Abstract
When diffuse gliomas (DG) affect the brain’s potential to reorganize functional networks, patients can exhibit seizures and/or language/cognitive impairment. The tumor–brain interaction and the individual connectomic organization cannot be predicted preoperatively. We aimed to, first, investigate the relationship between preoperative assessment and intraoperative findings of eloquent tumors in 36 DG operated with awake surgery. Second, we also studied possible mechanisms of tumor-induced brain reorganization in these patients. FLAIR-MRI sequences were used for tumor volume segmentation and the Brain-Grid system (BG) was used as an overlay for infiltration analysis. Neuropsychological (NPS) and/or language assessments were performed in all patients. The distance between eloquent spots and tumor margins was measured. All variables were used for correlation and logistic regression analyses. Eloquent tumors were detected in 75% of the patients with no single variable able to predict this finding. Impaired NPS functions correlated with invasive tumors, crucial location (A4C2S2/A3C2S2-voxels, left opercular-insular/sub-insular region) and higher risk of eloquent tumors. Epilepsy was correlated with larger tumor volumes and infiltrated A4C2S2/A3C2S2 voxels. Language impairment was correlated with infiltrated A3C2S2 voxel. Peritumoral cortical eloquent spots reflected an early compensative mechanism with age as possible influencing factor. Preoperative NPS impairment is linked with high risk of eloquent tumors. A systematic integration of extensive cognitive assessment and advanced neuroimaging can improve our comprehension of the connectomic brain organization at the individual scale and lead to a better oncological/functional balance.
Highlights
IntroductionRecent advances in neuroimaging and direct brain mapping have shown that the brain is capable of significant redistribution of function in response to injury [1,2,3]
In 34 patients, the tumors were located on the left dominant hemisphere, while, in two patients, the tumor was located on the right hemisphere but the patients displayed preoperative bi-hemispheric dominance
What we know about the peritumoral milieu is that, when epileptic onset is triggered, it starts from the peritumoral cortical areas and not from the tumor core [2,24,27]. In support of this theory, the epileptic onset was correlated with the presence of peritumoral eloquent spots at the cortical level and at the same time the intratumoral eloquent spots subcortically. This implicates that when the epileptic activity emerges: (1) the tumor has already invaded subcortical larger networks limiting the possible large-scale reorganization/adaptation of the neural activity; (2) the peritumoral cortices have been recruited within the same functional hub through short intermediate fibers as the first mechanism of local reorganization; and (3) the subcortical networks newly invaded by the tumors are a constant correlation in both epilepsy and if we analyze the relationship among the different categories of eloquent spots, we identify a negative correlation between peritumoral cortical eloquent spots and intratumoral cortical eloquent spots
Summary
Recent advances in neuroimaging and direct brain mapping have shown that the brain is capable of significant redistribution of function in response to injury [1,2,3]. Brain plasticity most commonly refers to adaptive changes in neural pathways, synapses and glial cells, leading to functional or morphological reorganization [2,4,5]. (WHO II and III) are primary slow-growing brain tumors derived from glial cells. Due to their relatively slow natural course, the brain has time to recruit significant compensatory 4.0/). Recruitment of healthy/redundant neural circuitry both ipsilateral (first) and contralateral (long term) is a known key mechanism compensating for glioma-induced injury at both cortical and subcortical level [2,4,7,8]
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