Rate of Infarct–Edema Growth on CT Predicts Need for Surgical Intervention and Clinical Outcome in Patients with Cerebellar Infarction

Background: Up to 20% of patients with cerebellar infarcts will develop malignant edema and deteriorate clinically. Radiologic measures, such as initial infarct size, aid in identifying individuals at risk. Studies of anterior circulation stroke suggest that mapping early edema formation improves the ability to predict deterioration; however, the kinetics of edema in the posterior fossa have not been well characterized. We hypothesized that faster edema growth within the first hours after acute cerebellar stroke would be an indicator for individuals requiring surgical intervention and those with worse neurological outcomes. Methods: Consecutive patients admitted to the neurological intensive care unit with acute cerebellar infarction were retrospectively identified. Hypodense regions of infarct and associated edema, “infarct–edema”, were delineated by using ABC/2 for all computed tomography (CT) scans up to 14 days from last known well. To examine how rate of infarct–edema growth varied across clinical variables and surgical intervention status, nonlinear and linear mixed-effect models were performed over 2 weeks and 2 days, respectively. In patients with at least two CT scans, multivariable logistic regression examined clinical and radiological predictors of surgical intervention (defined as extraventricular drainage and/or posterior fossa decompression) and poor clinical outcome (discharge to skilled nursing facility, long-term acute care facility, hospice, or morgue). Results: Of 150 patients with acute cerebellar infarction, 38 (25%) received surgical intervention and 45 (30%) had poor clinical outcome. Age, admission National Institutes of Health Stroke Scale (NIHSS) score, and baseline infarct–edema volume did not differ, but bilateral/multiple vascular territory involvement was more frequent (87% vs. 50%, p < 0.001) in the surgical group than that in the medical intervention group. On 410 serial CTs, infarct–edema volume progressed rapidly over the first 2 days, followed by a subsequent plateau. Of 112 patients who presented within two days, infarct–edema growth rate was greater in the surgical group (20.1 ml/day vs. 8.01 ml/day, p = 0.002). Of 67 patients with at least two scans, after adjusting for baseline infarct–edema volume, vascular territory, and NIHSS, infarct–edema growth rate over the first 2 days (odds ratio 2.55; 95% confidence interval 1.40–4.65) was an independent, and the strongest, predictor of surgical intervention. Further, early infarct–edema growth rate predicted poor clinical outcome (odds ratio 2.20; 95% confidence interval 1.30–3.71), independent of baseline infarct–edema volume, brainstem infarct, and NIHSS. Conclusions: Early infarct–edema growth rate, measured via ABC/2, is a promising biomarker for identifying the need for surgical intervention in patients with acute cerebellar infarction. Additionally, it may be used to facilitate discussions regarding patient prognosis.