Dynamic cerebral autoregulation in acute lacunar and middle cerebral artery territory ischemic stroke

Abstract

Background and Purpose - We addressed whether dynamic cerebral autoregulation (dCA) is affected in middle cerebral artery (MCA) territory (MCAS) and lacunar ischemic stroke (LS). Methods - Blood pressure (MAP) and MCA velocity (V) were measured in 10 patients with large MCAS (National Institutes of Health Stroke score, 17±2; mean±SEM), in 10 with LS (score, 9±1), and in 10 reference subjects. dCA was evaluated in time (delay of the MCA Vmean counter-regulation during changes in MAP) and frequency domains (cross-spectral MCA Vmean-to-MAP phase lead). Results - In reference subjects, latencies for MAP increments (5.3±0.5 seconds) and decrements (5.6±0.5 seconds) were comparable, and low frequency MCA Vmean-to-MAP phase lead was 56±5 and 59±5° (left and right hemisphere). In MCAS, these latencies were 4.6±0.7 and 5.6±0.5 seconds in the nonischemic hemisphere and not detectable in the ischemic hemisphere. In the unaffected hemisphere, phase lead was 61±6° versus 26±6° on the ischemic side (P<0.05). In LS, no latency and smaller phase lead bilaterally (32±6 and 33±5°) conformed to globally impaired dCA. Conclusions - In large MCAS infarcts, dynamic cerebral autoregulation was impaired in the affected hemisphere. In LS, dynamic cerebral autoregulation was impaired bilaterally, a finding consistent with the hypothesis of bilateral small vessel disease in patients with lacunar infarcts. © 2005 American Heart Association, Inc.