Cognitive Impairment, Functional Outcome, and Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage

BACKGROUND: Measures such as modified Rankin Scale (mRS) may not reflect cognitive outcome following aneurysmal subarachnoid hemorrhage. The aim of this study was to assess the relationship between functional outcome, measured by mRS, and cognition, measured by mini-mental state examination (MMSE), after aSAH. A secondary analysis evaluated the impact of delayed cerebral ischemia (DCI) on the proportion of patients who had cognitive impairment. METHODS: We performed a post hoc analysis of the Clazosentan to Overcome Neurological Ischemia and Infarction Occurring After Subarachnoid Hemorrhage (CONSCIOUS-1) trial data. MMSE and mRS scores were compared using Kruskal-Wallis equality-of-populations rank test with pairwise comparison post hoc analysis. Cognitive impairment was defined as MMSE score <27. A stepwise logistic regression model evaluated whether DCI was a predictor of cognitive impairment. RESULTS: CONSCIOUS-1 comprised 413 patients. Of these, 337 took an MMSE at their 12-week follow-up. Mean MMSE score was 27 with a median of 29 (range, 0-30; SD 5.4). There were no significant differences between MMSE scores of patients who had 12-week mRS scores of 0-2. On multivariate analysis, DCI was independently associated with cognitive impairment after aSAH. CONCLUSIONS: Patients considered to have a good outcome on mRS had varying degrees of cognitive function on MMSE, whereas development of DCI was an independent predictor of cognitive impairment after aSAH. MMSE may not be sensitive enough to discern subtle defects in cognition, as the median score was 29 out of 30.