• Ying Meng, Brandon Santhumayor, Elad Mashiach, Kenneth Bernstein, Jason Gurewitz, Benjamin T Cooper, Erik Sulman, Joshua Silverman, and Douglas Kondziolka.
• Department of Neurosurgery, NYU Grossman School of Medicine, New York, New York, USA.
• Neurosurgery. 2024 Aug 28.

Background And ObjectivesStereotactic radiosurgery (SRS) is effective for patients with medically refractory trigeminal neuralgia with a 75%-90% response rate. Consideration of the integral dose (ID) to the target nerve within the 50% isodose line was reported to help select prescription doses to maximize effectiveness and minimize bothersome numbness. The objective of this study was to externally validate the ID as a predictor of outcomes after SRS.MethodsWe reviewed the outcomes and parameters of 94 consecutive patients of type 1 trigeminal neuralgia who had SRS for the first time where nerve ID was calculated. 70% of the prescription doses were 80 Gy, with 28% at 85 Gy, and 2% at 70 Gy.ResultsThe median follow-up time was 14.4 months. A total of 85 (90%) patients reported significant pain relief (Barrow Neurological Institute I-III) after initial SRS. The median pain recurrence-free survival was 82 months (95% CI 41.1-NA), and estimates at 1, 3, and 5 years were 80.5%, 65.5%, and 55.9%, respectively. The ID was not significantly associated with initial pain relief, or affect the risk of pain recurrence or sensory dysfunction after SRS using the Cox proportional hazards model. A nerve mean dose ≥65 Gy was associated with a reduced risk of pain recurrence on multivariate analysis (hazard ratio 0.408, P = .039). Twenty (21%) patients experienced sensory dysfunction after SRS with 3 (3%) requiring further medications, which was not correlated with the prescription dose or brainstem maximum dose.ConclusionThe ID did not predict recurrence-free survival or sensory dysfunction. Our observations suggest improved nerve coverage by the most powerful area of the isocenter, for instance, by targeting a narrower segment if feasible, could result in more durable pain relief. Further studies to validate these findings are needed.Copyright © Congress of Neurological Surgeons 2024. All rights reserved.

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