Gamma Knife Stereotactic Radiosurgery for Trigeminal Neuralgia Secondary to Petroclival Meningiomas

Introduction: Long-term pain outcomes after stereotactic radiosurgery (SRS) are not well-reported for patients with trigeminal neuralgia (TGN) associated with petroclival meningiomas. The present study describes both the tumor and TGN response.

Methods: During a 35-year interval 50 patients (26 female) presented with trigeminal neuralgia secondary to petroclival meningiomas. Twenty patients also had detectable trigeminal neuropathy. Pre-SRS BNI pain intensity scores were IIIa (2), IIIb (19), IV (12), and V (1). Sixteen patients were not medically managed for TGN before SRS and were omitted from pre-SRS BNI scoring. Median age at SRS was 64 (range: 25-87) years. Eight patients had a previous partial tumor resection. One patient had a pre-SRS glycerol rhizotomy. Thirty-three patients whose BNI score were IIIa or higher underwent meningioma SRS and one additional patient underwent both tumor trigeminal nerve SRS. The median tumor volume was 3.5 (range: 0.74-20.55) cc. The median margin dose for the meningiomas was 12.5 (range: 11-18) Gy.

Results: The median clinical follow-up was 44 (range: 5-321) months. Two patients had tumor progression (7 and 150 months after SRS) and both underwent subsequent surgical resection. Sixteen patients (47%) reported pain improvement, including 3 who became pain free off medication. Nine patients reported persistent TGN. Five patients underwent glycerol rhizotomy, one patient underwent microvascular decompression, and four required continued medical pain management. The remaining patients were managed with additional medication. Tumor growth control was obtained in 48 (96%) patients. No patient sustained adverse radiation effects.

Conclusion : Despite successful petroclival meningioma growth control, associated TGN relief is possible in only about half the patients after SRS.