Involvement of white matter in cognitive flexibility in patients with right hemisphere glioma.
Summary
As key element of executive function, cognitive flexibility incorporates multiple component processes, enabling adaptation in response to a constantly changing environment. Preserving cognitive flexibility during surgical resection of a low-grade glioma is of great importance to maintain quality of life and recover optimally from this life event. Dysconnectivity within the fronto-parieto-temporal network of the right parietal lobe has previously been linked to cognitive flexibility deficits, suggesting white matter involvement. To further explore the involvement of white matter in cognitive flexibility, a multicentred international collaboration was established. Nineteen patients, who underwent surgical resection for a low-grade glioma in the right parietal lobe, were assessed pre- and post-surgery, using the Trail Making Test and Stroop-Color-Word-Test to administer cognitive flexibility. Volume measurements and lesion-symptom mapping analyses were performed on postoperative MRI scans. Results showed that the Superior Longitudinal Fasciculus III (SLF III), Arcuate Fasciculus (AF) and Inferior Fronto-Occipital Fasciculus (IFOF) were damaged in both cognitively declined patients (n=4) and cognitively non-declined patients (n=15). Tractographic resection simulations presented similar patterns of dysconnectivity in the right parietal lobe in both groups. In addition, a greater extent of resection was not linked to a decline in cognitive flexibility after surgery. Our findings neither confirm nor deny the proposed involvement of the SLF III, AF and IFOF in cognitive flexibility. Yet, it is clear that cognitive inflexibility is not related to the extent of resection. The integration of DTI and intraoperative monitoring in standard clinical practice is needed for localization and comprehension of cognitive outcomes after neurosurgery.