Elucidating the structural–functional connectome of language in glioma‐induced aphasia using nTMS and DTI

Abstract

Glioma-induced aphasia (GIA) is frequently observed in patients with newly diagnosed gliomas. Previous studies showed an impact of gliomas not only on local brain regions but also on the functionality and structure of brain networks. The current study used navigated transcranial magnetic stimulation (nTMS) to localize languagerelated regions and to explore language function at the network level in combination with connectome analysis. Thirty glioma patients without aphasia (NA) and 30 patients with GIA were prospectively enrolled. Tumors were located in the vicinity of arcuate fasciculus-related cortical and subcortical regions. The visualized ratio (VR) of each tract was calculated based on their respective fractional anisotropy (FA) and maximal FA. Using a thresholding method of each tract at 25% VR and 50% VR, DTI-based tractography was performed to construct structural brain networks for graph-based connectome analysis, containing functional data acquired by nTMS.The average degree of left hemispheric networks (M left ) was higher in the NA group than in the GIA group for both VR thresholds. Differences of global and local efficiency between 25% and 50% VR thresholds were significantly lower in the NA group than in the GIA group. Aphasia levels correlated with connectome properties in M left and networks based on positive nTMS mapping regions (M pos ). A more substantial relation to language performance was found in M pos and M left compared to the network of negative mapping regions (M neg ). Gliomas causing deterioration of language are related to various cerebral networks. In NA patients, mainly M neg was impacted, while M pos was impacted in GIA patients.

Structural connectome-based predictive modeling of cognitive deficits in treated glioma patients

“…They observed that local (node) efficiency, a measure for communication strength among the first neighbors of a node, was generally reduced in tumor patients and particularly related to memory function in temporal tumors and to information processing speed in frontal tumors. Zhang et al 16 applied navigated transcranial magnetic stimulation (nTMS) and whole-brain deterministic tractography in left-sided tumors and observed a correlation between the average node degree (and other connectome properties) of the left-hemispheric/nTMS-positive networks and the degree of aphasia. A network-level approach was also adopted by Mrah et al, 19 who computed lesion overlap and white matter dysconnectivity scores for several atlas-based functional networks in low-grade glioma.…”

Alternations and Applications of the Structural and Functional Connectome in Gliomas: A Mini-Review

“…Structural–functional coupling describes anatomical support for functional communications across brain regions ( Baum et al, 2020 ; Gu et al, 2021 ). Zhang et al (2021) reported the structural–functional connectome of language in glioma-induced aphasia, and patients with aphasia were without sufficient functional compensation in the supplementary motor area, which was mainly involved in aphasia. Traditionally, correlation analysis was commonly used for the structural connection (SC) and functional connection (FC) strength to obtain a structural–functional coupling matrix.…”

Preoperative Navigated Transcranial Magnetic Stimulation: New Insight for Brain Tumor-Related Language Mapping

“…In this regard, a recent study aimed to evaluate the global and local properties of function-specific connectomes derived from linguistic mapping with rnTMS in patients with or without aphasia. The results showed that the global interference of gliomas in the distribution and performance of various brain networks leads to the clinical manifestation of different levels of aphasia [ 66 ]. Alterations in the efficiency of various networks between patients with and without aphasia reflect the interaction of different brain regions in the transmission of information, supporting the theory of language function based on the link between dorsal and ventral streams [ 67 ].…”