Stereotactic Radiosurgery for Multiple Sclerosis Associated Trigeminal Neuralgia

Abstract

Trigeminal neuralgia in the setting of multiple sclerosis (MS-TN) is a challenging condition to manage and frequently does not respond as well to medications or surgical intervention when compared with classic TN. Gamma Knife radiosurgery (GKRS) is a commonly used treatment modality for these patients, however, data regarding the efficacy of this treatment is limited. Here we report a large single institution retrospective analysis for MS-TN treated with GKRS. A retrospective review of our GKRS database was performed to identify patients with MS-TN treated with GKRS between 2001 and 2016. Seventy-seven cases of unilateral MS-TN (UMSTN) in 74 patients were treated with GKRS at our institution between 2001 and 2016. Background medical history, treatment outcomes and complications, and dosimetric data were obtained by retrospective chart reviews and telephone interviews. Time-to-failure outcomes were estimated using the Kaplan-Meier method. Cox proportional hazards methods were used to estimate the hazard ratios (HR) associated with patient and treatment-related variables for time-to-failure outcomes. Seventy-four of 77 cases of UMSTN had sufficient follow up to determine BNI pain score outcomes. Three patients had both nerves treated. Sixty-one out of 74 cases (82%) of UMSTN achieved BNI IIIb or better pain relief following initial GKRS, with 18 cases (24%) achieving BNI I pain relief. Median time to BNI IIIb pain relief was 1.8 weeks. At a median follow up of 2.5 years, the estimated median duration of BNI IIIb pain relief after initial GKRS was 1.1 years. Estimated rates of pain relief at 1, 3 and 5 years were 51%, 37%, and 27% respectively. Three cases (4.1%) developed bothersome numbness and three cases (4.1%) developed ipsilateral corneal anesthesia, although none experienced vision loss. No patients experienced anesthesia dolorosa. Thirty-seven of the original 77 cases of UMSTN were treated with repeat GKRS after initial treatment failure. Of 35 patients with sufficient follow up to determine pain outcomes, 30 (86%) achieved BNI IIIb or better pain relief, with 12 (34%) achieving BNI I following repeat GKRS. Median time to BNI IIIb pain relief was 4.5 weeks. At a median follow up of 2.3 years from repeat GKRS, the median duration of BNI IIIb pain relief after repeat GKRS was 2.8 years. Estimated rates of pain relief at 1 and 3 years were 67% and 49% respectively. One case (2.9%) developed bothersome numbness after repeat GKRS, and three cases (8.6%) developed new ipsilateral corneal anesthesia, but none reported vision loss. No patients developed anesthesia dolorosa. Patients with episodic pain were more likely to achieve a good pain outcome after repeat GKRS than those with atypical symptoms (HR 10.51, p = 0.03). GKRS is a viable, well tolerated treatment option for patients with MS-TN. More durable relief is often achieved with a second application of GKRS. Patients with episodic pain are more likely to have successful second procedure.