Cerebral aneurysm

Alternative names:

aneurysm - cerebral

Definition:

A disorder that involves localized widening of one or more blood vessel(s) in the brain.

Causes, incidence, and risk factors:

Aneurysms in the brain occur when there is a weakened area in the wall of a blood vessel. They may occur as a congenital defect or may develop later in life.

A saccular aneurysm (berry aneurysm) is usually small in size. The aneurysm resembles a sack of blood attached to one side of the blood vessel by a narrow neck. These are more common in adults. Multiple berry aneurysms are not unusual. They occur in any part of the brain but are most often seen in the large arteries at the base of the brain. Berry aneurysm is also associated with polycystic kidney disease and coarctation of the aorta. Rarely, berry aneurysm can run in families.

Other types of cerebral aneurysm may involve widening (dilatation) of the entire circumference of the blood vessel in an area, or may appear as a ballooning out of part of a blood vessel. These types of aneurysms can occur in any part of the brain.

Symptoms usually do not appear until complications develop. Bleeding is the most common cause of symptoms, with subarachnoid hemorrhage the usual type of bleed. Weakness, numbness, or other loss of nerve function (neurologic deficits) may occur because of pressure from the aneurysm on adjacent brain tissue or because of reduced blood flow caused by a spasm of other blood vessels near a ruptured aneurysm.

It is estimated that 5% of the population has some type of aneurysm. However, the incidence of ruptured aneurysm is approximately 4 out of 100,000 people per year.