Aneurysm in the brain

Definition

An aneurysm is an abnormal widening or ballooning of a section of a blood vessel. When an aneurysm occurs in the brain, it is called a cerebral aneurysm.

Alternative Names

Causes

Aneurysms in the brain occur when there is a weakened area in the wall of a blood vessel. They may occur as a congenital (present from before birth) defect or may develop later in life. It is estimated that 5% of the population has some type of aneurysm in the brain.

A saccular aneurysm (berry aneurysm) can vary in size from a few millimeters to over a centimeter. Giant berry aneurysms can reach well over 2 centimeters. 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.

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 blood vessel that supplies the brain. Trauma and infection, which can injure the blood vessel wall, can cause such aneurysms.

Risk factors include a family history of cerebral aneurysms, and some medical problems, including polycystic kidney disease and coarctation of the aorta.