Changes in Functional Connectivity After Surgical Resection of High-grade Gliomas: A Systematic Review

Introduction: High-grade gliomas (HGGs) disrupt the neuroanatomical structure and functional connectivity of the brain, causing neurological deficits and adaptive changes. This systematic review explores how the surgical resection of HGGs affects functional networks, cognitive function, quality of life, and specific neuroanatomical areas. Additionally, we investigate how different intraoperative and postoperative techniques can predict changes in functional connectivity and cognitive outcomes in HGG patients.

Methods: A comprehensive PubMed search was conducted for data collection. The PubMed search was a systematic review performed under the guidelines of Preferred Reporting Items for Systematic Review and Meta-Analyses. The articles were abstracted and examined for qualitative and quantitative variables, including article type, patients included in each study, surgical resection, intraoperative imaging, cognitive outcomes, neuroanatomical changes, and postoperative imaging and cognitive assessments.

Results: From the PubMed search, 42 articles were included, with representation of a total of 4,507 patients, and 1,749 of these patients having had HGGs (38.8%). The articles consisted of a combined retrospective and prospective study, a cross-sectional study, retrospective studies, prospective studies, and review articles. Of the total 42 articles included in the study, 22 articles discussed functional connectivity in HGG (52%), 26 articles analyzed cognitive outcomes in relation to HGGs (62%), seven articles examined neuroanatomical changes with surgical resection of HGG (17%), and 20 articles provided information regarding preoperative and/or postoperative imaging techniques in HGG (48%).

Conclusion : Our study affirmed that HGG growth and surgical resection can disrupt functional networks, leading to neurological and cognitive impairments both pre- and post-operatively. However, we found that these outcomes tend to be poorly reported. Furthermore, the use of various neuroimaging techniques has demonstrated post-surgical alterations in functional connectivity within specific brain networks. Neurosurgeons can utilize intraoperative identification of regions that influence cognitive outcomes to help preserve these functions in patients post-operatively.