESULTS
  The latency of wIII was not found to be significantly different between groups I and II. The amplitude of wIII was significantly decreased in the group with HL. Regression analysis did not find any increased odds of HL with changes in the amplitude of wIII.
  
  
  CONCLUSIONS
  Changes in wave III did not increase the odds of HL in patients who underwent brain stem auditory evoked potential s during MVD. This information might be valuable to evaluate the value of wIII as an alarm criterion during MVD to prevent HL.
authors.affiliation: *Department of Neurologic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, U.S.A., and †Department of Neuroscience, University of Pittsburgh Medical Center, Pittsburgh, PA, U.S.A., and ‡Department of Neurology, University of Pittsburgh Medical Center, Pittsburgh, PA, U.S.A.
authors.forename: Parthasarathy D
authors.initials: PD
authors.lastname: Thirumala
authors.forename: Balaji
authors.initials: B
authors.lastname: Krishnaiah
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Crammond
authors.forename: Miguel E
authors.initials: ME
authors.lastname: Habeych
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Balzer
mesh_terms: D000162:Acoustics; D000328:Adult; D000368:Aged; D001301:Audiometry, Pure-Tone; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D005260:Female; D006309:Hearing; D019569:Hemifacial Spasm / Q000503:physiopathology* / Q000601:surgery*; D006801:Humans; D016015:Logistic Models; D008297:Male; D061145:Microvascular Decompression Surgery / Q000379:methods*; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D011930:Reaction Time; D012189:Retrospective Studies; D013067:Speech Perception