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source of direct external excitatory drive to local spinal networks caudal
to the injury. Here, we studied mice lacking functional muscle spindle
feedback to determine the role of this sensory input in gait control and
locomotor recovery after spinal cord injury. High-resolution kinematic
analysis of intact mutant mice revealed proficient execution in basic
locomotor tasks but poor performance in a precision task. After lateral
hemisection injury, wild-type mice spontaneously recovered basic lo-
comotor function, whereas mice with deficient muscle spindle feedback
failed to regain control over the ipsi-lesional hindlimb. Virus-mediated
tracing demonstrated that mutant mice exhibit defective rearrangements
of descending circuits projecting to deprived spinal segments following
injury. Our findings revealed an essential role for muscle spindle
feedback in directing basic locomotor recovery and facilitating des-
cending circuit reorganization after spinal cord injury.
Keywords: sensory feedback, proprioception, descending detour
circuit formation, locomotion
S07 Clinical Science of Sports Concussion
S07-01
EPIDEMIOLOGY OF SPORTS CONCUSSIONS
R. Dawn Comstock
1
1
Colorado School of Public Health, University of Colorado Anschutz
Medical Campus, Epidemiology, Aurora, USA
2
University of Colorado School of Medicine, Pediatric Emergency
Medicine, Aurora, USA
3
Pediatric Injury Prevention, Education, and Research (PIPER)
Program, Epidemiology, Aurora, USA
Introduction:
Concussions are a common sports injury, with an es-
timated 300,000 reported/recognized and 7–9 times as many unre-
ported/unrecognized sports concussions annually.
Objective:
To describe the epidemiology of sports concussion in
the US. More specifically to describe concussion rates and clinical
patterns by sport, athlete gender, and athlete age.
Design:
Descriptive epidemiology study coupling a literature re-
view with review of data captured by several national sports injury
surveillance systems including: The National Center for Catastrophic
Sports Injury Research, The National Collegiate Athletic Association
Injury Surveillance Program, NATA NATION, and High School RIO.
Results:
Rates and patterns of injury vary by sport, athlete gender, and
athlete age. Concussion rates are highest in full contact sports. In gender
comparable sports, females have higher concussion rates than males.
Older athletes have higher concussion rates than younger athletes.
Concussion rates have risen significantly over the past decade. The vast
majority of sports concussions are new injuries rather than recurrences.
Although there are some differences by gender and age, most athletes
report less than four concussion signs/symptoms upon presentation with
headache being the most commonly reported symptom and loss of
consciousness rarely reported, most athletes have all concussion symp-
toms resolve within one week of injury with few athletes experiencing
symptoms longer than 3 weeks, and although physicians are now in-
volved in the management of most injured athletes and most injured
athletes are now cleared for return to play by a physician, only a small
proportion of concussed athletes receive care from a specialist.
Conclusions:
The epidemiology of concussion varies by sport,
athlete gender, and athlete age. A knowledge of athlete subgroup
differences will help clinicians with staffing decisions, with clinical
expectations and comparisons, and with evaluation of efforts to pre-
vent sports concussions, to minimize those injuries that do occur, and
to improve patient outcomes.
Keywords: epidemiology, sports, gender, age, rates
S07-02
THE CHALLENGES OF CONCUSSION DIAGNOSIS IN
ATHLETES
Kevin Guskiewicz
University of North Carolina, Exercise and Sport Science, Chapel
Hill, USA
Previous concussion biomechanics research has relied heavily on the
animal model or laboratory reconstruction of concussive injuries captured
on video footage. The utility of head impact sensors/accelerometers has
received significant attention in recent years. Real-time data collection
involves a novel approach to better understanding the medical issues
related to sports concussion. Because of the varying magnitudes and lo-
cations of impacts resulting in concussion, as well as other factors such as
the frequency of sub-concussive impacts and number of prior concussions,
it may be difficult to establish a threshold for concussive injury that can be
applied to football and other helmeted contact sports such as hockey and
lacrosse. As reported previously in the literature, any proposed theoretical
injury threshold should be interpreted with caution. Despite this, biome-
chanics research has still provided us with valuable information for im-
proving safety in sports such as football and hockey. Our findings further
substantiate the notion that concussions must be managed using a multi-
faceted approach The most important findings of these combined studies
has been: 1) that concussions can occur at lower impact magnitudes than
previously thought; 2) that measures of linear acceleration appear equally
important to cause concussion as angular acceleration; 3) that athletes can
sustain a high number of head impacts in a season (many exceeding 80–
90 g) and never sustain a diagnosed concussion; and 4) clinicians should
not attempt to use impact magnitude or location to predict acute clinical
outcomes of symptom severity, neuropsychological function, and balance.
Our earlier studies, combined with those of several other studies on this
topic, call for more research to be conducted to investigate how linear and
rotational acceleration relate to measures of symptom severity, neuro-
cognitive function, and postural stability, in larger sample sizes across the
entire recovery period. Additionally, the role of this technology should be
further investigated to identify its utility for behavior modification and
improved player mechanics.
Keywords: biomechanics, head impact, concussion threshold
S07-03
EVIDENCE BASED ASSESSMENT TO SPORT CONCUSSION
MANAGEMENT
Gerard Gioia
Children’s National Medical Center, Neuropsychology, Rockville, USA
This presentation addresses the current state of evidence that supports the
valid assessment and management of sport related concussion from youth
to the professional ranks. While the interest in sport related concussion has
increased substantially over the past decade, the available clinical tools to
provide appropriate diagnostic and treatment guidance are in an active
state of development. Appropriate management of a concussion requires
clinical assessment and treatment methods to be supported by a strong
body of evidence to allow for valid and reliable clinical decisions to be
made. Key clinical domains in the assessment of concussion are discussed,
including cognition, symptom status, and balance/ vestibular/ ocular
function. The existing standards for test measurement and critical metrics
for valid clinical decisions will be applied to this discussion to provide a
framework for the essential evidence necessary for the valid use of tests in
a clinical context. Various assessment methods (computer-based, tradi-
tional administration) and measurement tools are highlighted with respect
to their existing evidence supporting clinical utility across the full age
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