Contralateral language network integration predicts and protects against naming decline after temporal lobe resection

Anterior temporal lobe resection (ATLR) is an effective treatment for drug-resistant temporal lobe epilepsy (TLE) but carries a substantial risk of language impairment, particularly in naming. Understanding and predicting the impact of ATLR on language functions remains a major clinical challenge.

In this study, we used functional magnetic resonance imaging (fMRI) to investigate the short-term effects of ATLR on the organization of the functional language connectome with a focus on the role of the nondominant hemisphere. We studied 44 patients with TLE due to unilateral hippocampal sclerosis (24 left, 20 right) who underwent language fMRI and neuropsychological testing preoperatively and 4 months after ATLR. We examined functional connectivity changes pre- and postsurgery and their relationship with neuropsychological performance.

ATLR induced widespread alterations in functional connectivity, with distinct ipsilateral disruptions and contralateral compensatory changes. Left ATLR reduced mainly interhemispheric temporal connectivity, whereas right ATLR primarily affected bilateral frontal connections. Postoperatively, left ATLR showed increased intrahemispheric frontotemporal connectivity, and right ATLR exhibited more widespread intra- and interhemispheric increases. In left TLE, better preoperative naming was associated with stronger connectivity of the right (nondominant) temporal lobe and between the left inferior frontal cortex and bilateral posterior hippocampi. Postoperatively, reduced right frontotemporal integration was linked to greater naming decline, underscoring a compensatory role of the nondominant hemisphere. Finally, a machine learning model using preoperative functional connectivity fingerprints outperformed demographic and clinical variables in predicting clinically significant naming decline following ATLR.

Our findings highlight the critical role of the right temporal lobe in supporting naming function after left ATLR and suggest that preoperative assessment of its connectivity may improve prediction of postoperative language outcomes.