A migraine is a kind of headache that causes throbbing pain. The pain typically occurs on one side of the head and may be accompanied by nausea, vomiting and an inability to tolerate lights and sounds. Symptoms vary in intensity and can last from several hours to several days.

About 20 to 30 percent of people with migraines experience warning symptoms, called an aura, before the onset of the headache. Signs associated with an aura include: seeing flashes of light or zigzag lines, blind spots in the field of vision, tingling or numbness on the arm or face, or difficulty speaking.

According to the National Headache Foundation, migraine affects more than 29.5 million Americans. Women are three times more likely to experience migraines than men.

Patent Foramen Ovale

Before a baby is born, it gets all of its oxygen directly from the mom's blood. Blood flowing through the fetal heart travels through a small hole in the wall between the two upper chambers of the heart. This hole, called a foramen ovale, allows oxygenated blood to bypass the lungs.

When the infant is born, flaps over the hole fuse, sealing off the hole. Blood is forced to follow a new route, flowing from the right side of the heart, to the lungs to pick up oxygen, back to the left side of the heart and on through the body. A hole that doesn't properly fuse is called a patent foramen ovale, or PFO.

A PFO acts like an extra valve in the heart. In most normal circumstances, it will stay closed and not cause a problem. However, when pressure increases inside the chest (like with certain types of activities, such as a cough or sneeze), the flap opens. As with a spring door, the flap will close back up again. But during the time the flap is open, deoxygenated blood from the right side of the heart can leak into the left side and re-circulate through the body.

The biggest danger associated with a PFO is an increased risk for stroke. Clots or tiny particles in the blood in the right atrium can travel through the PFO and into circulation. The debris can become lodged in tiny blood vessels in the brain and block the flow of blood. The National Stroke Association estimates patients with a PFO have about a 25 percent increased risk for stroke.

The PFO/Migraine Link - Fixing the Problem

Researchers have found about 40 to 60 percent of patients who experience migraine with an aura have a PFO. No one knows how PFO may be related to migraines. However, in many of these patients, repair of the PFO seems to alleviate the headache symptoms.

Doctors can repair a PFO with a man-made device that covers the hole. A catheter is inserted into a blood vessel in the groin and, using X-rays for guidance, snaked through the circulatory system to the heart. Once the tip of the catheter reaches the PFO, a closure device is released. One device, called STARFlex®, consists of two flaps that open like an umbrella and are connected in the middle. The catheter is inserted up to the PFO and one flap is opened to cover the back-end of the hole. Then the second flap is opened to cover the front end of the hole. When the catheter is withdrawn, the flaps cover the hole on both sides, like a bandage. Eventually, tissue grows over the closure device, permanently sealing the hole.

While closure of a PFO is very effective, long-term risks are unknown. Researchers report some patients experience low-grade inflammation that persists for years after implantation of the device. Theoretically, this could lead to development of later complications.

A New Device

Researchers are now testing a new device for closing a PFO in migraine patients with aura. The BioSTAR® Bioabsorbable Septal Occlusion Device is similar to the STARFlex, except the material covering the frame of the BioSTAR is re-absorbed by the body. Thus, over time, after the body has permanently sealed off the hole with its own tissue, only the BioSTAR frame will remain in the body.

The study is called MIST II (Migraine Intervention with STARFlex® Technology) PFO-Migraine Trial with BioSTAR® Bioabsorbable Septal Occlusion Device. Researchers hope to enroll about 600 patients. Half the participants will be randomly assigned to receive the BioSTAR® device. Investigators will study the safety of BioSTAR and determine if it helps with migraine reduction. For information about the clinical trial, log onto: http://www.pfo-migraine.com .

For information about the clinical trial, log onto http://www.pfo-migraine.com . Information about the trial also available at: http://clinicaltrials.gov. Type the trial identification number in the search box: NCT00283738.

Information about the technology is available at http://www.migraine-mist.org or http://www.pfo-migraine.com

For general information on migraines:

American Headache Society

National Headache Foundation

National Institute of Neurological Disorders and Stroke

For information on PFO:

National Heart, Lung and Blood Institute