Browsing by Author "Brolinson, Per Gunnar"

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    Development of a Concussion Risk Function for a Youth Population Using Head Linear and Rotational Acceleration
    Campolettano, Eamon T.; Gellner, Ryan A.; Smith, Eric P.; Bellamkonda, Srinidhi; Tierney, Casey T.; Crisco, Joseph J.; Jones, Derek A.; Kelley, Mireille E.; Urban, Jillian E.; Stitzel, Joel D.; Genemaras, Amaris; Beckwith, Jonathan G.; Greenwald, Richard M.; Maerlender, Arthur C.; Brolinson, Per Gunnar; Duma, Stefan M.; Rowson, Steven (Springer, 2019-10-28)
    Physical differences between youth and adults, which include incomplete myelination, limited neck muscle development, and a higher head-body ratio in the youth population, likely contribute towards the increased susceptibility of youth to concussion. Previous research efforts have considered the biomechanics of concussion for adult populations, but these known age-related differences highlight the necessity of quantifying the risk of concussion for a youth population. This study adapted the previously developed Generalized Acceleration Model for Brian Injury Threshold (GAMBIT) that combines linear and rotational head acceleration to model the risk of concussion for a youth population with the Generalized Acceleration Model for Concussion in Youth (GAM-CY). Survival analysis was used in conjunction with head impact data collected during participation in youth football to model risk between individuals who sustained medically-diagnosed concussions (n = 15). Receiver operator characteristic curves were generated for peak linear acceleration, peak rotational acceleration, and GAM-CY, all of which were observed to be better injury predictors than random guessing. GAM-CY was associated with an area under the curve of 0.89 (95% confidence interval: 0.82–0.95) when all head impacts experienced by the concussed players were considered. Concussion tolerance was observed to be lower for youth athletes, with average peak linear head acceleration of 62.4 ± 29.7 g compared to 102.5 ± 32.7 g for adults and average peak rotational head acceleration of 2609 ± 1591 rad/s2 compared to 4412 ± 2326 rad/s2. These data provide further evidence of age-related differences in concussion tolerance and may be used for the development of youth-specific protective designs.
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    Dual-Task Gait Performance Following Head Impact Exposure in Male and Female Collegiate Rugby Players
    Kieffer, Emily E.; Brolinson, Per Gunnar; Rowson, Steven (North American Sports Medicine Institute, 2022-04-01)
    Background: Gait impairments have been well-studied in concussed athletes. However, the sex-specific effect of cumulative head impacts on gait is not well understood. When a cognitive task is added to a walking task, dual-task gait assessments can help amplify deficits in gait and are representative of tasks in everyday life. Dual-task cost is the difference in performance from walking (single-task) to walking with a cognitive load (dual-task). Purpose: The objectives of this study were to explore the differences between sexes in 1) dual-task gait metrics, 2) gait metric changes from pre-season to post-concussion and post-season, and 3) the dual-task costs associated with gait metrics. Study Design: Cross-sectional study Methods: Over two seasons, 77 female athlete-seasons and 64 male athlete-seasons from collegiate club rugby teams participated in this study. Subjects wore inertial sensors and completed walking trials with and without a cognitive test at pre-season, post-season, and post-concussion (if applicable). Results: Females athletes showed improvement in cadence (mean = 2.7 step/min increase), double support time (mean = -0.8% gait cycle time decrease), gait speed (mean = 0.1 m/s increase), and stride length (mean = 0.2 m increase) in both task conditions over the course of the season (p < 0.030). Male athletes showed no differences in gait metrics over the course of the season, except for faster gait speeds and longer stride lengths in the dual-task condition (p < 0.034). In all four gait characteristics, at baseline and post-season, females had higher dual-task costs (mean difference = 4.4, p < 0.003) than the males. Conclusions: This results of this study showed little evidence suggesting a relationship between repetitive head impact exposure and gait deficits. However, there are sex-specific differences that should be considered during the diagnosis and management of sports-related concussion.
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    Head Impact Conditions and Helmet Performance in Snowsports
    Keim, Summer Blue (Virginia Tech, 2021-06-28)
    Mild traumatic brain injury in snowsports is a prevalent concern. With as many as 130,000 hospitalized injuries in the U.S. associated with snowsports in 2017, head injury constitutes about 28% and is the main cause of fatality. Studies have found that a combination of rotational and linear velocities is the most mechanistic way to model brain injury, but despite decades of research, the biomechanical mechanisms remain largely unknown. However, evidence suggests a difference in concussion tolerance may exist between athlete populations. To improve the ability to predict and therefore reduce concussions, we need to understand the impact conditions associated with head impacts across various sports. There is limited research on the conditions associated with head impacts in snowsports. These head impacts often occur on an angled slope, creating a normal and tangential linear velocity component. Additionally, the impact surface friction in a snowsport environment is highly variable, but could greatly influence the rotational kinematics of head impact. Currently helmet testing standards don't consider these rotational kinematics, or varying friction conditions that potentially occur in real-world scenarios. The purpose of this study is to investigate the head impact conditions in a snowsport environment to inform laboratory testing and evaluate snow helmet design. We determined head impact conditions through video analysis to determine the impact locations, mechanism of fall, and the kinematics pre-impact. We used these data to develop a test protocol that evaluates snowsport helmets in a realistic manner. Ultimately, the results from this research will provide snowsport participants unbiased impact data to make informed helmet purchases, while concurrently providing a realistic test protocol that allows for design interventions to reduce the risk of injury.
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    In-Season Concussion Symptom Reporting in Male and Female Collegiate Rugby Athletes
    Kieffer, Emily E.; Brolinson, Per Gunnar; Maerlender, Arthur C.; Smith, Eric P.; Rowson, Steven (2021-11-01)
    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.
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    Locomotor deficits in recently concussed athletes and matched controls during single and dual-task turning gait: preliminary results
    Fino, Peter C.; Nussbaum, Maury A.; Brolinson, Per Gunnar (2016-07-25)
    Background There is growing evidence that mild traumatic brain injury (concussion) can affect locomotor characteristics for prolonged periods of time even when physical signs and symptoms are absent. While most locomotor deficits post-concussion have involved straight walking, turning gait has received little attention despite its pervasiveness in everyday locomotion and athletic competition. Methods This study longitudinally examined kinematic characteristics during preplanned turning in a small sample of recently concussed athletes (n = 4) and healthy matched control athletes (n = 4) to examine potential deficits during single and dual-task turning gait over the initial 6 weeks post-injury, with a one-year follow-up. Turning path kinematics (curvature, obstacle clearance, path length), stride kinematics (stride length, stride width, stride time), and inclination angles were calculated from motion capture of participants walking around an obstacle. Results Concussed athletes had larger dual-task costs in turning speed and stride time compared to healthy controls. After controlling for speed and turn curvature, recently concussed athletes increased their inclination towards the inside of the turn over time and decreased their stride time compared to controls indicating a prolonged recovery. Kinematic differences between groups were estimated to recover to healthy levels between 100 and 300 days post-injury, suggesting future prospective longitudinal studies should span 6–12 months post-injury. Conclusion Turning gait should be included in future studies of concussion and may be a clinically useful tool. Future longitudinal studies should consider examining gait changes for up to 6–12 months post-injury.
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    Muscle Loading Treatments for Achilles Tendinopathy
    Easley, Dylan Cole (Virginia Tech, 2025-02-07)
    Tendinopathies are common, painful, and debilitating injuries that can be challenging to treat. Current treatment methods are limited to surgery, nonsteroidal anti-inflammatory drugs, dry needling, and injectable therapeutics, platelet rich plasma and corticosteroids. Unfortunately, these existing treatments display poor long-term outcomes and have an increased risk of reinjury. Additionally, the healing mechanism for injured tendons forms scar tissue which is characterized by disrupted extracellular matrix rather than complete injury resolution. These structural changes impact the mechanical properties of tendon, reducing their capacity to transfer and store energy, making them inferior to uninjured tendons. The reduced mechanical properties increase the risk of rupture, exacerbating this debilitating disease and decreasing quality of life. Physical therapy (eccentric loading) decreases the symptoms of tendinopathy and restores Achilles tendon functionality. However, the mechanism by which these mechanical stimulations induce healing is poorly understood. There is a clinically relevant motivation to better understand the healing cascade in response to eccentric exercises. We aim to identify and characterize the effects of eccentric rehabilitative muscle loading on the Achilles tendon and gastrocnemius muscle complex using our preclinical TGF-ß1-induced murine model of Achilles tendinopathy. To accomplish our objective, we tested three muscle loading magnitudes (50%, 75%, and 100% body weight), over three treatment durations (1, 2, and 4 weeks) to determine their effects on tendon healing. Age-matched injured/untreated and naïve groups accompanied each loading magnitude and duration period. The functional biomechanical properties, morphological adaptations, transcriptomic response, and muscle strength of the Achilles tendon were assessed. Injured/untreated tendons had a significantly increased cross-sectional area compared to naïve and all loading groups at 2 and 4 weeks. Maximum stress and elastic modulus of injured/untreated tendons were significantly lower compared to naïve and all loading groups after 4 weeks. Gastrocnemius muscle strength was maintained over time as loading magnitude increased. Force output was lower after 2 weeks at 100% body weight loading compared to the naïve group, then recovered to naïve levels after 4 weeks. Histological findings included increased cross-sectional area, matrix disorganization, and increased cellular density of injured/untreated tendons. The transcriptomic evaluation revealed several patterns of expression among exercised groups. Biological processes associated with exercised groups revealed genes responsible for inflammation, extracellular matrix organization, and cell to cell signaling. Overall, eccentric muscle loading improved tendon geometry and material properties compared to naïve levels and improved muscle strength over time. Morphological evaluation also showed improvements in cross-sectional area, and collagen orientation, and cell appearance after 2 and 4 weeks of eccentric loading. Similarly, the transcriptomic changes showed an effect from exercise and upregulation of genes essential for extracellular matrix organization, inflammatory regulation, and cell to cell signaling.
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    Optimal Head Impact Signal Processing and the Description and Perception of Head Impact Exposure in Female Adolescent Ice Hockey Players
    Gellner, Ryan Aaron (Virginia Tech, 2024-08-29)
    Concussion and repetitive head impact exposure are significant media, clinical, and research topics. Long-term symptomatic outcomes of sub-injurious head impact exposure have become a topic of concern for professional and youth contact sport athletes alike. Vulnerable populations such as females and pediatric athletes deserve special attention but are understudied. It is known that females tend to be diagnosed with concussions more frequently and incur them at lower peak head kinematic values than their male counterparts. Sex-specific symptom presentation has been demonstrated, but little is known about the effect of athlete perception of head impact exposure or skill level on symptom reporting. Injury biomechanics research has begun to converge on using instrumented mouthguards to monitor head impact exposure in various sports. These devices offer six-degree-of-freedom head kinematic measurements and direct coupling to the measurement point of interest, the skull, by connecting to the upper dentition. However, published post-processing recommendations for these devices differ from one another and manufacturer practices. This lack of commonization makes cross-study comparison difficult. Additionally, the devices are plagued by relative motion artifacts that can leak into reported kinematic signals. The research presented in this dissertation aimed to first address a lack of common post-processing methods available for instrumented mouthguard measurements made with three linear accelerometers and three gyroscopes. We developed an optimal combination of cutoff frequencies for filters applied to these instruments by quantifying the minimal error from a transformation function. We then applied those same methods to instrumented mouthguards, minimizing error based on sport-specific impact duration. Next, mouthguard decoupling artifacts were described in a laboratory study. Decoupling increased kinematic error relative to ground truth measurements from an instrumented headform. We used these data to develop a classification algorithm that found signal features related to mouthguard decoupling while recording an acceleration event in an instrumented mouthguard. We proceeded to salvage impacts with decoupling artifacts. When decoupling was identified, the primary head acceleration signal could be salvaged by wavelet deconstruction. We removed high-frequency content that was representative of decoupling artifacts. We applied these optimized post-processing techniques to instrumented mouthguard data from a group of adolescent female ice hockey players. Their documented head impact exposure was correlated to symptom outcomes and ocular motor evaluation scores. Their sleep and menstrual cycle patterns were included as potential confounding factors. In this sample of athletes, sleep was more strongly associated with symptom presentation than head impact exposure. Ocular motor results showed a possible association with head acceleration exposure severity and menstrual cycle phase, but further study is warranted. Finally, a self-reported association between symptoms and head impact exposure appears to be individual- and skill-level specific, as we saw many variations between individuals of the same sex in what they called a "memorable" head impact.
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    Osteopathy in the Cranial Field as a Method to Enhance Brain Injury Recovery: A Preliminary Study
    Dickerson, Michelle R.; Murphy, Susan; Hyppolite, Natalie; Brolinson, Per Gunnar; VandeVord, Pamela J. (Mary Ann Liebert, 2022-10)
    The clinical burden of traumatic brain injury (TBI) continues to grow worldwide, with patients often developing chronic neurological, behavorial, and cognitive deficits. Treatment and management strategies remain a key challenge, given that they target the symptoms and not the underlying pathological response. To advance pre-clinical research and therapeutic developments, there is a need to study treatment strategies that improve brain injury recovery. Cranial osteopathic manipulative medicine (cOMM) is a non-invasive and non-pharmacological strategy that has been shown to improve quality of life for several medical conditions and injuries, and may be able to treat TBI and reduce subsequent symptoms. In this study, we aimed to evaluate the neurobiological effect of cOMM on the injury response and its potential to alleviate symptoms. We investigated the ability of cOMM to enhance fluid transport by quantifying fluorescent tracer clearance throughout the brain. Further, using an in vivo TBI model, male rats were exposed to a repeated blast overpressure that was followed by cOMM treatment 24 h later. Our findings indicated that cOMM treatment attenuated acute and subacute anxiety-like behaviors. Post-mortem pathological examination in the hippocampus, pre-frontal, and motor cortices indicated improvements in glial pathology in cOMM-treated animals compared to the untreated injury group. Overall, this is the first study to explore cOMM as a treatment option for brain injury, demonstrating its capability to improve TBI outcomes.
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    Perturbation-based balance training targeting both slip- and trip-induced falls among older adults: a randomized controlled trial
    Allin, Leigh J.; Brolinson, Per Gunnar; Beach, Briana M.; Kim, Sunwook; Nussbaum, Maury A.; Roberto, Karen A.; Madigan, Michael L. (2020-06-12)
    Background Falls are the leading cause of injuries among older adults. Perturbation-based balance training (PBT) is an innovative approach to fall prevention that aims to improve the reactive balance response following perturbations such as slipping and tripping. Many of these PBT studies have targeted reactive balance after slipping or tripping, despite both contributing to a large proportion of older adult falls. The goal of this randomized controlled trial was to evaluate the effects of PBT targeting slipping and tripping on laboratory-induced slips and trips. To build upon prior work, the present study included: 1) a control group; 2) separate training and assessment sessions; 3) PBT methods potentially more amenable for use outside the lab compared to methods employed elsewhere, and 4) individualized training for older adult participants. Methods Thirty-four community-dwelling, healthy older adults (61–75 years) were assigned to PBT or a control intervention using minimization. Using a parallel design, reactive balance (primary outcome) and fall incidence were assessed before and after four sessions of BRT or a control intervention involving general balance exercises. Assessments involved exposing participants to an unexpected laboratory-induced slip or trip. Reactive balance and fall incidence were compared between three mutually-exclusive groups: 1) baseline participants who experienced a slip (or trip) before either intervention, 2) post-control participants who experienced a slip (or trip) after the control intervention, and 3) post-PBT participants who experienced a slip (or trip) after PBT. Neither the participants nor investigators were blinded to group assignment. Results All 34 participants completed all four sessions of their assigned intervention, and all 34 participants were analyzed. Regarding slips, several measures of reactive balance were improved among post-PBT participants when compared to baseline participants or post-control participants, and fall incidence among post-PBT participants (18%) was lower than among baseline participants (80%). Regarding trips, neither reactive balance nor fall incidence differed between groups Conclusions PBT targeting slipping and tripping improved reactive balance and fall incidence after laboratory-induced slips. Improvements were not observed after laboratory-induced trips. The disparity in efficacy between slips and trip may have resulted from differences in dosage and specificity between slip and trip training. Trial registration Name of Clinical Trial Registry: clinicaltrials.gov Trial Registration number: NCT04308239. Date of Registration: March 13, 2020 (retrospectively registered).
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    Sex-Specific Head Impact Exposure in Rugby: Measurement Considerations and Relationships to Clinical Outcomes
    Kieffer, Emily Elana (Virginia Tech, 2021-05-05)
    Concussions are diffuse injuries that affect areas of the brain responsible for a person's physical, cognitive, and emotional health. Although concussions were once thought only to present transient symptoms, mounting evidence suggests potential for long-term neurological impairments. The deleterious effects of concussion can be from a single, high severity impact event or the accumulation of lower severity impacts. Clinical changes that can result from concussion include an elevated symptom presentation and changes in gait, or an individual's walking pattern. It is not well understood if similar deficits result after an accumulation of subconcussive impacts. The majority of research on human tolerance to head injury has been based on American football, using helmet-mounted sensors in male athletes. Limited studies have attempted to quantify biomechanical tolerance in women, despite the sex-specific nature of presentation and outcome of concussion. Biomechanical, physiologic, and psychosocial factors differ between males and females, likely contributing to this difference. The research presented in this dissertation was aimed at describing sex-specific outcomes of subconcussion in a matched cohort of male and female athletes to gain a better sense of unhelmeted, sex-specific tolerance to head impacts. On-field data were collected from collegiate rugby players using instrumented mouthguards. Rugby involves high energy, frequent head impacts, does not require protective headgear, and is played the same for both men and women. The females in our study sustained fewer impacts per session than the males, but their impacts had similar linear acceleration magnitudes. The kinematics of the concussive male impacts were higher than the kinematics of the concussive female impacts. Both sexes reported concussion-like symptoms in the absence of diagnosed concussion during a season. Females reported more symptoms with a higher severity in-season compared to males after subconcussive and concussive impacts. Female athletes saw deficits in cadence, double support time, gait speed, and stride length post-concussion. The majority of athletes improved in their dual-task gait assessment by the end of the season, suggesting there may not be a negative effect on gait after an accumulation of subconcussive impacts. This work assessed the biomechanics of head impacts and concussions of this population, and evaluated changes in symptom presentation through weekly graded symptom surveys and dual-task gait assessments both after a concussion and as an effect of subconcussive impacts. Understanding the sex-specific clinical effects of head impacts is critical, and can provide insight into concussion diagnostic, management, and prevention tools that are appropriate and effective.