Prediction of Malignant Edema Formation After Endovascular Treatment for Middle Cerebral Artery Infarction: The Added Value of Intracranial Cerebrospinal Fluid Volume

Introduction: Prediction models may guide decisions in the management of patients at risk for malignant middle cerebral artery infarction. The ratio of intracranial cerebrospinal fluid (CSF) volume to intracranial volume (ICV) has been identified as a predictor of malignant edema in ischemic stroke patients treated with intravenous thrombolysis. The added predictive value in stroke patients who received endovascular treatment is unknown. Methods: Patients with available thin-slice non-contrast CT data on admission were selected from the MR CLEAN Registry, which is a prospective national multicenter registry of patients with large vessel occlusion who were treated with endovascular treatment between 2014 and 2017. Baseline characteristics and CT imaging data were collected. The CSF/ICV ratio was automatically measured on baseline thin-slice non-contrast CT. The primary outcome was the formation of malignant edema based on clinical and imaging features on follow-up. A previously built logistic regression model was fitted and included the following baseline predictors: age, National Institutes of Health Stroke Scale, Alberta Stroke Program Early CT score, poor collateral filling and reperfusion. An extended model with the CSF/ICV ratio was compared to the previous model by using the likelihood ratio test. Odds ratios (OR), areas under the receiver operating characteristic curve (AUROC) and 95% confidence intervals (CI) were reported. Results: Of the included 683 patients 40 (6%) developed malignant edema. The CSF/ICV ratio of the group with malignant edema (mean 9±5%) was lower than the group without malignant edema (mean 14±6%, P<0.001). In the extended model, the CSF/ICV ratio was associated with the formation of malignant edema (per one percent decrease OR 1.2, 95% CI 1.1-1.3, P<0.001). In addition, the discriminative performance of the model with the CSF/ICV ratio (AUROC 0.87, 95% CI 0.82-0.91) was higher than that of the model without the CSF/ICV ratio (AUROC 0.84, 0.78-0.89, P<0.001). Conclusions: The CSF/ICV ratio improves the prediction of malignant edema formation in ischemic stroke patients who received endovascular treatment.