Preoperative ipsilateral thalamic volume reduction as a prognostic marker in malignant middle cerebral artery infarction undergoing decompressive craniectomy.

Objective: Malignant middle cerebral artery infarction is associated with high mortality and severe disability despite decompressive craniectomy. The thalamus plays a central role in arousal and sensorimotor integration and may be vulnerable to early compression from cerebral mass effect. This study evaluates whether preoperative ipsilateral thalamic volume reduction predicts functional outcomes following decompressive craniectomy. Methods: This retrospective cohort study included 41 adult patients with malignant middle cerebral artery infarction who underwent decompressive craniectomy between April 2017 and September 2022. Preoperative computed tomography scans were analysed for infarct volume, midline shift, herniation markers, and percentage ipsilateral thalamic volume reduction. Functional outcomes were assessed at discharge and 90 days using the Full Outline of UnResponsiveness score, National Institutes of Health Stroke Scale, modified Rankin Scale, Barthel Index, and Disability Rating Scale. Logistic regression and receiver operating characteristic analyses were performed. Results: Mean ipsilateral thalamic volume reduction was 15.1%. Each 1% increase in thalamic volume loss independently increased the odds of poor functional outcome, defined as modified Rankin Scale scores of 5-6, at discharge and 90 days. Greater thalamic distortion was associated with higher National Institutes of Health Stroke Scale scores. Receiver operating characteristic analysis demonstrated good discrimination, with optimal thresholds of 14% at discharge and 19% at 90 days. Increased thalamic compression was associated with postoperative infections and longer hospital stays. Conclusions: Preoperative ipsilateral thalamic volume reduction is a strong imaging biomarker for predicting outcomes after decompressive craniectomy in malignant middle cerebral artery infarction.