Dynamic Cerebral Autoregulation in Acute Intracerebral Hemorrhage

Background and Purpose Cerebral autoregulation (CA) is not universally impaired in acute intracerebral hemorrhage (ICH); however, the dynamic components of CA are probably more vulnerable. This study, therefore, evaluates the time course of dynamic CA in acute ICH and its relationship to clinical outcome. Methods Twenty-six patients with ICH were studied on days 1, 3, and 5 after ictus. Dynamic CA was measured from spontaneous fluctuations in blood pressure and middle cerebral artery flow velocity by transfer function phase (reflecting rapidity of CA) and gain (reflecting damping characteristics of CA) in the low frequency range. Results were compared with those from 55 controls and related with clinical factors and 90-day outcome (modified Rankin scale). Results Phase did not fluctuate significantly over time, nor did it differ between sides or differ from controls. Gain was always higher in patients than in controls but showed no significant association with outcome or other clinical factors. At day 1, poorer ipsilateral phase was associated with lower blood pressure and higher ICH volume. Poorer phase always coincided with lower Glasgow Coma Scale values. Poorer ipsilateral phase on day 5 was related with poorer clinical outcome according to multivariate analysis (P=0.013). Conclusions Dynamic temporal characteristics of CA (phase) are not generally altered in acute ICH. Poorer individual phase values are, however, associated with larger ICH volume, lower blood pressure, and worsened outcome. Dampening characteristics of CA (gain) are generally impaired in acute ICH but not related to clinical factors or outcome.