title: Management of vestibular schwannoma: A pilot case series with postoperative ABR monitoring.
abstract: OBJECTIVE
  Auditory brainstem response (ABR) monitoring is regularly used in surgery of vestibular schwannoma to achieve hearing preservation. Despite ABR preservation at the end of surgery, there are cases with postoperative deafness. To date it is unclear whether these are false positive ABR data or cases of secondary hearing loss. In this pilot study, we focused on the early postoperative phase and possible ABR changes in this period.
  
  
  METHODS
  In a prospective study from March 2008 to April 2009, eleven patients (5 female and 6 male) with vestibular schwannoma and preoperative residual hearing were investigated by repeated postoperative ABR investigation at seven dates during the first week. ABR results, hearing function and tumor extension were categorized according to Hannover classification system. The postoperative developments of the first week after surgery are described.
  
  
  RESULTS
  Hearing preservation was achieved in 55% (6 of 11) of the patients. In the early postoperative phase, three patients with an ABR loss at the end of surgery showed some kind of recovery. In one case, a permanent recovery could be reproduced and developed step by step during the early postoperative phase. Three patients showed a postoperative deterioration resulting in a complete ABR loss. In one of these cases, it was probably a technical problem, but in the two other cases it was a real impairment. In 8 of 11 ABR, quality changed considerably during the early postoperative phase.
  
  
  CONCLUSIONS
  This pilot study identifies considerable change of ABR formation occurring in a considerable proportion of patients early after vestibular schwannoma resection. Obviously, in some patients, the endoperative state of the ABR is not the final state. Some patients show a postoperative improvement and some a deterioration towards a complete loss of all ABR components. Whether secondary hearing loss could be presented by early detection, will be a matter of further studies.
authors.affiliation: Department of Neurosurgery, University Hospital Würzburg, Josef-Schneider-Straße 11, 97080 Würzburg, Germany. Electronic address: Hummel_M@ukw.de.
authors.forename: Maria
authors.initials: M
authors.lastname: Hummel
authors.affiliation: B.A.D. Gesundheitsvorsorge und Sicherheitstechnik GmbH, Eifelweg 8-10, 63069 Offenbach, Germany.
authors.forename: Christin
authors.initials: C
authors.lastname: Krausgrill
authors.affiliation: Department of Neurosurgery, University Hospital Würzburg, Josef-Schneider-Straße 11, 97080 Würzburg, Germany.
authors.forename: Jose
authors.initials: J
authors.lastname: Perez
authors.affiliation: Department of Otolaryngology, University Hospital Würzburg, Josef-Schneider-Straße 11, 97080 Würzburg, Germany.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Hagen
authors.affiliation: Department of Neurosurgery, University Hospital Würzburg, Josef-Schneider-Straße 11, 97080 Würzburg, Germany.
authors.forename: Ralf-Ingo
authors.initials: RI
authors.lastname: Ernestus
authors.affiliation: Department of Neurosurgery, University Hospital Würzburg, Josef-Schneider-Straße 11, 97080 Würzburg, Germany.
authors.forename: Cordula
authors.initials: C
authors.lastname: Matthies
mesh_terms: D000328:Adult; D001301:Audiometry, Pure-Tone / Q000379:methods; D019468:Disease Management; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D005260:Female; D034381:Hearing Loss / Q000175:diagnosis* / Q000209:etiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000175:diagnosis / Q000601:surgery*; D010865:Pilot Projects; D011182:Postoperative Care / Q000379:methods; D011183:Postoperative Complications / Q000175:diagnosis* / Q000209:etiology; D011446:Prospective Studies
keywords: Acoustic neuroma/vestibular schwannoma; After surgery; Auditory brainstem responses (ABR) monitoring; Hearing function; Hearing monitoring