Patients
vary widely in their response to concussion, but scientists haven’t
understood why. Now, using a new technique for analyzing data from brain
imaging studies, researchers at Albert Einstein College of Medicine of
Yeshiva University and Montefiore Medical Center have found that
concussion victims have unique spatial patterns of brain abnormalities
that change over time.
The
new technique could eventually help in assessing concussion patients,
predicting which head injuries are likely to have long-lasting
neurological consequences, and evaluating the effectiveness of
treatments, according to lead author Michael L. Lipton, M.D., Ph.D.,
associate director of the Gruss Magnetic Resonance Research Center at
Einstein and medical director of magnetic resonance imaging (MRI)
services at Montefiore. The findings are published today in the online
edition of Brain Imaging and Behavior.
The
Centers for Disease Control and Prevention estimates that more than one
million Americans sustain a concussion (also known as mild traumatic
brain injury, or mTBI) each year. Concussions in adults result mainly
from motor vehicle accidents or falls. At least 300,000 adults and
children are affected by sports-related concussions each year. While
most people recover from concussions with no lasting ill effects, as
many as 30% suffer permanent impairment—undergoing a personality change
or being unable to plan an event. A 2003 federal study called
concussions “a serious public health problem” that costs the U.S. an
estimated $80 billion a year.
Previous
imaging studies found differences between the brains of people who have
suffered concussions and normal individuals. But those studies couldn’t
assess whether concussion victims differ from one another.
“In
fact, most researchers have assumed that all people with concussions
have abnormalities in the same brain regions,” said Lipton, who is also
associate professor of radiology, of psychiatry and behavioral sciences,
and in the Dominick P. Purpura Department of Neuroscience at Einstein.
“But that doesn’t make sense, since it is more likely that different
areas would be affected in each person because of differences in
anatomy, vulnerability to injury and mechanism of injury.”
In
the current study, the Einstein researchers used a recently developed
MRI technique called diffusion tensor imaging (DTI) on 34 consecutive
patients (19 women and 15 men aged 19 to 64) diagnosed with mTBI at
Montefiore in the Bronx and on 30 healthy controls. The patients were
imaged within two weeks of injury and again three and six months
afterward.
The
imaging data were then analyzed using a new software tool called
Enhanced Z-score Microstructural Assessment Pathology (EZ-MAP), which
allows researchers for the first time to examine microstructural
abnormalities across the entire brain of individual patients. EZ-MAP was
developed by Dr. Lipton and his colleagues at Einstein.
DTI
detects subtle damage to the brain by measuring the direction of
diffusion of water in white matter. The same technology was used by Dr.
Lipton and his team in widely publicized research on more than 30
amateur soccer players who had all played the sport since childhood.
They found that frequent headers showed brain injury similar to that
seen in patients with concussion.
The
uniformity of diffusion direction—an indicator of whether tissue has
maintained its microstructural integrity—is measured on a zero-to-one
scale called fractional anisotropy (FA). In the latest study, areas of
abnormally low FA (reflecting abnormal brain regions) were observed in
concussion patients but not in controls. Each concussion patient had a
unique spatial pattern of low FA that evolved over the study period.
Surprisingly,
each patient also had a unique, evolving pattern of abnormally high FA
distinct from the areas of low FA. “We found widespread high FA at every
time point, all the way out to six months and even in patients more
than one year out from their injury.” said Dr. Lipton. “We suspect that
high FA represents a response to the injury. In other words, the brain
may be trying to compensate for the injury by developing and enhancing
other neural connections. This is a new and unexpected finding.”
At
present, diagnosis of concussions is based mainly on the nature of the
patient’s accident and the presence of symptoms including headache,
dizziness and behavioral abnormalities. DTI, combined with EZ-MAP
analysis, might offer a more objective tool for diagnosing concussion
injuries and for predicting which patients will have persistent and
progressive symptoms.
The
paper is titled “Robust Detection of Traumatic Axonal Injury in
Individual Mild Traumatic Brain Injury Patients: Intersubject Variation,
Change Over Time and Bidirectional Changes in Anisotropy.”
Source: Yeshiva University
