Efficacy of Cerebral Autoregulation in Early Ischemic Stroke Predicts Smaller Infarcts and Better Outcome

Background and Purpose: Effective cerebral autoregulation (CA) may protect the vulnerable ischemic penumbra from blood pressure fluctuations and minimize neurological injury. We aimed to measure dynamic CA within 6 hours of ischemic stroke (IS) symptoms onset and to evaluate the relationship between CA, stroke volume and neurological outcome. Methods: We enrolled 30 patients with acute middle cerebral artery IS. Within 6 hours of IS we measured for 10 minutes arterial blood pressure (Finometer), cerebral blood flow velocity (transcranial Doppler) and end-tidal-CO2. Transfer function analysis (coherence, phase, and gain) assessed dynamic CA, and receiver-operating curves calculated relevant cut-off values. National Institute of Health Stroke Scale was measured at baseline. Computed tomography at 24 hours evaluated infarct volume. Modified Rankin Scale (MRS) at 3 months evaluated the outcome. Results: The odds of being independent at 3 months (MRS 0-2) was 8-fold higher when 6 hours CA was intact (Phase>37 degrees) (OR = 8.0 (IC95% 1.5-42.0), p=0.014). Similarly, infarct volume was significantly smaller with intact CA median (range) 1.1 (0.2-7.0) vs 13.1 (1.3-110.5) ml, p=0.002. Conclusions: In this pilot study, early effective CA was associated with better neurological outcome in patients with IS. Dynamic CA may carry significant prognostic implications.