Micro-Embolic Events and Their Clearing in the Brain. A Narrative Review

The cerebral circulation is continuously challenged by intravascular micrometer-sized particles that become trapped microvascular-emboli. These particles may include micro-thrombi, stiffened erythrocytes, and leukocytes, while also fat particles, air, and microplastics may cause microvascular embolism.

In this narrative review, we discuss these embolization processes and their acute and chronic consequences. These relate to the local flow interruption as well as the direct interaction with the endothelium. In addition, we address the clearing processes, including local thrombolysis and extravasation, or angiophagy, of the emboli.

A continuous balance exists between embolic events and their resolution under normal conditions. Increased micro-embolic rates, as occur in e.g., atrial fibrillation, or decreased clearing, possibly related to endothelial cell dysfunction, disturb this balance. This could lead to continuing loss of capillaries, micro-infarcts, and cognitive decline.