title: Analysis of interpeak latencies of brainstem auditory evoked potential waveforms during microvascular decompression of cranial nerve VII for hemifacial spasm.
abstract: OBJECTIVE
  Microvascular decompression (MVD) of the facial nerve is an effective treatment for patients with hemifacial spasm. Intraoperative monitoring of brainstem auditory evoked potentials (BAEPs) during MVD can reduce the incidence of hearing loss. In this study the authors' goal was to evaluate changes in interpeak latencies (IPLs) of Waves I-V, Waves III-V, and Waves I-III of BAEP Waveforms I, III, and V during MVD and correlate them with postoperative hearing loss. To date, no such study has been performed. Hearing loss is defined as nonuseful hearing (Class C/D), which is a pure tone average of more than 50 dB and/or speech discrimination score of less than 50%.
  
  
  METHODS
  The authors performed a retrospective analysis of IPLs of BAEPs in 93 patients who underwent intraoperative BAEP monitoring during MVD. Patients who did not have hearing loss were in Class A/B and those who had hearing loss were in Class C/D.
  
  
  RESULTS
  Binary logistic regression analysis of independent IPL variables was performed. A maximum change in IPLs of Waves I-III and Waves I-V and on-skin change in IPLs of Waves I-V increases the odds of hearing loss. However, on adjusting the same variables for loss of response, change in IPLs did not increase the odds of hearing loss.
  
  
  CONCLUSIONS
  Changes in IPL measurements did not increase the odds of postoperative hearing loss. This information might be helpful in evaluating the value of IPLs as alarm criteria during MVD to prevent hearing loss.
authors: Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA. thirumalapd@upmc.edu
authors: Parthasarathy D
authors: PD
authors: Thirumala
authors: Preethi
authors: P
authors: Ilangovan
authors: Miguel
authors: M
authors: Habeych
authors: Donald J
authors: DJ
authors: Crammond
authors: Jeffrey
authors: J
authors: Balzer
mesh_terms: D001301:Audiometry, Pure-Tone; D004576:Electromyography; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D005154:Facial Nerve / Q000601:surgery; D005155:Facial Nerve Diseases / Q000150:complications / Q000601:surgery*; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis / Q000453:epidemiology / Q000517:prevention & control*; D019569:Hemifacial Spasm / Q000209:etiology / Q000601:surgery*; D006801:Humans; D015994:Incidence; D007431:Intraoperative Complications / Q000175:diagnosis / Q000453:epidemiology / Q000517:prevention & control*; D061145:Microvascular Decompression Surgery; D016343:Monitoring, Intraoperative / Q000379:methods*; D009408:Nerve Compression Syndromes / Q000150:complications / Q000601:surgery*; D011182:Postoperative Care; D011237:Predictive Value of Tests; D011300:Preoperative Care; D011930:Reaction Time; D012189:Retrospective Studies; D000159:Vestibulocochlear Nerve / Q000503:physiopathology*; D061285:Vestibulocochlear Nerve Injuries / Q000175:diagnosis / Q000453:epidemiology / Q000517:prevention & control*