Football results in more concussions than any other
competitive sport; but a concussion diagnosis isn’t the sole measure of brain
damage. It doesn’t take a 10-year career in the National Football League
(NFL)to cause substantial changes in brain cells. In fact, researchers at the
University of Texas Southwestern (UT Southwestern) Medical Center discovered
that a single season at the high school level is enough to Football results in
more concussions than any other competitive sport; but a concussion diagnosis
isn’t the sole measure of brain damage. It doesn’t take a 10-year career in the
National Football League (NFL)to cause substantial changes in brain cells. In
fact, researchers at the University of Texas Southwestern (UT Southwestern)
Medical Center discovered that a single season at the high school level is
enough to do just that. “Studies like this are important to understand how and
where long-term damage might be occurring, so that we can then take the
necessary steps to prevent it,” first author Elizabeth Davenport, PhD, in the
Department of Radiology and the Advanced Imaging Research Center, said in a
news release.
A total of 38 football players wore sensory helmets which
recorded head impact during practices and games. The researchers measured total
impacts, summed acceleration, and Risk Weighted cumulative Exposure (RWE). None
of the participants had been clinically diagnosed with a concussion. Pre- and
post- season assessments included magnetic resonance imaging (MRI) and
Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) revealed
brain health outcomes.
The authors concluded that just one season of high school
football is enough to cause brain cell changes noticeable in diffusional
kurtosis imaging (DKI) – which measures water diffusion in biological cells. In
addition, DKI revealed white matter abnormalities which were apparent in this
population, as described in the Journal of Neurotrauma.
“Work of this type, combining biomechanics, imaging, and
cognitive evaluation is critical to improving our understand of the effects of
subconcussive impacts of the develop brain,” explained senior author Joseph
Maldijan, MD, chief of the Neuroradiology Division and Director of the Advanced
Neuroscience Imaging Research Lab at UT Southwestern.
____________________________________________________________________________
Davenport EM,
Apkarian K, Whitlow CT, Urban JE, Jensen JH, Szuch E, Espeland MA, Jung Y,
Rosenbaum DA, Gioia G, Powers AK, Stitzel JD, Maldjian JA. Abnormalities in
Diffusional Kurtosis Metrics Related to Head Impact Exposure in a Season of
High School Varsity Football. J Neurotrauma. 2016 Apr 4. [Epub ahead of print]
Abstract
The purpose of this study is to determine if the effects of
cumulative head impacts during a season of high school football produce changes
in diffusional kurtosis imaging (DKI) metrics in the absence of clinically
diagnosed concussion. Subjects were recruited from a high school football team
and were outfitted with the Head Impact Telemetry System (HITs) during all practices
and games. Biomechanical head impact exposure metrics were calculated
including: total impacts, summed acceleration, and Risk Weighted cumulative
Exposure (RWE). Twenty-four players completed pre- and post-season MRI,
including DKI; players who experienced clinical concussion were excluded.
Fourteen subjects completed pre- and post-season Immediate Post-Concussion
Assessment and Cognitive Testing (ImPACT). DKI-derived metrics included mean
kurtosis (MK), axial kurtosis (K axial), and radial kurtosis (K radial), and
white matter modeling (WMM) parameters included axonal water fraction (AWF),
tortuosity of the extra-axonal space, extra-axonal diffusivity
(D<sub>e</sub> axial and radial), and intra-axonal diffusivity.
These metrics were used to determine the total number of abnormal voxels,
defined as 2 standard deviations above or below the group mean. Linear
regression analysis revealed a statistically significant relationship between
RWE<sub>CP</sub> and MK. Secondary analysis of other DKI-derived and
WMM metrics demonstrated statistically significant linear relationships with
RWE<sub>CP</sub> after covariate adjustment. These results were
compared with the results of DTI-derived metrics from the same imaging sessions
in this exact same cohort. Several of the DKI-derived scalars
(D<sub>a</sub>, MK, K axial, and K radial) explained more variance
when compared to RWE<sub>CP</sub>, suggesting that DKI may be more
sensitive to subconcussive head impacts. No significant relationships between
DKI-derived metrics and ImPACT measures were found. It is important to note,
the pathological implications of these metrics are not well understood. In
summary, we demonstrate a single season of high school football can produce DKI
measurable changes in the absence of clinically diagnosed concussion.
No comments:
Post a Comment