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May 1997 Vol. 12, No. 5   RSS Feed for Undercurrent Issues
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Brain Lesions

A hidden heart defect raises the risks

from the May, 1997 issue of Undercurrent   Subscribe Now

A few years ago researchers discovered that a tiny hole in the heart that affects about a quarter of the population increases one's susceptibility to the bends.

Now, researchers from the University of Heidelberg found that some frequent divers who seem to be perfectly healthy have brain lesions -- and those with the tiny hole are at most risk of the brain damage.

The hole, known as a patent foramen ovale, exists when a fetus is developing, but for most people it closes at birth; in about a quarter of the population it stays open and in some cases the opening is big enough to let blood clots or air bubbles through.

The researchers used magnetic resonance to study the brains 87 divers with an average of more than 500 dives each. "A total of 41 brain lesions were detected in 11 of the 87 divers," they reported in the British Medical Journal. "The three divers with multiple brain lesions were nonsmokers, aged in their 40s, and did not have any other multiple risk factors." What was different was that they had the little holes.

"The association of multiple brain lesions with a large patent foramen ovale supports the hypothesis that the brain lesions were due to arterial gas embolism during or shortly after decompression," they wrote.

Peter Wilmshurst, a cardiac consultant at the Royal Shrewsbury Hospital in England, told Reuters news agency that divers with the defect could give up diving, stay in shallow water, or not stay down as long as other divers. Ultrasound scans could show whether divers had the PFO and they could choose to have surgery to close it.

Dr. Kelly Hill (who is with Our Lady of the Lake Medical Center in Baton Rouge and medical columnist for NAUI's Sources) told us that the study seems to indicate that divers with PFO are "in danger of suffering brain damage to some degree. Since the brain never heals, no damage is better than some damage." Hill says the number of divers found with lesions "gets my interest because it is higher than I would expect," but he adds, "This is only an indication of a potential problem; the studies are still inconclusive."

Because the cost of an MRI on the heart is roughly $1,000, Hill says, "it's too much to ask for routine checks. However, he said, "when someone comes through our chamber with a bad hit and indication of potential neurological problems, I recommend an evaluation for PFO. While research hasn't proved that PFO is a major problem, the studies that have been conducted indicate that something is going on."

Ben Davison

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