Assessment of Network Integrity in Right-Hemispheric Glioma Patients Using Function-Based Tractography and Domain-Specific Cognitive Testing

Abstract

Objective: Gliomas disrupt functional brain networks and impair neurological functions. While left-hemispheric tumors are well-studied because of their impact on language domains, the influence of right-sided gliomas on higher cognitive functions remains less understood. This study aimed to assess pre- and postoperative neurocognitive performance and to link cognitive outcomes with structural findings derived from function-based tractography in patients with right-hemispheric gliomas. Methods: Patients with gliomas were enrolled in this prospective observational study. A structured neurocognitive test battery was administered preoperatively, postoperatively, and at 3-month follow-up. Preoperative cortical mapping using navigated transcranial magnetic stimulation (nTMS) and function-based fiber tracking, based on diffusion tensor imaging (DTI), was performed. Results: Eighteen patients aged 52.7 ± 18.3 years were included. Preoperatively, 88.8% of patients showed impairments in at least one cognitive test, most frequently in the Nine-Hole Peg Test (66.7%), Bells Test task completion time (61.1%), Trail Making Test A and B (TMT-A: 50.0%; TMT-B: 44.4%), and digit symbol substitution test (27.8%). At follow-up, task performance improved on most cognitive tests. Function-based tractography showed that involvement of the superior longitudinal fasciculi I–III (44.4% of cases) was associated with impairments in attention, executive function, visuospatial processing, and processing speed. The involvement of the inferior frontooccipital fasciculus (55.5% of cases) was related to deficits in processing speed, attention, executive function, and episodic memory. Conclusions: Neurocognitive deficits are common in patients with right-hemispheric gliomas even before surgery. Maximal safe resection and sparing of these tracts is associated with cognitive recovery at follow-up. Function-based tractography emphasizes the structural involvement of key association fibers related to these cognitive deficits.