Intracranial Berry Aneurysm - Pathophysiology

Pathophysiology

Berry aneurysms are usually found in the region of the Circle of Willis. Berry aneurysms are congenital in nature and result in a weakness of the blood vessel wall. Weak or thinned parts of the cerebral vasculature usually consist of fibrous tissue only. These are vulnerable to the increased hydrostatic pressure caused by hypertension, and will bulge out. Berry aneurysms tend to have a lack of tunica media and elastic lamina around its dilated location (congenital), with wall of sac made up of thickened hyalinized intima and adventitia. In addition, some parts of the brain vasculature are inherently weak—particularly areas along the Circle of Willis, where small communicating vessels link the main cerebral vessels. These areas are particularly susceptible to berry aneurysms. Approximately 25% patients have multiple aneurysms, predominantly when there is familial pattern.