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 ofmagnetic
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
percent 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 Dr. 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.
More
information: "Robust
Detection of Traumatic Axonal Injury in Individual Mild Traumatic Brain Injury
Patients: Intersubject Variation, Change Over Time and Bidirectional Changes in
Anisotropy." Brain Imaging and Behavior
Provided
by Albert
Einstein College of Medicine
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