Outcomes of Gamma Knife Radiosurgery for Drug-Resistant Primary Trigeminal Neuralgia

OBJECTIVE: To evaluate the result of gamma knife radiosurgery (GKRS) for drug-resistant primary trigeminal neuralgia (TN). METHODS: Patients who were diagnosed with drug-resistant primary TN were treated with GKRS at the Nuclear Medicine and Oncology Center, Bach Mai Hospital from January 2015 to June 2020. Using the pain rating scale of the Barrow Neurological Institute (BNI), follow-ups and evaluations were conducted at 1 month, 3 months, 6 months, and 9 month, and 1, 2 years, 3 years, and 5 years after radiosurgery. Comparisons of pain levels was performed before and after radiosurgery according to the BNI scale. RESULTS: From January 2015 to June 2020, 33 patients were treated with GKS. There were 23 female patients and 10 male patients; the average age was 61.9. The average onset time of disease was 4.42 years. Among all patients, 84.8% of patients were relieved from pain and 78.8% were pain-free without medication. The mean time for pain relief was 3 months and was not related to the dose of GKS (<80 Gy and ≥80 Gy). The efficacy of pain relief is not related to blood vessel contact with the trigeminal nerve, the dose of GKS, and the onset of disease. The rate of recurrence after the first pain relief was low (14.3%). CONCLUSIONS: Gamma knife is an effective method for the treatment of primary drug-resistant TN, especially in elderly patients with underlying medical conditions. The analgesic effect does not depend on the presence of nerve-vascular conflict.