• About Us
• Office Information
• Spine Animations
• Spine Education
• Brain Education
  • Hydrocephalus
  • Normal Pressure Hydrocephalus
  • Pseudotumor Cerebri
  • Chiari Malformation
  • Pituitary Tumor
  • Brain Tumor
  • Metastatic Brain Tumor
  • Cerebral Vasculature
  • Cerebral Aneurysm
  • Subarachnoid Hemorrhage
  • Arteriorvenous Malformation
• Patient Testimonials
• Useful Links

Print this Page

Brain Education: Cerebral Aneurysm

Common locations of cerebral saccular aneurysms. The relative incidences are shown. Copyright 2006 Massachusetts Medical Society. All rights reserved. Click for larger image »

Cerebral Aneurysm

• Definition and Types
• Causes, Frequency, and Symptoms

The word aneurysm comes from the Latin word aneurysma, which means dilatation. A cerebral aneurysm (also known as an intracranial or intracerebral aneurysm) is a weak or thin spot on a blood vessel in the brain that balloons out and fills with blood. The bulging aneurysm can put pressure on a nerve or surrounding brain tissue. It may also leak or rupture, spilling blood into the surrounding tissue (called a hemorrhage). Some cerebral aneurysms, particularly those that are very small, do not bleed or cause other problems. Cerebral aneurysms can occur anywhere in the brain, but most are located along a loop of arteries that run between the underside of the brain and the base of the skull.

Types of Aneurysm

Aneurysms can be true or false. A false aneurysm is a cavity lined by blood clot.

Aneurysms are also classified by size. Small aneurysms are less than 11 millimeters in diameter (about the size of a large pencil eraser), larger aneurysms are 11–25 millimeters (about the width of a dime), and giant aneurysms are greater than 25 millimeters in diameter (more than the width of a quarter).

There are three types of cerebral aneurysm.

• A saccular aneurysm is a rounded or pouch-like sac of blood that is attached by a neck or stem to an artery or a branch of a blood vessel. Also known as a berry aneurysm (because it resem-bles a berry hanging from a vine), this most common form of cerebral aneurysm is typically found on arteries at the base of the brain. Saccular aneurysms occur most often in adults.
• A lateral aneurysm appears as a bulge on one wall of the blood vessel.
• A fusiform aneurysm is formed by the widening along all walls of the vessel.

Causes, Frequency, and Symptoms »