title: Intracapsular decompression or radical resection followed by Gamma Knife surgery for patients harboring a large vestibular schwannoma.
abstract: OBJECTIVE
  Microsurgery is the primary treatment used for patients harboring a large vestibular schwannoma (VS). However, its outcome may lead to hearing impairment and facial nerve dysfunction particularly when resection is extended outside the tumor capsule. When surgery for a large VS consists of intracapsular resection and decompression, better preservation of facial and hearing function are obtained. In this study, the authors compared outcomes of intracapsular decompression followed by Gamma Knife surgery (GKS) with outcomes of standard microsurgery followed by radiosurgery.
  
  
  METHODS
  Between August 2003 and October 2008, 35 patients harboring large VSs (> 3 cm in diameter) were enrolled in this study. Eighteen patients underwent intracapsular decompression followed by GKS (Group I), and 17 patients underwent radical extracapsular resection followed by GKS (Group II). In all cases GKS was performed with a margin dose of 12 Gy. All patients were followed up for at least 3 years. All patients also underwent periodic audiography, electroneuronography (ENoG), MR imaging, and testing with the SF-36 form. The Student t-test and repeated ANOVA were used for statistical analysis.
  
  
  RESULTS
  The mean ages of the patients (± SEM) in Groups I and II were 50 ± 3.0 and 49 ± 2.3 years, respectively. The female/male ratios were 8:10 in Group I and 7:10 in Group II. All patients had excellent facial function as measured according to the House-Brackmann Facial Grading System (Grade I or II) preoperatively. After the operation, 16 patients (89%) in Group I retained excellent facial function, whereas only 6 patients (35%) in Group II had excellent facial function (p < 0.01). In Group I, 11 patients had serviceable hearing, and all 11 (100%) retained hearing function after the operation. In Group II, 11 patients had serviceable hearing, but none retained hearing function postoperatively (p < 0.001). In Group I, the mean tumor volume (± SEM) was 17.5 ± 1.1 cm(3), and the postoperative volume was 9.35 ± 1.02 cm(3). In Group II, the mean tumor volume was 16.4 ± 0.95 cm(3), whereas the postoperative volume was 1.1 ± 0.14 cm(3) (p < 0.001). After GKS, the tumor volume was reduced to 5.12 ± 1.1 cm(3) and 0.9 ± 0.1 cm(3) in Groups I and II, respectively. No patients experienced adverse effects after GKS. The mean return-to-work times were 2.4 ± 0.16 and 33.4 ± 4.3 weeks in Groups I and II, respectively (p < 0.001). According to the results obtained using the 36-Item Short Form Health Survey (SF-36), patients in Group I enjoyed more significant improvements in quality of life than patients in Group II (p < 0.001).
  
  
  CONCLUSIONS
  Intracapsular decompression followed by GKS afforded a better neurological outcome and quality of life than radical extracapsular resection followed by GKS. Further application of this approach in patients harboring large VSs seems warranted.
authors.affiliation: Department of Neurosurgery, Taichung Veterans General Hospital, Taichung, Taiwan.
authors.forename: Hung-Chuan
authors.initials: HC
authors.lastname: Pan
authors.forename: Jason
authors.initials: J
authors.lastname: Sheehan
authors.forename: Meei-Ling
authors.initials: ML
authors.lastname: Sheu
authors.forename: Wen-Ta
authors.initials: WT
authors.lastname: Chiu
authors.forename: Dar-Yu
authors.initials: DY
authors.lastname: Yang
mesh_terms: D000328:Adult; D001932:Brain Neoplasms / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D019299:Decompression, Surgical / Q000379:methods*; D005154:Facial Nerve / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D005260:Female; D034381:Hearing Loss / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D011184:Postoperative Period; D011788:Quality of Life; D016634:Radiosurgery / Q000295:instrumentation*; D062707:Return to Work; D016896:Treatment Outcome