title: Radiosurgical treatment of vestibular schwannomas in patients with neurofibromatosis type 2: tumor control and hearing preservation.
abstract: BACKGROUND
  The radiosurgical treatment of vestibular schwannomas in patients with neurofibromatosis type 2 (NF2) is controversial. The authors investigated the radiologically proven tumor control rate after gamma knife radiosurgery. The factors that affect tumor control and serviceable hearing preservation were analyzed.
  
  
  METHODS
  Thirty-six lesions in 30 patients were included. The median lengths of the clinical and radiologic follow-ups were 48.5 months and 36.5 months, respectively. The median tumor volume was 3.2 cm3. The mean marginal dose was 12.1 grays (Gy) (range, 8-14 Gy) at an isodose line of 50%+/-0.6%. The Kaplan-Meier method and Cox proportional hazards model were used for the statistical analyses.
  
  
  RESULTS
  The actuarial tumor control rate was 81%, 74%, and 66%, respectively, in the first, second, and fifth years. Five tumors required a salvage surgery because of tumor control failure. A low marginal dose and a young age at radiosurgery were associated with poor tumor control. Of the 16 tumors with which ipsilateral hearing was serviceable, the actuarial serviceable hearing preservation rates were 50%, 45%, and 33%, respectively, in the first, second, and fifth years. Better ipsilateral hearing (Gardner-Robertson grade 1, compared with grade 2) at the time of radiosurgery was associated with significantly greater serviceable hearing preservation.
  
  
  CONCLUSIONS
  Gamma knife radiosurgery for vestibular schwannomas in NF2 patients provided 5-year tumor control in approximately two-thirds of patients and preserved serviceable hearing in approximately one-third. The rates of other cranial nerve deficits were low, and no secondary malignancy was observed. Radiosurgery should be included in treatment options for NF2 patients.
authors.affiliation: Department of Neurosurgery, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Ji Hoon
authors.initials: JH
authors.lastname: Phi
authors.forename: Dong Gyu
authors.initials: DG
authors.lastname: Kim
authors.forename: Hyun-Tai
authors.initials: HT
authors.lastname: Chung
authors.forename: Joongyub
authors.initials: J
authors.lastname: Lee
authors.forename: Sun Ha
authors.initials: SH
authors.lastname: Paek
authors.forename: Hee-Won
authors.initials: HW
authors.lastname: Jung
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D003390:Cranial Nerve Neoplasms / Q000601:surgery*; D003638:Deafness / Q000517:prevention & control*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016518:Neurofibromatosis 2 / Q000150:complications; D009464:Neuroma, Acoustic / Q000150:complications / Q000401:mortality / Q000601:surgery*; D011379:Prognosis; D016634:Radiosurgery / Q000009:adverse effects