NEW YORK (Reuters Health) - New research suggests that cluster headache, a severe type of headache that usually begins around one eye, often occurs together with a heart defect called patent foramen ovale (PFO), in which blood can pass through a small hole from the right to the left side of the heart without going through the lungs first.

In the fetus, the hole (foramen ovale) is open, since blood does not need pass through the lungs to pick up oxygen while the baby is in the womb. After birth, the hole normally closes, but quite often this closure is incomplete. Since it is a small defect, people are often unaware that they have an open (patent) foramen ovale.

As reported in the medical journal Neurology, Dr. Cinzia Finocchi and colleagues, from the University of Genoa in Italy, used ultrasound to look for PFO in 40 people with cluster headache and 40 similar subjects without such headaches.

There was evidence of PFO in 17 patients with cluster headache compared with just 7 headache-free subjects. Having a cluster headache more than tripled the odds of having a PFO.

So, why do the two conditions often occur together? The reason is unclear, but it may relate to lower oxygen levels in the blood. With PFO, blood that bypasses lungs carries less oxygen than normal, and previous reports have suggested that poorly oxygenated blood may help induce cluster headaches.

Further studies are needed to better understand the association between cluster headache and PFO, the investigators conclude.

SOURCE: Neurology, October 12, 2004.

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