title: Fractionated stereotactic radiosurgery and preservation of hearing in patients with vestibular schwannoma: a preliminary report.
abstract: OBJECTIVE
  Microsurgery and stereotactic radiosurgery (SRS) for vestibular schwannomas are associated with a relatively high incidence of sensorineural hearing loss. A prospective trial of fractionated SRS was undertaken in an attempt to preserve hearing and minimize incidental cranial nerve injury.
  
  
  METHODS
  Thirty-three patients with vestibular schwannomas were treated with 2100 cGy in three fractions during a 24-hour period using conventional frame-based linear accelerator radiosurgery. The median tumor diameter was 20 mm (range, 7-42 mm). Baseline and follow-up evaluations included audiometry and contrast-enhanced magnetic resonance imaging. End points were tumor progression, preservation of serviceable hearing, and treatment-related complications.
  
  
  RESULTS
  Thirty-one patients (32 tumors) were assessable for tumor progression and treatment-related complications and 21 patients for preservation of serviceable hearing, with a median follow-up interval of 2 years (range, 0.5-4.0 yr). Tumor regression or stabilization was documented in 30 patients (97%) and tumor progression in 1 (3%). The patient with tumor progression remains asymptomatic and has not required surgical intervention. Five patients (16%) developed trigeminal nerve injury at a median of 6 months (range, 4-12 mo) after SRS; two of these patients had preexisting trigeminal neuropathy. One patient (3%) developed facial nerve injury (House-Brackmann Class 3) 7 months after SRS. Preservation of useful hearing (Gardner-Robertson Class 1-2) was 77% at 2 years. All patients with pretreatment Gardner-Robertson Class 1 to 2 hearing maintained serviceable (Class 1-3) hearing as of their last follow-up examination.
  
  
  CONCLUSIONS
  Three-fraction SRS with a conventional stereotactic frame is feasible and well tolerated in the treatment of acoustic neuroma. This study demonstrates a high rate of hearing preservation and few treatment-related complications among a relatively high-risk patient cohort (tumors >15 mm or neurofibromatosis Type 2). Longer follow-up will be required to assess the durability of tumor control.
authors.affiliation: Department of Radiation Oncology, Stanford University School of Medicine, California 94305, USA.
authors.forename: J C
authors.initials: JC
authors.lastname: Poen
authors.forename: A J
authors.initials: AJ
authors.lastname: Golby
authors.forename: K M
authors.initials: KM
authors.lastname: Forster
authors.forename: D P
authors.initials: DP
authors.lastname: Martin
authors.forename: D M
authors.initials: DM
authors.lastname: Chinn
authors.forename: S L
authors.initials: SL
authors.lastname: Hancock
authors.forename: J R
authors.initials: JR
authors.lastname: Adler
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001299:Audiometry; D018450:Disease Progression; D020220:Facial Nerve Injuries / Q000175:diagnosis / Q000209:etiology; D005260:Female; D005500:Follow-Up Studies; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control*; D006801:Humans; D007089:Image Enhancement; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000175:diagnosis / Q000601:surgery*; D011183:Postoperative Complications / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control*; D011446:Prospective Studies; D016634:Radiosurgery; D016896:Treatment Outcome; D014276:Trigeminal Nerve / Q000473:pathology; D061221:Trigeminal Nerve Injuries; D014277:Trigeminal Neuralgia / Q000175:diagnosis / Q000209:etiology