Gamma Knife surgery in the treatment paradigm for foramen magnum meningiomas

Clinical article

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Microsurgical management of foramen magnum meningiomas (FMMs) can be associated with significant morbidity and mortality. Stereotactic radiosurgery may be an efficient and safe alternative treatment modality for such tumors. The object of this study was to increase the documented experience with Gamma Knife surgery (GKS) for FMMs and to delineate its role in an overall management paradigm.


The authors report on their experience with 24 patients harboring FMMs managed with GKS. Twelve patients had primary symptomatic tumors, 5 had asymptomatic but enlarging primary tumors, and 7 had recurrent or residual tumors after a prior surgery.


Follow-up clinical and imaging data were available in 21 patients at a median follow-up of 47 months (range 3–128 months). Ten patients had measurable tumor regression, which was defined as an overall volume reduction > 25%. Eleven patients had no further tumor growth. Two patients died as a result of advanced comorbidities before follow-up imaging. One patient was living 8 years after GKS but had no clinical evaluation. Ten of 17 symptomatic patients with at least 6 months of follow-up had symptom improvement, and 7 remained clinically stable. Smaller tumors were more likely to regress. No patient suffered an adverse radiation effect after radiosurgery.


Gamma Knife surgery was a safe management strategy for small, minimally symptomatic, or growing FMMs as well as for residual tumors following conservative microsurgical removal.

Abbreviations used in this paper:FMM = foramen magnum meningioma; GKS = Gamma Knife surgery.

Article Information

Address correspondence to: Georgios Zenonos, M.D., Department of Neurological Surgery, 200 Lothrop Street, Suite B400, UPMC Presbyterian Hospital, Pittsburgh, Pennsylvania 15213. email:

Please include this information when citing this paper: published online September 14, 2012; DOI: 10.3171/2012.8.JNS111554.

© AANS, except where prohibited by US copyright law.



  • View in gallery

    Axial and sagittal MR images with contrast showing a left FMM. Images without (A, 1–6) and with (B, 1–6) the radiosurgical dose plan are shown. This tumor received a margin dose of 11.5 Gy and a maximum dose of 23 Gy.

  • View in gallery

    Bar graph demonstrating radiographic tumor progression and symptom progression in patients with at least 6 months of follow-up imaging data in relation to the initial tumor size. Tumor regression was defined as > 25% reduction in tumor volume. The average follow-up interval was similar in the 3 groups (< 3 cm3 group: 52 months, 3–6 cm3 group: 45 months, > 6 cm3 group: 47 months). Asymptomatic lesions were not included in the symptom progression analysis. Dark gray bars represent tumor regression; light gray bars, improved symptoms.

  • View in gallery

    Proposed management algorithm for FMMs.



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