Resection of glioblastoma with white-matter tract involvement can be associated with improvement in postoperative cognitive function

Introduction: Cognitive deterioration in glioblastoma is an independent predictor of reduced survival. The impact of surgery on cognition is unclear. We investigate the effect of surgery on cognition in glioblastoma patients using preoperative, postoperative cognitive tests and correlate cognition with structural imaging using longituinal voxel-lesion symptom mapping.

Methods: 40 patients with glioblastoma were recruited from Cambridge University Hospital NHS Trust. Preoperatively (within 2 weeks) patients were tested with the OCS-Bridge cogntive screening assessment tool. The same tests were conducted early (within 1 week) and late (6 -8 weeks) post-surgery, prior to starting chemoradiotherapy.

Principal component analysis was used to define the latent cognitve space. Preoperative and postoperative (within 72 hours) structural MRI were used with to segment tumour volumes and postoperative resection cavities. Clinical variables and imaging features were used in linear mixed effects models to seperately model the effect of predictors on postoperative cognitive scores.

Longitudinal VLSM was performed with the resection cavities, using an extension of the non-parametric Brunner–Munzel rank test for multi-factorial designs with within- and between-subject factors.

Results: Preoperative test score [1.64, 95% CI:1.15 – 2.12, p< 0.001], PHQ-9 score [-1.78, 95% CI:-3.45 – -0.12, p=0.037], left-sided tumours [-1.42, 95% CI:-2.09 – -0.76, p< 0.001], steroid use [-0.18, 95% CI:-0.28 – -0.08, p=0.002], time since surgery [0.01, 95% CI:0.01 – 0.02, p=0.002], whole-tumour volume [0.01, 95% CI:0.01 – 0.02, p=0.001] and resection volume [-0.04, 95% CI:-0.05 – -0.02, p=0.001] were associated with postoperative Attention, Visual memory and Executive function.

VLSM showed that lesions in the left IFOF and corpus collosum were associated with lower postoperative Attention/Visual memory scores. However, resection of tumour in the left IFOF and long segment of the right arcuate fasciculus was associated with improved late postoperative Executive function scores.

Conclusion : While patients show capacity to recover cognitive function in the pre-chemoradiotherapy stage, this may be limited by the degree of pre-existing tumour-related injury. Future work will aim to characterise individual damage to white-matter in patients by analysing white-matter integrity and connectivity using diffusion MRI.