Influence of Neurovascular Conflict on the Outcome of Primary Gamma Knife Radiosurgery for Trigeminal Neuralgia: A Single-Center Retrospective Study

Background: Gamma Knife Radiosurgery (GKRS) is an established effective treatment for medically intractable trigeminal neuralgia (TN), but outcome predictors remain controversial. Notably, the influence of neurovascular conflict (NVC) evident on magnetic resonance imaging on the outcomes of radiosurgery is debated. This study aims to evaluate whether a NVC with the trigeminal nerve in the posterior fossa influences pain and sensory outcomes after primary GKRS for TN. Methods: A retrospective review of our GKRS database identified 148 patients who underwent GKRS as the initial treatment for medically intractable TN between 2014 and 2024. Background medical history, treatment outcomes and complications, and dosimetric data were collected through chart review. NVC was graded based on high-resolution magnetic resonance images obtained prior to treatment, according to a 4-tier severity scale. Results: After GKRS, 132 (89%) patients achieved Barrow Neurological Institute (BNI) grade IIIb or better pain relief. At a median follow-up of 39 months, pain recurred in 27 (20%) patients, and 47 (32%) developed facial sensory disturbances, which were bothersome in 18 (12%). Estimated rates of pain relief at 1, 3, 5, 7 years were 77%, 72%, 68%, and 64%, respectively. The median maximum dose was 85Gy. The presence and severity of NVC did not predict pain or sensory outcomes after GKRS, whereas facial sensory disturbances were associated with long-term pain relief. Conclusions: GKRS is an effective treatment for medically intractable TN but may lead to facial sensory disturbances. The presence or severity of NVC with the trigeminal nerve in the posterior fossa did not influence the outcomes of primary GKRS.