Cortical Myeloarchitectonic Changes in Patients with Classical Trigeminal Neuralgia

Objective. Classic trigeminal neuralgia (TN) is a common chronic pain syndrome whose pathogenesis is not limited to the trigeminal system. Despite significant progress in understanding its mechanisms, data on the role of morphological changes in the cerebral cortex remain limited. In this study, we assessed cortical myeloarchitecture using T1w/T2w mapping, a post-processing method for MRI images. The T1w/T2w ratio is considered a reliable marker of myelin content in the cortex and is currently being explored as a promising clinical biomarker.

Materials and Methods. The study involved 41 patients with unilateral classical TN and 40 healthy volunteers. All participants underwent high-resolution brain MRI with 3D T1-weighted and 3D T2-weighted images. In the first stage, automatic cortex par-cellation was performed using FreeSurfer version 7.4.1 software. T1w/T2w ratio maps were then constructed using the MRTool (SPM12) package. The resulting T1w/T2w ratio maps were coregistered with the cortex parcellation results, after which mean values were extracted for each region according to the Desikan — Killiany atlas. For statistical analysis, analyses of covariance (ANCOVA) were performed, where group membership (patients with TN, healthy volunteers) was considered as an intergroup factor, the T1w/T2w ratio values in different areas of the cerebral cortex were considered as a dependent variable, and the age and gender of the patients were taken into account as covariates.

Results. In the group of patients with trigeminal neuralgia, compared with the group of healthy volunteers, a statistically significant decrease in the mean T1w/T2w ratio was found in the regions of the left hemisphere, including the inferior parietal lobule, isthmus and posterior cingulate gyrus, lateral occipital, parahippocampal, and precen-tral cortex (p < 0.05, FDR-corrected). In the right hemisphere, a decrease in T1w/T2w values was observed in the lateral occipital, fusiform, lingual, and transverse temporal cortex (p < 0.05, FDR-corrected).

Conclusion. Our results indicate that classical trigeminal neuralgia is associated with myeloarchitectonic changes in individual areas of the cerebral cortex, reflecting the complex nature of the pathogenesis of this condition.

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