People who have a traumatic brain injury may be more likely to suffer a
stroke, a large new study suggests.
And while the chances of having a stroke are still small, incurring a
traumatic brain injury (TBI) may be as big a risk factor as is high blood
pressure, said study author Dr James Burke.
While stroke risk is usually tied to older adults, about 20% occur in those
under 65, said Burke, a research fellow in the neurology department at the
University of Michigan Medical School. "Stroke is not typically associated with
young people, and why younger people have strokes is not well understood."
But when younger adults do suffer a stroke, the effects can be daunting.
Dr John Volpi, co-director of the Eddy Scurlock Stroke Center in Houston,
recalled a patient who had a minor bike accident and seemed just fine. But after
just a few days, the man – who was only 45 – had a stroke. "It was a slow
recovery, getting back to walking and talking, and because he was an
ophthalmologist, it took him a long time to be able to go back to work," Volpi
While study author Burke said stroke prevention has come a long way in the
last 20 years or so, acute stroke treatment has seen only one significant
advance, the administration of a powerful blood clot destroyer called tissue
plasminogen activator (tPA).
Intravenous tPA is used in the first hours after a stroke to help break up
blood clots associated with ischemic stroke, in which blood flow to part of the
brain is blocked. Ischemic stroke accounts for about 87% of all cases, according
to the American Heart Association.
"The next place to hit a potential home run [in preventing stroke] is to find
other risk factors that could be playing a key role, especially in younger
people," Burke said.
It is unclear how a traumatic brain injury might raise a person's stroke
risk, he added. "TBI patients may have more headaches, more fear of seizures,
diet changes, genuine brain rewiring, or they may be affected by the stress of
TBI, or atherosclerotic plaques may be activated."
The study tapped several databases of adults in California who went to the
emergency department or were discharged from a hospital between 2005 and 2009.
More than 400 000 people with traumatic brain injury and more than 700 000
people with trauma but no brain injury were included in the study. The average
age of all participants was about 50.
About 28 months after the injury, more than 11 000 people – 1.1% – had an
ischemic stroke. But among those who had trauma but no brain injury, only 0.9%
had a stroke. While that difference may seem small, it is significant because
the overall risk of stroke for people this age is so tiny, Burke explained.
After taking into account factors that can affect the risk of stroke, such as
heart disease, high blood pressure, high cholesterol, the severity of the trauma
and age, the scientists found that those with TBI were 30% more likely to
develop a stroke than were those with trauma but no brain injury.
Volpi said the study involved a large number of patients with robust results
and high-quality data. Yet, he noted that the connection between trauma and
stroke is still unclear. "It could be a cause-and-effect relationship, but we
don't know for sure. It is possible that an injury to the head could lead to an
artery being injured," he said.
"The most likely answer to the connection might be that when the inner tube
within the vessel comes apart because it gets a tiny tear from trauma, it allows
the blood to push its way into the two layers and stopping or slowing down the
flow of blood, which can cause blockage," Volpi suggested.
He had some practical advice for those at risk for sports injuries. "I'd be
asking my doctor, trainer or coach about what kinds of head injuries they expect
and what they are doing to prevent head injury," he said.
Study author Burke remained sceptical about how much his own research really
confirms. While there are a fairly sizable number of strokes in people under 65,
the risk factors are still quite unclear, he said. "The most I can honestly say
is that this study is helping to inform what we should pursue next in
Learn more about stroke from the US Centers for Disease
Control and Prevention.
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