A network-level approach of cognitive flexibility impairment after surgery of a right temporo-parietal glioma

Abstract

Objective: The right "non-dominant" temporo-parietal junction is usually not considered as a highly eloquent area. This contrasts with its mirrored left "dominant" counterpart, which is known as highly eloquent regarding language function. The question arises about which functions should be monitored when operating lesions of the right temporo-parietal junction under awake conditions.

Methods: We report the case of a patient who underwent a surgical resection of a glioma located in the right temporo-parietal junction. Cognitive evaluations were performed preoperatively and 4 months after surgery, as well as resting state fMRI and diffusion-based tractography.

Results: Long-term postoperative cognitive examination revealed an important deterioration of cognitive control abilities, especially regarding set-shifting abilities as measured by Trail making test part B. Based on pre- and postoperative resting state fMRI and diffusion-based tractography, we demonstrate that surgical resection massively impacted structural and functional connectivity of the right fronto-parieto-temporal network, a network that is classically involved in cognitive control, reasoning and working memory.

Conclusion: This case clearly illustrates how a white matter focal lesion can generate a neuropsychological deficit by remotely disconnecting distant cortical areas belonging to a functional network. Furthermore, our observation strongly supports the use of intraoperative cognitive control tests during surgery of the right temporo-parietal junction and promote the interest of pre and postoperative resting state functional connectivity to explore the potential mechanisms causing cognitive deficits.

Keywords: Awake surgery; Cognitive flexibility; Functional connectivity; Glioma; Structural connectivity; Trail making test.