Elsevier

Surgical Neurology

Volume 51, Issue 3, March 1999, Pages 268-273
Surgical Neurology

Neoplasms
Stereotactic radiosurgery for anterior foramen magnum meningiomas

https://doi.org/10.1016/S0090-3019(98)00099-8Get rights and content

Abstract

BACKGROUND

Total microsurgical resection is the procedure of choice for growing and symptomatic foramen magnum meningiomas. We hypothesized that for patients with advanced age, complicating medical conditions, or residual or recurrent meningiomas at the foramen magnum, stereotactic radiosurgery would be a useful adjunctive (n = 2) or alternative (n = 3) treatment.

METHODS

We report our experience in five elderly patients (73–84 years) who underwent gamma knife radiosurgery. The median tumor volume was 10.5 ml and the tumor margin dose varied from 10 to 16 Gy. Because of the irregular tumor volumes along the inferior clivus, multiple isocenters of irradiation were required (range, 2–8; mean 4.4).

RESULTS

During the follow-up interval of 1–5 years (median, 3 years), one patient died of an intercurrent illness, and all remaining patients were stable without any further deterioration in their clinical condition. Follow-up imaging studies revealed a reduction in tumor volume in one patient and no further growth in the remaining four.

CONCLUSION

We believe that stereotactic radiosurgery provides safe and effective management for patients who are poor candidates for resection of their foramen magnum meningiomas.

Section snippets

Clinical materials and methods

Between August 1987 and April 1997, five patients (three men and two women) with foramen magnum meningiomas underwent stereotactic radiosurgery with the 201-source cobalt-60 gamma knife at the Center for Image-Guided Neurosurgery, University of Pittsburgh. Three patients had radiosurgery as their primary procedure and two patients had radiosurgery for a recurrence of their previously operated foramen magnum meningioma. All patients had been rejected for either initial or repeat surgical

Case 1

An 82-year-old female with a history of congestive heart failure presented with difficulty in walking and ataxia. Imaging confirmed a meningioma in the region of the anterior foramen magnum. Neurological examination revealed a broad-based ataxic gait, impaired tandem walking, and positive Romberg sign. She declined open surgical resection and was referred for Gamma Knife radiosurgery. The tumor had a volume of 12 ml. She was treated with a maximum dose of 30 Gy, tumor margin dose of 15 Gy with

Case 2

An 81-year-old male presented with a 5-year history of cervical pain and a 2-month history of progressive upper extremity numbness and weakness combined with increasing lower extremity spasticity. Neurologic examination demonstrated weakness of the right arm with increased reflexes, patchy sensory loss and marked spasticity of the lower extremities with associated ankle and patellar clonus. He underwent posterior fossa craniectomy and upper cervical laminectomy followed by partial tumor

Case 3

An 81-year-old man with a history of dysequilibrium and vertigo had undergone craniotomy 3 years before presentation for a large foramen magnum-clival meningioma. At presentation he had a memory deficit and disturbance of equilibrium. MRI scans showed hydrocephalus and a large tumor measuring 18.5 ml in volume. The maximum tumor dose was 25 Gy and the tumor margin dose was 10 Gy (40% isodose). Eight isocenters of irradiation were used using a combination of three 18-mm, on 14-mm, and four 8-mm

Case 4

A 73-year-old woman had a history of pituitary tumor for which she underwent two resections and radiation therapy. She developed a foramen magnum meningioma that gradually enlarged on serial imaging studies. Radiosurgery was performed for a tumor volume of 1.8 ml. The tumor received a maximum dose of 28 Gy and a margin dose of 14 Gy using five 8 mm isocenters. At follow-up 1 year later she was clinically unchanged and the tumor volume was stable.

Case 5

An 84-year-old man developed progressive limb weakness, decreased hearing, diplopia, and hoarseness of voice. MRI revealed a foramen magnum and clival tumor measuring 4.6 ml in volume. In view of his age, surgery was deemed too high a risk. Radiosurgery was performed using a maximum dose of 32 Gy and a margin dose of 16 Gy with two isocenters of irradiation (one 18-mm and one 8-mm collimator) (Figure 3). Four and half years after treatment, follow-up imaging showed a reduction in the size of

Discussion

Foramen magnum meningiomas are relatively rare lesions. Yasuoka et al reported an incidence of 3.2% among 1139 meningiomas encountered during a 20-year period [25]. These tumors pose a formidable challenge to surgeons because of their anterior location that prevents easy access to the tumor. In addition, adjacent critical neural and vascular structures may be injured during the course of tumor removal or exposure. Initial neurosurgical experience suggested that the lower cranial nerves and

The role of radiosurgery

Radiosurgery for meningiomas in other locations has provided safe and effective tumor control with follow-up that now extends to 10 years 7, 11, 14, 15, 17, 21. The twin goals of radiosurgery are tumor control and reduced morbidity. In all five patients in this series these goals were acheived. No patient showed growth of the tumor or additional neurological deficits attributable to radiosurgery. No patient showed imaging signal changes in the adjacent brainstem or spinal cord. We believe that

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