P11.09.B STRUCTURAL REORGANIZATION IN MOTOR-ELOQUENT GLIOMA PATIENTS EXHIBITING MOTOR DEFICITS

Abstract

Abstract BACKGROUND Recent advancements in navigated transcranial magnetic stimulation (nTMS) have significantly improved the localization of motor functions in human subjects. Although previous studies have demonstrated the occurrence of tumor-induced motor plasticity, the detailed mechanisms of motor function plasticity and reorganization in patients with tumors affecting motor-eloquent regions are not fully elucidated. Our study aims to investigate the functional plasticity of motor functions in patients with gliomas located within motor-eloquent regions, providing deeper insights into the mechanisms of functional plasticity. MATERIAL AND METHODS In this research, we studied 60 glioma patients with tumors located in the motor-eloquent region. These patients were categorized into two groups depending on whether they experienced motor impairments in the upper extremities. We utilized nTMS, including Motor Evoked Potentials (MEP), to outline the control regions of motor function in terms of area, localization, and Center of Gravity (CoG). These identified regions also acted as seeds for tracing the Corticospinal Tract (CST). RESULTS The study unveiled significant variations in cortical and subcortical motor function localizations between the groups. Patients with motor impairments exhibited a broader cortical distribution connected to motor functions and increased volumes of CST, reflecting compensatory adaptations with different fractional anisotropy (FA) values (FA 0.15, p=0.02; FA 0.10, p=0.04). The analysis of the CST also showed overlapping regions, particularly within the hand-knob areas, which is indicative of these areas acting as critical motor output pathways. Despite varying degrees of functional impairment, all patients maintained some degree of motor output capability. CONCLUSION These findings suggest that motor-eloquent gliomas induce significant cortical and subcortical reorganization of motor functions. A persistent network of CST fibers, crucial for preserving motor function, highlights a complex interplay between cortical adaptation and subcortical reorganization. This study underscores the resilience of motor pathways and their pivotal role in functional recovery and plasticity, emphasizing the clinical relevance of nTMS in the therapeutic planning and monitoring of patients with motor-eloquent gliomas.