A brain aneurysm (also called a cerebral aneurysm) is a weakening in the wall of a section of an artery feeding the brain. The force of blood rushing through the artery can cause the affected area of the wall to bulge out, causing the aneurysm to enlarge. As the section balloons out, it can put pressure on surrounding brain tissue or a nerve. Sometimes the aneurysm becomes dangerously thin. Like a balloon with a weak spot, the wall can eventually burst, or rupture (a brain hemorrhage). The section of brain normally fed by the artery may be deprived of oxygen and the brain cells may die. This is a type of stroke called a subarachnoid hemorrhage. In addition, blood leaking from the vessel can seep into the surrounding tissue and damage the nerve cells in the brain.

The Brain Aneurysm Foundation estimates about three to six million Americans may have a brain aneurysm. Smoking, traumatic brain injury, excessive consumption of alcohol, use of oral contraceptives, family history of brain aneurysms and personal history of certain medical disorders increases the risk of developing a brain aneurysm. About 27,000 people experience a brain aneurysm rupture. This is a medical emergency. Half of these patients die within minutes; 12 percent die before they get to the hospital and 30 to 40 percent die within 30 days.

Treating Unruptured Aneurysms

Most people with a brain aneurysm don't have any symptoms. If an aneurysm is detected, doctors may decide to intervene to reduce the risk of rupture. There are two main treatments. The first is microvascular clipping. An incision is made into the scalp and a portion of the skull is removed to access the brain. Once the aneurysm is located, a tiny metal clip is placed across the neck, where the aneurysm opens into the artery. The clip closes off the opening into the aneurysm - preventing blood from flowing into the bulging sac, thus reducing the risk of rupture. The piece of skull bone is replaced and the incision in the scalp is closed.

A second method of intervention is endovascular embolization. Using X-rays for guidance, a catheter is fed through the circulatory system up to the brain until it reaches the aneurysm. Then, tiny coils are fed into the aneurysm. The coils fill up the space inside the aneurysm, preventing blood from flowing inside. In addition, the coils cause the blood to clot, sealing off the aneurysm from blood flow.

An Aneurysm Bypass

When an aneurysm has damaged the artery, doctors may perform a procedure called occlusion and bypass surgery. The section of the artery with the aneurysm is clamped to stop the blood flow through the artery. Then one side of a small section of vein (often taken from the leg) is sewn onto the affected artery, in front of the occlusion. The other end of the vein is sewn onto another section of artery. Blood then flows around the aneurysm through the newly placed vessel.

David J. Langer, M.D., a Neurosurgeon at Roosevelt Hospital, says the risk of a traditional cerebral bypass is bleeding. The flow of blood must be temporarily stopped to prevent the blood from leaking out of the vessel as the hole is made in the artery wall to connect the bypass. During this time, the brain cells may die from a lack of oxygen.

Langer has recently performed a new brain bypass procedure, called Excimer Laser Assisted Non-occlusive Anastomosis (ELANA). First, doctors obtain two small sections of a vein taken from the leg. A special ring is attached to the one end of each of the vessels. Then the ringed ends are sewn onto the cerebral artery - one section on each side of the aneurysm. No hole or opening is made into the brain artery yet.

Next, a catheter with a laser tip is inserted into one of the donor veins. A vacuum pump sucks the air out of the vein, pulling the walls of the vessel against the catheter. Then the laser light cuts a small hole into the wall of the cerebral artery. The catheter is removed and the donor vessel is temporarily clamped to prevent blood loss and keep blood flowing normally through the cerebral artery. Then the catheter is placed in the second section of donor vein. The process is repeated for the second section of vein.

Next, the two free ends of the donor veins are connected, creating one section of vein for the bypass. The temporary clips are removed from the donor veins and blood flows through the donor veins. Finally, tiny clips are placed on each side of the aneurysm (between the aneurysm and the newly connected veins). The clips block the flow of blood through that section of the cerebral artery and force it to flow through the new bypass - avoiding the aneurysm. Unlike a traditional cerebral bypass, blood flow through the brain is never disrupted.

The ELANA technique is not yet approved in the U.S. It was first performed at Roosevelt Hospital last December under a special compassionate use exemption from the FDA. Clinical trials are expected to start this summer at the following anticipated sites:

University of Arkansas Medical Center, Little Rock, AK

University of Miami, Miami, FL

University of Illinois Medical Center, Chicago, IL

St. Luke's Roosevelt Hospital, New York, NY

UT Southwestern Medical Center, Dallas, TX

For information about the ELANA procedure, log onto the doctor's website at:

http://www.drdavidlanger.com/research_tech/technology/elana/index.html

Information is also available on the company's website at:

http://www.elana.com

For general information on brain aneurysms:

American Heart Association

The Aneurysm and AVM Foundation

Brain Aneurysm Foundation

National Institute of Neurological Disorders and Stroke