title: Auditory Monitoring in Vestibular Schwannoma Surgery: Intraoperative Development and Outcome.
abstract: OBJECTIVE
  The auditory brainstem response (ABR) may be a predictor of postoperative cochlear nerve function. In this study, the course of intraoperative ABR monitoring was analyzed to find predictive markers for postoperative hearing function.
  
  
  METHODS
  From 2010 to 2012, 46 patients who had had vestibular schwannoma surgery were investigated by intraoperative ABR monitoring. The type of ABR development was identified: type A, improved or stable ABR; type B, fluctuating or deteriorated ABR; and type C, slow or sudden ABR loss. Hearing function was correlated with ABR monitoring.
  
  
  RESULTS
  The different types of ABR development showed a strong correlation with postoperative hearing (P < 0.001). ABR quality after 60% tumor removal was independently significant for hearing outcome. Possible interpretations are: 1) Independent of positive factors at the start of surgery at the final phase of tumor resection, what mattered for hearing outcome was the ABR quality (P < 0.001). 2) Dependence on ABR quality in the last phase might be a result of what the cochlear nerve has endured during resection. 3) The importance of ABR quality in the last phase might be because the tumor capsule is dissected from the nerves in that final phase.
  
  
  METHODS
  of critical actions with incidence of ABR impairment showed that dissection in the internal auditory canal and drilling were most critical.
  
  
  CONCLUSIONS
  Intraoperative ABR development is a predictive factor for postoperative hearing outcome. Deterioration should be avoided, because ABR improvement as a result of good status at the beginning of surgery could not be assumed.
authors.affiliation: Department of Neurosurgery, University Hospital Würzburg, Würzburg, Germany. Electronic address: Hummel_M@ukw.de.
authors.forename: Maria
authors.initials: M
authors.lastname: Hummel
authors.affiliation: Department of Neurosurgery, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Jose
authors.initials: J
authors.lastname: Perez
authors.affiliation: Department of Otolaryngology, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Hagen
authors.affiliation: Institute for Clinical Epidemiology and Biometry, Julius-Maximilians University Würzburg, Würzburg, Germany.
authors.forename: Götz
authors.initials: G
authors.lastname: Gelbrich
authors.affiliation: Department of Neurosurgery, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Ralf-Ingo
authors.initials: RI
authors.lastname: Ernestus
authors.affiliation: Department of Neurosurgery, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Cordula
authors.initials: C
authors.lastname: Matthies
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001299:Audiometry; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D009464:Neuroma, Acoustic / Q000503:physiopathology* / Q000601:surgery*; D019635:Neurosurgical Procedures / Q000379:methods*; D011930:Reaction Time / Q000502:physiology; D013067:Speech Perception / Q000502:physiology; D016896:Treatment Outcome
keywords: ABR; Auditory brainstem response; Hearing; Predictive factors; Surgery; Vestibular schwannoma