Acute hemispheric swelling associated with thin subdural hematomas: pathophysiology of repetitive head injury in sports

The spectrum of acute and chronic consequences of neurotrauma in professional and amateur boxing - A call to action is advocated to better understand and prevent this phenomenon

Introduction

Despite changes in regulations, boxing-related injuries and fatalities are still occurring. The numbers available in the literature regarding mortality and long-term consequences may not accurately represent the actual situation. Indeed, the real extent of this phenomenon remains poorly known.

Research question

Delineating the spectrum of acute and chronic consequences of boxing-related traumatic brain injuries (TBI).

Material and methods

Narrative review of the literature concerning acute and chronic boxing-related TBI. Keywords such as mortality, boxing, subdural hematoma were used to search in PubMed and Google scholar. An updated analysis of the Velazquez fatalities collection in boxing was undertaken.

Results

The Velazquez collection includes 2076 fatalities from 1720 to the present with a death rate of 10 athletes per year. More than half of the deaths (N = 1354, 65.2%) occurred after a knock-out, and nearly 75% happened during professional bouts. In Australia, from 1832 to 2020, 163 fatalities were recorded (75% professional). In Japan, from 1952 to 2016, 38 deaths were recorded with a mean age of 23.9 years. Up to 40% of retired professional boxers in the United States were diagnosed with symptoms of chronic brain injury. Clinical dementia is far more prevalent among professional boxers than in amateurs with an incidence of 20%.

Discussion and conclusions

A concerted effort to raise awareness and shed light on boxing-related neuro-trauma is required. Similar considerations can be made for other combat sports or contact sports. A call to action to address this knowledge gap, decrease and prevent this phenomenon is advocated.

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.

Second Impact Syndrome. Myth or reality?

INTRODUCTION

Second impact syndrome (SIS) is a devastating condition occurring in sport-induced mild brain injury. SIS is drastically defined by anamnestic, clinical and radiological criteria, which is unusual in the field of cranial traumatology. The purpose of this study was to provide a literature review of this syndrome.

MATERIAL AND METHODS

We conducted a literature review of all published studies on PubMed. The keywords were "second impact syndrome and catastrophic head injury", "second impact syndrome and sport", "repeat concussion and catastrophic brain injury", "catastrophic head injury and concussion", "catastrophic head injury", "concussion and second impact syndrome", "concussion and repetitive head injury".

RESULTS

Eighty-two full-text articles were assessed for eligibility. Finally, 41 studies were included in qualitative synthesis and 21 were included in quantitative synthesis.

DISCUSSION

The number of cases reported in the literature was extremely small compared to the population at risk, i.e., the number of athletes exposed to repeated concussions. SIS was similar to talk and die syndrome, with which it shares certain characteristics. If we consider SIS according to "talk and deteriorate tables", it opens up interesting perspectives because they are specific in children and adolescents. Taking into account the scarcity of this syndrome, one may question whether athlete-intrinsic features may be involved in at least some cases of SIS. On a pathophysiological level, many explanations remained unsatisfactory because they were unable to explain all the clinical phenomena and observed lesions. Triggering the trigeminocardiac reflex is a crucial element in explaining the sequence of clinical events. Its association with a state of neurogenic inflammation provides an almost complete explanation for this particular condition. Finally, on a practical level, a concussion occurring during the playing of a sport must be considered as any other injury before allowing a return to play.

Advances and Future Directions of Diagnosis and Management of Pediatric Abusive Head Trauma: A Review of the Literature

Abusive head trauma (AHT) is broadly defined as injury of the skull and intracranial contents as a result of perpetrator-inflicted force and represents a persistent and significant disease burden in children under the age of 4 years. When compared to age-matched controls with typically single occurrence accidental traumatic brain injury (TBI), mortality after AHT is disproportionately high and likely attributable to key differences between injury phenotypes. This article aims to review the epidemiology of AHT, summarize the current state of AHT diagnosis, treatment, and prevention as well as areas for future directions of study. Despite neuroimaging advances and an evolved understanding of AHT, early identification remains a challenge for contemporary clinicians. As such, the reported incidence of 10–30 per 100,000 infants per year may be a considerable underestimate that has not significantly decreased over the past several decades despite social campaigns for public education such as “Never Shake a Baby.” This may reflect caregivers in crisis for whom education is not sufficient without support and intervention, or dangerous environments in which other family members are at risk in addition to the child. Acute management specific to AHT has not advanced beyond usual supportive care for childhood TBI, and prevention and early recognition remain crucial. Moreover, AHT is frequently excluded from studies of childhood TBI, which limits the precise translation of important brain injury research to this population. Repeated injury, antecedent abuse or neglect, delayed medical attention, and high rates of apnea and seizures on presentation are important variables to be considered. More research, including AHT inclusion in childhood TBI studies with comparisons to age-matched controls, and translational models with clinical fidelity are needed to better elucidate the pathophysiology of AHT and inform both clinical care and the development of targeted therapies. Clinical prediction rules, biomarkers, and imaging modalities hold promise, though these have largely been developed and validated in patients after clinically evident AHT has already occurred. Nevertheless, recognition of warning signs and intervention before irreversible harm occurs remains the current best strategy for medical professionals to protect vulnerable infants and toddlers.

Treatments and rehabilitation in the acute and chronic state of traumatic brain injury

Traumatic brain injury (TBI) is a major cause of acquired disability globally, and effective treatment methods are scarce. Lately, there has been increasing recognition of the devastating impact of TBI resulting from sports and other recreational activities, ranging from primarily sport-related concussions (SRC) but also more severe brain injuries requiring hospitalization. There are currently no established treatments for the underlying pathophysiology in TBI and while neuro-rehabilitation efforts are promising, there are currently is a lack of consensus regarding rehabilitation following TBI of any severity. In this narrative review, we highlight short- and long-term consequences of SRCs, and how the sideline management of these patients should be performed. We also cover the basic concepts of neuro-critical care management for more severely brain-injured patients with a focus on brain oedema and the necessity of improving intracranial conditions in terms of substrate delivery in order to facilitate recovery and improve outcome. Further, following the acute phase, promising new approaches to rehabilitation are covered for both patients with severe TBI and athletes suffering from SRC. These highlight the need for co-ordinated interdisciplinary rehabilitation, with a special focus on cognition, in order to promote recovery after TBI.

Traumatic brain injury may worsen clinical outcomes after prolonged partial resuscitative endovascular balloon occlusion of the aorta in severe hemorrhagic shock model

BACKGROUND

The use of partial resuscitative endovascular balloon occlusion of the aorta (pREBOA) in combined hemorrhagic shock (HS) and traumatic brain injury (TBI) has not been well studied. We hypothesized that the use of pREBOA in the setting of TBI would be associated with worse clinical outcomes.

METHODS

Female Yorkshire swine were randomized to the following groups: HS-TBI, HS-TBI-pREBOA, and HS-pREBOA (n = 5/cohort). Animals in the HS-TBI group were left in shock for a total of 2 hours, whereas animals assigned to pREBOA groups were treated with supraceliac pREBOA deployment (60 minutes) 1 hour into the shock period. All animals were then resuscitated, and physiologic parameters were monitored for 6 hours. Further fluid resuscitation and vasopressors were administered as needed. At the end of the observation period, brain hemispheric swelling (%) and lesion size (mm) were assessed.

RESULTS

Mortality was highest in the HS-TBI-pREBOA group (40% [2/5] vs. 0% [0/5] in the other groups, p = 0.1). Severity of shock was greatest in the HS-TBI-pREBOA group, as defined by peak lactate levels and pH nadir (p < 0.05). Fluid resuscitation and norepinephrine requirements were significantly higher in the HS-TBI-pREBOA group (p < 0.05). No significant differences were noted in brain hemispheric swelling and lesion size between the groups.

CONCLUSION

Prolonged application of pREBOA in the setting of TBI does not contribute to early worsening of brain lesion size and edema. However, the addition of TBI to HS-pREBOA may worsen the severity of shock. Providers should be aware of the potential physiologic sequelae induced by TBI.

What Definition Is Used to Describe Second Impact Syndrome in Sports? A Systematic and Critical Review

Concern about what has been termed, "second impact syndrome" (SIS) is a major factor determining return-to-play decisions after concussion. However, definitions of SIS vary. We used Scopus to conduct a systematic review and categorize the definitions used to describe SIS. Of the 91 sources identified, 79 (87%) clearly specified that SIS involved either cerebral edema or death after a concussion when a prior concussion had not resolved. Twelve articles (13%) could be interpreted as merely the events of two consecutive concussions. Among the articles that listed mortality rates, nearly all (33/35, 94%) said the rate of death was "high" (e.g., 50% to 100%). Our review found that most articles define SIS as a syndrome requiring catastrophic brain injury after consecutive concussive episodes. Given that it is unclear how common it is to have a second concussion while not fully recovered from a first concussion, the actual mortality rate of SIS is unknown.

Neuropsychiatric aspects of concussion: acute and chronic sequelae

Concussion – also known as mild traumatic brain injury – is a transient disturbance of neurological function resulting from traumatic forces imparted to the brain that often produce cognitive, behavioral and systemic symptoms. In this review of the literature, we discuss the pathophysiology of both acute and chronic neuropsychiatric sequelae of concussions, followed by a brief overview of evaluation and management of these sequelae.

Neuropsychiatric aspects of concussion

Over the past decade, concussion has become the most widely discussed injury in contact sports. However, concussions also occur in several other settings, such as non-contact sports, elderly individuals, young children, military personnel, and victims of domestic violence. Concussion is frequently undiagnosed as a cause of psychiatric morbidity, especially when the patient has no history of loss of consciousness or direct head trauma. Almost all of the extant literature focuses on traumatic brain injury and assumes that concussion is merely a mild form of traumatic brain injury, which has resulted in a lack of understanding about what concussion is, and how to diagnose, monitor, and treat its varied neuropsychiatric symptoms. In this Review, we address key issues so that the psychiatric clinician can better understand and treat patients with a clinical phenotype that might be the direct result of, or be exacerbated by, concussion. Future research needs to focus on prospective clinical trials in all affected patient populations (ie, those affected by concussion and those affected by various degrees of traumatic brain injury), the identification of reliable biomarkers that can be used to assist with diagnosis and treatment response, and the development of effective treatment interventions. Clearly differentiating concussion from traumatic brain injury is essential to achieve reliable and clinically relevant outcomes.

The Controversial Second Impact Syndrome: A Review of the Literature

BACKGROUND

Second impact syndrome is a devastating injury that primarily affects athletic children and young adults. It occurs when a second concussion occurs before symptoms from the first concussion have resolved. Diffuse and often catastrophic cerebral edema results. Reports of second impact syndrome are few, and some argue that second impact syndrome is simply diffuse cerebral swelling unrelated to the first concussion.

METHODS

Ovid and PubMed were searched from years 1946 to 2015 using the terms "second impact syndrome," "repeat concussion," and "catastrophic brain injury." In addition, review articles were found using a combination of the terms, "concussion," "second impact syndrome," and "repetitive head trauma."

RESULTS

Seventeen patients in seven publications met the criteria of having two witnessed hits and persistent symptoms from the first to the second concussion. Ten of the 17 (59%) included individuals were football players. All were male. Ages ranged from 13 to 23 years. All children with poor outcomes (death or permanent disability) were younger than 20 years, while four of the five players with good outcomes were older than 19 years. The lag time from first to second concussion ranged from one hour to four weeks, and in many cases, at least one of the two hits appeared minor.

CONCLUSIONS

American football, male gender, and young age appear to be associated with second impact syndrome. Controversies surrounding this syndrome are discussed. There is a need for prospective studies to clarify risk factors and outcomes of second impact syndrome to guide return-to-play recommendations for young athletes.

A Review of Sport-Related Head Injuries

We review current topics in sport-related head injuries including acute subdural hematoma (ASDH), traumatic cerebrovascular disease, cerebral concussion, and chronic traumatic encephalopathy (CTE). Sports-related ASDH is a leading cause of death and severe morbidity in popular contact sports like American football and Japanese judo. Rotational acceleration can cause either cerebral concussion or ASDH due to rupture of a parasagittal bridging vein. Although rare, approximately 80% of patients with cerebral infarction due to sport participation are diagnosed with ischemia or infarction due to arterial dissection. Computed tomography angiography, magnetic resonance angiography, and ultrasound are useful for diagnosing arterial dissection; ultrasound is particularly useful for detecting dissection of the common and internal carotid arteries. Repeated sports head injuries increase the risks of future concussion, cerebral swelling, ASDH, and CTE. To avoid fatal consequences of CTE, it is essential to understand the criteria for safe post-concussion sports participation. Once diagnosed with a concussion, an athlete should not be allowed to return to play on the same day and should not resume sports before the concussion symptoms have completely resolved. Information about the risks and management of head injuries in different sports should be widely disseminated in educational institutions and by sport organization public relations campaigns.

Head injury predictors in sports trauma--a state-of-the-art review

Head injuries occur in a great variety of sports. Many of these have been associated with neurological injuries, affecting the central nervous system. Some examples are motorsports, cycling, skiing, horse riding, mountaineering and most contact sports such as football, ice and field hockey, soccer, lacrosse, etc. The outcome of head impacts in these sports can be very severe. The worst-case scenarios of permanent disability or even death are possibilities. Over recent decades, many In recent decades, a great number of head injury criteria and respective thresholds have been proposed. However, the available information is much dispersed and a consensus has still not been achieved regarding the best injury criteria or even their thresholds. This review paper gives a thorough overview of the work carried out by the scientific community in the field of impact biomechanics about head injuries sustained during sports activity. The main goal is to review the head injury criteria, as well as their thresholds. Several are reviewed, from the predictors based on kinematics to the ones based on human tissue thresholds. In this work, we start to briefly introduce the head injuries and their mechanisms commonly seen as a result of head trauma in sports. Then, we present and summarize the head injury criteria and their respective thresholds.

Sudden cardiac death while playing Australian Rules football: a retrospective 14 year review

Australian Rules football is a sport which evolved from Gaelic football and which is played by a large number of predominantly male participants in a number of countries. The highest participation rates are in the southern states of Australia. A retrospective review over a period of 14 years identified 14 cases of sudden cardiac death that occurred in individuals while playing the sport. All were male and ranged in age from 13 to 36 years with a mean and median age of 23 years. A spectrum of cardiac causes was identified including coronary artery atherosclerosis, myocarditis, anomalous coronary artery anatomy, arrhythmogenic right ventricular cardiomyopathy, and healed Kawasaki disease. In 5 cases the heart was morphologically normal raising the possibility of a channelopathy. No traumatic deaths were identified. Some of the individuals had experienced symptoms prior to the fatal episode and the role of pre participation screening in reducing mortality is discussed.

The Diagnosis and Management of Concussion in Children and Adolescents

BACKGROUND

Concussion is a complex brain injury that results in more than 100,000 emergency department visits for school-aged children each year in the United States. All 50 US states have passed concussion legislation designed to promote safety in youth sports. Most of these laws require medical clearance by a licensed health care provider before returning to sport, which may have contributed to an increase in pediatric subspecialty referrals, particularly referrals to the child neurologist.

METHODS

We reviewed the literature on pediatric concussion.

RESULTS

This review summarizes the current knowledge and recommendations for concussion diagnosis and management in children and adolescents, athletes and nonathletes. It highlights concussion epidemiology, pathophysiology, advances in neuroimaging, and potential health risks including second impact syndrome and chronic traumatic encephalopathy. It also underscores clinical areas where evidence is lacking.

CONCLUSIONS

The diagnosis and management of concussion requires specific considerations in children. Further concussion research must be done to minimize injury risk and to optimize medical care for this common problem.

Physicians' Management Practices and Perceived Health Risks When Postconcussion Symptoms Persist

Background:

Concussion guidelines recommend physical and cognitive rest until all postconcussion symptoms resolve, in part because of potential health risks, including catastrophic injury related to a second impact. However, when postconcussion symptoms persist for weeks or months, these risks are poorly characterized.

Hypothesis:

Physicians’ perceived health risks and management strategies for patients with persistent postconcussion symptoms will vary.

Study Design:

Cross-sectional study.

Level of Evidence:

Level 3.

Methods:

A survey of the physician members of the American College of Sports Medicine assessed the perceived health risks related to advancing activity, the indications for neuroimaging, and the referral patterns for patients with persistent postconcussion symptoms.

Results:

A total of 572 physicians completed the survey (response rate, 27.2%). The majority of physicians recommended physical rest (97.4%) and cognitive rest (93.8%) within the first week of injury. Perceived health risks related to advancing activity in the symptomatic patient differed at 2 weeks versus 3 months after injury (P < 0.001 for all comparisons). Respondents from the United States were more likely to list second impact syndrome as a potential health risk at 2 weeks compared with respondents from other countries (P = 0.04). The majority (56%) responded that the risk of second impact syndrome remains until all symptoms resolve. When postconcussion symptoms persist beyond 1 month, 61.9% of physicians responded that neuroimaging is indicated. Approximately 60% of respondents had access to a multidisciplinary concussion clinic within 60 miles of their practice.

Conclusion:

When postconcussion symptoms persist, the perceived health risks, management practices, and access to multidisciplinary care vary among physicians.

Neurological consequences of traumatic brain injuries in sports

Traumatic brain injury (TBI) is common in boxing and other contact sports. The long term irreversible and progressive aftermath of TBI in boxers depicted as punch drunk syndrome was described almost a century ago and is now widely referred as chronic traumatic encephalopathy (CTE). The short term sequelae of acute brain injury including subdural haematoma and catastrophic brain injury may lead to death, whereas mild TBI, or concussion, causes functional disturbance and axonal injury rather than gross structural brain damage. Following concussion, symptoms such as dizziness, nausea, reduced attention, amnesia and headache tend to develop acutely but usually resolve within a week or two. Severe concussion can also lead to loss of consciousness. Despite the transient nature of the clinical symptoms, functional neuroimaging, electrophysiological, neuropsychological and neurochemical assessments indicate that the disturbance of concussion takes over a month to return to baseline and neuropathological evaluation shows that concussion-induced axonopathy may persist for years. The developing brains in children and adolescents are more susceptible to concussion than adult brain. The mechanism by which acute TBI may lead to the neurodegenerative process of CTE associated with tau hyperphosphorylation and the development of neurofibrillary tangles (NFTs) remains speculative. Focal tau-positive NFTs and neurites in close proximity to focal axonal injury and foci of microhaemorrhage and the predilection of CTE-tau pathology for perivascular and subcortical regions suggest that acute TBI-related axonal injury, loss of microvascular integrity, breach of the blood brain barrier, resulting inflammatory cascade and microglia and astrocyte activation are likely to be the basis of the mechanistic link of TBI and CTE. This article provides an overview of the acute and long-term neurological consequences of TBI in sports. Clinical, neuropathological and the possible pathophysiological mechanisms are discussed. This article is part of a Special Issue entitled 'Traumatic Brain Injury'.

The neuropathology of traumatic brain injury

Traumatic brain injury, a leading cause of mortality and morbidity, is divided into three grades of severity: mild, moderate, and severe, based on the Glasgow Coma Scale, the loss of consciousness, and the development of post-traumatic amnesia. Although mild traumatic brain injury, including concussion and subconcussion, is by far the most common, it is also the most difficult to diagnose and the least well understood. Proper recognition, management, and treatment of acute concussion and mild traumatic brain injury are the fundamentals of an emerging clinical discipline. It is also becoming increasingly clear that some mild traumatic brain injuries have persistent, and sometimes progressive, long-term debilitating effects. Evidence indicates that a single traumatic brain injury can precipitate or accelerate multiple age-related neurodegenerations, increase the risk of developing Alzheimer's disease, Parkinson's disease, and motor neuron disease, and that repetitive mild traumatic brain injuries can provoke the development of a tauopathy, chronic traumatic encephalopathy. Clinically, chronic traumatic encephalopathy is associated with behavioral changes, executive dysfunction, memory loss, and cognitive impairments that begin insidiously and progress slowly over decades. Pathologically, chronic traumatic encephalopathy produces atrophy of the frontal and temporal lobes, thalamus, and hypothalamus, septal abnormalities, and abnormal deposits of hyperphosphorylated tau (τ) as neurofibrillary tangles and disordered neurites throughout the brain. The incidence and prevalence of chronic traumatic encephalopathy and the genetic risk factors critical to its development are currently unknown. Chronic traumatic encephalopathy frequently occurs as a sole diagnosis, but may be associated with other neurodegenerative disorders, including Alzheimer's disease, Lewy body disease, and motor neuron disease. Currently, chronic traumatic encephalopathy can be diagnosed only at autopsy; however, promising efforts to develop imaging, spinal fluid, and peripheral blood biomarkers are underway to diagnose and monitor the course of disease in living subjects.

Current topics in sports-related head injuries: a review

We review the current topic in sports-related head injuries including acute subdural hematoma (ASDH), concussion, and chronic traumatic encephalopathy (CTE). Sports-related ASDH is a leading cause of death and severe morbidity in popular contact sports like American football in the USA and judo in Japan. It is thought that rotational acceleration is most likely to produce not only cerebral concussion but also ASDH due to the rupture of a parasagittal bridging vein, depending on the severity of the rotational acceleration injury. Repeated sports head injuries increase the risk for future concussion, cerebral swelling, ASDH or CTE. To avoid fatal consequences or CTE resulting from repeated concussions, an understanding of the criteria for a safe post-concussion return to play (RTP) is essential. Once diagnosed with a concussion, the athlete must not be allowed to RTP the same day and should not resume play before the concussion symptoms have completely resolved. If brain damage has been confirmed or a subdural hematoma is present, the athlete should not be allowed to participate in any contact sports. As much remains unknown regarding the pathogenesis and pathophysiology of sports-related concussion, ASDH, and CTE, basic and clinical studies are necessary to elucidate the crucial issues in sports-related head injuries.

Investigation of Sudden Death in Athletes: The Fittest Bodies in the Morgue

Sporting events are generally viewed as regulated activities with fit and healthy participants; therefore, when deaths occur, they draw considerable public interest. Athletic participants can be considered a vulnerable population based on inherent risks within certain sports and the associated physiologic stresses, which may complicate underlying medical conditions. Sudden deaths in young athletes participating in high school and collegiate organized sports occur at an average of four to six deaths per year; however, sudden deaths related to exercise outside of an organized sport setting remain unaccounted for in the overall prevalence of these deaths. A typical forensic pathology practice will see not only these higher-profile deaths occurring during an organized sporting event, but also lower-profile occurrences of individuals dying during more recreational or unstructured exercise. Sport-related deaths can essentially be categorized as those that occur due to dangers inherent in the sport itself, such as forms of heat-related illnesses, blunt force trauma, and water-related deaths, and those that occur due to susceptibilities of a given predisposed participant, including sickle cell trait, hypertrophic cardiomyopathy, and other cardiovascular diseases. This article will address both types of vulnerabilities and provide guidance for appropriate and specific medicolegal death investigation and autopsy procedures in these deaths.

Concussion in sports

Context:

Recently, concussion has become a topic of much discussion within sports. The goal of this review is to provide an overview of the literature concerning the definition of concussion, management of initial injury, return to play, and future health risks.

Evidence Acquisition:

This article reviews the most recent findings on recognizing and managing sports-related concussion, which has become a significant health risk. We reviewed articles from the literature discussing concussion and its effects.

Results:

Though concussion patients typically have negative head imaging, imaging is warranted in those with severe mechanism, significant loss of consciousness, focal neurologic deficit, or worsening symptoms. The existence of “second-impact syndrome,” whereby a first minor head injury predisposes an athlete to later catastrophic injury, remains controversial; however, it is clear that concussion has significant effects on a patient and should be considered carefully in return-to-play decisions.

Conclusions:

A comprehensive understanding of concussion and its related risks is important in making return-to-play decisions as well as health care and league policy.

The neuropathology of sport

The benefits of regular exercise, physical fitness and sports participation on cardiovascular and brain health are undeniable. Physical activity reduces the risk for cardiovascular disease, type 2 diabetes, hypertension, obesity, and stroke, and produces beneficial effects on cholesterol levels, antioxidant systems, inflammation, and vascular function. Exercise also enhances psychological health, reduces age-related loss of brain volume, improves cognition, reduces the risk of developing dementia, and impedes neurodegeneration. Nonetheless, the play of sports is associated with risks, including a risk for mild TBI (mTBI) and, rarely, catastrophic traumatic injury and death. There is also growing awareness that repetitive mTBIs, such as concussion and subconcussion, can occasionally produce persistent cognitive, behavioral, and psychiatric problems as well as lead to the development of a neurodegeneration, chronic traumatic encephalopathy (CTE). In this review, we summarize the beneficial aspects of sports participation on psychological, emotional, physical and cognitive health, and specifically analyze some of the less common adverse neuropathological outcomes, including concussion, second-impact syndrome, juvenile head trauma syndrome, catastrophic sudden death, and CTE. CTE is a latent neurodegeneration clinically associated with behavioral changes, executive dysfunction and cognitive impairments, and pathologically characterized by frontal and temporal lobe atrophy, neuronal and axonal loss, and abnormal deposits of paired helical filament (PHF)-tau and 43 kDa TAR deoxyribonucleic acid (DNA)-binding protein (TDP-43). CTE often occurs as a sole diagnosis, but may be associated with other neurodegenerative disorders, including motor neuron disease (CTE-MND). Although the incidence and prevalence of CTE are not known, CTE has been reported most frequently in American football players and boxers. Other sports associated with CTE include ice hockey, professional wrestling, soccer, rugby, and baseball.

The impact of arterial hypertension on polytrauma and traumatic brain injury

BACKGROUND

Pre-hospital hypotension in trauma patients is associated with high mortality. Especially for patients with severe traumatic brain injury (TBI), arterial normotension or even hypertension (AHT) is considered an important mechanism for sustaining adequate cerebral perfusion pressure. The effect of pre-hospital arterial hypertension (pAHT) on in-hospital mortality after trauma has not been studied to date.

METHODS

We retrospectively analyzed data in the trauma registry of the German Society for Trauma Surgery (DGU) on all trauma patients in Germany from 1993 to 2008 who were 16 to 80 years old at the time of the trauma and had an injury severity score (ISS) of 9 or above (total, 42 500 patient data sets). For the analysis, we divided the patients into two groups: those with and those without TBI. We further divided the TBI patients into five subgroups depending on the course of their systolic blood pressure up to the moment of their arrival at the hospital. We also analyzed the patients' demographic data, patterns of injury, and accident mechanisms.

RESULTS

Trauma patients with TBI and pAHT (142 of 561 patients) had a significantly higher mortality than normotensive TBI patients (25.3% vs. 13.5%, p<0.001). Arterial hypertension that either rises or falls before the patient reaches the hospital is associated with higher in-hospital mortality. A logistical regression analysis of 5384 patients revealed that patients with pAHT (n = 561) had an odds ratio of 1.9 (95% confidence interval, 1.4 to 1.6) for death in the hospital compared to normotensive patients (n = 6020).

CONCLUSION

Systolic blood pressure values above 160 mm Hg before arrival in the hospital worsen the outcome of trauma patients with TBI.

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.

The pathophysiology of brain swelling associated with subdural hemorrhage: the role of the trigeminovascular system

INTRODUCTION

This paper reviews the evidence in support of the hypothesis that the trigeminal system mediates brain swelling associated with subdural bleeding. The trigeminovascular system has been extensively studied in migraine; it may play an important but under-recognized role in the response to head trauma. Nerve fibers originating in trigeminal ganglion cells are the primary sensors of head trauma and, through their collateral innervation of the intracranial and dural blood vessels, are capable of inciting a cascade of vascular responses and brain swelling. The extensive trigeminal representation in the brainstem initiates and augments autonomic responses. Blood and tissue injury in the dura incite neurogenic inflammatory responses capable of sensitizing dural nerves and potentiating the response to trauma.

DISCUSSION

The trigeminal system may provide the anatomo-physiological link between small-volume, thin subdural bleeds and swelling of the underlying brain. This physiology may help to explain the poorly understood phenomena of "second-impact syndrome," the infant response to subdural bleeding (the "big black brain"), as well as post-traumatic subdural effusions. Considerable age-specific differences in the density of dural innervation exist; age-specific responses of this innervation may explain differences in the brain's response to trauma in the young. An understanding of this pathophysiology is crucial to the development of intervention and treatment of these conditions. Antagonists to specific neuropeptides of the trigeminal system modify brain swelling after trauma and should be further explored as potential therapy in brain trauma and subdural bleeding.

The pathophysiology of concussion

Concussion is defined as a biomechanically induced brain injury characterized by the absence of gross anatomic lesions. Early and late clinical symptoms, including impairments of memory and attention, headache, and alteration of mental status, are the result of neuronal dysfunction mostly caused by functional rather than structural abnormalities. The mechanical insult initiates a complex cascade of metabolic events leading to perturbation of delicate neuronal homeostatic balances. Starting from neurotoxicity, energetic metabolism disturbance caused by the initial mitochondrial dysfunction seems to be the main biochemical explanation for most postconcussive signs and symptoms. Furthermore, concussed cells enter a peculiar state of vulnerability, and if a second concussion is sustained while they are in this state, they may be irreversibly damaged by the occurrence of swelling. This condition of concussion-induced brain vulnerability is the basic pathophysiology of the second impact syndrome. N-acetylaspartate, a brain-specific compound representative of neuronal metabolic wellness, is proving a valid surrogate marker of the post-traumatic biochemical damage, and its utility in monitoring the recovery of the aforementioned "functional" disturbance as a concussion marker is emerging, because it is easily detectable through proton magnetic resonance spectroscopy.

Current issues in pediatric sports concussion

This article reviews current issues in the following areas of pediatric sports-related concussion: incidence of concussion, potential long-term effects, return to play, and the emergence of legislation regarding concussion education and management programs. Incidence of concussion is presented in context of emergency room visits, as well as under-reporting of concussions. The literature on history of concussion is reviewed, for high school, collegiate, and professional athletes, with respect to potential long-term effects of cerebral concussion. Specific discussions of effects include: decreased cognition and increased symptom reporting following multiple concussions, and recent diagnoses of chronic traumatic encephalopathy in non-professional and youth athletes. Recent legislative and advocacy efforts are reviewed, including mandated programs in specific states.

The "Shaken Baby" syndrome: pathology and mechanisms

The "Shaken Baby" syndrome (SBS) is the subject of intense controversy; the diagnosis has in the past depended on the triad of subdural haemorrhage (SDH), retinal haemorrhage and encephalopathy. While there is no doubt that infants do suffer abusive injury at the hands of their carers and that impact can cause catastrophic intracranial damage, research has repeatedly undermined the hypothesis that shaking per se can cause this triad. The term non-accidental head injury has therefore been widely adopted. This review will focus on the pathology and mechanisms of the three physiologically associated findings which constitute the "triad" and are seen in infants suffering from a wide range of non-traumatic as well as traumatic conditions. "Sub" dural bleeding in fact originates within the deep layers of the dura. The potential sources of SDH include: the bridging veins, small vessels within the dura itself, a granulating haemorrhagic membrane and ruptured intracranial aneurysm. Most neuropathologists do not routinely examine eyes, but the significance of this second arm of the triad in the diagnosis of Shaken Baby syndrome is such that it merits consideration in the context of this review. While retinal haemorrhage can be seen clinically, dural and subarachnoid optic nerve sheath haemorrhage is usually seen exclusively by the pathologist and only rarely described by the neuroradiologist. The term encephalopathy is used loosely in the context of SBS. It may encompass anything from vomiting, irritability, feeding difficulties or floppiness to seizures, apnoea and fulminant brain swelling. The spectrum of brain pathology associated with retinal and subdural bleeding from a variety of causes is described. The most important cerebral pathology is swelling and hypoxic-ischaemic injury. Mechanical shearing injury is rare and contusions, the hallmark of adult traumatic brain damage, are vanishingly rare in infants under 1 year of age. Clefts and haemorrhages in the immediate subcortical white matter have been assumed to be due to trauma but factors specific to this age group offer other explanations. Finally, examples of the most common causes of the triad encountered in clinical diagnostic and forensic practice are briefly annotated.

Tightly coupled repetitive blast-induced traumatic brain injury: development and characterization in mice

A mouse model of repeated blast exposure was developed using a compressed air-driven shock tube, to study the increase in severity of traumatic brain injury (bTBI) after multiple blast exposures. Isoflurane anesthetized C57BL/6J mice were exposed to 13.9, 20.6, and 25 psi single blast overpressure (BOP1) and allowed to recover for 5 days. BOP1 at 20.6 psi showed a mortality rate of 2% and this pressure was used for three repeated blast exposures (BOP3) with 1 and 30 min intervals. Overall mortality rate in BOP3 was increased to 20%. After blast exposure, righting reflex time and body-weight loss were significantly higher in BOP3 animals compared to BOP1 animals. At 4 h, brain edema was significantly increased in BOP3 animals compared to sham controls. Reactive oxygen species in the cortex were increased significantly in BOP1 and BOP3 animals. Neuropathological analysis of the cerebellum and cerebral cortex showed dense silver precipitates in BOP3 animals, indicating the presence of diffuse axonal injury. Fluoro-Jade B staining showed increased intensity in the cortex of BOP3 animals indicating neurodegeneration. Rota Rod behavioral test showed a significant decrease in performance at 10 rpm following BOP1 or BOP3 at 2 h post-blast, which gradually recovered during the 5 days. At 20 rpm, the latency to fall was significantly decreased in both BOP1 and BOP3 animals and it did not recover in the majority of the animals through 5 days of testing. These data suggest that repeated blast exposures lead to increased impairment severity in multiple neurological parameters of TBI in mice.

Return-to-play decisions

Concussions occur as a result of forces directed to the head or neck, or from impulsive forces transmitted from the body to the head. They result in the rapid onset and spontaneous recovery of short-lived impairment of neurologic function. Concussions represent a functional, rather than structural, disturbance, and do not result in abnormalities on standard structural imaging. This article discusses a comprehensive approach to return to play in sports concussion, including managing athletes returning after prolonged postconcussion syndrome, multiple concussions, and intracranial hematomas and craniotomy.

Sports Medicine

An estimated 10% of head and spinal cord injuries are due to sports-related activities. As the popularity of sports increases so does the incidence of sports-related injuries. In recent years, concussion has received significant media attention as high-profile athletes have come forward to share their experiences and long-term struggles with this specific type of traumatic brain injury. Public health initiatives such as the “Heads Up: Concussion in Youth Sports” program run by the Center for Disease Control and Prevention have been developed to raise awareness regarding concussion injuries. These programs target not only athletes themselves but also include coaches, medical professionals, and parents to ensure that all individuals involved in sports, be it directly or peripherally, obtain the education required to prevent, correctly diagnose, and treat concussion. They are a testament to how elementary our understanding of concussion continues to be. They also demonstrate that misinformation and lack of awareness pose a significant obstacle to proper diagnosis and treatment. In this review, the authors discuss concussion both as a medical challenge and as a public health concern. The authors examine the definition as well as diagnostic criteria that have been agreed on during the Third International Conference on Concussion in Sport in Zurich 2008. Furthermore, current options and limitations in preventing and treating concussion are reviewed. Finally, the 2 most commonly used standardized grading systems as well as guidelines for return to play are reviewed. Overall, this article will offer health care providers and members of the general public alike the current understanding of concussion.

Color changing photonic crystals detect blast exposure

Blast-induced traumatic brain injury (bTBI) is the "signature wound" of the current wars in Iraq and Afghanistan. However, with no objective information of relative blast exposure, warfighters with bTBI may not receive appropriate medical care and are at risk of being returned to the battlefield. Accordingly, we have created a colorimetric blast injury dosimeter (BID) that exploits material failure of photonic crystals to detect blast exposure. Appearing like a colored sticker, the BID is fabricated in photosensitive polymers via multi-beam interference lithography. Although very stable in the presence of heat, cold or physical impact, sculpted micro- and nano-structures of the BID are physically altered in a precise manner by blast exposure, resulting in color changes that correspond with blast intensity. This approach offers a lightweight, power-free sensor that can be readily interpreted by the naked eye. Importantly, with future refinement this technology may be deployed to identify soldiers exposed to blast at levels suggested to be supra-threshold for non-impact blast-induced mild TBI.

Boxing-related head injuries

Fatalities in boxing are most often due to traumatic brain injury that occurs in the ring. In the past 30 years, significant improvements in ringside and medical equipment, safety, and regulations have resulted in a dramatic reduction in the fatality rate. Nonetheless, the rate of boxing-related head injuries, particularly concussions, remains unknown, due in large part to its variability in clinical presentation. Furthermore, the significance of repeat concussions sustained when boxing is just now being understood. In this article, we identify the clinical manifestations, pathophysiology, and management of boxing-related head injuries, and discuss preventive strategies to reduce head injuries sustained by boxers.

Second-impact syndrome and a small subdural hematoma: an uncommon catastrophic result of repetitive head injury with a characteristic imaging appearance

There have been a handful of previously published cases of athletes who were still symptomatic from a prior head injury, and then suffered a second injury in which a thin, acute subdural hematoma (SDH) with unilateral hemisphere vascular engorgement was demonstrated on CT scan. In those cases, the cause of the brain swelling/dysautoregulation was ascribed to the presence of the acute SDH rather than to the acceleration/deceleration forces that caused the SDH. We believe that the brain swelling is due to "second-impact dysautoregulation," rather than due to the effect of the SDH on the underlying hemisphere. To support our hypothesis, we present 10 additional cases of acute hemispheric swelling in association with small SDHs in athletes who received a second head injury while still symptomatic from a previous head injury. The clinical history and the unique neuroimaging features of this entity on CT are described and illustrated in detail. The CT findings included an engorged cerebral hemisphere with initial preservation of grey-white matter differentiation, and abnormal mass effect and midline shift that appeared disproportionately greater than the size of the SDH. In addition, the imaging similarities between our patients and those with non-accidental head trauma (shaken-baby syndrome) will be discussed.

Sport-related concussion in adolescents

Sport-related concussion is a common problem encountered by pediatricians and other primary care physicians. Assessment of concussion is based on clinical evaluation. The Zurich consensus statement provides a basic framework to guide concussion management decisions and recommends an individualized approach and the exercising of clinical judgment in return-to-play decisions. This article reviews practice aspects of concussion for the adolescent athletes who present in the primary care office or clinic setting.

Concussion understanding and management among New England high school football coaches

PRIMARY OBJECTIVE

To determine high school football coaches' understanding, management and sources of information of concussion at schools without a certified athletic trainer (ATC) or without one at practice.

RESEARCH DESIGN

Anonymous survey of head football coaches at New England high schools.

METHODS AND PROCEDURES

Surveys were mailed to 254 New England high school head football coaches. One hundred and nine (43%) surveys were returned, of which 62 respondents indicated there was no ATC either at the school or at practice. These 62 respondents were used for data analysis.

MAIN OUTCOMES AND RESULTS

Coaching associations and conferences were the two most common sources of information received about concussion. Coaches were significantly more knowledgeable about concussion than a general public sample, from which data were available from a prior study. When given potential symptoms of concussion, 70-95% of coaches reported that they would consult a healthcare professional before allowing a player to return to action, consistent with most return-to-play guidelines.

CONCLUSIONS

Participants demonstrated greater knowledge about concussions than the general public and most, but not all, coaches reported taking a conservative approach to concussion management. Ramifications of the results are discussed.

What are the real risks of sport-related concussion, and are they modifiable?

Over the past two decades, the management of sport-related concussion has been the topic of increased attention in the scientific literature and in the popular media. Despite a proliferation of competing guidelines for concussion management, the widespread use of neuropsychological "baseline" testing designed to monitor postinjury recovery, and several prospective controlled studies of the natural history of concussion, there has been virtually no attempt to quantify the risks associated with sport-related concussion or to determine whether these risks are modifiable via management strategies. Using American football as a model, the short- and long-term risks of sport-related concussion are reviewed. It is concluded that serious short-term consequences of sport-related concussion are extremely rare and unlikely to be significantly modified via management strategies that rely on baseline testing. Other less serious short-term adverse outcomes are also quite rare, transient, and not likely to be altered by specific management guidelines. The long-term consequences of multiple sport-related head trauma remain unclear but are potentially of greater public health concern and should be the focus of increased research. Based on available evidence, there is little rationale for the use of rigid strategies or guidelines in the place of individual clinical decision-making in the management of these injuries.

Concussion symptom inventory: an empirically derived scale for monitoring resolution of symptoms following sport-related concussion

Self-report post-concussion symptom scales have been a key method for monitoring recovery from sport-related concussion, to assist in medical management, and return-to-play decision-making. To date, however, item selection and scaling metrics for these instruments have been based solely upon clinical judgment, and no one scale has been identified as the "gold standard". We analyzed a large set of data from existing scales obtained from three separate case-control studies in order to derive a sensitive and efficient scale for this application by eliminating items that were found to be insensitive to concussion. Baseline data from symptom checklists including a total of 27 symptom variables were collected from a total of 16,350 high school and college athletes. Follow-up data were obtained from 641 athletes who subsequently incurred a concussion. Symptom checklists were administered at baseline (preseason), immediately post-concussion, post-game, and at 1, 3, and 5 days post-injury. Effect-size analyses resulted in the retention of only 12 of the 27 variables. Receiver-operating characteristic analyses were used to confirm that the reduction in items did not reduce sensitivity or specificity. The newly derived Concussion Symptom Inventory is presented and recommended as a research and clinical tool for monitoring recovery from sport-related concussion.

Acute subdural hematoma because of boxing

BACKGROUND

To identify factors determining the clinical characteristics and prognosis of acute subdural hematoma (ASDH) arising from boxing injuries by comparing with ASDH due to any nonboxing cause.

METHODS

Two groups were selected for this study: 10 patients with ASDH because of boxing injuries and 26 patients with nonboxer ASDH. All of the patients underwent neurologic examination by neurosurgeons. Primary resuscitation and stabilization as well as operative therapy were performed to all patients according to the European Brain Injury Consortium Guidelines. Two groups were compared in terms of age, the Glasgow Coma Scale at admission, neurologic findings, craniogram and brain computed tomography scan findings, operative findings, and prognosis. As potential prognostic indicators for boxers, the time interval until surgery, the Glasgow Outcome Scale, hematoma thickness, midline shift, and the site of bleeding were analyzed.

RESULTS

The characteristics of patients because of boxing injuries are that patients were younger, had lucid interval, and had no cerebral contusion or contralateral brain injury. There was no significant difference in initial Glasgow Coma Scale, hematoma thickness, midline shift, and their prognosis. The most peculiar clinical presentation of boxers' ASDH was that all bleedings were limited from "bridging veins" or "cortical veins." The prognosis of boxers was most closely correlated with the site of bleeding (r2 = 0.81; p = 0.0001) and the midline shift (r2 = 0.67; p = 0.007).

CONCLUSIONS

Our study shows that ASDH because of boxing is characterized by bleeding from bridging or cortical veins, and that the site of bleeding is a significant determinant of their prognosis.