BackgroundNeurosurgeons are increasingly capable of maintaining language and motor functions in glioma patients following surgery due to the ability to preserve traditionally "eloquent" structures. However, glioma patients continue to present with severe morbidity in cognitive functions due to the lack of familiarity in the neurosurgical community with non-traditionally "eloquent" brain networks. Therefore, the authors sought to identify and describe the frequency of invasion and/or proximity

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... Insulo-Sylvian gliomas to portions of non-traditional, large scale brain networks during surgery.MethodsA retrospective analysis was completed of consecutive adult patients undergoing surgery for newly diagnosed glioma at a single center between 2017-2020 with WHO grade II-IV infiltrating gliomas centered in the insula, opercular cortices or temporal stem. Diffusion tensor imaging (DTI)-based tractography was completed by creating a personalized brain connectome atlas based on the Human Connectome parcellation scheme with Quicktome software. This algorithm utilizes an machine learning (ML)-approach to assign voxels of the cerebral cortex to various brain regions according to structural connectivity patterns of voxels in the brain region of interest utilizing neuroimaging data specifically from normal healthy adults. Insulo-Sylvian tumors were categorized based on their involvement with non-traditional cognitive networks versus traditionally eloquent structures.Results45 patients were included (47±15 years, 51% female) consisting of mostly high grade (IV)-gliomas (56%) compared WHO grade II (22%) or III (22% tumors). Ultimately, 44/45 (98%) patients demonstrated tumor involvement (<1cm proximity or invasion) to the cortical or subcortical components of a non-traditional, large scale brain network or major white matter pathway involved in cognition. In comparison, 35/45 (78%) patients demonstrated tumor involvement of traditionally considered "eloquent" structures like the corticospinal tract or language regions/tracts. The most common non-traditional cognitive networks involved in cases included the salience network (60%) followed by the central executive network (56%). ConclusionsNon-traditionally "eloquent" brain networks are increasingly encountered during surgical resection of Insulo-Sylvian gliomas in both hemispheres and must be considered moving forward. Damage or dysfunction in these networks has been shown to result in severe cognitive morbidity and an improved understanding of their presence can allow for more informed surgical decisions based on patient onco-functional goals.