gms | German Medical Science

Objective: Cognitive deficits in glioma patients are often neglected in clinical routine and neural correlates not well understood. We hypothesized that cognitive dysfunction might depend on network alterations rather than on local tumor extent and aimed at investigating functional connectivity of the frontoparietal (FPN) and the default-mode network (DMN) using resting-state fMRI (rs-fMRI). We wanted to examine whether functional connectivity is related to cognitive performance in glioma patients.

Methods: 15 patients with newly diagnosed cerebral glioma (mean age 44.9+/-14.6 yrs; 10 male; 14 right handed, 8 right hemispheric, mean tumor volume 57+/-64 ml, 5 WHO II, 6 WHO III, 4 WHO IV) as well as 15 age-, sex-, handedness and education-wise matched healthy controls were preoperatively enrolled in the study. Subjects underwent rs-fMRI and a standardized neuropsychological exami-nation (verbal learning memory task (VLMT), trail-making test (TMT-A/B)). To account for differences in tumor characteristics a ROI-based analysis was applied and mean functional connectivity defined (for the contratumoral, ipsitumoral, and both hemispheres, respectively) within each network (FPN, DMN) and across networks (global). Behavioural and functional connectivity measures were compared between patients and controls, and correlation of functional connectivity with behavioural parameters were examined.

Results: Patients and healthy controls differed significantly in perceptual and performance speed (TMT-A/B; p<0.021, p<0.022). Correspondingly, mean functional connectivity (FC) of the FPN within the ipsitumoral hemisphere was significantly decreased in the patient group as com-pared to healthy controls (p<0.025), while no significant differences were observed with regard to the DMN. While cognitive perfor-mance and connectivity measures within resting-state networks were independent of tumor size and grade, cognitive performance with regard to verbal learning (p<0.017) and verbal recognition (p<0.016) was significantly correlated with global FC across networks, and perceptual speed (TMT-A) significantly correlated (p<0.041) with FC of the contratumoral hemisphere in the patient group.

Conclusion: Executive dysfunction in glioma patients was related to decreased functional connectivity within the frontoparietal network in the ipsitumoral hemisphere, while network integrity in tumor distant areas appeared to be relevant for partial maintenance of cognitive functions.