New Ways to Diagnose Traumatic Brain Injury
Distinguishing different types of brain injury more quickly could improve treatment.
In honor of Veterans Day,Technology Review is again highlighting some recent advances in understanding traumatic brain injury–a central
issue for many of the troops returning from Iraq
and Afghanistan.
We first highlighted this problem in a feature in 2007, Brain Trauma in Iraq.
This year, David Moore, a neurologist highlighted in the
feature, showed that diffusion tensor imaging, a brain imaging technology,
could distinguish between blast-related injuries and other sources of concussion.
According to a recent story of ours:
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The blasts caused by improvised explosive devices in Iraq
and Afghanistan appear to inflict a fundamentally different type of brain
damage than do more traditional sources of concussions, such as blunt trauma.
The findings point toward new approaches to diagnosing and monitoring these
injuries, which have been a huge concern to the military in recent years. The
research also begins to resolve a controversy in brain-injury research–whether soldiers who
are near an explosion but don’t get hit in the head can still suffer a unique
type of brain damage.
Regular concussions are typically caused by direct impact to the head, such
as in a fall, or acceleration injuries, as in car accidents. In contrast,
blast-induced brain injuries can include both of these factors as well as one
that is unique to explosions–a rapid pressure wave that may wreak its own
havoc on the brain. As a growing number of troops return from Iraq and
Afghanistan with signs of brain injury–post-deployment surveys suggest that 10
to 20 percent of all deployed troops have experienced concussions–the military
has been under increasing pressure to understand how this pressure wave affects
the brain, as well as how best to diagnose and treat the resulting injuries.
Typically, damage from concussions does not show up on traditional medical
imaging tests, such as CT scans or MRIs. But scientists have recently begun
using a variation of MRI known as diffusion tensor imaging (DTI) to detect damage to the
brain’s white matter–the neural wiring that connects cells–after mild
traumatic brain injury.
In the new study, David Moore, a neurologist and deputy director for research at the Defense
and Veterans Brain Injury Center in Washington, D.C., and
colleagues used DTI to assess troops who had been diagnosed with mild traumatic
brain injury following a blast, a direct impact, or an acceleration-induced
injury several months prior, as well as healthy people who had never suffered a
concussion. They found that those with blast-linked trauma had a more diffuse
pattern of damage to the white matter, described as a “pepper-spray
pattern,” than those whose concussions were caused by direct impact or
acceleration. The research was presented at the World Congress for Brain Mapping and Image Guided Therapy
conference in Boston
last month.
Researchers are also pushing forward a blood test to assess
more severe brain injuries. According to the piece,
One blood test already used in Europe
to screen head-trauma patients before CT scans detects a protein called S100B,
which is released by astrocyte cells in the brain after injury. “The
thinking is, if you don’t have [this marker] in the blood, then you don’t have
the kind of brain injury you could see on CAT scan,” says Jeffrey Bazarian, an emergency-room physician and scientist
at the University of Rochester Medical Center, in New York. The test is not approved for use
in the United States,
however. In a set of clinical guidelines for evaluating head trauma published
recently, Bazarian and others estimated that the S100B test could significantly
reduce unnecessary CT scanning. “We predict it could eliminate unnecessary
radiation in a lot of people–about 30 percent [of those who come into the ER
with brain injury],” he says.