WEDNESDAY, April 13 (HealthDay News) -- A new report suggests that researchers should explore ways to redesign football helmets to reduce the risk of brain hemorrhage after a collision, a rare occurrence but one that could kill a player.

In recent years, football organizations and the media have largely focused on the risk for concussions during games, especially in light of evidence that they can lead to permanent brain damage. Bleeding in the brain has received less attention.

Dr. Jonathan A. Forbes, a resident in neurosurgery at Vanderbilt University and lead author of the new report, said that the research findings suggest that "it's worth taking a new look at the safety of helmets."

Since 1945, more than 350 football players wearing helmets have died of bleeding in the brain after collisions, according to the report. However, deaths directly due to incidents on the football field have become rare in recent decades. Four deaths were reported in 2007, according to an annual survey, compared with 36 in 1968, while more than 600 were reported from 1931 to 1965.

For reasons that aren't clear, the most serious head injuries are about three times more common among high school football players than college athletes. It's rare to hear about brain bleeding in a pro football player, Forbes said.

Football helmets prevent injury by spreading the force of a collision around the head, Forbes said. In the new study, the researchers looked at something called rotational acceleration, a reference to how a blow pushes the head around, like when a boxer is punched in the side of the face.

Tests of helmet safety focus on something else, known as translational acceleration -- a reference to pushing the head back and forth or side to side -- because it's been linked to fractures of the head, Forbes explained. But, he said, research suggests that brain bleeding is significantly linked to rotational acceleration.

The findings "present some evidence that maybe we should start paying more attention to rotational acceleration," he said. "We're not trying to say that everything should be changed. We're saying these events of catastrophic head injury strongly correlate with peak levels of rotational acceleration," Forbes explained.

"Future research should take that into consideration, and maybe we should consider making sure that helmets prevent these dangerous levels of rotational acceleration," Forbes said.

The report's findings were scheduled to be presented Wednesday in Denver at a meeting of the American Association of Neurological Surgeons. Experts note that research presented at meetings has not been subjected to the same type of rigorous scrutiny given to research published in peer-reviewed medical journals.

Dr. Michael L. Levy, a professor of pediatric neurosurgery at the University of California, San Diego, said it's important to think about improving helmets, "but I don't know of anybody who has a conception of what you could do to a helmet to make it more protective against these types of injuries."

Levy, who has treated National Football League players and other athletes with head injuries, asked, "What would you do? What you're talking is something completely different than what we're dealing with now: It's not just increasing the padding or hardening the helmet. There's something else that needs to be done."

More information

The American Academy of Orthopaedic Surgeons has more on preventing football injuries.