Spreading Diffusion-Restriction Events in the Gyrencephalic Brain After Subarachnoid Hemorrhage Revealed by...

Area of Science:

• Neuroscience
• Neurocritical Care
• Medical Imaging

Background:

• Spreading depolarizations (SDs) are critical events in the brain, particularly after injury.
• Understanding SD propagation in the complex gyrencephalic brain, including sulci and deeper areas, is clinically significant.
• This study investigates spontaneous SDs following subarachnoid hemorrhage in a juvenile swine model.

Purpose of the Study:

• To investigate the three-dimensional spread of spontaneous spreading depolarizations (SDs) in the gyrencephalic brain.
• To characterize the origin and propagation patterns of SDs after induced subarachnoid hemorrhage.
• To explore the clinical implications for neurocritical care.

Main Methods:

• Utilized continuous diffusion-weighted magnetic resonance imaging (DW-MRI) in juvenile swine for up to 6 hours post-injury.
• Acquired high-resolution images across multiple coronal slices to capture transient diffusion restriction caused by SDs.
• Applied image processing techniques including spatial drift correction, temporal smoothing, and signal intensity normalization to analyze SD propagation.

Main Results:

• Observed ten discrete events of focal diffusion restriction propagating through the cerebral cortex.
• SDs originated in the cortex surrounding the sulcal clot, either in the gyrus or sulcal depth.
• Multiple independent waves spread simultaneously, traversing sulci and spreading to adjacent gyri and deeper regions.

Conclusions:

• Spreading depolarizations in injured gyrencephalic brains originate near the injury focus.
• SDs can spread extensively through the cortex to wide and deep uninjured areas.
• Findings have implications for managing transient neurologic deficits and guiding patient monitoring and therapeutics in neurocritical care.