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Even low-level shocks to the head can cause concussions, new research shows

Researchers at St. Michael’s Hospital new Keenan Research Centre say blows to the head may also be more significant than previously thought

Toronto, May 5, 2011

Blows or other impacts to the head may not have to be as hard as previously thought to cause physical damage or changes to the brain.

That’s the growing consensus of physicians and researchers at St. Michael’s Hospital and its new state-of-the-art Keenan Research Centre who study traumatic brain injuries such as concussions, and how to prevent them—research particularly pertinent to soldiers and athletes.

About 50,000 Canadians are hospitalized every year with traumatic brain injury and the number of cases being diagnosed is growing. Doctors are better able to recognize the symptoms -- even in people who have not lost consciousness or suffered an obvious physical injury. The public and the media are also more aware of the issue after several high-profile athletes have been sidelined by concussions.

As director of the Head Injury Clinic at St. Michael’s, Dr. Donna Ouchterlony’s patients include soldiers injured in Afghanistan, where the incidence of head injuries is higher than in any previous conflict. Dr. Andrew Baker, chief of critical care, takes her observations about their symptoms into his research lab to find out what’s happening at the cellular level. Dr. Michael Cusimano, a neurosurgeon, uses the key learnings of those studies to develop strategies to prevent traumatic brain injuries, especially in athletes.

Encouraging this kind of collaboration among researchers and clinicians is the purpose behind the hospital’s new Keenan Research Centre, being celebrated today. The Keenan Research Centre and the adjacent Li Ka Shing International Healthcare Education Centre were among the first in the world – and the only ones in Toronto – specifically designed to bring together researchers, educators and clinicians to brainstorm ideas and bring medical breakthroughs from lab bench to patients faster.

Shock-wave exposure from improvised explosive devices or heavy shelling has been implicated as a possible contributing factor to neurological impairment reported in combat veterans. Low-level blasts have been suspected as a potential cause of mild traumatic brain injury, the so-called signature injury of the Iraq War. Evidence has been difficult to obtain, especially when soldiers have no visible bleeding or external injuries.

New research by Dr. Baker, published in The Journal of Neurotrauma, found changes in the “white matter” of the brain after exposure to low-intensity blast waves. White matter sends messages from the “gray matter” of the brain to the rest of the body. It also connects different gray matter sites to one another, which enables thinking functions such as attention and memory.

Dr. Baker found that even low-intensity blast waves broke some white matter cells or caused them to transmit electric signals more slowly, The experimental blasts were adjusted to represent about one-quarter of the minimum intensity of the blast force of an IED that would cause physical symptoms– a level at which a soldier would not necessarily lose consciousness or appear to be injured.

Significantly, he also found that while some of the changes to the brain took place at the time of the injury, cells continued to break down days later.

“This means there could be opportunities, perhaps through some future drug, to intervene after a concussion has taken place to prevent further damage,” Dr. Baker said. “In the meantime, we now have a better understanding of the underlying mechanisms, and are in a better position to discover an effective drug.”

Dr. Cusimano said Dr. Baker’s research could have implications for athletes.

“It would mean it’s not just the major obvious mid-ice huge body check that knocks the player onto the ice that’s worrisome, but many of the smaller blows that people brush off during contact sports such as hockey and football,” said Dr. Cusimano, who was one of the first to warn of the dangers of bodychecking, especially in young people.

Based on his and others’ research that show brain injuries are much more common in hockey than previously thought and are most often associated with bodychecking, Cusimano has called for rule changes and changes in sports culture to eliminate bodychecking for children and youth. In the meantime, Drs. Baker and Ouchterlony are studying blood tests taken shortly after a person suffers a head injury to see if that can help determine the extent of the injury and the prognosis for recovery. Certain blood proteins are known to be elevated in people with damage to their nervous systems. Dr. Cusiamno, meanwhile, is leading a team of researchers funded by the Canadian Institutes of Health Research that is studying brain injuries and violence in sport and other settings.

About St. Michael’s

St. Michael’s Hospital provides compassionate care to all who walk through its doors. The Hospital also provides outstanding medical education to future health care professionals in more than 23 academic disciplines. Critical care and trauma, heart disease, neurosurgery, diabetes, cancer care, and care of the homeless are among the Hospital’s recognized areas of expertise. Through the Keenan Research Centre and the Li Ka Shing Knowledge Institute, research at St. Michael’s Hospital is recognized and put into practice around the world. Founded in 1892, the Hospital is fully affiliated with the University of Toronto.

Media Contact

For more information please contact:

Leslie Shepherd
Senior Public Relations Specialist
St. Michael's Hospital
416-864-6094 or 647-300-1753
shepherdl@smh.ca