Cerebral microembolization. II. Morphological studies.

Area of Science:

• Neuroscience
• Cerebrovascular Research
• Pathology

Background:

• Microembolization is a significant factor in cerebrovascular events.
• Understanding the immediate effects of microemboli on brain tissue is crucial for developing therapeutic strategies.

Purpose of the Study:

• To investigate the acute effects of massive cerebral microembolization on brain structure and function in a feline model.
• To characterize the distribution of microspheres and the subsequent blood-brain barrier integrity changes.

Main Methods:

• Cats received carotid infusion of microspheres, inducing massive microembolization.
• Intravascular dyes (Evans blue, sodium fluorescein) were used to assess blood-brain barrier permeability.
• Fluorescence microscopy examined emboli distribution, hyperemia, extravasation, and tissue damage.

Main Results:

• Microembolization led to brain death within 4 hours, with most emboli impacting the ipsilateral hemisphere's grey matter.
• Initial hyperemia was observed, followed by multifocal blood-brain barrier extravasations in the cortex and basal ganglia.
• Severe vasogenic brain edema developed, migrating into white matter and causing neuroglial and axonal swelling, leading to secondary white matter damage and cortical degenerative foci.

Conclusions:

• Massive microembolization causes rapid brain death and significant blood-brain barrier disruption.
• Edema migration from grey to white matter contributes to secondary white matter injury following embolic stroke.
• Early hyperemia and blood-brain barrier damage correlate with subsequent degenerative changes in the cerebral cortex.