Utility of the Integral Dose for Predicting Radiosurgery Response in Patients with Trigeminal Neuralgia

Saturday, May 4, 2024

4:24 PM – 4:26 PM CT

Location: S405b

Presenting Author(s)

Ying Meng

Fellow
NYU Langone Medical Center
Brampton, ON, CA

Co-Author(s)

KB

Kenneth Bernstein, MS

Medical Physicist
NYU Langone Medical Center, United States
BC

Benjamin Cooper, MD

Radiation Oncologist
NYU Langone Medical Center, United States
JG

Jason Gurewitz, MD

Resident, Radiation Oncology
NYU Langone Medical Center
New York, New York, United States
Douglas Kondziolka, MD, MSc

Neurosurgeon
NYU Langone Medical Center
New York, NY, US
Elad Mashiach, MSc (he/him/his)

Medical Student
NYU Langone Medical Center
New York, New York, United States
Brandon A. Santhumayor, BA

Medical Student
NYU Langone Medical Center
Piscataway, NJ, US
JS

Joshua Silverman, MD

Radiation Oncologist
NYU Langone Medical Center, United States
ES

Erik Sulman, MD

Radiat
NYU Langone Medical Center
Houston, Texas, United States

Disclosure(s):

Ying Meng: No financial relationships to disclose

Douglas Kondziolka, MD, MSc: No financial relationships to disclose

Brandon A. Santhumayor, BA: No financial relationships to disclose

Introduction: Stereotactic radiosurgery is effective for patients with medically refractory trigeminal neuralgia with approximately 75-90% response rate. The integral dose (ID) of the nerve targeted within the 50% isodose line (the focused energy deposition) may help select the prescription dose to maximize effectiveness and minimize bothersome sensory dysfunction.

Methods: We reviewed the dosimetry parameters and outcomes of consecutive type 1 trigeminal neuralgia patients undergoing stereotactic radiosurgery for the first time between 2012 and 2023 at NYU. MS/tumor-related pain was excluded.

Results: 94 patients were identified for analysis. 70% of the prescription doses were 80Gy, with 28% at 85Gy and 2% at 70Gy. The mean follow-up time was 26.7 months. 85 (90%) patients reported significant pain relief (Barrow Neurological Institute pain intensity score I – III), with 30 (32%) achieving pain relief off medications. The median pain-free survival was 82 months (95% CI 41.1 – NA). The estimated pain free survival rates at 1, 3, and 5 years were 80.5%, 65.5% and 55.9% respectively. The ID was not significantly related to initial pain relief, or pain free survival using Cox proportional hazards model (p = 0.327). Cases with higher mean and minimal dose of the target nerve within the 50% isodose line had reduced risk of pain recurrence (HR 0.364, p = 0.017; HR 0.438, p = 0.069), but only the former measure remained significant on multivariate analysis (HR of 0.408, p = 0.039). Twenty (21%) patients experienced numbness post radiosurgery with three (3%) requiring further medications. We did not find a significant relationship between ID or maximum brainstem dose with bothersome sensory dysfunction.

Conclusion : The ID did not appear to predict pain relief or recurrence. A higher mean dose may be associated with durability. While radiosurgery is an effective option for trigeminal neuralgia, it remains challenging to predict the outcome on an individual basis.