Diagnostic Performance of Magnetic Resonance Imaging in the Detection of Neurovascular Compression in Hemifacial Spasm

Abstract To evaluate the diagnostic performance of magnetic resonance imaging (MRI) in patients with hemifacial spasm (HFS), using surgical findings as the reference standard. In this cross-sectional study, 75 patients with HFS who underwent microvascular decompression were included. All patients underwent preoperative MRI using a standardized protocol with high-resolution, three-dimensional (3D) T2-weighted (T2W) and 3D time-of-flight (TOF) angiography sequences. Neurovascular conflict (NVC) characteristics on MRI were assessed and compared with intraoperative findings. Associations between imaging features and demographic and clinical variables were analyzed. Agreement between MRI and surgical findings was evaluated using Cohen's kappa, while Fisher's exact and Pearson's chi-squared tests were used for statistical comparisons. A significant association was found between the site of NVC and both patient sex and symptom laterality (p < 0.05). The degree of compression was significantly associated with involvement of the full root exit zone (REZ), pontine segment, anterior inferior cerebellar artery (AICA), and specific morphological patterns, such as the arachnoid type (p < 0.05). The MRI scans demonstrated substantial to almost perfect agreement with surgical findings across all evaluated parameters, including vascular type, conflict site, segment, degree, morphology, and classification (kappa: 0.744–0.939), with accuracy ranging from 85.6 to 98%. High-resolution MRI combining 3D T2W and 3D TOF sequences provides a reliable preoperative assessment of neurovascular conflict in HFS. Conflicts involving the full REZ and pontine segment are more frequent and, generally, associated with higher-grade compression. Arachnoid-type conflicts, particularly in association with the AICA, are more often related to lower-grade compression.