Persistence of hyperdense middle cerebral artery sign on follow-up CT scan after intravenous thrombolysis is associated with poor outcome

Background: The rates and extent of recovery in acute ischemic stroke (AIS) patients treated with intravenous tissue plasminogen activator (IV-tPA) remain highly variable. Hyperdense middle cerebral artery sign (HMCAS) on pretreatment unenhanced computerized tomography (CT) of the brain represents the presence of thrombus, often associated with severe neurological deficits and poor clinical outcome at 3 months. However, HMCAS is reliable only in AIS patients managed conservatively. In patients treated with systemic thrombolysis, HMCAS may disappear (representing clot dissolution) or persist (persisting clot) on the follow-up CT scan of the brain. We aimed at evaluating whether disappearance or the persistence of HMCAS on follow-up CT scan of the brain can predict the final outcome at 3 months.

Methods: Data from consecutive AIS patients treated with IV-tPA, in a standardized protocol, from January 2007 to March 2010 were included in the prospective thrombolysis registry at our tertiary care center. For this evaluation, posterior circulation stroke was excluded. HMCAS was assessed on admission as well as follow-up CT by 2 independent stroke neurologists, blinded to the patient data or outcomes. Functional outcomes assessed by the modified Rankin Scale (mRS) at 3 months were dichotomized as good (mRS score 0-1) and poor (mRS score 2-6). The data were analyzed for the early predictors of poor functional outcome with SPSS version 19 for Windows.

Results: Of the total of 2,238 patients admitted during the study period, 226 (11%) with anterior circulation AIS treated with intravenous thrombolysis were included. Median age of the patients was 65 years (range 19-92), 63% were males and they had a median National Institutes of Health Stroke Scale (NIHSS) score of 16 points (range 4-32). HMCAS was observed on admission CT scan in 109 (48.2%) patients and persisted on follow-up CT in 52 (47.7%) of them. Overall, 108 (47.8%) patients achieved poor functional outcome at 3 months. Admission NIHSS score (OR per 1-point increase = 1.241; 95% CI = 1.151-1.337, p < 0.0005), lesser change in NIHSS score at 24 h (OR per 1-point reduction = 0.730; 95% CI = 0.666-0.800, p < 0.0005) and persistence of HMCAS on follow-up CT scan (OR = 3.352; 95% CI = 1.991-11.333, p = 0.039) were associated with poor outcome at 3 months.

Conclusion: Persistence of HMCAS on the follow-up CT scan of the brain in acute ischemic stroke patients treated with IV-tPA can be used as an early predictor of poor functional outcome.