Endovascular Coiling

By Sara M. Foster, RN, MPH

(Coiling, Coil Embolization, Detachable Coil Embolization, Endovascular Embolization, Intracranial Aneurysm Repair)

Procedure Overview

What is endovascular coiling?

Endovascular coiling, also called coiling or endovascular embolization, is a procedure performed to block blood flow into an aneurysm (a weakened area in the wall of an artery). An aneurysm in the brain may be called a cerebral aneurysm, a brain aneurysm, or an intracranial aneurysm.

Preventing blood flow into an aneurysm helps to keep the aneurysm from rupturing (bursting). Coiling does not require a surgical procedure. Rather, a catheter (a long, thin tube) is inserted into an artery in the groin, then advanced into the affected artery in the brain. X-rays are used to guide the catheter into the artery.

Coiling may also be used to treat a condition called arteriovenous malformation, or AVM. An AVM is an abnormal connection between an artery and a vein that may occur in the brain, spinal cord, or elsewhere in the body.

The coils used in this procedure are made of soft platinum metal, and are shaped like a spring. These coils are very small and thin, ranging in size from about twice the width of a human hair (largest) to less than one hair's width (smallest).

Aneurysms may be treated in different ways, depending on the type of aneurysm, where it is located in the brain, and the patient's medical condition. The standard method for treating a cerebral aneurysm is called aneurysm clipping. In this procedure, a small metal clip is used stop blood flow into the aneurysm, after an opening has been made in the skull to reach the aneurysm in the brain. The clip looks much like a clothespin. It is placed on the neck (opening) of the aneurysm to obstruct the flow of blood, and remains inside the brain.

Coiling is a newer procedure that has become available since the mid-1990's. Coiling has advantages over surgical aneurysm clipping, because it does not involve opening the skull, and hospitalization time and recovery time are often shorter. However, not everyone with a cerebral aneurysm or AVM is a suitable candidate for a coiling procedure.

Other related procedures that may be used to diagnose or treat brain disorders include cerebral arteriogram, computed tomography (CT) scan of the brain, electroencephalogram (EEG), magnetic resonance imaging (MRI) of the brain, positron emission tomography (PET) scan, x-rays of the skull, and craniotomy. Please see these procedures for additional information.

What is an aneurysm?

A cerebral aneurysm is a bulging, weakened area in the wall of an artery in the brain, resulting in an abnormal widening or ballooning. Because there is a weakened spot in the artery wall, there is a risk for rupture (bursting) of the aneurysm.

A cerebral aneurysm generally occurs in an artery located in the front part of the brain which supplies oxygen-rich blood to the brain tissue. A normal artery wall is made up of three layers. The aneurysm wall is thin and weak because of an abnormal loss or absence of the muscular layer of the artery wall, leaving only two layers.

The most common type of cerebral aneurysm is called a saccular, or berry, aneurysm, occurring in 90 percent of cerebral aneurysms. This type of aneurysm looks like a "berry" with a narrow stem. More than one aneurysm may be present at the same time.

Two other types of cerebral aneurysms are fusiform and dissecting aneurysms. A fusiform aneurysm bulges out on all sides (circumferentially). Fusiform aneurysms are generally associated with atherosclerosis.

A dissecting aneurysm may result from a tear in the inner layer of the artery wall, causing blood to leak into the layers. This may cause a ballooning out on one side of the artery wall or it may block off or obstruct blood flow through the artery. Dissecting aneurysms may occur with traumatic injury. The shape and location of the aneurysm may affect what treatment is performed.

Most cerebral aneurysms (around 90 percent) are present without any symptoms and are small in size (less than 10 millimeters in diameter, which is less than four-tenths of an inch). Smaller aneurysms may have a lower risk of rupture.