title: Multisession stereotactic radiosurgery for vestibular schwannomas:  single-institution experience with 383 cases.
abstract: BACKGROUND
  Single-session stereotactic radiosurgery (SRS) treatment of vestibular schwannomas results in excellent tumor control. It is not known whether functional outcomes can be improved by fractionating the treatment over multiple sessions.
  
  
  OBJECTIVE
  To examine tumor control and complication rates after multisession SRS.
  
  
  METHODS
  Three hundred eighty-three patients treated with SRS from 1999 to 2007 at Stanford University Medical Center were retrospectively reviewed. Ninety percent were treated with 18 Gy in 3 sessions, targeting a median tumor volume of 1.1 cm3 (range, 0.02-19.8 cm3).
  
  
  RESULTS
  During a median follow-up duration of 3.6 years (range, 1-10 years), 10 tumors required additional treatment, resulting in 3- and 5-year Kaplan-Meier tumor control rates of 99% and 96%, respectively. Five-year tumor control rate was 98% for tumors < 3.4 cm3. Neurofibromatosis type 2-associated tumors were associated with worse tumor control (P = .02). Of the 200 evaluable patients with pre-SRS serviceable hearing (Gardner-Robertson grade 1 and 2), the crude rate of serviceable hearing preservation was 76%. Smaller tumor volume was associated with hearing preservation (P = .001). There was no case of post-SRS facial weakness. Eight patients (2%) developed trigeminal dysfunction, half of which was transient.
  
  
  CONCLUSIONS
  Multisession SRS treatment of vestibular schwannomas results in an excellent rate of tumor control. The hearing, trigeminal nerve, and facial nerve function preservation rates reported here are promising.
authors.affiliation: Division of Neurological Surgery, Department of Surgery, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Ake
authors.initials: A
authors.lastname: Hansasuta
authors.forename: Clara Y H
authors.initials: CY
authors.lastname: Choi
authors.forename: Iris C
authors.initials: IC
authors.lastname: Gibbs
authors.forename: Scott G
authors.initials: SG
authors.lastname: Soltys
authors.forename: Victor C K
authors.initials: VC
authors.lastname: Tse
authors.forename: Robert E
authors.initials: RE
authors.lastname: Lieberson
authors.forename: Melanie G
authors.initials: MG
authors.lastname: Hayden
authors.forename: Gordon T
authors.initials: GT
authors.lastname: Sakamoto
authors.forename: Griffith R
authors.initials: GR
authors.lastname: Harsh
authors.forename: John R
authors.initials: JR
authors.lastname: Adler
authors.forename: Steven D
authors.initials: SD
authors.lastname: Chang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D034381:Hearing Loss / Q000209:etiology; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D016518:Neurofibromatosis 2 / Q000209:etiology; D009464:Neuroma, Acoustic / Q000401:mortality / Q000601:surgery*; D016634:Radiosurgery / Q000379:methods*; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult