Abstract 93: Relation Between Outcome and Infarct Size and Location in Brainstem Stroke

Abstract

Introduction: Although MR is frequently used for the diagnosis of brainstem stroke, there is little consensus regarding the ultimate prognostic implications of the findings. Hypothesis: MR imaging characteristics will be useful in the determination of outcome following brainstem infarction. Methods: We performed a retrospective review of patients treated for basilar distribution infarction at a Joint Commission Certified Primary Stroke Center and identified through a prospective registry begun in 8/06. Standard demographic and clinical data were recorded on admission and MR scans analyzed. Routine 5mm T2 and DWI sequences were utilized starting at the level of the P2 vessel, comprising 2 midbrain, 3 pontine and 3 medullary slices. Volumes were computed by manually tracing the signal abnormality and employing the supplied software package (Carestream PACS, Rochester NY). Outcomes were dichotomized as non-functional (dead, comatose, locked-in) and functional (all others) at 6 months. Results: There were 38 patients in the registry, of whom 25 had MR documented brainstem infarctions. There were 11/14 M/F, average age 64.7 years. Average admit NIHSS was 17.4 and the LOS was 21.5 days. MR was performed at a median of 1 day post admission. Mid-pontine was the most common stroke location (19/25) and about half of the DWI lesions (12/25) crossed midline. Outcome was deceased in 8 (5 in-hospital, 3 hospice), 4 locked-in and 13 functional survivors. Both T2 and DWI volumes correlated with outcome (p<.0001), but DWI was slightly superior (AUC/ROC .865/.862). DWI volume, not T2, correlated with initial NIHSS (p=.05, linear regression). In the stepwise logistic regression, DWI volume alone correlated with functional survival (p=.0003), not age, admission NIHSS, midline-crossing lesions nor anatomic location. DWI volume predicted 86% of the variation in outcome (c-statistic) and no patient with a DWI volume >3cm3 had a functional outcome. Conclusion: In this population of patients with brainstem stroke, MR appears to be a potent tool for predicting outcome with DWI volume being the most useful indicator.