Concussion-like Symptoms Research Articles

Lipidomic Analysis Reveals Systemic Alterations in Servicemen Exposed to Repeated Occupational Low-Level Blast Waves.

Occupational exposure to blast is a prevalent risk experienced by military personnel. While low-level exposure may not manifest immediate signs of illness, prolonged and repetitive exposure may result in neurophysiological dysfunction. Such repeated exposure to occupational blasts has been linked to structural and functional modifications in the brain, adversely affecting the performance of servicemen in the field. These neurological changes can give rise to symptoms resembling concussion and contribute to the development of post-traumatic stress disorder. To understand long-term effects of blast exposure, the study was conducted to assess memory function, serum circulatory protein and lipid biomarkers, and associated concussive symptomology in servicemen. Concussion-like symptoms were assessed using the Rivermead Post-Concussion Symptoms Questionnaire (RPSQ) along with memory function using PGI memory scale. The serum protein biomarkers were quantified using a sandwich ELISA assay, and the serum lipid profile was measured using liquid chromatography-mass spectrometer. The findings revealed that repeated low-level blast exposure resulted in impaired memory function, accompanied by elevated levels of serum neurofilament light chain (neuroaxonal injury) and C-reactive protein. Furthermore, alterations in the lipid profile were observed, with an increase in lipid species associated with immune activation. These changes collectively point to systemic inflammation, neuronal injury, and memory dysfunction as pathological characteristics of repeated low-level blast exposure. The results of our preliminary investigation offer valuable insights for further large-scale study and provide a guiding principle that necessitates a suitable mitigation approach to safeguard the health of personnel against blast overpressure.

Baseline Evaluation of Concussion-Like Symptoms and Modifying Factors in Collegiate Club-Sport Athletes.

Collegiate club-sport athletes participate in a variety of competitive sports and have been understudied in the concussion literature. Baseline performance measures are warranted to better understand assessment and management. To quantify normative values and the effects of modifying factors sex, concussion history, diagnosed attention disabilities (attention-deficit/hyperactivity disorder [ADHD]), and sport type on baseline symptom evaluation among collegiate club-sport athletes. Cross-sectional study. Retrospective chart review. A total of 1034 collegiate club-sport athletes (N = 649 males, 62.7%) from 29 sports at a single institution. Chart reviews were conducted for club-sport athletes who completed athlete background and symptom information on the Sport Concussion Assessment Tool-5th edition as a baseline concussion assessment during a single academic year. Demographics (eg, age, sex, sport), background medical information (eg, concussion history, ADHD), and symptom evaluation, consisting of individual 22-item symptom reports, the total number of symptoms, symptom severity scores, and symptom factors (eg, physical, cognitive, insomnia, and emotional), were analyzed. On baseline symptom reporting, 68% of club-sport athletes were asymptomatic, with mild symptoms described by 3% to 12% and moderate or severe symptoms by ≤4%. Modifier groups differed with a higher total number of symptoms and symptom severity in females (P < .001), individuals reporting a history of concussion (P < .001), and those with ADHD (total number P = .04, symptom severity P = .02). Similar significant findings were noted for females and the history of concussion group on all 4 symptom factors; however, those in collision or contact sports also indicated greater cognitive (P = .03) and insomnia (P = .02) factors. Those with ADHD endorsed more cognitive (P < .001) factors. Normative symptoms for a collegiate club-sport sample revealed approximately 70% were asymptomatic. Higher total number of symptoms and symptom severity were demonstrated by females and those with a history of concussion. Cognitive-specific symptoms were greater in those diagnosed with ADHD and those who participated in collision or contact sports.

Impact of Preparticipation Hypohydration on Cognitive Performance and Concussion-like Symptoms in Recreational Athletes.

Sports-related concussion is a relevant risk of contact sports, with several million cases per year worldwide. Prompt identification is crucial to prevent complications and late effects but may be impeded by an overlap with dehydration-associated impairment of cognitive function. Researchers have extensively studied the effects of pronounced dehydration in endurance sports, especially in the heat. However, little is known about the effects of isolated and mild dehydration. Healthy recreational athletes underwent a standardized fluid deprivation test. Hypohydration was assessed by bioelectrical impedance analysis (BIA) and laboratory testing of electrolytes and retention parameters. Participants underwent cardiopulmonary exercise testing (CPET) with a cycle ramp protocol. Each participant served as their own control undergoing CPET in a hypohydrated [HYH] and a euhydrated [EUH] state. Effects were assessed using a shortened version of Sport Concussion Assessment Tool 3 (SCAT3). Fluid deprivation caused a mild (2%) reduction in body water, resulting in a calculated body mass loss of 0.8% without alterations of electrolytes, serum-osmolality, or hematocrit. Athletes reported significantly more (1.8 ± 2.2 vs. 0.4 ± 0.7; p < 0.01) and more severe (4.4 ± 6.2 vs. 1.0 ± 1.9; p < 0.01) concussion-like symptoms in a hypohydrated state. Balance was worse in HYH by trend with a significant difference for tandem stance (1.1 ± 1.3 vs. 0.6 ± 1.1; p = 0.02). No relevant differences were presented for items of memory and concentration. Mild dehydration caused relevant alterations of concussion-like symptoms and balance in healthy recreational athletes in the absence of endurance exercise or heat. Further research is needed to clarify the real-life relevance of these findings and to strengthen the differential diagnosis of concussion.

Early Moderate to Vigorous Physical Activity After Concussion Is Associated With Faster Symptom Resolution Time.

Early physical activity (PA) after concussion may promote symptom resolution. Prior studies have investigated exercise frequency/duration, yet precise PA intensity or volume required for optimal recovery requires further investigation. moderate to vigorous physical activity (MVPA) is beneficial for physical health. We investigated whether sedentary time, light activity time, MVPA time, or activity frequency in the weeks following concussion are associated with time to symptom resolution among adolescents. Prospective cohort study. Adolescents 10-18years of age were tested ≤14days of concussion and followed until symptom resolution. At the initial visit, participants rated symptom severity and were provided wrist-worn activity trackers to monitor PA for the following week. PA behavior was categorized each day based on heart rate: sedentary (resting), light PA (50%-69% age-predicted max heart rate), and MVPA (70%-100% age-predicted max heart rate). Symptom resolution was defined as the date when participants reported cessation of concussion-like symptoms. Patients were not given specific PA instructions, though some may have received instructions from their physician. Fifty-four participants were included in the study (54% female; mean age = 15.0 [1.8]y; initially assessed 7.5 [3.2]d after concussion). Female athletes recorded more sedentary time (900 [46] vs 738 [185]min/d; P = .01; Cohen d = 0.72), and less time in light PA (194.7 [64.5] vs 224 [55]min/d; P = .08; Cohen d = 0.48) and MVPA (23 [17] vs 38 [31]min/d; P = .04; Cohen d = 0.58) than male athletes. After adjusting for sedentary time, hours per day with >250 steps, sex, and initial symptom severity, more MVPA time was associated with faster symptom resolution time (hazard ratio = 1.016; 95% confidence interval, 1.001-1.032; P = .04). Our findings offer preliminary insight into how varying PA intensities affect concussion recovery, as MVPA may be a higher intensity than what is typically prescribed in concussion care.

Sensitivity and Specificity of Exercise Intolerance on Graded Exertion Testing for Diagnosing Sport-related Concussion: A Systematic Review and Exploratory Meta-Analysis.

There is no single gold standard test to diagnose sport-related concussion (SRC). Concussion-related exercise intolerance, i.e., inability to exercise to the individual's appropriate level due to exacerbation of concussion-like symptoms, is a frequent finding in athletes early after SRC that has not been systematically evaluated as a diagnostic test of SRC. We performed a systematic review and proportional meta-analysis of studies that evaluated graded exertion testing in athletes after SRC. We also included studies of exertion testing in healthy athletic participants without SRC to assess specificity. Pubmed and Embase were searched in January 2022 for articles published since 2000. Eligible studies included those that performed graded exercise tolerance tests in symptomatic concussed participants (> 90% of subjects SRC, seen within 14 days of injury) at the time of clinical recovery from SRC, in healthy athletes, or both. Study quality was assessed using the Newcastle-Ottawa Scale. Twelve articles met inclusion criteria, most of which were of poor methodological quality. The pooled estimate of incidence of exercise intolerance in participants with SRC equated to an estimated sensitivity of 94.4% (95% CI 90.8, 97.2). The pooled estimate of incidence of exercise intolerance in participants without SRC equated to an estimated specificity of 94.6% (95% CI 91.1, 97.3). The results suggest that exercise intolerance measured on systematic testing within 2 weeks of SRC may have excellent sensitivity for helping to rule in the diagnosis of SRC and excellent specificity for helping to rule out SRC. A prospective validation study to determine the sensitivity and specificity of exercise intolerance on graded exertion testing for diagnosing SRC after head injury as the source of symptoms is warranted.

Biomechanical induction of mild brain trauma in larval zebrafish: effects on visual startle reflex habituation.

A mild traumatic brain injury is a neurological disturbance of transient or/and chronic nature after a direct blow of the head/neck or exposure of the body to impulsive biomechanical forces, indirectly affecting the brain. The neuropathological events leading to the clinical signs, symptoms and functional disturbances are still elusive due to a lack of sensitive brain-screening tools. Animal models offer the potential to study neural pathomechanisms in close detail. We recently proposed a non-invasive protocol for inducing concussion-like symptoms in larval zebrafish via exposure to rapid linearly accelerating-decelerating body motion. By mean of auditory 'startle reflex habituation' assessments-an established neurophysiological health index-we probed acute and chronic effects that mirror human concussion patterns. This study aimed at expanding our previous work by assessing the ensuing effects with visual-as opposed to auditory-'startle reflex habituation' quantifications, by using the same methodology. We observed that immediately after impact exposure, the fish showed impaired sensory reactivity and smaller decay constant, possibly mirroring acute signs of confusion or loss of consciousness in humans. By 30-min post-injury, the fish display temporary signs of visual hypersensitivity, manifested as increased visuomotor reactivity and a relatively enlarged decay constant, putatively reflecting human post-concussive sign of visual hypersensitivity. In the following 5-24 h, the exposed fish progressively develop chronic signs of CNS dysfunction, in the form of low startle responsivity. However, the preserved decay constant suggests that neuroplastic changes may occur to restore CNS functioning after undergoing the 'concussive procedure'. The observed findings expand our previous work providing further behavioural evidence for the model. Limitations that still require addressment are discussed, advancing further behavioural and microscopic analyses that would be necessary for the validation of the model in its putative relatability with human concussion.

Acute effects of concussion among adolescents with attention-deficit/hyperactivity disorder

ABSTRACT Adolescents with ADHD have a greater lifetime history of concussion and experience concussion-like symptoms in the absence of a concussion, complicating concussion assessment and management. It is well established that individuals who experience greater acute symptoms following concussion are at risk for slower recovery and persistent symptoms. We examined whether youth with ADHD experience worse acute effects, within the first 72 h following concussion, compared to youth without ADHD. We hypothesized that youth with ADHD would perform worse on neurocognitive testing and endorse more severe symptoms acutely following injury, but the magnitude of change from pre injury to post injury would be similar for both groups, and thus comparable to baseline group differences. The sample included 852 adolescents with pre-injury and post-injury ImPACT results (within 72 h); we also conducted supplementary case-control analyses on a subset of youth with and without ADHD matched on demographics and pre-injury health history. For both samples, there were significant interaction effects for the Verbal Memory and Visual Motor Speed composites (p < 0.01, η 2 =.01–.07, small-medium effect), such that youth with ADHD showed a greater magnitude of diminished cognitive functioning from pre-injury to post-injury testing. There were no significant differences in the magnitudes of changes from pre injury to post injury with regard to overall symptom reporting (i.e., total symptom severity scores, total number of symptoms endorsed); however, there were group differences in endorsement rates for several individual symptoms. Further research is needed to determine whether such differential acute effects are associated with recovery time in youth with ADHD.

The Effect of Aerobic Exercise on Recovery in Adolescents who Report Emotional and Cognitive Symptoms after Sport-Related Concussion

<h3>Research Objectives</h3> Aerobic exercise speeds recovery from sport-related concussion (SRC) and reduces the incidence of prolonged symptoms; however, evidence for emotional and cognitive symptom recovery among this population is limited. This study determined whether aerobic exercise following SRC improved recovery in adolescents who reported emotional and cognitive symptoms. <h3>Design</h3> Meta-analysis of two published randomized control trials. <h3>Setting</h3> Four sports medicine clinics specializing in concussion management. <h3>Participants</h3> Male and female adolescents (13-18 years, n=212, 59% male) who were diagnosed with SRC within ten days of injury and reported emotional or cognitive symptoms on the Post-Concussion Symptom Scale (PCSS) or Post-Concussion Symptom Inventory (PCSI). <h3>Interventions</h3> Participants were assigned to individualized aerobic exercise (n=109) or to a placebo-like stretching program (n=103). <h3>Main Outcome Measures</h3> Recovery from SRC, defined as a participant having no concussion-like symptoms, a normal physical examination, and a return to normal exercise tolerance. <h3>Results</h3> A fixed-effects meta-analysis determined the probability of recovery between aerobic vs. stretching exercise. Participants with high emotional (≥1/24), low emotional (=0/24) and low cognitive (≤10/30) symptom scores had a higher probability of recovering when prescribed aerobic exercise, respectively (61% p=0.028, 60% p=0.030, 47%, p=0.025). However, results were inconclusive regarding recovery in those with high cognitive (>10/30) symptoms when prescribed aerobic exercise (p=0.175). <h3>Conclusions</h3> Our data suggest that participants with emotional symptoms and with low cognitive symptom burden benefited from aerobic exercise more than from stretching. Clinicians ideally should manage SRC based on individual clinical profiles and should recommend aerobic exercise for patients with significant emotional symptoms. Patients with high cognitive symptoms also benefit from aerobic exercise but appear to need specialized intervention. <h3>Author(s) Disclosures</h3> Authors have no disclosures.

Optimizing Concussion Care Seeking: A Longitudinal Analysis of Recovery

Background: Approximately half of concussions go undisclosed and therefore undiagnosed. Among diagnosed concussions, 51% to 64% receive delayed medical care. Understanding the influence of undiagnosed concussions and delayed medical care would inform medical and education practices. Purpose: To compare postconcussion longitudinal clinical outcomes among (1) individuals with no concussion history, all previous concussions diagnosed, and ≥1 previous concussion undiagnosed, as well as (2) those who have delayed versus immediate symptom onset, symptom reporting, and removal from activity after concussion. Study Design: Cohort study; Level of evidence, 2. Methods: Participants included 2758 military academy cadets and intercollegiate athletes diagnosed with concussion in the CARE Consortium. We determined (1) each participant’s previous concussion diagnosis status self-reported at baseline (no history, all diagnosed, ≥1 undiagnosed) and (2) whether the participant had delayed or immediate symptom onset, symptom reporting, and removal from activity. We compared symptom severities, cognition, balance, and recovery duration at baseline, 24 to 48 hours, date of asymptomatic status, and date of unrestricted return to activity using tests of parallel profiles. Results: The ≥1 undiagnosed concussion group had higher baseline symptom burdens (P < .001) than the other 2 groups and poorer baseline verbal memory performance (P = .001) than the all diagnosed group; however, they became asymptomatic and returned to activity sooner than those with no history. Cadets/athletes who delayed symptom reporting had higher symptom burdens 24 to 48 hours after injury (mean ± SE; delayed, 28.8 ± 0.8; immediate, 20.6 ± 0.7), took a median difference of 2 days longer to become asymptomatic, and took 3 days longer to return to activity than those who had immediate symptom reporting. For every 30 minutes of continued participation after injury, days to asymptomatic status increased 8.1% (95% CI, 0.3%-16.4%). Conclusion: Clinicians should expect that cadets/athletes who delay reporting concussion symptoms will have acutely higher symptom burdens and take 2 days longer to become asymptomatic. Educational messaging should emphasize the clinical benefits of seeking immediate care for concussion-like symptoms.

Head Trauma and Concussions in Film and Television Stunt Performers: An Exploratory Study.

The aims of the study were to assess prevalence and management of head impacts in stunt performers and to evaluate performers' quality of life and ability to work after head injury. Stunt performers completed an online survey about head impacts/head whips history, diagnosed concussions, reasons for not reporting injuries, health care sought after head impacts, attitudes toward on-set concussion management, perceived ability to work as a stunt performer, and health-related quality of life. One hundred seventy-three performers (80%) indicated at least one head impact/head whip during their stunt career. Of these, 86% exhibited concussion-like symptoms and 38% received one or more concussion diagnoses. Sixty-five percent continued working with concussion-like symptoms. Short Form-12 mental component scores were suggestive of depression in 42%. Concussion seems to be a serious occupational health issue in stunt performers. We suggest that concussion management, risk reduction, and education should be addressed in this community.

An acute bout of controlled subconcussive impacts can alter dynamic cerebral autoregulation indices: a preliminary investigation.

There is growing concern repetitive head contacts sustained by soccer players may lead to long-term health ramifications. Therefore, this preliminary investigation examined the impact an acute soccer heading bout has on dynamic cerebral autoregulation (dCA) metrics. In this preliminary investigation, 40 successful soccer headers were performed in 20min by 7 male elite soccer players (24.1 ± 1.5years). Soccer balls were launched at 77.5 ± 3.7km/h from JUGS soccer machine, located 35m away from participants. Linear and rotational head accelerations impacts were measured using an accelerometer (xPatch). The SCAT3 indexed concussion symptom score and severity before and after: soccer headers, sham (body contact only), and control conditions. Squat-stand maneuvers were performed at 0.05Hz and 0.10Hz to quantity dCA through measures of coherence, phase, and gain. Cumulative linear and rotational accelerations during soccer headers were 1574 ± 97.9g and 313,761 ± 23,966 rads/s2, respectively. SCAT3 symptom severity was elevated after the soccer heading bout (pre 3.7 ± 3.6, post 9.4 ± 7.6: p = 0.030) and five of the seven participants reported an increase in concussion-like symptoms (pre: 2.6 ± 3.0, post: 6.7 ± 6.2; p = 0.078). Phase at 0.10Hz was elevated following soccer heading (p = 0.008). No other dCA metric differed following the three conditions. These preliminary results indicate an acute bout of soccer heading resulted in alterations to dCA metrics. Therefore, future research with larger sample sizes is warranted to fully comprehend short- and long-term physiological changes related to soccer heading.

Parents and coaches as transformational leaders: Motivating high school athletes’ intentions to report concussion symptoms across socioeconomic statuses

PurposeStudies demonstrate that parents and coaches play a role in an athlete's concussion reporting decision primarily through their influence on the decision environment. Little work, however, has explored how a given parenting/coaching style operates to promote intentions and much less work has examined whether the impact of parenting/coaching on concussion reporting differs by socioeconomic status. Transformational parenting/coaching (i.e., a focus on building autonomy and self-efficacy in athletes) represents one promising approach given its effects on other outcomes (e.g., health, burnout, aggression). We hypothesize that athlete perceptions of transformational parenting/coaching will be associated with their reporting intentions directly and through the athlete's motivation for playing their sport regardless of household income. MethodsA national survey of 1023 high-school athletes measured athlete perceptions of transformational parenting/coaching, sport motivation, and reporting intentions. Structural Equation Modeling was used to examine hypotheses. ResultsTransformational parenting was directly associated with reporting intentions (β: Reporting Intentions = .265; Scenario 1 = 0.206; Scenario 2 = 0.260) and indirectly through increased autonomous/decreased controlled motivation. Transformational coaching was not directly associated with Reporting Intentions (β = 0.008, p = .816) or Scenario 2 (β = 0.046, p = .198) but was for Scenario 1 (β = 0.077, p = .003). Transformational coaching was also associated with reporting intention indirectly through increased autonomous, but not controlled motivation. Athletes with household income of $50,000+ were more likely to report transformational parenting/coaching; however, the effects of transformational parenting/coaching did not differ for athletes from higher versus lower-income households. ConclusionsTransformational parenting/coaching may encourage greater concussion reporting intentions primarily through increased autonomous (i.e., self-directed) sport motivation regardless of socioeconomic status. Cultivating transformational leadership in parents/coaches can have a positive impact on the athlete's intention to report concussion-like symptoms.

In-Season Concussion Symptom Reporting in Male and Female Collegiate Rugby Athletes.

Symptom inventories are generally only collected after a suspected concussion, but regular in-season monitoring may allude to clinical symptoms associated with repetitive subconcussive impacts and potential undiagnosed concussions. Despite sex-specific differences in symptom presentation and outcome of concussion, no return-to-play protocol takes sex into account. The objective of this study was to monitor a cohort of contact-sport athletes and compare the frequency and severity of in-season concussion-like symptom reporting between sexes. Graded symptom checklists from 144 female and 104 male athlete-seasons were administered weekly to quantify the effect of subconcussive impacts on frequency and severity of in-season symptom reporting. In-season, mean symptom severity score (SSS) (p = 0.026, mean difference of 1.8), mean number of symptoms (p = 0.044, mean difference of 0.9), max SSS (p < 0.001, mean difference of 19.2), and max number of symptoms (p < 0.001, mean difference of 6.8) were higher in the females. The females' survey results showed differences between elevated and concussed SSS (p < 0.005, mean difference of 28.1) and number of symptoms reported (p = 0.001, mean difference of 6.6). The males did not have a difference in SSS (p = 0.97, mean difference of 1.12) nor in number of symptoms (p = 0.35, mean difference of 1.96) from elevated to concussed athletes. Rugby players report concussion-like symptoms in the absence of a diagnosed concussion in-season. Female athletes reported elevated symptom frequencies with greater severities than the males, but both sexes reported considerable levels throughout the season.

The Association Between Concussion History and Increased Symptom Severity Reporting Is Independent of Common Medical Comorbidities, Personality Factors, and Sleep Quality in Collegiate Athletes.

We investigated the degree to which the association between history of concussion with psychological distress and general symptom severity is independent of several factors commonly associated with elevated symptom severity. We also examined whether symptom severity endorsement was associated with concussion injury specifically or response to injury in general. Academic medical center. Collegiate athletes ( N = 106; age: M = 21.37 ± 1.69 years; 33 female) were enrolled on the basis of strict medical/psychiatric exclusion criteria. Cross-sectional single-visit study. Comprehensive assessment, including semistructured interviews to retrospectively diagnose the number of previous concussions, was completed. Single-predictor and stepwise regression models were fit to examine the predictive value of prior concussion and orthopedic injuries on symptom severity, both individually and controlling for confounding factors. Psychological distress was operationalized as Brief Symptom Inventory-18 Global Severity Index (BSI-GSI) ratings; concussion-related symptom severity was measured using the Sport Concussion Assessment Tool. Controlling for baseline factors associated with the symptom outcomes (agreeableness, neuroticism, negative emotionality, and sleep quality), concussion history was significantly associated with psychological distress ( B = 1.25 [0.55]; P = .025, Δ R2 = 0.034) and concussion-like symptom severity ( B = 0.22 [0.08]; P = .005, Δ R2 = 0.064) and accounted for a statistically significant amount of unique variance in symptom outcomes. Orthopedic injury history was not individually predictive of psychological distress ( B = -0.06 [0.53]; P = .905) or general symptom severity ( B = 0.06 [0.08]; P = .427) and did not explain the relationship between concussion history and symptom outcomes. Concussion history is associated with subtle elevations in symptom severity in collegiate-aged athletes; this relationship is independent of medical, lifestyle (ie, sleep), and personality factors. Furthermore, this relationship is associated with brain injury (ie, concussion) and is not a general response to injury history.

Concussion Reporting and Safeguarding Policy Development in British American Football: An Essential Agenda.

The objective of this study was to examine concussion reporting and safeguarding policy in British American Football (BAF). Data were collected via an online survey tool. The data presented are part of a broader study that examined injury profiles, concussion reporting behaviors, and medical provision in BAF. Concussion-like symptoms were found in over half (58.8%) of the participants. Of those, 36.4% reported they had previously been formally diagnosed with a concussion while playing BAF. Just under half of the participants (44.7%) had suspected they had had a concussion, although it was not formally diagnosed, and 23.5% of the participants had previously hidden concussion symptoms. Fifty-eight percent of the teams reported they did not have a regular game-day medic, with a range of hired medical personnel who attended the games. Prominent barriers to hiring a medic included budget, institutional support shortfall, and lack of medic reliability and game knowledge. BAF is a developing sport with a clear vision for growth of participation. Yet, the current concussion and medical provision policies do not address the sport's welfare needs. Through discussion of these policies in the context of this study's findings, we highlight vital areas of concern in policy and practice that the British American Football Association needs to address in their medical and concussion policies.

Sleep Insufficiency and Baseline Preseason Concussion-Like Symptom Reporting in Youth Athletes.

To examine the association between insufficient sleep and baseline symptom reporting in healthy student athletes. Cross-sectional cohort study. Preseason testing for student athletes. Student athletes (n = 19 529) aged 13 to 19 years who completed the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT), including the number of hours slept the night before, and denied having developmental/health conditions, a concussion in the past 6 months, and a previous history of 2 or more concussions. Total hours of sleep the night before testing (grouped by ≤5, 5.5-6.5, 7-8.5, and ≥9 hours), gender, and concussion history. Symptom burden on the Post-Concussion Symptom Scale (modified to exclude sleep-related items), cognitive composite scores, and prevalence of athletes who reported a symptom burden resembling the International Classification of Diseases, 10th Revision (ICD-10) diagnosis of postconcussional syndrome (PCS). Fewer hours of sleep, gender (ie, girls), and 1 previous concussion (vs 0) were each significantly associated with higher total symptom scores in a multivariable model (F = 142.01, P < 0.001, R2 = 0.04). When a gender-by-sleep interaction term was included, the relationship between sleep and symptoms was stronger for girls compared with boys. In healthy athletes who slept ≤5 hours, 46% of girls and 31% of boys met the criteria for ICD-10 PCS compared with 16% of girls and 11% of boys who slept ≥9 hours. Sleep duration was not meaningfully associated with neurocognitive performance. Insufficient sleep the night before testing is an important factor to consider when interpreting symptom reporting, especially for girls. It will be helpful for clinicians to take this into account when interpreting both baseline and postinjury symptom reporting.

Neurotrauma Biomarker Levels and Adverse Symptoms Among Military and Law Enforcement Personnel Exposed to Occupational Overpressure Without Diagnosed Traumatic Brain Injury

There is a scientific and operational need to define objective measures of exposure to low-level overpressure (LLOP) and concussion-like symptoms among persons with specialized occupations. To evaluate serum levels of neurotrauma biomarkers and their association with concussion-like symptoms reported by LLOP-exposed military and law enforcement personnel who are outwardly healthy and cleared to perform duties. This retrospective cohort study, conducted from January 23, 2017, to October 21, 2019, used serum samples and survey data collected from healthy, male, active-duty military and law enforcement personnel assigned to operational training at 4 US Department of Defense and civilian law enforcement training sites. Personnel aged 18 years or older with prior LLOP exposure but no diagnosed traumatic brain injury or with acute blast exposure during sampling participated in the study. Serum samples from 30 control individuals were obtained from a commercial vendor. Serum levels of glial fibrillary acidic protein, ubiquitin carboxyl hydrolase (UCH)-L1, neurofilament light chain, tau, amyloid β (Aβ)-40, and Aβ-42 from a random sample (30 participants) of the LLOP-exposed cohort were compared with those of 30 age-matched controls. Associations between biomarker levels and self-reported symptoms or operational demographics in the remainder of the study cohort (76 participants) were assessed using generalized linear modeling or Spearman correlations with age as a covariate. Among the 30 randomly sampled participants (mean [SD] age, 32 [7.75] years), serum levels of UCH-L1 (mean difference, 4.92; 95% CI, 0.71-9.14), tau (mean difference, 0.16; 95% CI, -0.06 to 0.39), Aβ-40 (mean difference, 138.44; 95% CI, 116.32-160.56), and Aβ-42 (mean difference, 4.97; 95% CI, 4.10-5.83) were elevated compared with those in controls. Among the remaining cohort of 76 participants (mean [SD] age, 34 [7.43] years), ear ringing was reported by 44 (58%) and memory or sleep problems were reported by 24 (32%) and 20 (26%), respectively. A total of 26 participants (34%) reported prior concussion. Amyloid β-42 levels were associated with ear ringing (F1,72 = 7.40; P = .008) and memory problems (F1,72 = 9.20; P = .003). The findings suggest that long-term LLOP exposure acquired during occupational training may be associated with serum levels of neurotrauma biomarkers. Assessment of biomarkers and concussion-like symptoms among personnel considered healthy at the time of sampling may be useful for military occupational medicine risk management.

Measurements of Infrasound Signatures From Grenade Blast During Training.

Military personnel during training and military operations are exposed to a large number of repeated exposures to low-level blast overpressure from a variety of sources. These exposures rarely produce a concussion, but anecdotal evidence from soldiers indicates that it can still cause transient neurological effects. Impulsive acoustic sources, such as the ones encountered during military training, are characterized by a broadband energy distribution with resulting pressure measurements that exhibit frequency components well within the infrasound range. This infrasound can couple directly with the human body and in this way alter or influence physiological processes up to inducing concussion-like symptoms. This study explores the presence of infrasound energy in measured acoustic signals collected during grenade training at Ft. Benning, GA. Acoustic data from traditional microphones and specialized infrasound microphones were collected during one training session and time and time-frequency analysis was performed to highlight the frequency content of the signals. The analysis of the collected measurements indicates peak SPLs between 140 and 160 dB during explosions corresponding to the shockwave. Also, high-intensity infrasound was observed during grenade explosions with significant energy in the infrasound range and in particular below 3 Hz. This energy appears in the form of three distinct tones at frequencies of 1.987, 2.296, and 2.528 Hz that are present only for the duration of the blast wave. The results presented in this article suggest that reported symptoms from military personnel exposed to repeated low-level blast may also be because of acoustic loading. Therefore, to take into account these findings, future studies aimed at characterizing the effects of repeated low-level blast exposure should consider including acoustic measurements in their investigations.

A computational investigation of strain concentration in the brain in response to a rapid temperature rise

Following the mysterious health attacks on U.S. diplomats in Cuba in 2016, the cause of concussion-like symptoms concurrent with strange noises heard by the diplomats remains undetermined. A wide range of possible causes of the sensations have been proposed: pulsed microwave exposure, infrasound acoustic devices, pesticides/neurotoxins, and even mass hysteria (psychogenic illness). Here, we numerically examine the pulsed microwave exposure hypothesis and the simulated mechanical response of brain tissue. A computational model is used to examine the influence of various spatially varying temperature gradients and pulse durations on the mechanical response of brain tissue. We show that a stress-focusing effect due to a rapid temperature increase may result in brain tissue strains larger than the initially applied thermal strains.

Elevated In-Season Presentation of Concussion-Like Symptoms in the Absence of Diagnosed Concussion

The objective of this study was to quantify elevated in-season presentation of concussion-like symptoms in the absence of diagnosed concussion in a cohort of collegiate rugby players. It is well known that many sports-related concussions are unreported. Athletes that do not immediately report concussion symptoms and continue to participate in activities are at higher risk for longer recoveries and sustain post-concussion symptoms longer. How regularly athletes experience elevated concussion symptoms in-season is unknown. Athletes from men's and women's rugby teams were recruited and consented in accordance with the Virginia Tech Institutional Review Board. 63 males and 78 females participated over three seasons. Subjects completed a symptom and exposure query (SEQ) weekly throughout their season. The SEQ asked subjects if, in the past week, they experienced the 27 symptoms from the Graded Symptom Checklist for concussion. Subjects graded each symptom on a scale of 0-6, with 0 being no presentation and 6 being the most severe presentation. The graded severities of each symptom were summed to compute the overall Symptom Severity Score (SSS). Surveys that indicated confounding circumstances leading to symptoms were removed from analysis. The 99th percentile of SSS from baseline data was used as a metric of "elevated SSS," which corresponded to an SSS of 11. 1,214 SEQs were collected. There were 77 surveys from 43 athletes, 10 (15.8%) men and 33 (42.3%) women, who reported elevated SSS. In a given season, 16.3% of males and 41.7% of females reported elevated symptoms at least once. The surveys identified 11 additional suspected concussions based on symptom scores beyond the 8 that were clinically diagnosed. This provides some evidence that constellations of concussion symptoms are commonly experienced by collegiate rugby athletes in-season. Some are at severities typically associated with concussion, but most are below current clinical concussion diagnostic thresholds.