Gamma Knife Radiosurgery for Bilateral Trigeminal Neuralgia

Abstract

Bilateral trigeminal neuralgia (BTN) makes up a small subset of patients with trigeminal neuralgia. These patients have a higher incidence of familial TN and multiple sclerosis and their management is controversial. Here we report a large single institution retrospective cohort of patients with BTN treated with stereotactic radiosurgery (SRS). SRS database review identified 78 nerves in 52 patients with BTN who underwent at least one SRS between 1999 and 2017. Background history, demographics, treatment outcomes, complications, and dosimetric data were obtained by retrospective chart review. Long-term follow-up was obtained by a standardized telephone interview performed by a physician. Successful treatment was defined as BNI IIIb or better pain relief. Time-to-failure outcomes were estimated by the Kaplan-Meier method. Hazard ratios (HR) associated with patient and treatment-related variables for time-to-failure outcomes were estimated by Cox proportional hazards methods. Of the 78 individual nerves treated with a first SRS, 77 had sufficient follow up data to determine BNI pain score outcomes. Sixty-seven of the 77 nerves (87%) achieved ≥ BNI IIIb pain relief, with 34 (44%) achieving BNI I pain relief. The median time to BNI IIIb pain relief was 3.5 weeks. At a median follow-up of 3.4 years, the median duration of ≥ BNI IIIb pain relief was 2.5 years. The estimated 1, 3, and 5-year rates of ≥ BNI IIIb pain relief were 71%, 43%, and 32%. Post-SRS facial numbness was seen in 33 (43%) cases, with five (6.5%) being bothersome. Two (2.6%) cases of anesthesia dolorosa (AD) and five (6.4%) cases of corneal numbness were reported. SRS with a maximal post procedure BNI of IIIb were more likely to experience pain relapse than those who achieved BNI I relief (HR 2.55, p = 0.04), as were those who had a history of prior ipsilateral microvascular decompression (MVD) (HR 2.64, p = 0.03). Left sided pain was more likely to relapse than right sided (HR 2.22, p = 0.02). Twenty-two nerves underwent repeat SRS for recurrent pain, of which 20 had sufficient follow up to determine BNI pain score outcomes. Of these, 19 (95%) had ≥ BNI IIIb pain relief, with 8 (40%) reaching BNI I relief. The median time to BNI IIIb pain relief was 8 weeks. At a median follow-up of 4.1 years, the median duration of BNI IIIb or better pain relief was 8 years, with estimated 1, 3, and 5-year rates of pain relief of 89%, 62%, and 62% respectively. Eleven (55%) experienced facial numbness after repeat SRS with four (20%) being bothersome. One case (5.6%) of corneal numbness and zero cases of AD were reported after repeat SRS. SRS is an effective, well-tolerated treatment modality for patients with BTN. Patients with prior MVD or SRS that resulted in maximal pain relief of BNI IIIb are more likely to experience pain relapse than those who achieved BNI I relief. Repeat SRS appears to have greater efficacy and durability than initial SRS, and despite increased bothersome facial numbness remains well tolerated.