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 V mean counter-regulation during changes in MAP) and frequency domains (cross-spectral MCA V mean -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 V mean -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.