Outcome Predictors after Microvascular Decompression for Trigeminal Neuralgia: Expanding the Scope with MRI-based Morphometric Analysis

Objective: Microvascular decompression (MVD) is an effective treatment for pain-relief in trigeminal neuralgia (TN) patients with vessel compression. Although several prognostic factors for pain relief outcomes have been studied, literature on MRI-based morphometrics is limited. Our study analyzes outcome predictors, including MRI measurements, for MVD. Methods: A retrospective chart review was performed for all patients who underwent MVD for TN at our institution from 2013–2024. Demographic data, procedural details, and Barrow Neurological Index (BNI) pain scale were collected. MRI-based morphometric measurements were taken using Constructive Interference in Steady State (CISS) MRI. These include trigeminal nerve (CN V) cisternal segment length and distances between CN V-CNVII, CN V-porus acusticus, and CN V-transverse-sigmoid sinus junction. Angle measurements were taken for CN V-anterior pons and CN V-midline. Regression models evaluated outcomes of initial post-op BNI score ≥3 and last follow-up BNI score ≥3. Results: Our analysis included 179 patients with median BMI of 28.3 and age of 66.0 years at median follow-up of 6 months. Sex, laterality, pre-MVD numbness, hypertension, and prior balloon rhizotomy or gamma knife were not associated with BNI score of ≥3. In univariable regression, higher CN V length was associated with lower chance of BNI ≥3, indicating better outcomes ( p = 0.024). Multivariable logistic regression showed significant association between increased CNV-Midline angle ( p = 0.0017) and initial post-op BNI of ≥3. Higher BMI and increased CN V-CNVII distance were associated with increased chance of BNI score ≥3 on both initial ( p = 0.0239 & p = 0.0053) and last follow-up ( p = 0.0457 & p = 0.0164). In the subgroup that excluded patients with prior non-medical interventions and any non-vascular compression, every predictor that was significant in the full cohort stayed significant except the CN?VII-CN?V distance for the initial post-op BNI outcome. In the arterial compression only subgroup, BMI emerged as the lone significant predictor of initial post-op BNI≥3, while CN?VII-CN?V distance was the single significant predictor at last follow-up. Conclusion: Our study identifies predictors of pain outcomes following MVD for TN, incorporating MRI-based morphometrics. After controlling for confounding factors, we found that a greater CN V–CN VII distance was associated with worse initial and long-term pain outcomes, a larger CN V–midline angle correlated with higher immediate postoperative pain scores, and increased CN V length was linked to improved long-term outcomes. These findings suggest that both morphometric and demographic factors may influence MVD efficacy, providing valuable insights for patient selection and counseling. Publication History Article published online: 27 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany