Long-Term Efficacy of Gamma Knife Radiosurgery on Pain Control in Trigeminal Neuralgia

AIM: To investigate the efficacy of Gamma Knife radiosurgery (GKRS) in patients with Burchiel type 1 and 2 trigeminal neuralgia (TN). MATERIAL and METHODS: A retrospective analysis of prospectively collected data of 163 patients who underwent GKRS between December 2006 and December 2021 was performed. The median follow-up was 37 (range, 6-168) months. The target was the cisternal portion of the trigeminal nerve, and the median prescribed dose was 85 (range, 75-90) Gy. Pain severity was evaluated using the Barrow Neurological Institute (BNI) pain intensity score. All patients had BNI IV or V before GKRS. BNI IIIb or better was defined as adequate pain relief. Logistic regression analysis was conducted to determine the prognostic significance of different pretreatment and treatment variables. RESULTS: The initial pain relief rate was 85%, with a median period of 25 (range, 1-90) days. At the final follow-up, 62.5% of patients had adequate pain relief. BNI I was achieved in 8% of patients within the first 24 h after GKRS; this rate was 22% at the final follow-up. The pain-free interval was significantly shorter in the 75 Gy group than in the 90 Gy group (p=0.04). The predicted adequate pain relief rates at the 3rd and 6th month and 1st, 3rd, 5th, and 7th year were 84%, 79%, 76%, 67%, 59%, and 55%, respectively. The complication rate was 8%, with disturbing facial sensorial dysfunction in four patients, decreased corneal reflex in three patients, and masseter dysfunction in six patients. Univariate and multivariate logistic regression analyses revealed Burchiel type 1 TN (p=0.001) and male gender (p=0.037) as predictors of increased initial pain relief rate and shorter time to initial pain relief day, respectively. CONCLUSION: Appropriate patient selection is the key to successful TN treatment. GKRS can be recommended, especially for patients with Burchiel type 1 TN, with low complication rates and effective long-term pain relief.