Gamma Knife radiosurgery for posterior fossa meningiomas: a multicenter study

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Posterior fossa meningiomas represent a common yet challenging clinical entity. They are often associated with neurovascular structures and adjacent to the brainstem. Resection can be undertaken for posterior fossa meningiomas, but residual or recurrent tumor is frequent. Stereotactic radiosurgery (SRS) has been used to treat meningiomas, and this study evaluates the outcome of this approach for those located in the posterior fossa.


At 7 medical centers participating in the North American Gamma Knife Consortium, 675 patients undergoing SRS for a posterior fossa meningioma were identified, and clinical and radiological data were obtained for these cases. Females outnumbered males at a ratio of 3.8 to 1, and the median patient age was 57.6 years (range 12–89 years). Prior resection was performed in 43.3% of the patient sample. The mean tumor volume was 6.5 cm3, and a median margin dose of 13.6 Gy (range 8–40 Gy) was delivered to the tumor.


At a mean follow-up of 60.1 months, tumor control was achieved in 91.2% of cases. Actuarial tumor control was 95%, 92%, and 81% at 3, 5, and 10 years after radiosurgery. Factors predictive of tumor progression included age greater than 65 years (hazard ratio [HR] 2.36, 95% CI 1.30–4.29, p = 0.005), prior history of radiotherapy (HR 5.19, 95% CI 1.69–15.94, p = 0.004), and increasing tumor volume (HR 1.05, 95% CI 1.01–1.08, p = 0.005). Clinical stability or improvement was achieved in 92.3% of patients. Increasing tumor volume (odds ratio [OR] 1.06, 95% CI 1.01–1.10, p = 0.009) and clival, petrous, or cerebellopontine angle location as compared with petroclival, tentorial, and foramen magnum location (OR 1.95, 95% CI 1.05–3.65, p = 0.036) were predictive of neurological decline after radiosurgery. After radiosurgery, ventriculoperitoneal shunt placement, resection, and radiation therapy were performed in 1.6%, 3.6%, and 1.5%, respectively.


Stereotactic radiosurgery affords a high rate of tumor control and neurological preservation for patients with posterior fossa meningiomas. Those with a smaller tumor volume and no prior radiation therapy were more likely to have a favorable response after radiosurgery. Rarely, additional procedures may be required for hydrocephalus or tumor progression.

ABBREVIATIONSCI = confidence interval; CN = cranial nerve; CPA = cerebellopontine angle; GKRS = Gamma Knife radiosurgery; HR = hazard ratio; OR = odds ratio; SRS = stereotactic radiosurgery.

Article Information

Correspondence Jason P. Sheehan, Department of Neurological Surgery, University of Virginia, Charlottesville, VA 22908. email

INCLUDE WHEN CITING Published online April 10, 2015; DOI: 10.3171/2014.10.JNS14139.

DISCLOSURE Dr. Lunsford is a consultant and stockholder in AB Elekta.

© AANS, except where prohibited by US copyright law.



  • View in gallery

    Kaplan-Meier plot of progression-free survival after SRS for all 675 patients with posterior fossa meningiomas. Numbers in parentheses represent the number of patients reaching each significant timeline milestone.

  • View in gallery

    Kaplan-Meier plot of progression-free survival after SRS for patients with and without a prior resection (upper), and for patients with tumors < 6.5 cm3 versus those with tumors ≥ 6.5 cm3 (lower). Numbers in parentheses represent the number of patients reaching each significant timeline milestone.

  • View in gallery

    Kaplan-Meier plot of progression-free survival after SRS for meningiomas in a specific location in the posterior fossa. Figure is available in color online only.


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