An update on pathophysiology and treatment of sports-mediated brain injury

Traumatic brain injury (TBI) is a neurological disorder which represents a major health issue worldwide. It causes mortality and disability among all group ages, caused by external force, sports-related events or violence and road traffic accidents. In the USA, approximately one-third people die annually due to injury and 1.7 million people suffer from traumatic brain injury. Every year in India around 1.6 million individuals suffer from sustain brain injury with 200,000 deaths and approximately one million person needed recovery treatment at any stage of time. Sports-related head impact and trauma has become an extremely controversial public health and medico-legal problem that accounts for 20% of all brain injury (including concussion). It is difficult to reverse the primary injury but the secondary injury can be minimized by using proper pharmacological intervention during the initial hours of injury. This article highlights the pathophysiology and types of TBI along with treatment therapies. Till date, there is no single medication that can decrease the progression of the disease so that symptomatic treatment is given to the patient by determining proper pathology. Recently various herbal medicine therapies and traditional supplements have been developed for TBI. Nutritional supplementation and nutraceuticals have exposed potential in the treatment of TBI when used before and after TBI. The compiled data will enable the readers to know the pathophysiology as well as the allopathic and natural remedies to treat the TBI.

The effect of dietary supplementation with high- or low-dose omega-3 fatty acid on inflammatory pathology after traumatic brain injury in rats

This study investigated dietary supplementation as a prophylactic for neuroinflammation following traumatic brain injury (TBI) in a preclinical model. Adult male Sprague-Dawley rats received 30 days of supplementation with either water or two dietary supplements. The first consisted of high-dose omega-3 fatty acid (O3FA) (supplement A) along with vitamin D3 and vitamin E. The second had the same ingredients at different doses with an addition of cannabidiol (supplement B). Rats were subjected to an impact TBI and then euthanized 7 days post-injury and neuroinflammation quantified by histological detection of glial fibrillary acidic protein (GFAP), a marker of astrocyte activation, and CD68, a marker of microglial activity. There was a trend toward increased GFAP staining in injured, unsupplemented animals as compared to sham, unsupplemented animals, consistent with increased activation of astrocytes in response to trauma which was reversed by supplement A but not by supplement B. The pattern of CD68 staining across groups was similar to that of GFAP staining. There was a trend toward an increase in the injured unsupplemented group, relative to sham which was reversed by supplement A but not by supplement B. CD68 staining in injured animals was concentrated in the perivascular domain. The consistency between trends across different measures of neuroinflammation showing benefits of high-dose O3FA supplementation following TBI suggests that the observed effects are real. These findings are preliminary, but they justify further study to determine the functional benefits associated with improvements in histological outcomes and understand associated dose-response curves.

An Overview and Therapeutic Promise of Nutraceuticals against Sports-Related Brain Injury

Sports-related traumatic brain injury (TBI) is one of the common neurological maladies experienced by athletes. Earlier the term 'punch drunk syndrome' was used in the case TBI of boxers and now this term is replaced by chronic traumatic encephalopathy (CTE). Sports-related brain injury can either be short term or long term. A common instance of brain injury encompasses subdural hematoma, concussion, cognitive dysfunction, amnesia, headache, vision issue, axonopathy, or even death if remain undiagnosed or untreated. Further, chronic TBI may lead to pathogenesis of neuroinflammation and neurodegeneration via tauopathy, formation of neurofibrillary tangles, and damage to the blood-brain barrier, microglial, and astrocyte activation. Thus, altered pathological, neurochemical, and neurometabolic attributes lead to the modulation of multiple signaling pathways and cause neurological dysfunction. Available pharmaceutical interventions are based on one drug one target hypothesis and thereby unable to cover altered multiple signaling pathways. However, in recent time's pharmacological intervention of nutrients and nutraceuticals have been explored as they exert a multifactorial mode of action and maintain over homeostasis of the body. There are various reports available showing the positive therapeutic effect of nutraceuticals in sport-related brain injury. Therefore, in the current article we have discussed the pathology, neurological consequence, sequelae, and perpetuation of sports-related brain injury. Further, we have discussed various nutraceutical supplements as well as available animal models to explore the neuroprotective effect/ upshots of these nutraceuticals in sports-related brain injury.

N-docosahexaenoylethanolamine reduces neuroinflammation and cognitive impairment after mild traumatic brain injury in rats

At present, there is a growing interest in the study of the neurotropic activity of polyunsaturated fatty acids ethanolamides (N-acylethanolamines). N-docosahexaenoylethanolamine (DHEA, synaptamide) is an endogenous metabolite and structural analogue of anandamide, a widely studied endocannabinoid derived from arachidonic acid. The results of this study demonstrate that DHEA, when administered subcutaneously (10 mg/kg/day, 7 days), promotes cognitive recovery in rats subjected to mild traumatic brain injury (mTBI). In the cerebral cortex of experimental animals, we analyzed the dynamics of Iba-1-positive microglia activity changes and the expression of pro-inflammatory markers (IL1β, IL6, CD86). We used immortalized mouse microglial cells (SIM-A9) to assess the effects of DHEA on LPS-induced cytokines/ROS/NO/nitrite, as well as on CD206 (anti-inflammatory microglia) and the antioxidant enzyme superoxide dismutase (SOD) production. In vivo and in vitro experiments showed that DHEA: (1) improves indicators of anxiety and long-term memory; (2) inhibits the pro-inflammatory microglial cells activity; (3) decrease the level of pro-inflammatory cytokines/ROS/NO/nitrites; (4) increase CD206 and SOD production. In general, the results of this study indicate that DHEA has a complex effect on the neuroinflammation processes, which indicates its high therapeutic potential.

Sports-Injury Encephalopathy

Sports-related encephalopathies are a growing concern among athletes who have experienced head trauma. Anxiety is heightened for the public and especially among parents of children playing contact sports. The most common neuropsychological conditions are concussions and traumatic encephalopathies. Concussions result from brain traumas that can be asymptomatic, but more serious concussions can include loss of consciousness, neurological abnormalities, and/or posttraumatic amnesias. Repetitive concussions lead to persistent brain pathology, known as chronic traumatic encephalopathies. This gradually progressive neurodegenerative disease frequently presents with cognitive and neurological deficits, which can result in significant parkinsonian features and dementia. Imaging studies may be noncontributory; however, diffusion tensor imaging, magnetic resonance spectroscopy, and functional magnetic resonance imaging can detect changes indicative of these encephalopathies. Progressive neuronal degeneration with tau proteins are documented on pathological examination. Prevention, early diagnosis, and proper treatment are the recommended approach to these conditions.

A New Model of Repetitive Traumatic Brain Injury in Mice

Repetitive traumatic brain injury (rTBI) is a major health care concern that causes substantial neurological impairment. To better understand rTBI, we introduced a new model of rTBI in mice induced by sudden rotation in the coronal plane combined with lateral translation delivered twice at an interval of 24 h. By routine histology, histological examination of Prussian blue-stained sections revealed the presence of microbleed in the corpus callosum and brain stem. Amyloid precursor protein (β-APP) and neurofilament heavy-chain (NF-200) immunohistochemistry demonstrated axonal injury following rTBI. Swelling, waving, and enlargement axons were observed in the corpus callosum and brain stem 24 h after injury by Bielschowsky staining. Ultrastructural studies by electron microscopy provided further insights into the existence and progression of axonal injury. rTBI led to widespread astrogliosis and microgliosis in white matter, as well as significantly increased levels of tumor necrosis factor (TNF)-α and interleukin (IL)-1β. rTBI mice showed a significantly increased loss of righting reflex (LRR) duration within each time point compared with that of sham animals, which was under 15 min. rTBI mice exhibited depression-like behavior at 1 month. rTBI mice also demonstrated deficits in MWM testing. These results suggested that this model might be suitable for investigating rTBI pathophysiology and evaluating preclinical candidate therapeutics.

Association Between Statin Use and Risk of Dementia After a Concussion

Importance

Concussions are an acute injury that may lead to chronic disability, while statin use might improve neurologic recovery.

Objective

To test whether statin use is associated with an increased or decreased risk of subsequent dementia after a concussion.

Design, Setting, and Participants

Large extended population-based double cohort study in Ontario, Canada, from April 1, 1993, to April 1, 2013 (enrollment), and continued until March 31, 2016 (follow-up). Dates of analysis were April 28, 2014, through March 21, 2019. Participants were older adults diagnosed as having a concussion, excluding severe cases resulting in hospitalization, individuals with a prior diagnosis of dementia or delirium, and those who died within 90 days.

Exposure

Statin prescription within 90 days after a concussion.

Main Outcome and Measure

Long-term incidence of dementia.

Results

This study identified 28 815 patients diagnosed as having a concussion (median age, 76 years; 61.3% female), of whom 7058 (24.5%) received a statin, and 21 757 (75.5%) did not receive a statin. A total of 4727 patients subsequently developed dementia over a mean follow-up of 3.9 years, equal to an incidence of 1 case per 6 patients. Patients who received a statin had a 13% reduced risk of dementia compared with patients who did not receive a statin (relative risk, 0.87; 95% CI, 0.81-0.93; P < .001). The decreased risk of dementia associated with statin use applied to diverse patient groups, remained independent of other cardiovascular medication use, intensified over time, was distinct from the risk of subsequent depression, and was not observed in patients after an ankle sprain.

Conclusions and Relevance

In this study, older adults had a substantial long-term risk of dementia after a concussion, which was associated with a modest reduction among patients receiving a statin.

Treatment of Pediatric Concussion

Concussions have gained attention in medical literature, legal literature, and lay media over the past several years as a public health affecting children, particularly those who do not improve in the first few days after an injury. We discuss strategies for acute management immediately after a concussion and an introduction to medical and non-medical options for treatment of the complex symptoms that persist in some patients with concussions. We examine the role of rest and exercise during recovery. We briefly discuss the role of the multidisciplinary approach to concussion in a setting that engages multiple specialists. Finally, we address policy changes related to sport-concussions and their efficacy in improving long term outcomes.

Sport-Related Concussion: Evaluation, Treatment, and Future Directions

Sport-related concussion (SRC) is a highly prevalent injury predominantly affecting millions of youth through high school athletes every year. In recent years, SRC has received a significant amount of attention due to potential for long-term neurologic sequelae. However, the acute symptoms and possibility of prolonged recovery account for the vast majority of morbidity from SRC. Modifying factors have been identified and may allow for improved prediction of a protracted course. Potential novel modifying factors may include genetic determinants of recovery, as well as radiographic biomarkers, which represent burgeoning subfields in SRC research. Helmet design and understanding the biomechanical stressors on the brain that lead to concussion also represent active areas of research. This narrative review provides a general synopsis of SRC, including relevant definitions, current treatment paradigms, and modifying factors for recovery, in addition to novel areas of research and future directions for SRC research.

Nurse practitioners' recommendations for pharmacotherapy in the management of adolescent concussion

BACKGROUND AND PURPOSE

Nurse practitioners (NPs) frequently treat acute conditions presenting in children and adolescents in the outpatient setting. No evidence-based guidance exists pertaining to the treatment of concussion with medications. The purpose of this study was to examine recommendations by NPs for pharmacotherapy of acute symptoms for adolescent concussion.

METHODS

This is a secondary analysis of data from a web-based census survey of all licensed NPs in Oregon and Washington State, where they practice as independent providers with prescriptive authority. Based on a standardized adolescent patient scenario video, NPs were asked to indicate prescription or nonprescription medication recommendations for concussion symptoms. Open-ended descriptions of medication recommendations were coded, summarized, and described.

CONCLUSIONS

In narrative text, 78.4% of the 991 respondents recommended at least one type of prescription or nonprescription medication. Prescription medications (recommended by 17.2%) included antiemetics and antimigraine medications; nonprescription medications (recommended by 75.5%) included nonsteroidal anti-inflammatory drugs, over-the-counter pain relievers, and herbal medications. Pharmacotherapy recommendations varied by NP practice setting and rurality.

IMPLICATIONS FOR PRACTICE

Nurse practitioners have full prescriptive authority in many states. No guidelines inform medication use in managing acute concussion symptoms, yet many providers recommend their use.

Protection Before Impact: the Potential Neuroprotective Role of Nutritional Supplementation in Sports-Related Head Trauma

Even in the presence of underreporting, sports-related concussions/mild traumatic brain injuries (mTBI) are on the rise. In the absence of proper diagnosis, an athlete may return to play prior to full recovery, increasing the risk of second-impact syndrome or protracted symptoms. Recent evidence has demonstrated that sub-concussive impacts, those sustained routinely in practice and competition, result in a quantifiable pathophysiological response and the accumulation of both concussive and sub-concussive impacts sustained over a lifetime of sports participation may lead to long-term neurological impairments and an increased risk of developing neurodegenerative diseases. The pathophysiological, neurometabolic, and neurochemical cascade that initiates subsequent to the injury is complex and involves multiple mechanisms. While pharmaceutical treatments may target one mechanism, specific nutrients and nutraceuticals have been discovered to impact several pathways, presenting a broader approach. Several studies have demonstrated the neuroprotective effect of nutritional supplementation in the treatment of mTBI. However, given that many concussions go unreported and sub-concussive impacts result in a pathophysiological response that, too, may contribute to long-term brain health, protection prior to impact is warranted. This review discusses the current literature regarding the role of nutritional supplements that, when provided before mTBI and traumatic brain injury, may provide neurological protection.

Prognostic Factors in Pediatric Sport-Related Concussion

PURPOSE OF REVIEW

Sport-related concussion (SRC) and mild traumatic brain injury (mTBI) have been thrust into the national spotlight, with youth athletes bearing the burden of this public health problem. The current review aims to provide a practical summary of pediatric SRC, including key terminology, return to play/school, and risk factors for post-concussion syndrome (PCS).

RECENT FINDINGS

While the majority of youth athletes recover within 2 to 4 weeks, approximately 10% of athletes experience a protracted recovery with symptoms lasting months, impacting social, scholastic, and sporting activities. In the pediatric population, the strongest predictors of PCS are initial symptom burden and prior concussion, with mixed results behind the factors of gender, headaches, and learning disability. The role of psychiatric, family history, sports, and socioeconomic factors remain in their infancy.

Characterizing Hospitalizations for Pediatric Concussion and Trends in Care

BACKGROUND

Children hospitalized for concussion may be at a higher risk for persistent symptoms, but little is known about this subset of children.

OBJECTIVE

Delineate a cohort of children admitted for concussion, describe care practices received, examine factors associated with prolonged length of stay (LOS) or emergency department (ED) readmission, and investigate changes in care over time.

DESIGN, SETTING

Retrospective analysis of data submitted by 40 pediatric hospitals to the Pediatric Health Information System.

PATIENTS

Children 0 to 17 years old admitted with a primary diagnosis of concussion from 2007 to 2014.

MEASUREMENTS

Descriptive statistics characterized this cohort and care practices delivered, logistic regression identified factors associated with a LOS of =2 days and ED readmission, and trend analyses assessed changes in care over time.

RESULTS

Of the 10,729 children admitted for concussion, 68.7% received intravenous pain or antiemetic medications. Female sex, adolescent age, and having government insurance were all associated (P = .02) with increased odds of LOS = 2 days and ED revisit. Proportions of children receiving intravenous ondansetron (slope = 1.56, P = .001) and ketorolac (slope = 0.61, P < .001) increased over time, and use of neuroimaging (slope = -1.75, P < .001) decreased.

CONCLUSIONS

Although concussions are usually selflimited, hospitalized children often receive intravenous therapies despite an unclear benefit. Factors associated with prolonged LOS and ED revisit were similar to predictors of postconcussive syndrome. Since there has been an increased use of specific therapeutics, prospective evaluation of their relationship with concussion recovery could lay the groundwork for evidenced-based admission criteria and optimize recovery.

Impact of nutrition on inflammation, tauopathy, and behavioral outcomes from chronic traumatic encephalopathy

BACKGROUND

Repetitive mild traumatic brain injuries (rmTBI) are associated with cognitive deficits, inflammation, and stress-related events. We tested the effect of nutrient intake on the impact of rmTBI in an animal model of chronic traumatic encephalopathy (CTE) to study the pathophysiological mechanisms underlying this model. We used a between group design rmTBI closed head injuries in mice, compared to a control and nutrient-treated groups.

METHODS

Our model allows for controlled, repetitive closed head impacts to mice. Briefly, 24-week-old mice were divided into five groups: control, rmTBI, and rmTBI with nutrients (2% of NF-216, NF-316 and NF-416). rmTBI mice received four concussive impacts over 7 days. Mice were treated with NutriFusion diets for 2 months prior to the rmTBI and until euthanasia (6 months). Mice were then subsequently euthanized for macro- and micro-histopathologic analysis for various times up to 6 months after the last TBI received. Animals were examined behaviorally, and brain sections were immunostained for glial fibrillary acidic protein (GFAP) for astrocytes, iba-1 for activated microglia, and AT8 for phosphorylated tau protein.

RESULTS

Animals on nutrient diets showed attenuated behavioral changes. The brains from all mice lacked macroscopic tissue damage at all time points. The rmTBI resulted in a marked neuroinflammatory response, with persistent and widespread astrogliosis and microglial activation, as well as significantly elevated phospho-tau immunoreactivity to 6 months. Mice treated with diets had significantly reduced inflammation and phospho-tau staining.

CONCLUSIONS

The neuropathological findings in the rmTBI mice showed histopathological hallmarks of CTE, including increased astrogliosis, microglial activation, and hyperphosphorylated tau protein accumulation, while mice treated with diets had attenuated disease process. These studies demonstrate that consumption of nutrient-rich diets reduced disease progression.

Visual perturbation impacts upright postural stability in athletes with an acute concussion

OBJECTIVE

The impact that visual perturbation has on upright postural stability in an athlete with a concussion has not been established. The present study aimed to characterize the influence that visual perturbation stimuli have on upright balance among athletes with acute concussions.

DESIGN

A 2X2X2 repeated measure designed was used.

METHOD

The present study examined the influence visual perturbation has on individuals suffering from an acute concussion. Fourteen participants (7 with a concussion and 7 matched controls) underwent various balance assessments with and without visual perturbation.

RESULTS

Overall, athletes with acute concussions demonstrated impairments in balance 24-48 hours following a concussion. However, when assessed using a visual perturbation task, athletes with acute concussions demonstrated improved balance, while control subjects did not show any significant changes during the same visual perturbation task.

CONCLUSION

An athlete's ability to disregard visual perturbation stimuli is imperative for successful participation in sports. Due to the observed alterations in balance when given a visual perturbation task, it is suggested that athletes with acute concussions place more attention on the balance task and may disregard other less meaningful tasks.

A Preliminary Examination of Concussion Knowledge by Collegiate Athletes and Non-Athletes

PURPOSE

Concussions affect various populations, including collegiate athletes and non-athletes. The purpose of this study was to compare collegiate varsity athletes, recreational athletes, and non-athletes' knowledge of concussion definition, symptoms, and support services available following injury. Preferred method of concussion education delivery was also examined.

METHOD

We surveyed 306 current college students using an online survey system. The survey included free recall and forced-choice question formats. Quantitative analyses were used to analyze results and compare responses among groups.

RESULTS

Collegiate athletes and non-athletes demonstrate incomplete knowledge of concussion definition, related symptoms, and professionals involved in postinjury management. Varsity athletes rated self-knowledge of concussion parameters significantly higher than the other groups (p < .001), though few significant differences in actual knowledge levels were observed. Overall, respondents reported having the highest preference for concussion education delivered by medical professionals.

CONCLUSION

Knowledge concerning concussion is incomplete in the collegiate population. Varsity athletes' exposure to formal education did not result in higher knowledge levels compared with other groups. Further examination of concussion educational delivery models' effect on change in concussion-related behavior in this population is warranted.

Blue-Light Therapy following Mild Traumatic Brain Injury: Effects on White Matter Water Diffusion in the Brain

Mild traumatic brain injury (mTBI) is a common and often inconspicuous wound that is frequently associated with chronic low-grade symptoms and cognitive dysfunction. Previous evidence suggests that daily blue wavelength light therapy may be effective at reducing fatigue and improving sleep in patients recovering from mTBI. However, the effects of light therapy on recovering brain structure remain unexplored. In this study, we analyzed white matter diffusion properties, including generalized fractional anisotropy, and the quantity of water diffusion in isotropic (i.e., isotropic diffusion) and anisotropic fashion (i.e., quantitative anisotropy, QA) for fibers crossing 11 brain areas known to be significantly affected following mTBI. Specifically, we investigated how 6 weeks of daily morning blue light exposure therapy (compared to an amber-light placebo condition) impacted changes in white matter diffusion in individuals with mTBI. We observed a significant impact of the blue light treatment (relative to the placebo) on the amount of water diffusion (QA) for multiple brain areas, including the corpus callosum, anterior corona radiata, and thalamus. Moreover, many of these changes were associated with improvements in sleep latency and delayed memory. These findings suggest that blue wavelength light exposure may serve as one of the potential non-pharmacological treatments for facilitating structural and functional recovery following mTBI; they also support the use of QA as a reliable neuro-biomarker for mTBI therapies.

Concussion in Ice Hockey: Current Gaps and Future Directions in an Objective Diagnosis

OBJECTIVE

This review provides an update on sport-related concussion (SRC) in ice hockey and makes a case for changes in clinical concussion evaluation. Standard practice should require that concussions be objectively diagnosed and provide quantitative measures of the concussion injury that will serve as a platform for future evidence-based treatment.

METHODS

The literature was surveyed to address several concussion-related topics: research in ice hockey-related head trauma, current subjective diagnosis, promising components of an objective diagnosis, and current and potential treatments.

MAIN RESULTS

Sport-related head trauma has marked physiologic, pathologic, and psychological consequences for athletes. Although animal models have been used to simulate head trauma for pharmacologic testing, the current diagnosis and subsequent treatment in athletes still rely on an athlete's motivation to report or deny symptoms. Bias-free, objective diagnostic measures are needed to guide quantification of concussion severity and assessment of treatment effects. Most of the knowledge and management guidelines of concussion in ice hockey are generalizable to other contact sports.

CONCLUSIONS

There is a need for an objective diagnosis of SRC that will quantify severity, establish a prognosis, and provide effective evidence-based treatment. Potential methods to improve concussion diagnosis by health care providers include a standardized concussion survey, the King-Devick test, a quantified electroencephalogram, and blood analysis for brain cell-specific biomarkers.

Sports-related concussions: diagnosis, complications, and current management strategies

Sports-related concussions (SRCs) are traumatic events that affect up to 3.8 million athletes per year. The initial diagnosis and management is often instituted on the field of play by coaches, athletic trainers, and team physicians. SRCs are usually transient episodes of neurological dysfunction following a traumatic impact, with most symptoms resolving in 7-10 days; however, a small percentage of patients will suffer protracted symptoms for years after the event and may develop chronic neurodegenerative disease. Rarely, SRCs are associated with complications, such as skull fractures, epidural or subdural hematomas, and edema requiring neurosurgical evaluation. Current standards of care are based on a paradigm of rest and gradual return to play, with decisions driven by subjective and objective information gleaned from a detailed history and physical examination. Advanced imaging techniques such as functional MRI, and detailed understanding of the complex pathophysiological process underlying SRCs and how they affect the athletes acutely and long-term, may change the way physicians treat athletes who suffer a concussion. It is hoped that these advances will allow a more accurate assessment of when an athlete is truly safe to return to play, decreasing the risk of secondary impact injuries, and provide avenues for therapeutic strategies targeting the complex biochemical cascade that results from a traumatic injury to the brain.

Biomarkers

Biomarkers are key tools and can provide crucial information on the complex cascade of events and molecular mechanisms underlying traumatic brain injury (TBI) pathophysiology. Obtaining a profile of distinct classes of biomarkers reflecting core pathologic mechanisms could enable us to identify and characterize the initial injury and the secondary pathologic cascades. Thus, they represent a logical adjunct to improve diagnosis, track progression and activity, guide molecularly targeted therapy, and monitor therapeutic response in TBI. Accordingly, great effort has been put into the identification of novel biomarkers in the past 25 years. However, the role of brain injury markers in clinical practice has been long debated, due to inconsistent regulatory standards and lack of reliable evidence of analytical validity and clinical utility. We present a comprehensive overview of the markers currently available while characterizing their potential role and applications in diagnosis, monitoring, drug discovery, and clinical trials in TBI. In reviewing these concepts, we discuss the recent inclusion of brain damage biomarkers in the diagnostic guidelines and provide perspectives on the validation of such markers for their use in the clinic.

Serum Tau Fragments Predict Return to Play in Concussed Professional Ice Hockey Players

The diagnosis of sports-related concussion is mainly based on subjective clinical symptoms and neuropsychological tests. Therefore, reliable brain injury biomarkers to assess when it is safe to return to play are highly desirable. The overall objective of this study was to evaluate the utility of two newly described tau fragments for diagnosis and prognosis of sports-related concussions. This multi-center prospective cohort study involved all 12 teams of the top professional ice hockey league in Sweden. A total of 288 players consented to participate in the study. Thirty-five players sustained concussions, of whom 28 underwent repeated blood samplings at 1, 12, 36, and 144 h after the trauma, or when the player returned to play (7 to >90 days). There was no significant increase in the levels of Tau-A in post-concussion samples compared with preseason values. However, serum levels of Tau-C were significantly higher in post-concussion samples compared with preseason. Further, levels of Tau-A correlated with the duration of post-concussive symptoms. Tau-A in serum, which is newly discovered biomarker, could be used to predict when it is safe to return to play after a sports-related concussion.

Predictors of postconcussion syndrome in collegiate student-athletes

OBJECTIVE

Sport-related concussion (SRC) has emerged as a public health problem, especially among student-athletes. Whereas most concussions resolve by 2 weeks, a minority of patients experience postconcussion syndrome (PCS), in which symptoms persist for months. The objective of this study was to elucidate factors predictive of PCS among a sample of National Collegiate Athletic Association (NCAA) student-athletes in the academic years 2009–2010 to 2014–2015.

METHODS

The SRC data originated from the NCAA Injury Surveillance Program (ISP) in the 2009–2010 to 2014–2015 academic seasons. The NCAA ISP is a prospective database made up of a convenience sample of schools across all divisions. All SRCs are reported by certified athletic trainers. The PCS group consisted of concussed student-athletes with concussion-related symptoms that lasted ≥ 4 weeks. The non-PCS group consisted of concussed student-athletes with symptom resolution in ≤ 2 weeks. Those with symptoms that resolved in the intermediate area of 2–4 weeks were excluded. Odds ratios (ORs) were estimated using logistic regression.

RESULTS

During the 2009–2010 to 2014–2015 seasons, 1507 NCAA student-athletes sustained an SRC, 112 (7.4%) of whom developed PCS (i.e., concussion-related symptoms that lasted ≥ 4 weeks). Men's ice hockey contributed the largest proportion of concussions to the PCS group (28.6%), whereas men's football contributed the largest proportion of concussions in the non-PCS group (38.6%). In multivariate analysis, recurrent concussion was associated with increased odds of PCS (OR 2.08, 95% CI 1.28–3.36). Concussion symptoms that were also associated with increased odds of PCS included retrograde amnesia (OR 2.75, 95% CI 1.34–5.64), difficulty concentrating (OR 2.35, 95% CI 1.23–4.50), sensitivity to light (OR 1.97, 95% CI 1.09–3.57), and insomnia (OR 2.19, 95% CI 1.30–3.68). Contact level, sex, and loss of consciousness were not associated with PCS.

CONCLUSIONS

Postconcussion syndrome represents one of the most impactful sequelae of SRC. In this study of exclusively collegiate student-athletes, the authors found that recurrent concussions and various concussion-related symptoms were associated with PCS. The identification of initial risk factors for the development of PCS may assist sports medicine clinicians in providing timely interventions and treatments to prevent morbidity and shorten recovery time after SRC.

Trigeminal Pain Molecules, Allodynia, and Photosensitivity Are Pharmacologically and Genetically Modulated in a Model of Traumatic Brain Injury

The pain-signaling molecules, nitric oxide synthase (NOS) and calcitonin gene-related peptide (CGRP), are implicated in the pathophysiology of post-traumatic headache (PTH) as they are for migraine. This study assessed the changes of inducible NOS (iNOS) and its cellular source in the trigeminal pain circuit, as well as the relationship between iNOS and CGRP after controlled cortical impact (CCI) injury in mice. The effects of a CGRP antagonist (MK8825) and sumatriptan on iNOS messenger RNA (mRNA) and protein were compared to vehicle at 2 weeks postinjury. Changes in CGRP levels in the trigeminal nucleus caudalis (TNC) in iNOS knockouts with CCI were compared to wild-type (WT) mice at 3 days and 2 weeks post injury. Trigeminal allodynia and photosensitivity were measured. MK8825 and sumatriptan increased allodynic thresholds in CCI groups compared to vehicle (p < 0.01), whereas iNOS knockouts were not different from WT. Photosensitivity was attenuated in MK8825 mice and iNOS knockouts compared to WT (p < 0.05). MK8825 and sumatriptan reduced levels of iNOS mRNA and iNOS immunoreactivity in the TNC and ganglia (p < 0.01). Differences in iNOS cellular localization were found between the trigeminal ganglia and TNC. Although the knockout of iNOS attenuated CGRP at 3 days (p < 0.05), it did not reduce CGRP at 2 weeks. CGRP immunoreactivity was found in the meningeal layers post-CCI, while negligible in controls. Findings support the importance of interactions between CGRP and iNOS in mediating allodynia, as well as the individual roles in photosensitivity. Mitigating prolonged increases in CGRP may be a promising intervention for treating acute PTH.

Clinical features of repetitive traumatic brain injury and chronic traumatic encephalopathy

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease characterized by a distinct pattern of hyperphosphorylated tau (p-tau). Thought to be caused by repetitive concussive and subconcussive injuries, CTE is considered largely preventable. The majority of neuropathologically confirmed cases have occurred in professional contact sport athletes (eg, boxing, football). A recent post-mortem case series has magnified concerns for the public's health following its identification in six high school level athletes. CTE is diagnosed with certainty only following a post-mortem autopsy. Efforts to define the etiology and clinical progression during life are ongoing. The goal of this article is to characterize the clinical concepts associated with short- and long-term effects of repetitive traumatic brain injury, with a special emphasis on new clinical diagnostic criteria for CTE. Utilizing these new diagnostic criteria, two cases of neuropathologically confirmed CTE, one in a professional football player and one in a professional boxer, are reported. Differences in cerebellar pathology in CTE confirmed cases in boxing and football are discussed.

Current and emerging rehabilitation for concussion: a review of the evidence

Concussion is one of the most hotly debated topics in sports medicine today. Research surrounding concussion has experienced significant growth recently, especially in the areas of incidence, assessment, and recovery. However, there is limited research on the most effective rehabilitation approaches for this injury. This review evaluates the current literature for evidence for and against physical and cognitive rest and the emerging areas targeting vestibular, oculomotor, and pharmacologic interventions for the rehabilitation of sport-related concussion.

Mild traumatic brain injury

Mild traumatic brain injury (TBI) is common but accurate diagnosis and defining criteria for mild TBI and its clinical consequences have been problematic. Mild TBI causes transient neurophysiologic brain dysfunction, sometimes with structural axonal and neuronal damage. Biomarkers, such as newer imaging technologies and protein markers, are promising indicators of brain injury but are not ready for clinical use. Diagnosis relies on clinical criteria regarding depth and duration of impaired consciousness and amnesia. These criteria are particularly difficult to confirm at the least severe end of the mild TBI continuum, especially when relying on subjective, retrospective accounts. The postconcussive syndrome is a controversial concept because of varying criteria, inconsistent symptom clusters and the evidence that similar symptom profiles occur with other disorders, and even in a proportion of healthy individuals. The clinical consequences of mild TBI can be conceptualized as two multidimensional disorders: (1) a constellation of acute symptoms that might be termed early phase post-traumatic disorder (e.g., headache, dizziness, imbalance, fatigue, sleep disruption, impaired cognition), that typically resolve in days to weeks and are largely related to brain trauma and concomitant injuries; (2) a later set of symptoms, a late phase post-traumatic disorder, evolving out of the early phase in a minority of patients, with a more prolonged (months to years), sometimes worsening set of somatic, emotional, and cognitive symptoms. The later phase disorder is highly influenced by a variety of psychosocial factors and has little specificity for brain injury, although a history of multiple concussions seems to increase the risk of more severe and longer duration symptoms. Effective early phase management may prevent or limit the later phase disorder and should include education about symptoms and expectations for recovery, as well as recommendations for activity modifications. Later phase treatment should be informed by thoughtful differential diagnosis and the multiplicity of premorbid and comorbid conditions that may influence symptoms. Treatment should incorporate a hierarchical, sequential approach to symptom management, prioritizing problems with significant functional impact and effective, available interventions (e.g., headache, depression, anxiety, insomnia, vertigo).

The pathophysiology underlying repetitive mild traumatic brain injury in a novel mouse model of chronic traumatic encephalopathy

BACKGROUND

An animal model of chronic traumatic encephalopathy (CTE) is essential for further understanding the pathophysiological link between repetitive head injury and the development of chronic neurodegenerative disease. We previously described a model of repetitive mild traumatic brain injury (mTBI) in mice that encapsulates the neurobehavioral spectrum characteristic of patients with CTE. We aimed to study the pathophysiological mechanisms underlying this animal model.

METHODS

Our previously described model allows for controlled, closed head impacts to unanesthetized mice. Briefly, 12-week-old mice were divided into three groups: Control, single, and repetitive mTBI. Repetitive mTBI mice received six concussive impacts daily, for 7 days. Mice were then subsequently sacrificed for macro- and micro-histopathologic analysis at 7 days, 1 month, and 6 months after the last TBI received. Brain sections were immunostained for glial fibrillary acidic protein (GFAP) for astrocytes, CD68 for activated microglia, and AT8 for phosphorylated tau protein.

RESULTS

Brains from single and repetitive mTBI mice lacked macroscopic tissue damage at all time-points. Single mTBI resulted in an acute rea ctive astrocytosis at 7 days and increased phospho-tau immunoreactivity that was present acutely and at 1 month, but was not persistent at 6 months. Repetitive mTBI resulted in a more marked neuroinflammatory response, with persistent and widespread astrogliosis and microglial activation, as well as significantly elevated phospho-tau immunoreactivity to 6-months.

CONCLUSIONS

The neuropathological findings in this new model of repetitive mTBI resemble some of the histopathological hallmarks of CTE, including increased astrogliosis, microglial activation, and hyperphosphorylated tau protein accumulation.

In search of evidence-based treatment for concussion: characteristics of current clinical trials

Abstract Objective: To assess the characteristics of current clinical trials investigating the treatment of concussion.

BACKGROUND

Recent systematic literature reviews have concluded that there is minimal evidence to support any specific treatment for concussion, including the principles of return-to-activity protocols such as type or duration of rest.

DESIGN/METHODS

Clinical trial data was extracted from Clinicaltrials.gov and seven additional World Health Organization primary registries. The trial databases were accessed up until 3 October 2013. This study used search terms of 'concussion' or 'mild traumatic brain injury' (mTBI) and filtered for interventional trials. Trials that were terminated, already published or not interventional trials of concussion/mTBI were excluded.

RESULTS

Of the 142 concussion/mTBI interventional clinical trials identified, 71 met inclusion criteria. Trials had a median estimated enrolment of 60 participants. There was a wide-range of treatments studied, including cognitive/behavioural therapies (28.2%), medications (28.2%), devices (11.3%), dietary supplements (8.5%), return-to-activity/rest (1.4%) and others (22.4%). Heterogeneity among trials for concussion identification/diagnosis and primary outcomes utilized was evident. Symptom-based questionnaires (39.4%) and neuropsychological tests (28.2%) were the most common outcome measures.

CONCLUSIONS

Diverse, potentially promising therapeutics are currently being studied for the treatment of concussion. However, several deficiencies were identified including a paucity of trials addressing return-to-activity principles. Also, small sample size and trial heterogeneity may threaten scientific evaluation and subsequent clinical application.

An empirical review of treatment and rehabilitation approaches used in the acute, sub-acute, and chronic phases of recovery following sports-related concussion

OPINION STATEMENT

Several treatment and rehabilitation approaches for sport-related concussion have been mentioned in recent consensus and position statements. These options range from the more conservative behavioral management approaches to aggressive pharmacological and therapeutic interventions. Moreover, clinical decision-making for sport-related concussion changes as symptoms and impairments persist throughout recovery. The current article provides an empirical review of proposed treatment and rehabilitation options for sport-related concussion during the acute, subacute, and chronic phases of injury.

The spectrum of neurobehavioral sequelae after repetitive mild traumatic brain injury: a novel mouse model of chronic traumatic encephalopathy

There has been an increased focus on the neurological sequelae of repetitive mild traumatic brain injury (TBI), particularly neurodegenerative syndromes, such as chronic traumatic encephalopathy (CTE); however, no animal model exists that captures the behavioral spectrum of this phenomenon. We sought to develop an animal model of CTE. Our novel model is a modification and fusion of two of the most popular models of TBI and allows for controlled closed-head impacts to unanesthetized mice. Two-hundred and eighty 12-week-old mice were divided into control, single mild TBI (mTBI), and repetitive mTBI groups. Repetitive mTBI mice received six concussive impacts daily for 7 days. Behavior was assessed at various time points. Neurological Severity Score (NSS) was computed and vestibulomotor function tested with the wire grip test (WGT). Cognitive function was assessed with the Morris water maze (MWM), anxiety/risk-taking behavior with the elevated plus maze, and depression-like behavior with the forced swim/tail suspension tests. Sleep electroencephalogram/electromyography studies were performed at 1 month. NSS was elevated, compared to controls, in both TBI groups and improved over time. Repetitive mTBI mice demonstrated transient vestibulomotor deficits on WGT. Repetitive mTBI mice also demonstrated deficits in MWM testing. Both mTBI groups demonstrated increased anxiety at 2 weeks, but repetitive mTBI mice developed increased risk-taking behaviors at 1 month that persist at 6 months. Repetitive mTBI mice exhibit depression-like behavior at 1 month. Both groups demonstrate sleep disturbances. We describe the neurological sequelae of repetitive mTBI in a novel mouse model, which resemble several of the neuropsychiatric behaviors observed clinically in patients sustaining repetitive mild head injury.

Smoking and increased Alzheimer's disease risk: a review of potential mechanisms

BACKGROUND

Cigarette smoking has been linked with both increased and decreased risk for Alzheimer's disease (AD). This is relevant for the US military because the prevalence of smoking in the military is approximately 11% higher than in civilians.

METHODS

A systematic review of published studies on the association between smoking and increased risk for AD and preclinical and human literature on the relationships between smoking, nicotine exposure, and AD-related neuropathology was conducted. Original data from comparisons of smoking and never-smoking cognitively normal elders on in vivo amyloid imaging are also presented.

RESULTS

Overall, literature indicates that former/active smoking is related to a significantly increased risk for AD. Cigarette smoke/smoking is associated with AD neuropathology in preclinical models and humans. Smoking-related cerebral oxidative stress is a potential mechanism promoting AD pathology and increased risk for AD.

CONCLUSIONS

A reduction in the incidence of smoking will likely reduce the future prevalence of AD.

ω-3 fatty acid supplementation as a potential therapeutic aid for the recovery from mild traumatic brain injury/concussion

Sports-related concussions or mild traumatic brain injuries (mTBIs) are becoming increasingly recognized as a major public health concern; however, no effective therapy for these injuries is currently available. ω-3 (n-3) fatty acids, such as docosahexaenoic acid (DHA), have important structural and functional roles in the brain, with established clinical benefits for supporting brain development and cognitive function throughout life. Consistent with these critical roles of DHA in the brain, accumulating evidence suggests that DHA may act as a promising recovery aid, or possibly as a prophylactic nutritional measure, for mTBI. Preclinical investigations demonstrate that dietary consumption of DHA provided either before or after mTBI improves functional outcomes, such as spatial learning and memory. Mechanistic investigations suggest that DHA influences multiple aspects of the pathologic molecular signaling cascade that occurs after mTBI. This review examines the evidence of interactions between DHA and concussion and discusses potential mechanisms by which DHA helps the brain to recover from injury. Additional clinical research in humans is needed to confirm the promising results reported in the preclinical literature.

Sport-related concussions

Traumatic brain injury (TBI) is a major cause of lifelong disability and death worldwide. Sport-related traumatic brain injury is an important public health concern. The purpose of this review was to highlight the importance of sport-related concussions. Concussion refers to a transient alteration in consciousness induced by external biomechanical forces transmitted directly or indirectly to the brain. It is a common, although most likely underreported, condition. Contact sports such as American football, rugby, soccer, boxing, basketball and hockey are associated with a relatively high prevalence of concussion. Various factors may be associated with a greater risk of sport-related concussion, such as age, sex, sport played, level of sport played and equipment used. Physical complaints (headache, fatigue, dizziness), behavioral changes (depression, anxiety, irritability) and cognitive impairment are very common after a concussion. The risk of premature return to activities includes the prolongation of post-concussive symptoms and increased risk of concussion recurrence.

Role of subconcussion in repetitive mild traumatic brain injury

Research now suggests that head impacts commonly occur during contact sports in which visible signs or symptoms of neurological dysfunction may not develop despite those impacts having the potential for neurological injury. Recent biophysics studies utilizing helmet accelerometers have indicated that athletes at the collegiate and high school levels sustain a surprisingly high number of head impacts ranging from several hundred to well over 1000 during the course of a season. The associated cumulative impact burdens over the course of a career are equally important. Clinical studies have also identified athletes with no readily observable symptoms but who exhibit functional impairment as measured by neuropsychological testing and functional MRI. Such findings have been corroborated by diffusion tensor imaging studies demonstrating axonal injury in asymptomatic athletes at the end of a season. Recent autopsy data have shown that there are subsets of athletes in contact sports who do not have a history of known or identified concussions but nonetheless have neurodegenerative pathology consistent with chronic traumatic encephalopathy. Finally, emerging laboratory data have demonstrated significant axonal injury, blood-brain barrier permeability, and evidence of neuroinflammation, all in the absence of behavioral changes. Such data suggest that subconcussive level impacts can lead to significant neurological alterations, especially if the blows are repetitive. The authors propose “subconcussion” as a significant emerging concept requiring thorough consideration of the potential role it plays in accruing sufficient anatomical and/or physiological damage in athletes and military personnel, such that the effects of these injuries are clinically expressed either contemporaneously or later in life.

The influence of chronic cigarette smoking on neurocognitive recovery after mild traumatic brain injury

The majority of the approximately 1.7 million civilians in the United States who seek emergency care for traumatic brain injury (TBI) are classified as mild (MTBI). Premorbid and comorbid conditions that commonly accompany MTBI may influence neurocognitive and functional recovery. This study assessed the influence of chronic smoking and hazardous alcohol consumption on neurocognitive recovery after MTBI. A comprehensive neurocognitive battery was administered to 25 non-smoking MTBI participants (nsMTBI), 19 smoking MTBI (sMTBI) 38 ± 22 days (assessment point 1: AP1) and 230 ± 36 (assessment point 2: AP2) days after injury. Twenty non-smoking light drinkers served as controls (CON). At AP1, nsMTBI and sMTBI were inferior to CON on measures of auditory-verbal learning and memory; nsMTBI performed more poorly than CON on processing speed and global neurocognition, and sMTBI performed worse than CON on working memory measures; nsMTBI were inferior to sMTBI on visuospatial memory. Over the AP1-AP2 interval, nsMTBI showed significantly greater improvement than sMTBI on measures of processing speed, visuospatial learning and memory, visuospatial skills, and global neurocognition, whereas sMTBI only showed significant improvement on executive skills. At AP2, sMTBI remained inferior to CON on auditory-verbal learning and auditory-verbal memory; there were no significant differences between nsMTBI and CON or among nsMTBI and sMTBI on any domain at AP2. Hazardous alcohol consumption was not significantly associated with change in any neurocognitive domain. For sMTBI, over the AP1-AP2 interval, greater lifetime duration of smoking and pack-years were related to significantly less improvement on multiple domains. Results suggest consideration of the effects of chronic cigarette smoking is necessary to understand the potential factors influencing neurocognitive recovery after MTBI.

The clinical spectrum of sport-related traumatic brain injury

Acute and chronic sports-related traumatic brain injuries (TBIs) are a substantial public health concern. Various types of acute TBI can occur in sport, but detection and management of cerebral concussion is of greatest importance as mismanagement of this syndrome can lead to persistent or chronic postconcussion syndrome (CPCS) or diffuse cerebral swelling. Chronic TBI encompasses a spectrum of disorders that are associated with long-term consequences of brain injury, including chronic traumatic encephalopathy (CTE), dementia pugilistica, post-traumatic parkinsonism, post-traumatic dementia and CPCS. CTE is the prototype of chronic TBI, but can only be definitively diagnosed at autopsy as no reliable biomarkers of this disorder are available. Whether CTE shares neuropathological features with CPCS is unknown. Evidence suggests that participation in contact-collision sports may increase the risk of neurodegenerative disorders such as Alzheimer disease, but the data are conflicting. In this Review, the spectrum of acute and chronic sport-related TBI is discussed, highlighting how examination of athletes involved in high-impact sports has advanced our understanding of pathology of brain injury and enabled improvements in detection and diagnosis of sport-related TBI.

A Case for Mental and Physical Rest in Youth Sports Concussion: It's Never too Late

Over the past decade, there has been a considerable increase in research on, and media attention to, sports-related concussion. However, despite accurate diagnosis, effective treatment and management of sports-related concussion have remained a challenge. There are approximately 1.8 million traumatic brain injuries in the United States annually (Faul et al., 2010) and emergency department pediatric visits for suspected concussion have doubled in the past decade (Bakhos et al., 2010). However, health care providers and medical researchers have yet to offer an effective, reliable evidence-based treatment for concussive brain injury. The Zurich 2008 Consensus Statement on Concussion in Sport codified the prescription for cognitive and physical rest immediately following a concussion based on clinical acumen and common sense (McCrory et al., 2009). Currently, rest is the considered the best immediate treatment for concussion. Other supportive and anecdotal treatments are often applied throughout the post-concussive recovery process to address persistent symptoms. The need for empirical research to translate current guidelines for rest into evidence-based treatment protocols is essential. A recent study evaluated the efficacy of comprehensive rest and concluded that such rest may be helpful whether applied soon after a concussion or weeks to months later (Moser et al., 2012). Here, we present a case illustrating the effectiveness of rest in a youth athlete, commenced after experiencing 13 months of post-concussion symptoms. There appears to be value in applying a specific period of cognitive and physical rest following concussion, whether immediately or later in the recovery phase.

Structural brain injury in sports-related concussion

Object

Sports-related concussions (SRCs) represent a significant and growing public health concern. The vast majority of SRCs produce mild symptoms that resolve within 1–2 weeks and are not associated with imaging-documented changes. On occasion, however, structural brain injury occurs, and neurosurgical management and intervention is appropriate.

Methods

A literature review was performed to address the epidemiology of SRC with a targeted focus on structural brain injury in the last half decade. MEDLINE and PubMed databases were searched to identify all studies pertaining to structural head injury in sports-related head injuries.

Results

The literature review yielded a variety of case reports, several small series, and no prospective cohort studies.

Conclusions

The authors conclude that reliable incidence and prevalence data related to structural brain injuries in SRC cannot be offered at present. A prospective registry collecting incidence, management, and follow-up data after structural brain injuries in the setting of SRC would be of great benefit to the neurosurgical community.

Postconcussion syndrome: a review of pathophysiology and potential nonpharmacological approaches to treatment

The incidence of all-cause concussions in the United States is estimated to range from 1.6 to 3.8 million annually, with the reported number of sport- or recreation-related concussions increasing dramatically, especially in youth sports.(1,2) Additionally, the use of roadside bombs in Iraq and Afghanistan has propelled the incidence of concussion and other traumatic brain injuries to the highest levels ever encountered by the US military. As a result, there has also been a marked increase in postconcussion syndrome (PCS) and the associated cognitive, emotional, and memory disabilities associated with the condition. Unfortunately, however, there have been no significant advancements in the understanding or treatment of PCS for decades. The current management of PCS mainly consists of rest, reduction of sensory inputs, and treating symptoms as needed. Recently, researchers investigating the underlying mechanisms of PCS have proposed that activation of the immune inflammatory response may be an underlying pathophysiology that occurs in those who experience prolonged symptoms after a concussion. This article reviews the literature and summarizes the immune inflammatory response known as immunoexcitotoxicity. This article also discusses the use of nonpharmacological agents for the management of PCS that directly address this underlying mechanism.