Washington, Feb. 8 (Reuters): Helmets that cool the brain may slow down the spreading damage caused by a stroke, buying precious hours for patients, according to a report by researchers.

Such a helmet might be used by ambulance crews to stabilise stroke victims while getting them to hospitals for brain-saving treatment, they said.

Stroke is the third leading cause of death in the US, with most caused by blood clots cutting off blood flow to the brain. The longer the clot lasts, the worse the damage. Clot-busting treatment can minimise damage but must be given within hours, usually three hours, of the stroke.

Cooling patients has been found to help prevent the damage of a heart attack and now two teams told the American Heart Association’s annual International Stroke Conference that it may work for stroke, too.

The problem has been how to cool the brain without affecting the rest of the body.

Kentaro Yamada of the National Cardiovascular Center in Osaka, Japan, and colleagues said they tested a “helmet-type cooling apparatus” on 17 patients with severe stroke. His team put the cooling helmet on patients three to 12 hours after their strokes and left it on for up to a week.

Some patients shivered mildly and had elevated potassium levels, mild skin damage and infections, but none had serious adverse effects, Yamada said.

A similar US study used liquid cooling technology developed by Nasa scientist William Elkins for space suits, said Huan Wang, a neurosurgeon at the University of Illinois in Peoria.