Gamma Knife radiosurgery for larger-volume vestibular schwannomas. Clinical article

J Neurosurg. 2011 Mar;114(3):801-7. doi: 10.3171/2010.8.JNS10674. Epub 2010 Aug 27.

Abstract

Object: Stereotactic radiosurgery (SRS) is an important management option for patients with small- and medium-sized vestibular schwannomas. To assess the potential role of SRS in larger tumors, the authors reviewed their recent experience.

Methods: Between 1994 and 2008, 65 patients with vestibular schwannomas between 3 and 4 cm in one extracanalicular maximum diameter (median tumor volume 9 ml) underwent Gamma Knife surgery. Seventeen patients (26%) had previously undergone resection.

Results: The median follow-up duration was 36 months (range 1-146 months). At the first planned imaging follow-up at 6 months, 5 tumors (8%) were slightly expanded, 53 (82%) were stable in size, and 7 (11%) were smaller. Two patients (3%) underwent resection within 6 months due to progressive symptoms. Two years later, with 63 tumors overall after the 2 post-SRS resections, 16 tumors (25%) had a volume reduction of more than 50%, 22 (35%) tumors had a volume reduction of 10-50%, 18 (29%) were stable in volume (volume change < 10%), and 7 (11%) had larger volumes (5 of the 7 patients underwent resection and 1 of the 7 underwent repeat SRS). Eighteen (82%) of 22 patients with serviceable hearing before SRS still had serviceable hearing after SRS more than 2 years later. Three patients (5%) developed symptomatic hydrocephalus and underwent placement of a ventriculoperitoneal shunt. In 4 patients (6%) trigeminal sensory dysfunction developed, and in 1 patient (2%) mild facial weakness (House-Brackmann Grade II) developed after SRS. In univariate analysis, patients who had a previous resection (p = 0.010), those with a tumor volume exceeding 10 ml (p = 0.05), and those with Koos Grade 4 tumors (p = 0.02) had less likelihood of tumor control after SRS.

Conclusions: Although microsurgical resection remains the primary management choice in patients with low comorbidities, most vestibular schwannomas with a maximum diameter less than 4 cm and without significant mass effect can be managed satisfactorily with Gamma Knife radiosurgery.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Cranial Nerve Neoplasms / pathology
  • Cranial Nerve Neoplasms / surgery*
  • Dose-Response Relationship, Radiation
  • Facial Nerve Diseases / epidemiology
  • Facial Nerve Diseases / etiology
  • Female
  • Follow-Up Studies
  • Hearing Disorders / epidemiology
  • Hearing Disorders / etiology
  • Humans
  • Kaplan-Meier Estimate
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Neuroma, Acoustic / pathology
  • Neuroma, Acoustic / surgery*
  • Postoperative Complications / epidemiology
  • Radiosurgery* / adverse effects
  • Retrospective Studies
  • Risk Management
  • Survival Analysis
  • Treatment Outcome
  • Vestibular Diseases / pathology
  • Vestibular Diseases / surgery*
  • Young Adult