# Differences in Executive Functioning Between Patients with IDH1-Mutant Oligodendroglioma and Astrocytoma Before and After Surgery

## TL;DR

This study finds that patients with oligodendroglioma experience greater declines in cognitive flexibility after surgery, especially when not using awake surgery techniques.

## Contribution

The study identifies subtype-specific cognitive risks in IDH1-mutant gliomas and emphasizes the impact of surgical approach on cognitive outcomes.

## Key findings

- Oligodendroglioma patients showed lasting decline in cognitive flexibility after asleep surgery.
- Astrocytoma patients remained stable in cognitive flexibility post-surgery.
- Awake surgery prevented cognitive decline in oligodendroglioma patients.

## Abstract

People with low-grade gliomas can live for many years, so preserving their executive functioning is crucial. Two common tumor types, oligodendroglioma and astrocytoma, grow differently in the brain and may affect important white matter tracts in different ways. We studied 162 adults with these tumors, testing their executive functions (such as inhibition and cognitive flexibility) before surgery and again 3 and 12 months afterwards. We also compared patients who had awake brain surgery with mapping of cognitive functions to those who were operated on under general anesthesia. We found that patients with oligodendroglioma were more likely to show lasting decline in cognitive flexibility, particularly when operated on asleep without mapping. These findings highlight the relevance of tumor subtype and surgical approach when dealing with infiltration of important white matter tracts in predicting and limiting cognitive risks following glioma surgery.

Background: IDH1-mutant oligodendroglioma and astrocytoma differ not only in growth rate but also in growth pattern. Oligodendrogliomas tend to infiltrate white matter tracts, whereas astrocytomas more often displace them. Such difference could lead to different cognitive outcomes. This study examined differences in executive functioning before and up to one year after surgery between patients with IDH1-mutant astrocytoma and oligodendroglioma. Methods: Patients with WHO grade 2–3 IDH1-mutant oligodendroglioma (1p19q-codeleted) or astrocytoma were included. Cognition was assessed preoperatively, and at 3 and 12 months postoperatively using standardized computerized and paper-and-pencil tests. Groups were compared on demographics, tumor characteristics, surgical modality, extent of resection, adjuvant treatment, and baseline cognition. Longitudinal mixed models were performed to investigate differences in performances over time for the total sample and stratified by surgical approach (awake vs. asleep). Results: 162 patients (67 oligodendroglioma, 95 astrocytoma) were included. Oligodendroglioma patients were older, with more frontal and fewer temporal tumors. Oligodendroglioma patients showed a greater impairment prevalence on a measure of inhibition before surgery. In the awake surgery group, no longitudinal differences were found between diagnoses. In the asleep surgery group, astrocytoma patients remained stable while oligodendroglioma patients declined on a measure of cognitive flexibility, with performance at 3 and 12 months significantly lower than at baseline. Conclusions: Specific aspects of executive functioning in IDH1-mutant gliomas may differ by subtype. Oligodendroglioma patients showed postoperative decline in cognitive flexibility that did not recover to baseline level, particularly in case of surgery under general anesthesia. These results highlight the potential relevance of tumor subtype and surgical approach in limiting cognitive risks after glioma surgery.