title: Microsurgery for vestibular schwannoma after Gamma Knife surgery: challenges and treatment strategies.
abstract: OBJECTIVE
  Resection of vestibular schwannoma (VS) after Gamma Knife surgery (GKS) is infrequently performed. The goals of this study were to analyze and discuss the neurological outcomes and technical challenges of VS resection and to explore strategies for treating tumors that progress after GKS.
  
  
  METHODS
  In total, 708 patients with VS underwent GKS between 1993 and 2012 at Taipei Veterans General Hospital. The post-GKS clinical courses, neurological presentations, and radiological changes in these patients were analyzed. Six hundred patients with imaging follow-up of at least 1 year after GKS treatment were included in this study.
  
  
  RESULTS
  Thirteen patients (2.2%) underwent microsurgery on average 36.8 months (range 3-107 months) after GKS. The indications for the surgery included symptomatic adverse radiation effects (in 4 patients), tumor progression (in 6), and cyst development (in 3). No morbidity or death as a result of the surgery was observed. At the last follow-up evaluation, all patients, except 1 patient with a malignant tumor, had stable or near-normal facial function.
  
  
  CONCLUSIONS
  For the few VS cases that require resection after radiosurgery, maximal tumor resection can be achieved with modern skull-based techniques and refined neuromonitoring without affecting facial nerve function.
authors.affiliation: Department of Neurosurgery, Neurological Institute, and.
authors.forename: Cheng-Chia
authors.initials: CC
authors.lastname: Lee
authors.forename: Hsiu-Mei
authors.initials: HM
authors.lastname: Wu
authors.forename: Wen-Yuh
authors.initials: WY
authors.lastname: Chung
authors.forename: Ching-Jen
authors.initials: CJ
authors.lastname: Chen
authors.forename: David Hung-Chi
authors.initials: DH
authors.lastname: Pan
authors.forename: Sanford P C
authors.initials: SP
authors.lastname: Hsu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006309:Hearing; D006801:Humans; D008297:Male; D008866:Microsurgery / Q000009:adverse effects / Q000379:methods* / Q000401:mortality; D008875:Middle Aged; D009017:Morbidity; D009464:Neuroma, Acoustic / Q000401:mortality / Q000601:surgery*; D016634:Radiosurgery / Q000009:adverse effects / Q000379:methods* / Q000401:mortality; D020127:Recovery of Function; D012086:Reoperation / Q000379:methods; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult
keywords: ARE = adverse radiation effect; EMG = electromyography; GKS = Gamma Knife surgery; Gamma Knife; NF = neurofibromatosis; SRS = stereotactic radiosurgery; VP = ventriculoperitoneal; VS = vestibular schwannoma; microsurgery; oncology; stereotactic radiosurgery; tumor; vestibular schwannoma