Arterial dissections occur when there is a tear in the innermost intimal lining of the vessel wall, causing disruption of the endothelium and the internal elastic lamina. Bleeding can then propagate between the layers, forming a pseudolumen. As bleeding continues, the intramural hematoma can enlarge within the pseudolumen, leading to occlusion of the vessel, thrombus formation and embolus, pseudoaneurysm, or rupture. (See Figure 1.) Unlike the extracranial arteries, the intracranial arteries have thinner outer layers and lack an external elastic lamina. Therefore, if the dissection extends intracranially, it can more easily lead to formation of a pseudoaneurysm or rupture, causing a subarachnoid hemorrhage.
To continue reading, please log in or purchase access.