Gamma Knife surgery for tumor-related trigeminal neuralgia: targeting both the tumor and the trigeminal root exit zone in a single session.

OBJECTIVE Gamma Knife surgery (GKS) represents an alternative treatment for patients with tumor-related trigeminal neuralgia (TRTN). However, in previous studies, the primary GKS target was limited to mass lesions. The authors evaluated whether GKS could target both the tumor and the trigeminal root exit zone (REZ) in a single session while providing durable pain relief and minimizing radiation dose-related complications for TRTN patients. METHODS The authors' institutional review board approved the retrospective analysis of data from 15 consecutive patients (6 men and 9 women, median age 67 years, range 45-79 years) with TRTN who had undergone GKS. In all cases, the radiation was delivered in a single session targeting both the tumor and trigeminal REZ. The authors assessed the clinical outcomes, including the extent of pain relief, durability of the treatment response, and complications. Radiation doses to organs at risk (OARs), including the brainstem and the cranial nerve VII-VIII complex, were analyzed as doses received by 2% or 50% of the tissue volume and the tissue volume covered by a dose of 12 Gy (V12Gy). RESULTS The median length of clinical follow-up was 38 months (range 12-78 months). Pain relief with GKS was initially achieved in 14 patients (93.3%) and at the last follow-up in 13 patients (86.7%). The actuarial recurrence-free survival rates were 93%, 83%, and 69% at 1, 3, and 5 years after GKS, respectively. Persistent facial numbness was observed in 3 patients (20.0%). There were no complications such as facial weakness, altered taste function, hearing impairment, and balance difficulties indicating impaired function of the cranial nerve VII-VIII complex. The V12Gy in the brainstem was less than or equal to 0.24 cm3 in all patients. There were no significant differences in any OAR values in the brainstem between patients with and without facial numbness after GKS. CONCLUSIONS The strategy of performing GKS for both tumor and trigeminal REZ in a single session is a safe and effective radiosurgical approach that achieves durable pain control for TRTN patients.