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

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 degrees (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 degrees versus 26 +/- 6 degrees on the ischemic side (P < 0.05). In LS, no latency and smaller phase lead bilaterally (32 +/- 6 and 33 +/- 5 degrees) 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.