Executive functioning following surgery near the frontal aslant tract in low-grade glioma patients: A patient-specific tractography study.

BACKGROUND

The Frontal Aslant Tract (FAT) has been associated with executive functions (EF), but it remains unclear what role the FAT plays in EF, and whether preoperative dysfunction of the FAT is associated to long-lasting postsurgical executive impairments.

METHODS

In this study, we examined the course of EF from pre-surgery (n = 75) to 3 (n = 61) and 12 (n = 25) months after surgery in patients with frontal and parietal low-grade gliomas (LGGs), to establish the degree to which long-term EF deficits exist. Secondly, we used patient-specific tractography to investigate the extent to which overlap of the tumor with the FAT, as well as integrity of the FAT, presurgery were related to EF on the short and longer term after surgery.

RESULTS

LGG patients performed worse than healthy controls on all EF tests before and 3 months postsurgery. Whereas performances on three out of the four tests had normalized 1 year postsurgery (n = 26), performance on the cognitive flexibility test remained significantly worse than in healthy controls. Patients in whom the tumor overlapped with the core of the right FAT performed worse presurgery on three of the EF tests compared to those in whom the tumor did not overlap with the right FAT. Presurgical right FAT integrity was not related to presurgical EF, but only to postsurgical EF (from pre-to 3 months postsurgery). Longitudinal analyses demonstrated that patients with right (but not left) FAT core overlap performed on average worse over the pre- and postsurgical timepoints on the cognitive flexibility test.

CONCLUSIONS

We emphasized that LGG patients perform worse than healthy controls on the EF tests, which normalizes 1-year postsurgery except for cognitive flexibility. Importantly, in patients with right hemispheric tumors, tumor involvement of the FAT was associated with worse pre- and 3- months postsurgical performance, specifically concerning cognitive flexibility.