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1.  When Treating Sport Concussion, Check the Boxes, But Also Go the Extra Mile 
doi:10.4085/1062-6050-48.4.14
PMCID: PMC3718345  PMID: 23855361
2.  Episodic Memory in Former Professional Football Players with a History of Concussion: An Event-Related Functional Neuroimaging Study 
Journal of Neurotrauma  2013;30(20):1683-1701.
Abstract
Previous research has demonstrated that sport-related concussions can have short-term effects on cognitive processes, but the long-term consequences are less understood and warrant more research. This study was the first to use event-related functional magnetic resonance imaging (fMRI) to examine long-term differences in neural activity during memory tasks in former athletes who have sustained multiple sport-related concussions. In an event-related fMRI study, former football players reporting multiple sport-related concussions (i.e., three or more) were compared with players who reported fewer than three concussions during a memory paradigm examining item memory (i.e., memory for the particular elements of an event) and relational memory (i.e., memory for the relationships between elements). Behaviorally, we observed that concussion history did not significantly affect behavioral performance, because persons in the low and high concussion groups had equivalent performance on both memory tasks, and in addition, that concussion history was not associated with any behavioral memory measures. Despite demonstrating equivalent behavioral performance, the two groups of former players demonstrated different neural recruitment patterns during relational memory retrieval, suggesting that multiple concussions may be associated with functional inefficiencies in the relational memory network. In addition, the number of previous concussions significantly correlated with functional activity in a number of brain regions, including the medial temporal lobe and inferior parietal lobe. Our results provide important insights in understanding the long-term functional consequences of sustaining multiple sports-related concussions.
doi:10.1089/neu.2012.2535
PMCID: PMC3840476  PMID: 23679098
cognitive function; head trauma; MRI
3.  Knowledge, Attitude, and Concussion-Reporting Behaviors Among High School Athletes: A Preliminary Study 
Journal of Athletic Training  2013;48(5):645-653.
Context:
Many athletes continue to participate in practices and games while experiencing concussion-related symptoms, potentially predisposing them to subsequent and more complicated brain injuries. Limited evidence exists about factors that may influence concussion-reporting behaviors.
Objective:
To examine the influence of knowledge and attitude on concussion-reporting behaviors in a sample of high school athletes.
Design:
Cross-sectional study.
Setting:
Participants completed a validated survey instrument via mail.
Patients or Other Participants:
A total of 167 high school athletes (97 males, 55 females, 5 sex not indicated; age = 15.7 ± 1.4 years) participating in football, soccer, lacrosse, or cheerleading.
Intervention(s):
Athlete knowledge and attitude scores served as separate predictor variables.
Main Outcome Measure(s):
We examined the proportion of athletes who reported continuing to participate in games and practices while symptomatic from possible concussion and the self-reported proportion of recalled concussion and bell-ringer events disclosed after possible concussive injury.
Results:
Only 40% of concussion events and 13% of bell-ringer recalled events in the sample were disclosed after possible concussive injury. Increased athlete knowledge of concussion topics (increase of 1 standard deviation = 2.8 points) was associated with increased reporting prevalence of concussion and bell-ringer events occurring in practice (prevalence ratio [PR] = 2.27, 95% confidence interval [CI] = 1.60, 3.21) and the reporting prevalence of bell-ringer-only events overall (PR = 1.87, 95% CI = 1.38, 2.54). Athlete attitude scores (increase of 1 standard deviation = 11.5 points) were associated with decreases in the proportion of athletes stating they participated in games (PR = 0.74, 95% CI = 0.66, 0.82) and practices (PR = 0.67, 95% CI = 0.59, 0.77) while symptomatic from concussions.
Conclusions:
Most recalled concussion events in our study were not reported to a supervising adult. Clinicians should be aware that knowledge and attitude influence concussion reporting. Clinicians and administrators should make concussion education a priority and encourage an optimal reporting environment to better manage and prevent concussive injuries in young athletes.
doi:10.4085/1062-6050-48.3.20
PMCID: PMC3784366  PMID: 23848520
education; brain injuries; care seeking
6.  Management of Cervical Spine Injuries in Athletes 
Journal of Athletic Training  2007;42(1):126-134.
Objective: Although the incidence of catastrophic cervical spine injury in sport has been significantly reduced over the past 3 decades, the injury warrants continued attention because of the altered quality of life that often accompanies such an injury. The purpose of our literature review was to provide athletic trainers with an understanding of the mechanisms, anatomical structures, and complications often associated with sport-related cervical spine injury. We also present the most current recommendations for management and treatment of these potentially catastrophic injuries.
Data Sources: A review of the most pertinent literature between 1970 and 2005 was conducted using MEDLINE and the search terms spinal cord injury, cervical spine injury, neurosurgical trauma, cervical spinal stenosis, and catastrophic spine injury.
Data Synthesis: Flexion of the head places the cervical spine into a straight line and prevents the neck musculature from assisting in force absorption. This mechanism is the primary cause of cervical fracture, dislocation, and quadriplegia. The most serious of the syndromes described in the literature involves a complete spinal cord injury with transverse myelopathy. This injury typically results in total loss of spinal function below the level of the lesion.
Conclusions/Recommendations: Spinal trauma may result in a variety of clinical syndromes, according to the type and severity of the impact and bony displacement, as well as subsequent secondary insults such as hemorrhage, ischemia, and edema. Athletic trainers should be prepared to promptly recognize these potentially catastrophic injuries and follow the recommendations of the Inter-Association Task Force for the Appropriate Care of the Spine Injured Athlete in managing such injuries.
PMCID: PMC1896065  PMID: 17597954
neck injury; spinal stenosis; quadriplegia; catastrophic injuries
7.  Postural Stability and Neuropsychological Deficits After Concussion in Collegiate Athletes 
Journal of Athletic Training  2001;36(3):263-273.
Objective:
Postural stability and neuropsychological testing are gradually becoming integral parts of postconcussion assessment in athletes. Clinicians, however, sometimes question the viability of instituting preseason baseline testing and the value of these results in making return-to-play decisions. Our purpose was to examine the course of recovery on various postural stability and neuropsychological measures after sport-related concussion. A secondary goal was to determine if loss of consciousness and amnesia, both of which are heavily weighted in most of the concussion classification systems, affect the rate of recovery.
Design and Setting:
All subjects underwent a battery of baseline postural stability and neuropsychological tests before the start of their respective seasons. Any athletes subsequently injured were followed up at postinjury days 1, 3, and 5. Matched control subjects were assessed using the same test battery at the same time intervals.
Subjects:
We studied 36 Division I collegiate athletes who sustained a concussion and 36 matched control subjects.
Measurements:
We assessed postural stability using the Sensory Organization Test on the NeuroCom Smart Balance Master System and the Balance Error Scoring System. Neurocognitive functioning was measured with several neuropsychological tests: Trail-Making Test, Wechsler Digit Span Test, Stroop Color Word Test, and Hopkins Verbal Learning Test.
Results:
Injured subjects demonstrated postural stability deficits, as measured on both the Sensory Organization Test and Balance Error Scoring System. These deficits were significantly worse than both preseason scores and matched control subjects' scores on postinjury day 1. Only the results on the Trail-Making Test B and Wechsler Digit Span Test Backward resulted in a logical recovery curve that could explain lowered neuropsychological performance due to concussive injury. Significant differences were revealed between the control and injured groups at day 1 postinjury, but a significant decline between baseline and postinjury scores was not demonstrated. Loss of consciousness and amnesia were not associated with increased deficits or slowed recovery on measures of postural stability or neurocognitive functioning.
Conclusions:
Athletes with cerebral concussion demonstrated acute balance deficits, which are likely the result of not using information from the vestibular and visual systems effectively. Neurocognitive deficits are more difficult to identify in the acute stages of concussion, although concentration, working memory, immediate memory recall, and rapid visual processing appear to be mildly affected. More research is necessary to determine the best neuropsychological test battery for assessing sport-related concussion.
PMCID: PMC155417  PMID: 12937495
mild head injury; balance; neurocognitive function
8.  Head Impact Exposure Sustained by Football Players on Days of Diagnosed Concussion 
Purpose
This study compares the frequency and severity of head impacts sustained by football players on days with and without diagnosed concussion and to identify the sensitivity and specificity of single impact severity measures to diagnosed injury.
Methods
1,208 players from eight collegiate and six high school football teams wore instrumented helmets to measure head impacts during all team sessions, of which 95 players were diagnosed with concussion. Eight players sustained two injuries and one three, providing 105 injury cases. Measures of head kinematics (peak linear and rotational acceleration, Gadd Severity Index (GSI), Head Injury Criteria (HIC15), change in head velocity (Δv)) and the number of head impacts sustained by individual players were compared between days with and without diagnosed concussion. Receiver operator characteristic curves were generated to evaluate the sensitivity and specificity of each kinematic measure to diagnosed concussion using only those impacts that directly preceded diagnosis.
Results
Players sustained a higher frequency of impacts and impacts with more severe kinematic properties on days of diagnosed concussion than on days without diagnosed concussion. Forty-five injury cases were immediately diagnosed following head impact. For these cases, peak linear acceleration and HIC15 were most sensitive to immediately diagnosed concussion (AUC = 0.983). Peak rotational acceleration was less sensitive to diagnosed injury than all other kinematic measures (p = 0.01) which are derived from linear acceleration (peak linear, HIC15, GSI, and Δv).
Conclusions
Players sustain more impacts and impacts of higher severity on days of diagnosed concussion than on days without diagnosed concussion. Additionally, of historical measures of impact severity, those associated with peak linear acceleration are the best predictors of immediately diagnosed concussion.
doi:10.1249/MSS.0b013e3182792ed7
PMCID: PMC3605215  PMID: 23135363
HIT System; Sport; impact biomechanics; MTBI; TBI; injury threshold
9.  Timing of Concussion Diagnosis is Related to Head Impact Exposure Prior to Injury 
Purpose
Concussions are commonly undiagnosed in an athletic environment because the post-injury signs and symptoms may be mild, masked by the subject, or unrecognized. This study compares measures of head impact frequency, location and kinematic response prior to cases of immediate and delayed concussion diagnosis.
Methods
Football players from eight collegiate and six high school teams wore instrumented helmets during play (n=1,208), of which ninety-five were diagnosed with concussion (105 total cases). Acceleration data recorded by the instrumented helmets was reduced to five kinematic metrics: peak linear and rotational acceleration, GSI, HIC15, and change in head velocity (Δv). Additionally, each impact was assigned to one of four general location regions (Front, Back, Side, and Top), and the number of impacts sustained prior to injury was calculated over two time periods (one and seven days).
Results
All head kinematic measures associated with injury, except peak rotational acceleration (p = 0.284), were significantly higher for cases of immediate diagnosis than delayed diagnosis (p<0.05). Players with delayed diagnosis sustained a significantly higher number of head impacts on the day of injury (32.9 ±24.9; p < 0.001) and within seven days of injury (69.7 ±43.3; p = 0.006) than players with immediate diagnosis (16.5 ±15.1 and 50.2 ±43.6). Impacts associated with concussion occurred most frequently to the Front of the head (46%) followed by the Top (25%), Side (16%), and Back (13%) with the number of impacts by location independent of temporal diagnosis (χ2(3) = 4.72; p = 0.19).
Conclusions
Concussions diagnosed immediately after an impact event are associated with the highest kinematic measures, while those characterized by delayed diagnosis are preceded by a higher number of impacts.
doi:10.1249/MSS.0b013e3182793067
PMCID: PMC3605273  PMID: 23135364
HIT System; impact biomechanics; MTBI; TBI; injury threshold; symptomatology
10.  Dehydration and Performance on Clinical Concussion Measures in Collegiate Wrestlers 
Journal of Athletic Training  2013;48(2):153-160.
Context:
The effects of dehydration induced by wrestling-related weight-cutting tactics on clinical concussion outcomes, such as neurocognitive function, balance performance, and symptoms, have not been adequately studied.
Objective:
To evaluate the effects of dehydration on the outcome of clinical concussion measures in National Collegiate Athletic Association Division I collegiate wrestlers.
Design:
Repeated-measures design.
Setting:
Clinical research laboratory.
Patients or Other Participants:
Thirty-two Division I healthy collegiate male wrestlers (age = 20.0 ± 1.4 years; height = 175.0 ± 7.5 cm; baseline mass = 79.2 ± 12.6 kg).
Intervention(s):
Participants completed preseason concussion baseline testing in early September. Weight and urine samples were also collected at this time. All participants reported to prewrestling practice and postwrestling practice for the same test battery and protocol in mid-October. They had begun practicing weight-cutting tactics a day before prepractice and postpractice testing. Differences between these measures permitted us to evaluate how dehydration and weight-cutting tactics affected concussion measures.
Main Outcome Measures:
Sport Concussion Assessment Tool 2 (SCAT2), Balance Error Scoring System, Graded Symptom Checklist, and Simple Reaction Time scores. The Simple Reaction Time was measured using the Automated Neuropsychological Assessment Metrics.
Results:
The SCAT2 measurements were lower at prepractice (P = .002) and postpractice (P < .001) when compared with baseline. The BESS error scores were higher at postpractice when compared with baseline (P = .015). The GSC severity scores were higher at prepractice (P = .011) and postpractice (P < .001) than at baseline and at postpractice when than at prepractice (P = .003). The number of Graded Symptom Checklist symptoms reported was also higher at prepractice (P = .036) and postpractice (P < .001) when compared with baseline, and at postpractice when compared with prepractice (P = .003).
Conclusions:
Our results suggest that it is important for wrestlers to be evaluated in a euhydrated state to ensure that dehydration is not influencing the outcome of the clinical measures.
doi:10.4085/1062-6050-48.1.07
PMCID: PMC3600917  PMID: 23672379
balance; mild traumatic brain injury; neurocognitive test; SCAT2
11.  Association between Previous Concussion History and Symptom Endorsement during Preseason Baseline Testing in High School and Collegiate Athletes 
Sports Health  2009;1(1):61-65.
Background:
A graded symptom checklist is a commonly used concussion evaluation measure. Little is known about preseason baseline symptomatology of high school and college athletes with and without a previous concussion history.
Hypothesis:
The primary hypothesis investigated was that those individuals with a concussion history would report more symptoms at baseline testing. The effects of sex and age on symptoms were also examined.
Study Design:
Cross-sectional study.
Methods:
Subjects included 8930 high school and collegiate athletes (height, 177.79 ± 9.97 cm; mass, 75.20 ± 19.21 kg; age, 16.60 ± 1.64 years). Subjects completed a self-report graded symptom checklist and concussion history questionnaire during a preseason clinical testing session. Symptoms reported (yes or no) on the 18-item graded symptom checklist served as the dependent variables.
Results:
A significant association was observed between symptoms on the graded symptom checklist and previous concussion history (P ≤ .001). No differences were observed between high school and college athletes regarding symptom endorsement (t8928 = 0.620; P = .535). A statistical but not clinically meaningful difference was observed between the means for males and females symptom endorsement (t8928 = −3.03; P = .002): men endorsed 1.88 ± 2.81 symptoms, and women endorsed 2.09 ± 2.90 symptoms. Headache, sleeping more than usual, difficulty concentrating, drowsiness, difficulty remembering, fatigue, difficulty sleeping, and irritability were reported by more than 10% of athletes.
Conclusion:
High school and college athletes with a history of multiple concussions may be at risk for experiencing concussion-linked symptoms well beyond the acute stage of injury. Clinicians should be mindful of previous concussion history in athletes with increased presence of base-rate symptoms as they may be predisposed to future injury.
doi:10.1177/1941738108325920
PMCID: PMC3445118  PMID: 23015855
preseason baseline; mild traumatic brain injury; symptomatology; concussion
12.  Return of Postural Control to Baseline After Anaerobic and Aerobic Exercise Protocols 
Journal of Athletic Training  2008;43(5):456-463.
Context:
With regard to sideline concussion testing, the effect of fatigue associated with different types of exercise on postural control is unknown.
Objective:
To evaluate the effects of fatigue on postural control in healthy college-aged athletes performing anaerobic and aerobic exercise protocols and to establish an immediate recovery time course from each exercise protocol for postural control measures to return to baseline status.
Design:
Counterbalanced, repeated measures.
Setting:
Research laboratory.
Patients Or Other Participants:
Thirty-six collegiate athletes (18 males, 18 females; age  =  19.00 ± 1.01 years, height  =  172.44 ± 10.47 cm, mass  =  69.72 ± 12.84 kg).
Intervention(s):
Participants completed 2 counterbalanced sessions within 7 days. Each session consisted of 1 exercise protocol followed by postexercise measures of postural control taken at 3-, 8-, 13-, and 18-minute time intervals. Baseline measures were established during the first session, before the specified exertion protocol was performed.
Main Outcome Measure(s):
Balance Error Scoring System (BESS) results, sway velocity, and elliptical sway area.
Results:
We found a decrease in postural control after each exercise protocol for all dependent measures. An interaction was noted between exercise protocol and time for total BESS score (P  =  .002). For both exercise protocols, all measures of postural control returned to baseline within 13 minutes.
Conclusions:
Postural control was negatively affected after anaerobic and aerobic exercise protocols as measured by total BESS score, elliptical sway area, and sway velocity. The effect of exertion lasted up to 13 minutes after each exercise was completed. Certified athletic trainers and clinicians should be aware of these effects and their recovery time course when determining an appropriate time to administer sideline assessments of postural control after a suspected mild traumatic brain injury.
PMCID: PMC2547864  PMID: 18833307
balance; fatigue; recovery; concussions; mild head injuries; mild traumatic brain injuries
13.  Assessment Tools for Identifying Functional Limitations Associated With Functional Ankle Instability 
Journal of Athletic Training  2008;43(1):44-50.
Context:
Assessment tools should identify functional limitations associated with functional ankle instability (FAI) by discriminating unstable from stable ankles.
Objective:
To identify assessment tools that discriminated FAI from stable ankles and determine the most accurate assessment tool for discriminating between FAI and stable ankles.
Design:
Case-control study.
Setting:
Research laboratory.
Patients or Other Participants:
Fifteen individuals with FAI and 15 healthy individuals; participants with unilateral FAI reported “giving-way” sensations and ankle sprains, whereas healthy participants did not.
Intervention(s):
Participants answered 12 questions on the Ankle Joint Functional Assessment Tool (AJFAT). They also performed a single-leg jump landing, which required them to jump to half their maximum jump height, land on a single leg, and stabilize quickly on a force plate.
Main Outcome Measure(s):
Receiver operating characteristic curves determined cutoff scores for discriminating between ankle groups for AJFAT total score and resultant vector (RV) time to stabilization. Accuracy values for discriminating between groups were determined by calculating the area under the receiver operating characteristic curves.
Results:
The cutoff score for discriminating between FAI and stable ankles was ≥26 (sensitivity  =  1, specificity  =  1) and ≥1.58 seconds (sensitivity  =  0.67, specificity  =  0.73) for the AJFAT total score and RV time to stabilization, respectively. The area under the curve for the AJFAT was 1.0 (asymptotic significance <.05), whereas the RV time to stabilization had an area under the curve of 0.72 (asymptotic significance <.05).
Conclusions:
The AJFAT was an excellent assessment tool for discriminating between ankle groups, whereas RV time to stabilization was a fair assessment tool. Although both assessments discriminated between ankle groups, the AJFAT more accurately discriminated between groups than the RV time to stabilization did. Future researchers should confirm these findings using a prospective research design.
PMCID: PMC2231396  PMID: 18335012
balance; ankle sprains; time to stabilization; Ankle Joint Functional Assessment Tool
14.  Muscle Stiffness and Spinal Stretch Reflex Sensitivity in the Triceps Surae 
Journal of Athletic Training  2008;43(1):29-36.
Context: Greater musculotendinous stiffness may enhance spinal stretch reflex sensitivity by improving mechanical coupling of the muscle spindle and the stretch stimulus. This heightened sensitivity would correspond with a shorter latency and higher-amplitude reflex response, potentially enhancing joint stability.
Objective: To compare spinal stretch reflex latency and amplitude across groups that differed in musculotendinous stiffness.
Design: Static group comparisons.
Setting: Research laboratory.
Patients or Other Participants: Forty physically active individuals (20 men, 20 women).
Intervention(s): We verified a sex difference in musculotendinous stiffness and compared spinal stretch reflex latency and amplitude in high-stiffness (men) and low-stiffness (women) groups. We also evaluated relationships between musculotendinous stiffness and spinal stretch reflex latency and amplitude, respectively.
Main Outcome Measure(s): Triceps surae musculotendinous stiffness and soleus spinal stretch reflex latency and amplitude were assessed at 30% of a maximal voluntary isometric plantar-flexion contraction.
Results: The high-stiffness group demonstrated significantly greater stiffness (137.41 ± 26.99 N/cm) than the low-stiffness group did (91.06 ± 20.10 N/cm). However, reflex latency (high stiffness = 50.11 ± 2.07 milliseconds, low stiffness = 48.26 ± 2.40 milliseconds) and amplitude (high stiffness = 0.28% ± 0.12% maximum motor response, low stiffness = 0.31% ± 0.16% maximum motor response) did not differ significantly across stiffness groups. Neither reflex latency (r = .053, P = .746) nor amplitude (r = .073, P = .653) was related significantly to musculotendinous stiffness.
Conclusions: A moderate level of pretension (eg, 30%) likely eliminates series elastic slack; thus, a greater change in force per unit-of-length change (ie, heightened stiffness) would have minimal effects on coupling of the muscle spindle and the stretch stimulus and, therefore, on spinal stretch reflex sensitivity. It appears unlikely that differences in musculotendinous stiffness influenced spinal stretch reflex sensitivity when initiated from a moderate level of pretension. Consequently, differences in musculotendinous stiffness did not appear to influence dynamic joint stability with respect to reflexive neuromuscular control.
PMCID: PMC2231394  PMID: 18335010
latency; amplitude; material modulus; compliance; neuromuscular control
16.  Athlete Characteristics and Outcome Scores for Computerized Neuropsychological Assessment: A Preliminary Analysis 
Journal of Athletic Training  2007;42(4):515-523.
Context: Computerized neuropsychological testing is used in athletics; however, normative data on an athletic population are lacking.
Objective: To investigate factors, such as sex, SAT score, alertness, and sport, and their effects on baseline neuropsychological test scores. A secondary purpose was to begin establishing preliminary reference data for nonsymptomatic collegiate athletes.
Design: Observational study.
Setting: Research laboratory.
Patients or Other Participants: The study population comprised 327 National Collegiate Athletic Association Division I athletes from 12 men's and women's sports.
Main Outcome Measure(s): Athletes were baseline tested before their first competitive season. Athletes completed demographics forms and self-reported history of concussion (1 or no concussion and 2 or more concussions) and SAT scores (<1000, 1000 to 1200, and >1200). The 108 women had a mean age of 18.39 ± 0.09 years, height of 167.94 ± 0.86 cm, and mass of 62.36 ± 1.07 kg. The 219 men had a mean age of 18.49 ± 0.07 years, height of 183.24 ± 1.68 cm, and mass of 88.05 ± 1.82 kg. Sports participation included women's soccer, lacrosse, basketball, and field hockey; men's football, soccer, lacrosse, and wrestling; and women's and men's track and cheerleading. We used the Automated Neuropsychological Assessment Metrics (Army Medical Research and Materiel Command, Ft Detrick, MD) and measured throughput scores (the number of correct responses per minute) as the dependent variable for each subtest, with higher scores reflecting increased speed and accuracy of responses. Subsets included 2 simple reaction time (SRT) tests, math processing (MTH), Sternberg memory search (ST6), matching to sample pairs (MSP), procedural reaction time (PRO), code digit substitution (CDS), and the Stanford sleep scale Likert-type score.
Results: Women scored better than men on the ST6 (P < .05), while men scored significantly better than women on the SRT and MSP tests. The highest-scoring SAT group performed better than other SAT groups on selected subtests (SRT, MTH, ST6, MSP, and CDS) (P < .05), and athletes tested during their season were more likely to score lower on the alertness scale (χ22[n = 322] = 11.32, P = .003). The lowest alertness group performed worse on the MSP and CDS subtests (P < .05). No differences were found between the group with a history of 1 or no concussion and the group with a history of 2 or more concussions (P > .05).
Conclusions: Performance on computerized neuropsychological tests may be affected by a number of factors, including sex, SAT scores, alertness at the time of testing, and the athlete's sport. To avoid making clinical misinterpretations, clinicians should acknowledge that individual baselines vary over time and should account for this variation.
PMCID: PMC2140078  PMID: 18174940
concussion; cognitive testing
17.  Neuropsychological Performance, Postural Stability, and Symptoms After Dehydration 
Journal of Athletic Training  2007;42(1):66-75.
Context: Dehydration and concussion are common in athletic performance. Some experts have speculated that dehydration may negatively influence performance on tests commonly used for concussion assessment.
Objective: To determine how the signs and symptoms, neuropsychological performance, and postural stability are affected by dehydration.
Design: Repeated-measures design assessing subjects in the euhydrated and dehydrated conditions.
Setting: Sports Medicine Research Laboratory.
Patients or Other Participants: Twenty-four healthy, male recreational athletes participated in the study.
Intervention(s): Subjects participated in 2 counterbalanced sessions (euhydrated and dehydrated) separated by at least 7 days. Subjects were dehydrated using fluid restriction and an exercise task. No direct intervention was provided for the euhydrated condition.
Main Outcome Measure(s): We used the Standardized Assessment of Concussion to test mental status, the Automated Neuropsychological Assessment Metrics (ANAM) to evaluate neuropsychological performance, the NeuroCom Sensory Organization Test and Balance Error Scoring System to test postural stability, the Graded Symptom Checklist to assess symptom presence and severity in our participants, and urine specific gravity and body mass to determine hydration status.
Results: No differences were noted for the Standardized Assessment of Concussion, total Balance Error Scoring System errors, composite Sensory Organization Test, and composite ANAM scores between conditions. Subjects in the dehydrated condition had significant deterioration in visual memory (t23 = 2.130, P < .001) and fatigue measures (t23 = −7.880, P < .001) as assessed by ANAM. The dehydrated condition resulted in subjects reporting a significantly higher number (t23 = −8.585, P < .001) and severity (t23 = −7.673, P < .001) of symptoms than the euhydrated subjects on the Graded Symptom Checklist.
Conclusions: Our results suggest that moderate dehydration (−2.5 ± 0.63%) significantly influenced the self-report of symptoms commonly associated with concussion. Dehydration resulted in a deterioration of visual memory and increases in the self-report of fatigue. Despite these findings, dehydration did not affect other neuropsychological and postural stability objective testing measures for concussion.
PMCID: PMC1896077  PMID: 17597946
cognition; balance; mild traumatic brain injury
18.  Psychometric and Measurement Properties of Concussion Assessment Tools in Youth Sports 
Journal of Athletic Training  2006;41(4):399-408.
Context: Establishing psychometric and measurement properties of concussion assessments is important before these assessments are used by clinicians. To date, data have been limited regarding these issues with respect to neurocognitive and postural stability testing, especially in a younger athletic population.
Objective: To determine the test-retest reliability and reliable change indices of concussion assessments in athletes participating in youth sports. A secondary objective was to determine the relationship between the Standardized Assessment of Concussion (SAC) and neuropsychological assessments in young athletes.
Design: We used a repeated-measures design to evaluate the test-retest reliability of the concussion assessments in young athletes. Correlations were calculated to determine the relationship between the measures. All subjects underwent 2 test sessions 60 days apart.
Setting: Sports medicine laboratory and school or home environment.
Patients or Other Participants: Fifty healthy young athletes between the ages of 9 and 14 years.
Main Outcome Measure(s): Scores from the SAC, Balance Error Scoring System, Buschke Selective Reminding Test, Trail Making Test B, and Coding and Symbol Search subsets of the Wechsler Intelligence Scale for Children were used in the analysis.
Results: Our test-retest indices for each of the 6 scores were poor to good, ranging from r = .46 to .83. Good reliability was found for the Coding and Symbol Search tests. The reliable change scores provided a way of determining a meaningful change in score for each assessment. We found a weak relationship ( r < .36) between the SAC and each of the neuropsychological assessments; however, stronger relationships ( r > .70) were found between certain neuropsychological measures.
Conclusions: We found moderate test-retest reliability on the cognitive tests that assessed attention, concentration, and visual processing and the Balance Error Scoring System. Our results demonstrated only a weak relationship between performance on the SAC and the selected neuropsychological tests, so it is likely that these tests assess somewhat different areas of cognitive function. Our correlational findings provide more evidence for using the SAC along with a more complex neuropsychological assessment battery in the evaluation of concussion in young athletes.
PMCID: PMC1752194  PMID: 17273465
neuropsychological testing; brain injury; athletic injuries; reliability
19.  Functional Balance Training, With or Without Exercise Sandals, for Subjects With Stable or Unstable Ankles 
Journal of Athletic Training  2006;41(4):393-398.
Context: Improving postural stability through balance training may prevent ankle sprains. Exercise Sandals may increase the demands placed on ankle muscles during rehabilitation, which could improve postural stability.
Objective: To examine the effects of functional balance training, with and without the use of Exercise Sandals, on postural stability in subjects with stable or unstable ankles.
Design: Prospective, nonrandomized clinical trial.
Setting: Sports medicine research laboratory.
Patients or Other Participants: Sixteen subjects with functional ankle instability and 16 subjects with no history of ankle sprains.
Intervention(s): Subjects were assigned to an Exercise Sandal functional balance training group or a shoe functional balance training group. Subjects trained 3 times per week for 8 weeks and then performed a single-limb stance posttest.
Main Outcome Measure(s): Subjects were required to remain as motionless as possible during a single-limb stance pretest. Anterior-posterior and medial-lateral center-of-pressure excursions were measured.
Results: Exercise Sandal balance training improved anterior-posterior postural stability in both ankle groups ( P < .05). Both training interventions improved medial-lateral postural stability in stable and unstable ankles ( P < .05).
Conclusions: Postural stability improved after subjects performed functional balance training programs, both with and without Exercise Sandals. Training with Exercise Sandals might not be any more effective in improving postural stability than performing functional balance training without Exercise Sandals. However, Exercise Sandals did not impair postural stability and, consequently, might serve as an alternative therapy to improve postural stability.
PMCID: PMC1748421  PMID: 17273464
balance shoes; chronic ankle instability; functional ankle instability
20.  Issues in Estimating Risks and Rates in Sports Injury Research 
Journal of Athletic Training  2006;41(2):207-215.
Objective: To describe 3 measures of incidence used in sports injury epidemiology.
Background: To promote safety in sports, athletic trainers must be able to accurately interpret and apply injury data and statistics. Doing so allows them to more efficiently articulate this information to school administrators in recommending increases in medical resources, such as more personnel, better services, and safer facilities and equipment.
Description: Using data from a study of high school sports injuries, we review incidence rates, epidemiologic incidence proportions, and clinical incidence. The incidence rate is the number of injuries divided by the number of athlete-exposures and is based on the epidemiologic concept of person-time at risk. It accounts for variation in exposure between athletes and teams and is widely used by researchers. The epidemiologic incidence proportion is the number of injured athletes divided by the number of athletes at risk. It is a valid estimator of average injury risk, yet it is rarely used in sports injury epidemiology to communicate information about such risks to nonscientists. Clinical incidence is a hybrid between the epidemiologic incidence proportion and the incidence rate in that it uses the number of injuries in the numerator but the number of athletes at risk in the denominator. It has been widely used in research on high school football injury but is neither a valid estimator of risk nor a true rate.
Advantages: Athletic trainers who understand the causes of and risk factors for sport-related injury are better positioned to make safe return-to-play decisions and decrease the likelihood of reinjury in athletes.
PMCID: PMC1472638  PMID: 16791309
injury epidemiology; injury prevention
21.  Recovery of Postural Control After Cerebral Concussion: New Insights Using Approximate Entropy 
Journal of Athletic Training  2006;41(3):305-313.
Context: The return-to-play decision after sport-related cerebral concussion depends in part on knowing when an athlete has fully recovered postural control after injury.
Objective: To describe the postconcussion recovery of postural control using approximate entropy (ApEn), a regularity statistic from nonlinear dynamics.
Design: Retrospective case series analysis.
Setting: Sports medicine research laboratory.
Patients or Other Participants: Collegiate athletes from whom center-of-pressure and symptom data were collected at preseason, less than 48 hours after injury, and 48 to 96 hours after injury.
Main Outcome Measure(s): Approximate entropy values reflecting the amount of randomness contained in center-of-pressure oscillations were calculated for anterior-posterior (AP) and medial-lateral (ML) time series. Equilibrium scores reflecting the amplitude of center-of-pressure AP oscillations were used to indicate postural stability. The number and severity of symptoms were described.
Results: Compared with the healthy preseason state, ApEn values for the AP and ML time series generally declined immediately after injury in both steady and unsteady injured athletes. At 48 to 96 hours after injury, ApEn values for the ML time series remained significantly depressed (mean difference compared with preseason = −0.268, standard error = 0.072), even among athletes whose initial postural instability had resolved. We found few significant relationships between changes in ApEn values and changes in symptoms before and after injury.
Conclusions: The effects of cerebral concussion on postural control appear to persist for longer than 3 to 4 days, even among athletes with no signs of unsteadiness. Our results may reflect changes in neurophysiologic or mechanical constraints on postural control. Approximate entropy provides a theoretically distinct, valuable measurement alternative that may prove useful for reducing uncertainty in the return-to-play decision.
PMCID: PMC1569549  PMID: 17043699
cerebral concussion; nonlinear dynamics; measurement
22.  Age-Related Differences and Reliability on Computerized and Paper-and-Pencil Neurocognitive Assessment Batteries 
Journal of Athletic Training  2012;47(3):297-305.
Context:
Neurocognitive testing is a recommended component in a concussion assessment. Clinicians should be aware of age and practice effects on these measures to ensure appropriate understanding of results.
Objective:
To assess age and practice effects on computerized and paper-and-pencil neurocognitive testing batteries in collegiate and high school athletes.
Design:
Cohort study.
Setting:
Classroom and laboratory.
Patients or Other Participants:
Participants consisted of 20 collegiate student-athletes (age  =  20.00 ± 0.79 years) and 20 high school student-athletes (age  =  16.00 ± 0.86 years).
Main Outcome Measure(s):
Hopkins Verbal Learning Test scores, Brief Visual-Spatial Memory Test scores, Trail Making Test B total time, Symbol Digit Modalities Test score, Stroop Test total score, and 5 composite scores from the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) served as outcome measures. Mixed-model analyses of variance were used to examine each measure.
Results:
Collegiate student-athletes performed better than high school student-athletes on ImPACT processing speed composite score (F1,38  =  5.03, P  =  .031) at all time points. No other age effects were observed. The Trail Making Test B total time (F2,66  =  73.432, P < .001), Stroop Test total score (F2,76  =  96.85, P  =  < .001) and ImPACT processing speed composite score (F2,76  =  5.81, P  =  .005) improved in test sessions 2 and 3 compared with test session 1. Intraclass correlation coefficient calculations demonstrated values ranging from 0.12 to 0.72.
Conclusions:
An athlete's neurocognitive performance may vary across sessions. It is important for clinicians to know the reliability and precision of these tests in order to properly interpret test scores.
PMCID: PMC3392160  PMID: 22892411
concussions; traumatic brain injuries; serial testing
24.  Exercise Sandals Increase Lower Extremity Electromyographic Activity During Functional Activities 
Journal of Athletic Training  2003;38(3):198-203.
Objective:
Anecdotal evidence suggests that use of Exercise Sandals results in a number of positive clinical outcomes. However, little research has been conducted to determine their efficacy objectively. Our purposes were to determine the effect of Exercise Sandals on lower leg electromyography (EMG) during activities in the Exercise Sandals and to compare EMG associated with Exercise Sandals with traditional lower extremity rehabilitation exercises.
Design and Setting:
Two within-subjects, repeated-measures designs were used to identify differences in lower extremity EMG: (1) between activities with and without Exercise Sandals and (2) between Exercise Sandals activities and traditional rehabilitation activities. All data were collected in the Sports Medicine Research Laboratory.
Subjects:
Eighteen subjects involved in rehabilitation using Exercise Sandals for at least 2 weeks within the year before data collection.
Measurements:
Mean EMG amplitudes from the tibialis anterior, peroneus longus, soleus, and lateral gastrocnemius muscles were measured during single-leg stance, side stepping, and “high knees,” all performed with and without the Exercise Sandals, as well as single-leg stance on a foam surface and T-band kicks in the sagittal and frontal planes.
Results:
Exercise Sandals increased lower leg EMG activity, particularly in the ankle invertors and evertors. Also, activities involving the Exercise Sandals resulted in EMG activity similar to or exceeding that associated with traditional ankle-rehabilitation exercises.
Conclusions:
These results, coupled with the fact that Exercise Sandals are used in a functional closed kinetic chain manner, suggest that they are an effective means of increasing lower extremity muscle activity.
PMCID: PMC233171  PMID: 14608427
balance training; ankle rehabilitation; closed kinetic chain rehabilitation
25.  A Survey of Practice Patterns in Concussion Assessment and Management 
Journal of Athletic Training  2001;36(2):145-149.
Objectives:
To identify methods used by athletic trainers to assess concussions and the use of that information to assist in return-to-play decisions and to determine athletic trainers' familiarity with new standardized methods of concussion assessment.
Design and Setting:
A 21-item questionnaire was distributed to attendees of a minicourse at the 1999 National Athletic Trainers' Association Annual Meeting and Clinical Symposia entitled “Use of Standardized Assessment of Concussion (SAC) in the Immediate Sideline Evaluation of Injured Athletes.”
Subjects:
A total of 339 valid surveys were returned by the attendees of the minicourse.
Measurements:
We used frequency analysis and descriptive statistics.
Results:
Clinical examination (33%) and a symptom checklist (15.3%) were the most common evaluative tools used to assess concussions. The Colorado Guidelines (28%) were used more than other concussion management guidelines. Athletic trainers (34%) and team physicians (40%) were primarily responsible for making decisions regarding return to play. A large number of respondents (83.5%) believed that the use of a standardized method of concussion assessment provided more information than routine clinical and physical examination alone.
Conclusions:
Athletic trainers are using a variety of clinical tools to evaluate concussions in athletes. Clinical evaluation and collaboration with physicians still appear to be the primary methods used for return-to-play decisions. However, athletic trainers are beginning to use standardized methods of concussion to evaluate these injuries and to assist them in assessing the severity of injury and deciding when it is safe to return to play.
PMCID: PMC155525  PMID: 12937455
mild brain injury; grading scales; head injury; evaluation

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