Association of homotopic areas in the right hemisphere with language deficits in the short term after tumor resection

OBJECTIVE It is important to identify language deficit and recovery in the week following a tumor resection procedure. The homotopic Broca's area and the superior longitudinal fasciculus in the right hemisphere participate in language func-tional compensation. However, the nodes in these structures, as well as their contributions to language rehabilitation, remain unknown. In this study, the authors investigated the association of homotopic areas in the right hemisphere with language deficit.METHODS The authors retrospectively reviewed the records of 50 right-handed patients with left hemispheric lower -grade glioma that had been surgically treated between June 2020 and May 2022. The patients were divided into normal and aphasia groups based on their postoperative aphasia quotient (AQ) from the Western Aphasia Battery. Preoperative (within 24 hours before surgery) and postoperative (7 days after tumor resection) diffusion tensor images were used to reveal alterations of structural networks by using graphic theory analysis. The shortest distance between the glioma and the nodes belonging to the language network (SDTN) was quantitatively assessed. Pearson's correlation and causal me-diation analyses were used to identify correlations and mediator factors among SDTN, topological properties, and AQs.RESULTS Postoperative nodal local efficiency of the node dorsal Brodmann area (BA) 44 (A44d; p = 0.0330), nodal clustering coefficient of the nodes A44d (p = 0.0402) and dorsal lateral BA6 (A6dl; p = 0.0097), and nodal degree cen- trality (p = 0.0058) of the node medial BA7 (A7m) were higher in the normal group than in the aphasia group. SDTN was positively correlated with postoperative AQ (r = 0.457, p = 0.0009) and Delta AQ (r = 0.588, p < 0.0001). The nodal local ef-ficiency of node A44d and the nodal efficiency, nodal betweenness centrality, and degree centrality of node A7m were mediators of SDTN and postoperative AQs.CONCLUSIONS The decreased ability of nodes A44d, A6dl, and A7m to convey information in the right hemisphere was associated with short-term language deficits after tumor resection. A smaller SDTN induced a worsened postopera- tive language deficit through a significant decrease in the ability to convey information from these three nodes.