Differentiating Dynamic Cerebral Autoregulation Across Vascular Territories.

Area of Science:

• Neuroscience
• Cerebrovascular Physiology
• Medical Imaging

Background:

• Cerebral autoregulation is crucial for maintaining stable brain blood flow.
• Transcranial Doppler (TCD) is a common tool for assessing cerebral autoregulation.
• Current TCD methods often focus on a single cerebral artery, limiting understanding of topographic variations.

Purpose of the Study:

• To conduct the first comprehensive comparison of cerebral autoregulation across all major cerebral arteries.
• To investigate topographic heterogeneity in dynamic cerebral autoregulation.
• To evaluate the feasibility of TCD for discriminating autoregulation between cerebrovascular territories.

Main Methods:

• Forty healthy adults underwent simultaneous monitoring of blood flow velocity in the anterior, middle, and posterior cerebral arteries.
• Arterial blood pressure was synchronized with flow velocity measurements.
• Transfer function analysis quantified the relationship between blood pressure and cerebral blood flow velocity to assess autoregulation.

Main Results:

• Autoregulation phase was similar across all measured cerebral arteries.
• Absolute gain was lower in the posterior cerebral artery, suggesting tighter regulation.
• Normalized gain was consistent across all vascular territories after accounting for baseline flow differences.

Conclusions:

• Dynamic cerebral autoregulation can be differentiated between cerebrovascular territories using a TCD-based approach.
• While absolute flow regulation is tighter in the posterior cerebral artery, relative flow regulation is uniform across territories in healthy individuals.
• This methodology holds potential for studying focal cerebrovascular diseases like stroke and PRES.