title: Improved preservation of function during acoustic neuroma surgery.
abstract: OBJECTIVE
  Restoration of cranial nerve functions during acoustic neuroma (AN) surgery is crucial for good outcome. The effects of minimizing the injury period and maximizing the recuperation period were investigated in 89 patients who consecutively underwent retrosigmoid unilateral AN surgery.
  
  
  METHODS
  Cochlear nerve and facial nerve functions were evaluated during AN surgery by use of continuous auditory evoked dorsal cochlear nucleus action potential monitoring and facial nerve root exit zone-elicited compound muscle action potential monitoring, respectively. Factors affecting preservation of function at the same (preoperative) grade were analyzed.
  
  
  RESULTS
  A total of 23 patients underwent standard treatment and investigation of the monitoring threshold for preservation of function; another 66 patients underwent extended recuperation treatment and assessment of its effect on recovery of nerve function. Both types of final action potential monitoring response and extended recuperation treatment were associated with preservation of function at the same grade.
  
  
  CONCLUSIONS
  Preservation of function was significantly better for patients who received extended recuperation treatment.
authors.affiliation: Department of Neurosurgery, University of Tokyo Hospital;
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Nakatomi
authors.forename: Hidemi
authors.initials: H
authors.lastname: Miyazaki
authors.forename: Minoru
authors.initials: M
authors.lastname: Tanaka
authors.forename: Taichi
authors.initials: T
authors.lastname: Kin
authors.forename: Masanori
authors.initials: M
authors.lastname: Yoshino
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Oyama
authors.forename: Masaaki
authors.initials: M
authors.lastname: Usui
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Moriyama
authors.forename: Hiromi
authors.initials: H
authors.lastname: Kojima
authors.forename: Kimitaka
authors.initials: K
authors.lastname: Kaga
authors.forename: Nobuhito
authors.initials: N
authors.lastname: Saito
mesh_terms: D000200:Action Potentials; D000328:Adult; D000368:Aged; D003056:Cochlear Nerve / Q000503:physiopathology; D004428:Ear Neoplasms / Q000601:surgery*; D005154:Facial Nerve / Q000503:physiopathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D009464:Neuroma, Acoustic / Q000601:surgery*; D019635:Neurosurgical Procedures / Q000009:adverse effects* / Q000379:methods*; D011182:Postoperative Care / Q000379:methods*; D011183:Postoperative Complications / Q000517:prevention & control; D016896:Treatment Outcome
keywords: AEDNAP = auditory evoked dorsal cochlear nucleus action potential; AN = acoustic neuroma; APR = amplitude preservation ratio; AUC = area under the curve; BAEP = brainstem auditory-evoked potential; FREMAP = facial nerve root exit zone–elicited compound muscle action potential; GR = Gardner-Robertson; HB = House-Brackmann; M-max = maximum peak-to-peak amplitude; ROC = receiver operating characteristic; acoustic neuroma surgery; continuous direct brainstem auditory evoked potential monitoring; oncology