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 (R² = 0.33 and 0.43, P < 0.01) and efficiency (R² = 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. To Claim CME Credits Complete the self-assessment activity and evaluation online at http://www.physiatry.org/JournalCME CME Objectives Upon completion of this article, the reader should be able to: (1) Define cerebral autoregulation; (2) Explain the importance of the integrity of cerebral autoregulation for longer-term functional and rehabilitation outcomes after aneurysmal subarachnoid hemorrhage; and (3) Theorize why treatment strategies that may be effective in reducing large-vessel vasospasms after an aneurysmal subarachnoid hemorrhage might not always translate into improved functional outcomes. Level Advanced Accreditation The Association of Academic Physiatrists is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The Association of Academic Physiatrists designates this Journal-based CME activity for a maximum of 0.5 AMA PRA Category 1 Credit(s)™. Physicians should only claim credit commensurate with the extent of their participation in the activity.