The Link Between Cerebrovascular Hemodynamics and Rehabilitation Outcomes After Aneurysmal Subarachnoid Hemorrhage

Objective: The aim of the study was to assess the relation between cerebrovascular function early after aneurysmal subarachnoid hemorrhage onset and functional and rehabilitation outcomes. Design: Observational cohort study of subarachnoid hemorrhage patients (n = 133) admitted to rehabilitation (n = 49), discharged home (n = 52), or died before discharge (n = 10). We obtained hemodynamic markers of cerebral autoregulatory function from blood flow velocities in the middle cerebral artery and arterial pressure waveforms, recorded daily on days 2-4 after symptom onset, and functional independence measure (FIM) scores and FIM efficiency for those admitted to acute rehabilitation. Results: Compared to those discharged home, the range of pressures within which autoregulation is effective was lower in patients admitted to rehabilitation (4.6 [0.2] vs. 3.9 [0.2] mm Hg) and those who died (2.7 [0.4], P = 0.04). For those admitted to rehabilitation, autoregulatory range and the ability of cerebrovasculature to increase flow were related to discharge FIM score (R-2 = 0.33 and 0.43, P < 0.01) and efficiency (R-2 = 0.33 and 0.47 P < 0.01). The latter marker, along with subarachnoid hemorrhage severity and admission FIM, explained 84% and 69% of the variability in discharge FIM score and efficiency, respectively, even after accounting for age. Conclusions: Early cerebrovascular function is a major contributor to functional outcomes after subarachnoid hemorrhage and may represent a modifiable target to develop therapeutic approaches.