Cerebral hemodynamic response to upright position in acute ischemic stroke

Area of Science:

• Neuroscience
• Cerebrovascular Physiology
• Stroke Medicine

Background:

• Early upright activity after ischemic stroke may reduce cerebral perfusion, posing a potential harm.
• Understanding the impact of sitting and standing on cerebral hemodynamics in acute stroke is crucial for patient management.
• Cerebral blood flow regulation can be compromised following a stroke, especially in the presence of occlusive disease.

Purpose of the Study:

• To quantify the effects of upright positions (sitting and standing) on cerebral hemodynamics within 48 hours and 3-7 days post-stroke.
• To compare these hemodynamic changes in stroke patients with and without occlusive disease against healthy controls.
• To investigate the relationship between early changes in cerebral blood flow and long-term functional outcomes.

Main Methods:

• Middle cerebral artery velocity (MCAv) was measured using transcranial Doppler in supine (0°) and upright (30°, 70°, 90° sitting, 90° standing) positions.
• Measurements were taken within 48 hours and again at 3-7 days post-stroke in 42 stroke patients and 22 controls.
• Mixed-effect linear regression models were employed to analyze MCAv differences and changes across positions and groups.

Main Results:

• Affected hemisphere MCAv decreased in both stroke groups (with and without occlusive disease) and controls upon assuming upright positions (<48h and 3-7 days post-stroke).
• The reduction in MCAv was more pronounced in stroke patients with occlusive disease compared to those without, particularly in the anterior circulation subgroup (p=0.02).
• No significant difference in MCAv changes was observed between stroke patients (with/without occlusive disease) and controls overall, nor was there an association with 30-day functional outcomes.

Conclusions:

• Assuming upright positions within 48 hours post-stroke leads to reduced MCAv in the affected hemisphere, a phenomenon observed in both stroke patients and controls.
• While a trend suggested greater MCAv reduction in stroke patients with occlusive disease, this did not reach statistical significance in the overall analysis, though a subgroup analysis showed a significant difference.
• Further research with larger sample sizes is needed to confirm the specific impact of occlusive disease on cerebral hemodynamic responses to upright posture in acute stroke.