Gyroscopic Radiosurgery for Trigeminal Neuralgia: Results of a Retrospective Series of >50 Patients

Background: Stereotactic radiosurgery (SRS) is an established treatment option for medically refractory trigeminal neuralgia (TN). However, clinical evidence regarding dedicated gyroscopic radiosurgery systems remains limited. This study aimed to evaluate the efficacy, latency of response, safety, retreatment rate, and potential clinical and dosimetric predictors of outcome following ZAP-X gyroscopic radiosurgery for TN. Methods: A consecutive series of patients with pharmacologically refractory TN treated with ZAP-X gyroscopic radiosurgery between February 2023 and September 2025 was analyzed. Treatment consisted of a single isocenter targeting approximately 5 mm of the cisternal-retrogasserian trigeminal nerve, with a maximum dose of 90 Gy and a V70 Gy coverage objective ≥ 50%, using 4 or 5 mm collimators. Pain outcome was assessed using the Barrow Neurological Institute Pain Intensity Scale (BNI), and sensory toxicity was evaluated using the BNI Facial Numbness Scale. Clinical and treatment-related predictors of failure and retreatment were explored using binary logistic regression. Results: Following radiosurgery, 87.5% of patients achieved satisfactory pain control (BNI I–IIIb; 95% CI, 78.8–96.2%), with a significant overall improvement in BNI score compared with baseline (p < 0.001) at the 12 months of follow-up. Half of the patients experienced clinical improvement within the first 15 days. Treatment-related toxicity occurred in 8.9% of patients, while 26.8% required repeat radiosurgery during follow-up. The decision to perform retreatment is made when the patient has shown no improvement in the BNI score at 6 months after the initial treatment. Baseline BNI grade V was the only statistically significant predictor of treatment failure, conferring a more than ninefold higher odds of non-response compared with BNI grade IV (OR 9.33; 95% CI, 1.66–52.3; p = 0.011). Female sex showed a nonsignificant trend toward a lower risk of failure (OR 0.65; 95% CI, 0.13–3.24; p = 0.596). Neither multiple sclerosis-associated TN nor other etiological or dosimetric variables significantly predicted treatment failure. A greater number of beams showed a trend toward an increased probability of retreatment (OR 1.01; p = 0.091), although statistical significance was not reached. Conclusions: Gyroscopic radiosurgery with ZAP-X provides high rates of pain control, rapid clinical response, and a favorable safety profile in patients with refractory TN. Greater baseline pain severity appears to be associated with poorer treatment response. These findings support ZAP-X as an effective frameless radiosurgical alternative for TN, although larger prospective studies are required to identify robust clinical, dosimetric, and radiobiological predictors of long-term outcome.