title: Stereotactic radiosurgery of cranial nonvestibular schwannomas: results of single- and multisession radiosurgery.
abstract: BACKGROUND
  Surgical resection of nonvestibular cranial schwannomas carries a considerable risk of postoperative complications. Stereotactic radiosurgery (SRS) offers a non-invasive treatment alternative. The efficacy and safety of multi-session SRS of nonvestibular cranial schwannomas has not been well studied.
  
  
  OBJECTIVE
  To analyze the results of single- and multi-session SRS of nonvestibular cranial schwannomas.
  
  
  METHODS
  From 2001 to 2007, 42 lesions in 40 patients were treated with SRS at Stanford University Medical Center, targeting schwannomas of cranial nerves IV (n = 1), V (n = 18), VII (n = 6), X (n = 5), XII (n = 2), jugular foramen (n = 8), and cavernous sinus (n = 2). SRS was delivered to a median marginal dose of 18 Gy (range, 15-33 Gy) in 1 to 3 sessions, targeting a median tumor volume of 3.2 cm (range, 0.1-23.7 cm). The median doses for treatments in 1 (n = 18), 2 (n = 9), and 3 (n = 15) sessions were 17.5, 20, and 18 Gy, respectively.
  
  
  RESULTS
  With a median follow-up of 29 months (range, 6-84 months), tumor control was achieved in 41 of the 42 lesions. Eighteen of 42 lesions (43%) decreased in size; 23 tumors (55%) remained stable. There were 2 cases of new or worsening cranial nerve deficits in patients treated in single session; no patient treated with multi-session SRS experienced any cranial nerve toxicity (P = 0.18).
  
  
  CONCLUSIONS
  SRS of nonvestibular cranial schwannomas provides excellent tumor control with minimal risk of complications. There was a trend towards decreased complications with multi-session SRS.
authors.affiliation: Department of Neurosurgery, Stanford University Medical Center, Stanford, California, USA. cyhchoi@stanford.edu
authors.forename: Clara Y H
authors.initials: CY
authors.lastname: Choi
authors.forename: Scott G
authors.initials: SG
authors.lastname: Soltys
authors.forename: Iris C
authors.initials: IC
authors.lastname: Gibbs
authors.forename: Griffith R
authors.initials: GR
authors.lastname: Harsh
authors.forename: Gordon T
authors.initials: GT
authors.lastname: Sakamoto
authors.forename: Deep A
authors.initials: DA
authors.lastname: Patel
authors.forename: Robert E
authors.initials: RE
authors.lastname: Lieberson
authors.forename: Steven D
authors.initials: SD
authors.lastname: Chang
authors.forename: John R
authors.initials: JR
authors.lastname: Adler
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003390:Cranial Nerve Neoplasms / Q000175:diagnosis / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009442:Neurilemmoma / Q000175:diagnosis / Q000601:surgery*; D016634:Radiosurgery / Q000379:methods*; D016896:Treatment Outcome; D055815:Young Adult