Chilling the body to well below its normal temperature does little to protect children from further damage after an accidental brain injury, and may even make things worse, researchers reported on Wednesday.

The study, published in the New England Journal of Medicine, marks another blow to the hope that chilling the brain might protect it from damage, as in animal studies and some small 1993 tests in adults.

The new findings show a six month death rate of 21 percent among 108 youngsters in Canada, Britain and France whose bodies were chilled to 90.5 degrees F (32.5 degrees C) for 24 hours, compared to a mortality rate of 12 percent for the 117 whose temperatures were kept at the normal 98.6 degrees F (37 degrees C).

When the team, led by James Hutchison of the Hospital for Sick Children in Toronto, included other bad outcomes, such as severe disability or persistent vegetative state, children treated using hypothermia also fared worse than those kept at normal temperature.

After a year, the children treated with hypothermia scored worse on tests of long-term visual memory.

All of the hypothermia treatments were administered within eight hours of the injury. Hutchison and his colleagues said they found that cooling the body sooner did not improve the odds.

Hypothermia also has not proven very useful for preventing brain damage in adults.

A study of 392 adult coma patients, reported in 2001, found that 48 hours of hypothermia did not improve the chance of recovery following head trauma. That test was cut short when it appeared the lowered body temperature may actually have made things worse.

Some studies have shown that hypothermia may help protect the brains of patients after stroke, however.