May 2018 CME Article No. 5: The Link Between Cerebrovascular Hemodynamics and Rehabilitation Outcomes After Aneurysmal Subarachnoid Hemorrhage

Additional Information

Objective:
To assess the relation between cerebrovascular function early after aneurysmal subarachnoid hemorrhage (SAH) onset and functional and rehabilitation outcomes.

Design:
Observational cohort study of SAH patients (n=133) admitted to rehabilitation (n=49), discharged home (n=52), or died before discharge (n=10). Hemodynamic markers of cerebral autoregulatory function obtained 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 mmHg) 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 SAH severity and admission FIM, explained 84% and 69% of the variability in discharge FIM score and efficiency.

Conclusions:
Early cerbrovascular function is a major contributor to functional outcomes after SAH, and may represent a modifiable target to develop therapeutic approaches.

Learning Objectives:

Define cerebal autoregulation
Explain the importance of the integrity of cerebral autoregulation for longer term functional and rehabilitation outcomes after aneurysmal subarachnoid hemorrhage
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

Summary