Traumatic brain injury among soldiers, sportsmen and women and accident survivors are common but may go undetected at the time of the event and manifest later in life. Now scientists are testing a tool that lights up the breaks these injuries leave deep in the brain's wiring, much like X-rays show broken bones.
About 1.7 million people suffer a traumatic brain injury, or TBI, in the U.S. each year. Some survivors suffer obvious disability, but most TBIs are concussions or other milder injuries that generally heal on their own. TBI also is a signature injury of the wars in Iraq and Afghanistan, affecting more than 200,000 soldiers by military estimates.
TBIs are caused by a bump, blow or jolt to the head or a penetrating head injury that disrupts the brain's normal function. Some people experience memory loss, mood changes or other problems after what was deemed a mild concussion, only to have CT scans indicate nothing's wrong. Repeated concussions raise the risk of developing permanent neurologic problems later in life, a concern highlighted when some retired football players sued the National Football League.
The new kind of MRI-based test really could pinpoint their injuries and one day guide rehabilitation. It's an example of the hunt for better brain scans, maybe even a blood test, to finally tell when a blow to the head causes damage that today's standard testing simply can't see. “We now have, for the first time, the ability to make visible these previously invisible wounds,” says Walter Schneider of the University of Pittsburgh, who is leading development of the experimental scan. “If you cannot see or quantify the damage, it is hard to treat it.”
Not being able to see underlying damage leads to frustration for patients and doctors alike, says Dr. Walter Koroshetz, deputy director of the National Institute of Neurological Disorders and Stroke.
Some people experience memory loss, mood changes or other problems after what was deemed a mild concussion, only to have CT scans indicate nothing's wrong. But Koroshetz says there's no way to tell how much damage someone is accumulating, if the next blow “is really going to cause big trouble.”
And with more serious head injuries, standard scans cannot see beyond bleeding or swelling to tell if the brain's connections are broken in a way it can't repair on its own. “You can have a patient with severe swelling who goes on to have a normal recovery, and patients with severe swelling who go on to die,” says Dr. David Okonkwo, a University of Pittsburgh Medical Center neurosurgeon who is part of the research. Current testing “doesn't tell you what the consequence of that head injury is going to be.”
In a report published Friday in the Journal of Neurosurgery, Schneider's team describes one potential candidate, called high-definition fiber tracking. Brain cells communicate with each other through a system of axons, or nerve fibers that acts like a telephone network. They make up what's called the white matter of the brain, and run along fiber tracts, cable-like highways containing millions of connections.
With the help of this new scan high-powered MRIs through a special computer program can map major fiber tracts, painting them in vivid greens, yellows and purples that designate their different functions. Researchers look for breaks in the fibers that could slow, even stop, those nerve connections from doing their assigned job.
Daniel Stunkard of New Castle, Pa., is among the first 50 TBI patients in Pitt's testing. He had suffered an automobile accident in 2010. CT and regular MRI scans showed only some bruising and swelling, unable to predict if he'd wake up and in what shape. He was paralyzed in his left leg, arm and hand when he awoke from coma. Doctors started rehabilitation in hopes of stimulating healing, and Okonkwo says the high-def fiber tracking predicted what happened. The scan found partial breaks in nerve fibers that control the leg and arm, and extensive damage to those controlling the hand. In six months, Stunkard was walking. He now has some arm motion. But he still can't use his hand, his fingers curled tightly into a ball. Okonkwo says those nerve fibers were too far gone for repair.
The new tool promises a much closer look at nerve fibers than is now possible through a technique called diffusion tensor imaging, says Dr. Rocco Armonda, a neurosurgeon at Walter Reed National Military Medical Center. “It's like comparing your fuzzy screen black-and-white TV with a high-definition TV,” he says.
Doctors are also turning to non-imaging techniques to study TBIs. A study in the March 1 issue of the New England Journal of Medicine found the flu drug amantadine may boost recovery from brain injuries.
The military is studying whether a souped-up kind of CT scan could help spot TBI by measuring changes in blood flow inside the brain. The National Institutes of Health is funding a search for substances that might leak into the bloodstream after a brain injury, allowing for a blood test that might at least tell “if a kid can go back to sports next week,” Koroshetz says. He cautions that just finding an abnormality doesn't mean it's to blame for someone's symptoms.
And however the hunt for better tests pans out, Walter Reed's Armonda says the bigger message is to take steps to protect your brain. “What makes the biggest difference is everybody - little kids riding their bicycles, athletes playing sports, soldiers at war - is aware of TBI,” he says.
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