Prediction of Post-Concussive Behavioral Changes in a Rodent Model Based on Head Rotational Acceleration Characteristics
Annals of Biomedical Engineering
Prediction of Post-Concussive Behavioral Changes in a Rodent Model Based on Head Rotational Acceleration Characteristics
MATTHEW D. BUDDE 1 2 3 4 5
ALEKSANDRA GLAVASKI-JOKSIMOVIC 1 2 3 4 5
MICHAEL MCCREA 1 2 3 4 5
SHEKAR N. KURPAD 1 2 3 4
FRANK A. PINTAR 1 2 3 4
0 Department of Pharmacology and Toxicology, Medical College of Wisconsin , Milwaukee , USA
1 Neurosurgery, Medical College of Wisconsin , Milwaukee , USA. Electronic mail:
2 Clement J. Zablocki Veterans Affairs Medical Center , Milwaukee , USA
3 acceleration , Animal model, Sports, Injury, Concussion
4 Department of Neurosurgery, Medical College of Wisconsin , Milwaukee , USA
5 Neuroscience Research Center, Medical College of Wisconsin , Milwaukee , USA
-Quantifying injury tolerance for concussion is complicated by variability in the type, severity, and time course of post-injury physiological and behavioral changes. The current study outlined acute and chronic changes in behavioral metrics following rotational acceleration-induced concussion in rats. The Medical College of Wisconsin (MCW) rotational injury model independently controlled magnitude and duration of the rotational acceleration pulse. Increasing rotational acceleration magnitude produced longer recovery times, which were used in this study and our prior work as an assessment of acute injury severity. However, longer duration rotational accelerations produced changes in emotionality as measured using the elevated plus maze. Cognitive deficits were for the most part not apparent in the Morris water maze assessment, possibly due to the lower severity of rotational acceleration pulses incorporated in this study. Changes in emotionality evolved between acute and chronic assessments, in some cases increasing in severity and in others reversing polarity. These findings highlight the complexity of quantifying injury tolerance for concussion and demonstrate a need to incorporate rotational acceleration magnitude and duration in proposed injury tolerance metrics. Rotational velocity on its own was not a strong predictor of the magnitude or type of acute behavioral changes following concussion, although its combination with rotational acceleration magnitude using multivariate analysis was the strongest predictor for acute recovery time and some chronic emotional-type behavioral changes.
Biomechanics; Traumatic brain injury; Angular
INTRODUCTION
It is becoming clear that rates of diagnosed
concussion in contact sports are increasing. Comparing
two studies that reported rates of concussion (per
10,000 exposures) reveals considerable increases for
high school sports between the late 1990s and the
2008–2010 seasons.27,38 The comparison reveals a 94%
increase in concussion rate for football, a 162%
increase for women’s soccer, and a 144% increase for
wrestling. Other studies have highlighted the
significant increase in concussion rate in high school sports
over a 6-year period, indicating that five of nine
investigated sports had statistically significant
increases.32 While explanations for these increases may
include increased awareness about concussions by
coaches, medical professionals, and athletes, increased
legislation, and better reporting of concussions at the
high school level, the possibility of increasing
concussion incidence should not be ignored. This comes at a
time of increased awareness of the chronic effects of
concussions. The significant life-long effects of
repetitive mild and moderate brain trauma have garnered
considerable media attention. The mechanism behind
these neurological declines appears to follow a dose
effect phenomenon, as evidenced by boxers with
neuropathological burden related to the length of a boxing
career and number of bouts.9 However, even lower
severity or less frequent injuries can lead to chronic
difficulties. For example, the work of Guskiewicz,
McCrea and colleagues has outlined significantly
increased rates of chronic cognitive difficulties and
emotional disturbances, including depression, for
retired professional football players that had sustained
0090-6964/16/1100-3252/0 2016 The Author(s). This article is published with open access at Springerlink.com
three or more concussions over the course of their
career compared to players that had sustained two or
fewer.16,17
The mechanism of concussion has long been
associated with head impact resulting in high rate head
rotational acceleration.30 Head accelerations lead to
tensile and shear strains within the brain tissues that
can exceed mechanical tolerance resulting in
physiologic dysfunction and/or mechanical injury. The
science of injury biomechanics would indicate that the
onset and outcomes from concussion should then be
correlated to head rotational acceleration
characteristics, which could include peak magnitude, positive
duration, or area under the curve (i.e., rotational
velocity). In other areas of injury biomechanics, the
risk of soft tissue cervical spine in (...truncated)