207 Intraoperative Functional Re-mapping Unveils Evolving Patterns of Cortical Plasticity

Abstract

INTRODUCTION: Diffuse low-grade gliomas (DLGG) induce a compensatory modulation of the anatomo-functional architecture, making this kind of brain tumours an ideal lesion model to study the dynamics of neuroplasticity. Direct electrostimulation (DES) mapping is a well-tried procedure used during awake resection surgeries to spare cortical epicenters which are critical for a range of functions. Because DLGG is a chronic disease, it inevitably relapses years after the initial surgery, and thus requires a second surgery to reduce tumour volume again. METHODS: We capitalized on a series of 101 DLGG patients who benefited from two DES-guided neurosurgeries usually spaced several years apart, resulting in a DES dataset of 2082 cortical sites. We used a multi-step approach to generate probabilistic neuroplasticity maps that reflected the dynamic rearrangements of cortical mappings from one surgery to another, both at the population and individual-level. RESULTS: Voxel-wise neuroplasticity maps revealed regions with a high potential of evolving reorganizations, including the supplementary motor area (SMA), the dorsolateral prefrontal cortex (dlPFC), the anterior ventral premotor cortex (vPMC) and the middle superior temporal gyrus (STG). Parcel-wise neuroplasticity maps confirmed this potential for the dlPFC, the anterior and the ventral precentral gyrus. A series of clustering analyses revealed a topological migration of clusters, especially within the left dlPFC and STG (language sites); the left vPMC (speech arrest/dysarthria sites) and the right SMA (negative motor response sites). At the individual level, these dynamic changes were confirmed for the dlPFC (bilateral), the left vPMC and the anterior left STG (threshold free cluster enhancement, 5000 permutations, family-wise-error-corrected). CONCLUSIONS: Our results provide a critical insight into the dynamic potential of DLGG-induced continuing rearrangements of the cerebral cortex, with considerable implications for re-operations.