Background: Although it is generally thought that patients with distal middle cerebral artery (MCA) occlusion have a favorable outcome, it has previously been demonstrated that a substantial minority will have a poor outcome by 90 days. We sought to determine whether the infarct location information encoded in the Alberta Stroke Program Early CT Score (ASPECTS) allows for defining distinct ASPECTS regions that are associated with a poor outcome to improve outcome prediction in in these patients.
Methods: We retrospectively analyzed patients with isolated acute distal MCA occlusion admitted to a single academic center between January 2010 to August 2012. Infarct regions were defined according to ASPECTS system on the initial head CT. Discriminant function analysis was used to define specific ASPECTS regions that are predictive of the 90 day functional outcome. In addition, logistic regression was used to model the relationship between each individual ASPECT region with poor outcome; for evaluation and comparison, odds ratios, c-statistics, and Akaike information criterion values were estimated for each region.
Results: 90 patients with isolated distal MCA were included in the final analysis. ASPECTS score ≤ 6 predicted poor outcome in this cohort (sensitivity=0.591, specificity=0.838, p<0.001). Using multiple statistic approaches we found that infarction in ASPECTS regions M3 and M6 were strongly associated with poor functional status (mRS 3-6) by 90 days.
Conclusion: ASPECTS regions M3 and M6 are key predictors of functional outcome following isolated distal MCA infarction. These findings will be helpful in stratifying outcomes if validated in future studies.