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

To investigate the efficacy of Gamma Knife radiosurgery (GKRS) in patients with Burchiel type 1 and 2 trigeminal neuralgia (TN).

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.

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.

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.