title: Multisession radiosurgery for optic nerve sheath meningiomas--an effective option: preliminary results of a single-center experience.
abstract: BACKGROUND
  Traditional treatment options for optic nerve sheath meningiomas (ONSMs) include observation, surgery, and radiotherapy, but to date none of these has become the clear treatment of choice.
  
  
  OBJECTIVE
  To evaluate the effectiveness and safety of multisession radiosurgery for ONSMs.
  
  
  METHODS
  From May 2004 to June 2008, 21 patients with ONSMs were treated by radiosurgery using the frameless CyberKnife system. Patient age ranged from 36 to 73 years (mean, 54 years). All patients were treated using multisession radiosurgery, with 5 fractions of 5 Gy each to a total dose of 25 Gy prescribed to the 75% to 85% isodose line. Patients were evaluated for tumor growth control and visual function.
  
  
  RESULTS
  The median pretreatment tumor volume was 2.8 mL (range, 0.3-23 mL). The mean follow-up was 30 months (range, 11-68 months). All patients tolerated treatment well, with only 1 patient in whom a mild optic neuropathy developed (which remitted after systemic steroid therapy). No other acute or late radiation-induced toxicities were observed. No patients showed ONSM progression on follow-up magnetic resonance imaging. Two patients (10%) had a partial response. No patients had worsening of visual function; visual function was stable in 65% and improved in 35% of patients.
  
  
  CONCLUSIONS
  Multisession radiosurgery for ONSMs was found to be safe and effective. The preliminary results from this study, in terms of growth control, visual function improvement, and toxicity, are quite promising. Further investigations are warranted.
authors.affiliation: Department of Neurosurgery, Radiotherapy Unit, Fondazione IRCCS Istituto Neurologico C. Besta, Milano, Italy. marchettimarcello@gmail.com
authors.forename: Marcello
authors.initials: M
authors.lastname: Marchetti
authors.forename: Stefania
authors.initials: S
authors.lastname: Bianchi
authors.forename: Ida
authors.initials: I
authors.lastname: Milanesi
authors.forename: Achille
authors.initials: A
authors.lastname: Bergantin
authors.forename: Livia
authors.initials: L
authors.lastname: Bianchi
authors.forename: Giovanni
authors.initials: G
authors.lastname: Broggi
authors.forename: Laura
authors.initials: L
authors.lastname: Fariselli
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008577:Meningeal Neoplasms / Q000473:pathology / Q000601:surgery*; D008579:Meningioma / Q000473:pathology / Q000601:surgery*; D008875:Middle Aged; D009900:Optic Nerve / Q000473:pathology / Q000528:radiation effects / Q000601:surgery*; D019574:Optic Nerve Neoplasms / Q000473:pathology / Q000601:surgery*; D016634:Radiosurgery / Q000379:methods*; D012189:Retrospective Studies; D016896:Treatment Outcome