Modifying the ICP pulse wave: effects on parenchymal blood flow pulsatility

Area of Science:

• Neuroscience
• Physiology
• Biomedical Engineering

Background:

• Cerebral blood flow (CBF) pulsation generates intracranial pressure (ICP) waves.
• Understanding the relationship between ICP and CBF pulsatility is crucial for neurological health.

Purpose of the Study:

• To investigate if external modification of ICP pulsatility affects parenchymal CBF pulsatility.
• To explore the mechanisms underlying the observed changes in CBF pulsatility.

Main Methods:

• A cardiac-gated inflatable device was used to manipulate ICP pulsatility in anesthetized canines.
• Cerebral blood flow (CBF) in each hemisphere was measured using laser Doppler velocimetry.
• ICP pulse reduction, inversion, and augmentation were performed.

Main Results:

• Reducing or inverting the ICP pulse significantly increased both mean CBF and its amplitude.
• ICP pulse inversion yielded larger changes in CBF compared to reduction.
• Augmenting the ICP pulse increased ipsilateral mean CBF but reduced contralateral CBF amplitude.

Conclusions:

• External manipulation of ICP pulsatility directly alters parenchymal CBF pulsatility.
• The observed effects are likely mediated by low-pressure vessels (capillaries/venules), not the arterial Windkessel mechanism.
• Further MRI studies are needed to quantify effects on global CBF.