Tumor Targeted Gamma Knife Radiosurgery in Patients with Trigeminal Neuralgia Secondary to Mass Lesion

Background: Patients with trigeminal neuralgia pain secondary to a mass lesion present a unique challenge. The goal of therapy should be aimed at tumor control and alleviation of pain. In patients in whom surgical resection is not a viable option, Gamma Knife Radiosurgery (GKRS) can be employed. There is limited data, however, on pain outcomes in these patients after tumor targeting GKRS. We sought to investigate pain outcomes in this group of patients and assess potential predictors of favorable pain outcomes.

Methods: All patients who underwent tumor targeted GKRS at our institution between 2005 and 2020 were queried for use of medications for trigeminal neuralgia (e.g., carbamazepine, oxcarbazepine, gabapentin). Patients were then included if pain onset was prior to GKRS and consistent with compression of the ipsilateral trigeminal nerve on MRI. Exclusion criteria included diagnosis of multiple sclerosis, prior surgical resection, or prior surgical treatment of TN pain (e.g., balloon compression, glycerol rhizotomy). Chart review was performed to collect baseline demographic data, medications, GKRS characteristics, and pain outcomes. The Barrow Neurological Institute (BNI) pain intensity score was recorded pre and posttreatment. The study endpoint was defined as either last documented clinical follow-up or additional treatment (e.g., percutaneous balloon compression). Univariable analyses for predictors of pain outcome were then performed.

Results: A total of 17 patients met inclusion/exclusion criteria. Median age was 73 (IQR: 57–83) and patients were majority female (65%). 12 meningiomas (71%), 4 vestibular schwannomas (24%), and one trigeminal schwannoma (6%) were identified. Median tumor volume was 5.04 cc (IQR: 3.2–5.98) and most patients received 12 or 13 Gy in one fraction (n = 14, 82%) while the remaining received 25 Gy in 5 fractions (n = 3, 18%). On imaging, most patients exhibited compression of the trigeminal nerve at the cisternal segment (n = 16, 94%) followed by Meckel's cave (n = 4, 24%), and cavernous sinus (n = 2, 12%; see [Figs. 1], [2]). Mean follow-up was 25.4 months. At study endpoint, 8 patients (47%) demonstrated an improved BNI pain score though only 5 patients (29%) were pain free. A favorable BNI pain score (defined as BNI I–IIIb) was exhibited by 10 patients (59%) at the study endpoint. Five patients (29%) went on to receive a percutaneous balloon compression procedure for their continued pain. Univariable analyses for predictors of outcome did not reach significance. A trend toward significance was noted suggesting reduced odds of being pain free at study endpoint for patients with a longer time from pain onset to GKRS (OR: 0.95, p = 0.08).

Conclusion: In our cohort of patients with TN pain secondary to tumor, about half of the patients demonstrated improved BNI pain scores by study endpoint though were unlikely to be pain free. Tumor targeted GKRS remains a viable treatment option for these patients that are unable to undergo surgery though may have limited efficacy in pain control.

Publication History

Article published online:
01 February 2023