The neuropsychological impact of sports-related concussion: a meta-analysis.

There is increasing interest in the potential neuropsychological impact of sports-related concussion. A meta-analysis of the relevant literature was conducted to determine the impact of sports-related concussion across six cognitive domains. The analysis was based on 21 studies involving 790 cases of concussion and 2014 control cases. The overall effect of concussion (d = 0.49) was comparable to the effect found in the non-sports-related mild traumatic brain injury population (d = 0.54; Belanger et al., 2005). Using sports-concussed participants with a history of prior head injury appears to inflate the effect sizes associated with the current sports-related concussion. Acute effects (within 24 hr of injury) of concussion were greatest for delayed memory, memory acquisition, and global cognitive functioning (d = 1.00, 1.03, and 1.42, respectively). However, no residual neuropsychological impairments were found when testing was completed beyond 7 days postinjury. These findings were moderated by cognitive domain and comparison group (control group versus preconcussion self-control). Specifically, delayed memory in studies utilizing a control group remained problematic at 7 days. The implications and limitations of these findings are discussed.     

Contributions of functional magnetic resonance imaging (fMRI) to sport concussion evaluation

Mild traumatic brain injury (mTBI) in contact sport is a problem of such magnitude that improved approaches to diagnosis, investigation and management are urgent. Concussion has traditionally been described as a transient, fully reversible, cerebral dysfunction. However, this seemingly 'mild' injury sometimes results in long-lasting and disabling post-concussion symptoms (PCS) and abnormal neuropsychological profiles characteristic of frontal and/or temporal lobe dysfunction. At present, the pathological changes following concussion remain unclear, but it is now widely accepted that concussion results mainly in functional disturbance rather than structural damage. Therefore, functional imaging techniques can help in demonstrating brain abnormalities undetectable by structural imaging methods. This paper will review the use of functional magnetic resonance imaging (fMRI) in studies of concussion. Our existing and ongoing fMRI studies will be described as examples to highlight the potential and contribution of this non-invasive functional neuroimaging technique in the assessment of sports-related concussion and its management.     

Persistent Post-Concussive Syndrome: A proposed methodology and literature review to determine the effects, if any, of mild head and other bodily injury

Following mild head injury, a subgroup of individuals exhibit a constellation of chronic symptoms, a condition Alexander (1995) labeled Persistent Post-Concussive Syndrome (PPCS). He implicated neurological factors in the initial phase of the syndrome but psychological factors in the maintenance of symptoms. However, it is unclear as to whether an initial mild head injury is necessary or sufficient to cause the symptoms of PPCS. We first outline a study design comparing a mild closed-head injury group to both a normal and an other injury control group to answer this question. Next, we review the literature since 1960 to determine the findings of any studies using this design. The results of the literature review indicate that few such studies exist. To date, those that have been done suggest that there is no strong evidence for a specific effect for mild head injury on cognitive functioning. We discuss directions for future research given these findings.     

Persistent Post-Concussive Syndrome: A Proposed Methodology and Literature Review to Determine the Effects,if Any,of Mild Head and Other Bodily Injury

Following mild head injury, a subgroup of individuals exhibit a constellation of chronic symptoms, a condition Alexander (1995) labeled Persistent Post-Concussive Syndrome (PPCS). He implicated neurological factors in the initial phase of the syndrome but psychological factors in the maintenance of symptoms. However, it is unclear as to whether an initial mild head injury is necessary or sufficient to cause the symptoms of PPCS. We first outline a study design comparing a mild closed-head injury group to both a normal and an other injury control group to answer this question. Next, we review the literature since 1960 to determine the findings of any studies using this design. The results of the literature review indicate that few such studies exist. To date, those that have been done suggest that there is no strong evidence for a specific effect for mild head injury on cognitive functioning. We discuss directions for future research given these findings.     

Neuropsychology of sports-related head injury: Dementia Pugilistica to Post Concussion Syndrome

This article reviews the existing literature in the following areas of sports neuropsychology: Dementia Pugilistica, concussion and Post Concussion Syndrome, Second Impact Syndrome, and the emerging role of the sports neuropsychologist regarding return to play decisions. Dementia Pugilistica is discussed as a condition that exists along a continuum: Although many boxers will develop mild neurocognitive deficits, it is not yet known what percent of these mild presentations will progress to diagnosable Dementia Pugilistica. Factors contributing to both increased and reduced risk are detailed. The role of neuropsychological assessment in research and clinical management is reviewed. Existing studies of concussion incurred during contact sports provide evidence of an important role for neuropsychology in assessment and management of mild head injuries. Issues in clinical assessment of concussion are reviewed. The importance of grading of concussions, monitoring of postconcussive symptom resolution, and the use of neuropsychological test results in return to play decisions is detailed. The Second Impact Syndrome is discussed with regard to return to play decisions. Recommendations are proposed for research and for clinical application of findings in sports neuropsychology.     

Diffusion tensor tractography characteristics of axonal injury in concussion/mild traumatic brain injury

The main advantage of diffusion tensor tractography is that it allows the entire neural tract to be evaluated.In addition,configurational analysis of reconstructed neural tracts can indicate abnormalities such as tearing,narrowing,or discontinuations,which have been used to identify axonal injury of neural tracts in concussion patients.This review focuses on the characteristic features of axonal injury in concussion or mild traumatic brain injury(m TBI)patients through the use of diffusion tensor tractography.Axonal injury in concussion(m TBI)patients is characterized by their occurrence in long neural tracts and multiple injuries,and these characteristics are common in patients with diffuse axonal injury and in concussion(m TBI)patients with axonal injury.However,the discontinuation of the corticospinal tract is mostly observed in diffuse axonal injury,and partial tearing and narrowing in the subcortical white matter are frequently observed in concussion(m TBI)patients with axonal injury.This difference appears to be attributed to the observation that axonal injury in concussion(m TBI)patients is the result of weaker forces than those producing diffuse axonal injuries.In addition,regarding the fornix,in diffuse axonal injury,discontinuation of the fornical crus has been frequently reported,but in concussion(m TBI)patients,many collateral branches form in the fornix in addition to these findings in many case studies.It is presumed that the impact on the brain in TBI is relatively weaker than that in diffuse axonal injury,and that the formation of collateral branches occurs during the fornix recovery process.Although the occurrence of axonal injury in multiple areas of the brain is an important feature of diffuse axonal injury,case studies in concussion(m TBI)have shown that axonal injury occurs in multiple neural tracts.Because axonal injury lesions in m TBI patients may persist for approximately 10 years after injury onset,the characteristics of axonal injury in concussion(m TBI)patients,which are reviewed and categorized in this review,are expected to serve as useful supplementary information in the diagnosis of axonal injury in concussion(m TBI)patients.     

The young brain and concussion: imaging as a biomarker for diagnosis and prognosis

Concussion (mild traumatic brain injury (mTBI)) is a significant pediatric public health concern. Despite increased awareness, a comprehensive understanding of the acute and chronic effects of concussion on central nervous system structure and function remains incomplete. Here we review the definition, epidemiology, and sequelae of concussion within the developing brain, during childhood and adolescence, with current data derived from studies of pathophysiology and neuroimaging. These findings may contribute to a better understanding of the neurological consequences of traumatic brain injuries, which in turn, may lead to the development of brain biomarkers to improve identification, management and prognosis of pediatric patients suffering from concussion.     

The impact of pediatric neuropsychological consultation in mild traumatic brain injury: a model for providing feedback after invalid performance

Objective: In recent years, pediatric practitioners have increasingly recognized the importance of objectively measuring performance validity during clinical assessments. Yet, no studies have examined the impact of neuropsychological consultation when invalid performance has been identified in pediatric populations and little published guidance exists for clinical management. Here we provide a conceptual model for providing feedback after noncredible performance has been detected. In a pilot study, we examine caregiver satisfaction and postconcussive symptoms following provision of this feedback for patients seen through our concussion program. Methods: Participants (N = 70) were 8–17-year-olds with a history of mild traumatic brain injury who underwent an abbreviated neuropsychological evaluation between 2 and 12 months post-injury. We examined postconcussive symptom reduction and caregiver satisfaction after neuropsychological evaluation between groups of patients who were determined to have provided noncredible effort (n = 9) and those for whom no validity concerns were present (n = 61). Results: We found similarly high levels of caregiver satisfaction between groups and greater reduction in self-reported symptoms after feedback was provided using the model with children with noncredible presentations compared to those with credible presentations. Conclusion: The current study lends preliminary support to the idea that the identification and communication of invalid performance can be a beneficial clinical intervention that promotes high levels of caregiver satisfaction and a reduction in self-reported and caregiver-reported symptoms.     

Residual deficits from concussion as revealed by virtual time-to-contact measures of postural stability.

OBJECTIVE: Traumatic brain injury (TBI), including mild traumatic brain injury (MTBI), commonly known as a "concussion", is still one of the most puzzling neurological disorders and least understood injuries facing sport medicine and the scientific community [Cantu R. Concussion assessment Ongoing controversy. In: Slobounov S, Sebastianelli W, editors. Foundations of sport-related brain injuries. New York: Springer Press; 2006. p. 87-111.]. It was our primary objective to assess the dynamic properties of postural control in subjects prior to and after sport-related MTBI using the traditional center of pressure (COP) and virtual time-to-contact (VTC) measures. METHODS: We assessed 12 student-athletes prior to and 30 days after they suffered sport-related MTBI on a number of standing still and dynamic postural tasks. All subjects were clinically asymptomatic at day 30 of testing and were cleared for full sport participation based upon neurological and neuropsychological assessments, as well as clinical symptoms resolution. RESULTS: The findings showed: (1) no significant differences for any of the standard COP-based measures of postural control (i.e., 90% ellipse COP area, COP velocity and Stability Index) as a function of testing day (prior to and 30 days post-injury, p>.05); (2) no differences in terms of VTC shape, distribution and nominal values before and after concussion during standing still postural tasks regardless of vision conditions, p>.05; and (3) there were significant alterations in VTC in terms of absolute values, range of VTC at the deflection points and mode at the day 30 post-injury. CONCLUSIONS: The deficits in VTC control are indicative of residual postural abnormality in subjects suffering from mild traumatic brain injuries and provide further evidence that VTC is used to regulate dynamic postural movement. SIGNIFICANCE: The results show that residual postural abnormalities in concussed individuals may be undetected using conventional research methods and the implications of this for clinical practice are discussed.     

A single mild fluid percussion injury induces short-term behavioral and neuropathological changes in the Long-Evans rat: support for an animal model of concussion

Brain concussion is a serious public health concern and is associated with short-term cognitive impairments and behavioral disturbances that typically occur in the absence of significant brain damage. The current study addresses the need to better understand the effects of a mild lateral fluid percussion injury on rat behavior and neuropathology in an animal model of concussion. Male Long-Evans rats received either a single mild fluid percussion injury or a sham-injury, and either a short (24 h) or long (4 weeks) post-injury recovery period. After recovery, rats underwent a detailed behavioral analysis consisting of tests for rodent anxiety, cognition, social behavior, sensorimotor function, and depression-like behavior. After testing all rats were sacrificed and brains were examined immunohistochemically with markers for microglia/macrophage activation, reactive astrocytosis, and axonal injury. Injured rats (mean injury force: 1.20 ± .03 atm) displayed significant short-term cognitive impairments in the water maze and significantly more anxiolytic-like behavior in the elevated-plus maze compared to sham controls. Neuropathological analysis of the brains of injured rats showed an acute increase in reactive astrogliosis and activated microglia in cortex and evidence of axonal injury in the corpus callosum. There were no significant long-term effects on any behavioral or neuropathological measure 4 weeks after injury. These short-term behavioral and neuropathological changes are consistent with findings in human patients suffering a brain concussion, and provide further evidence for the use of a single mild lateral fluid percussion injury to study concussion in the rat.     

Early metabolic crisis-related brain atrophy and cognition in traumatic brain injury

Traumatic brain injury often results in acute metabolic crisis. We recently demonstrated that this is associated with chronic brain atrophy, which is most prominent in the frontal and temporal lobes. Interestingly, the neuropsychological profile of traumatic brain injury is often characterized as ‘frontal-temporal’ in nature, suggesting a possible link between acute metabolic crisis-related brain atrophy and neurocognitive impairment in this population. While focal lesions and diffuse axonal injury have a well-established role in the neuropsychological deficits observed following traumatic brain injury, no studies to date have examined the possible contribution of acute metabolic crisis-related atrophy in the neuropsychological sequelae of traumatic brain injury. In the current study we employed positron emission tomography, magnetic resonance imaging, and neuropsychological assessments to ascertain the relationship between acute metabolic crisis-related brain atrophy and neurocognitive outcome in a sample of 14 right-handed traumatic brain injury survivors. We found that acute metabolic crisis‐related atrophy in the frontal and temporal lobes was associated with poorer attention, executive functioning, and psychomotor abilities at 12 months post-injury. Furthermore, participants with gross frontal and/or temporal lobe atrophy exhibited numerous clinically significant neuropsychological deficits in contrast to participants with other patterns of brain atrophy. Our findings suggest that interventions that reduce acute metabolic crisis may lead to improved functional outcomes for traumatic brain injury survivors.     

脑震荡综合征与功能性核磁共振成像

脑震荡综合征是轻型外伤性颅脑损伤后常见的一组临床症候群。虽然大多数轻型颅脑损伤患者在一个月之内能治愈,但是部分患者在脑外伤后会持续存在脑震荡综合征达数月或数年,甚至终生。目前。关于脑震荡综合征的病理改变还不是很清楚,但是大家普遍认为脑震荡结局是功能的改变而不是解剖结构的改变。因此,应用功能性核磁共振技术就能发现结构性影像所不能发现的脑组织功能变化,对轻型外伤性颅脑损伤作出及时而准确的诊断。本文就功能性核磁共振成像技术在脑震荡综合征中的应用做一综述。     

An overview of concussion in sport

Concussion is a sudden-onset, transient alteration of consciousness due to a combination of functional and structural brain disturbances following a physical impact transmitted to the brain. It is a common, although likely underreported, condition encountered in a wide range of sports. In the Australian Football League, concussion is estimated to occur at a rate of approximately seven injuries per team per season. While many instances of concussion are clinically mild, there is emerging evidence that a player’s full recovery from a concussive injury may be more delayed and the sequelae of repeated concussions more severe than previously thought. In this light, a more conservative and rigorous approach to managing players with concussive injuries may be warranted, with the guiding principle being the player’s immediate and long-term welfare. The current paper reviews the sports concussion literature. The definition, epidemiology, aetiology, pathophysiology, structural pathology, clinical features, assessment and investigation, treatment principles, and short-term and potential long-term complications of concussion are discussed. Special considerations in paediatric sports concussion, and the return-to-play implications of immediate, evolving and repetitive brain injury are also considered, as are the emerging concept and possible implications of subconcussive injury.     

A systematic review of sex differences in concussion outcome: What do we know?

Objective: The purpose of this review was to examine sex differences in concussion, or mild traumatic brain injury (mTBI) outcome, updating previous critical reviews of the literature.

Method: Within adult human studies, we reviewed a wide range of concussion outcome variables: prevalence of concussion, injury characteristics, postconcussion symptom trajectories and psychiatric distress, neuropsychological performance, and neuroimaging findings. Sports-related concussion, civilian, and military samples were included in the review.

Results: Given the robust concussion literature, there is a relative paucity of research addressing sex differences following concussion. The majority of available studies focused on sports-related concussion, with fewer studies targeting other civilian causes of concussion or military-related concussion in females. Prevalence of concussion was generally reported to be higher in females than males. Although symptom reporting largely showed a pattern for females to report greater overall symptoms than males, examining individual symptoms or symptom clusters resulted in mixed findings between the sexes. Neuropsychological studies generally showed females performing more poorly than males on measures of visual memory following concussion, though this finding was not consistently reported.

Conclusion: Research examining sex differences in humans following concussion, in general, is in its infancy, and exploration of sex differences in studies outside of the sports concussion domain is particularly nascent. Given the increased prevalence of concussion and potential higher symptom reporting among women, ongoing research is necessary to better understand the role of biological sex on outcome following concussion. Understanding sex differences has important implications for assessment, management, and treatment of concussion.     

Rehabilitation interventions after mild head injury

PURPOSE OF REVIEW: This review examines current management and rehabilitation strategies for mild traumatic brain injury, with emphasis on the need to address multiple potential causative factors in order to enhance outcomes and to conduct more controlled efficacy studies. RECENT FINDINGS: Whilst most individuals who sustain mild traumatic brain injury make a good recovery, a proportion experience significant ongoing disability. In some cases this is due to diffuse axonal injury and cognitive impairment, but in others symptoms are exacerbated by factors such as pain, stress, personality issues or litigation, or in children, previous head injury, behavioural or learning difficulties. Provision of information early after injury results in reduced symptom reporting in adults and children. There is also a need, however, to address these other factors in treatment. Psychological therapy using a cognitive behavioural approach may be helpful, but controlled evaluations of such interventions have been lacking. Recent uncontrolled studies have examined the impact of computer-mediated interventions to remediate visual and verbal processing and oculomotor problems and the impact of quantitative electroencephalography. More rigorous efficacy studies of these approaches are needed. Guidelines for management of sports-related concussion and timing of return to play also require a more solid scientific basis. SUMMARY: The evidence base for management of mild traumatic brain injury is still very limited. There is a need to conduct more carefully controlled prospective studies and examine the influence of factors not directly related to the brain injury as a basis for formulating more uniform management guidelines.     

Epidemiology of mild traumatic brain injury and neurodegenerative disease

Every year an estimated 42 million people worldwide suffer a mild traumatic brain injury (MTBI) or concussion. More severe traumatic brain injury (TBI) is a well-established risk factor for a variety of neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis (ALS). Recently, large epidemiological studies have additionally identified MTBI as a risk factor for dementia. The role of MTBI in risk of PD or ALS is less well established. Repetitive MTBI and repetitive sub-concussive head trauma have been linked to increased risk for a variety of neurodegenerative diseases including chronic traumatic encephalopathy (CTE). CTE is a unique neurodegenerative tauopathy first described in boxers but more recently described in a variety of contact sport athletes, military veterans, and civilians exposed to repetitive MTBI. Studies of repetitive MTBI and CTE have been limited by referral bias, lack of consensus clinical criteria for CTE, challenges of quantifying MTBI exposure, and potential for confounding. The prevalence of CTE is unknown and the amount of MTBI or sub-concussive trauma exposure necessary to produce CTE is unclear. This review will summarize the current literature regarding the epidemiology of MTBI, post-TBI dementia and Parkinson's disease, and CTE while highlighting methodological challenges and critical future directions of research in this field. This article is part of a Special Issue entitled SI:Traumatic Brain Injury.     

Epileptische Anf?lle nach leichten Sch?del-Hirn-Traumen

Formerly it was assumed that cerebral concussion and mild traumatic brain injury (MTBI) were not followed by posttraumatic epilepsy. Modern neuroimaging findings revealed, however, that a ??mild?? traumatic brain injury not infrequently only seems to be mild and MTBI may be followed by localized contusions and a diffuse axonal injury. It is well known that brain contusion may be followed by seizures but the question whether an isolated diffuse axonal injury may also be followed by seizures has to be clarified by further studies. Several studies have demonstrated an increased risk of epilepsy after MTBI. Whether repeated concussive or subconcussive blows cause permanent or cumulative brain injury is a complex and controversial question. The posttraumatic genesis of seizures after MTBI probably has to be accepted in medicolegal expert opinions more often than previously. The arguments arguing for or against a relationship between MTBI and epilepsy are discussed.     

Examining the relationship between blast‐induced mild traumatic brain injury and posttraumatic stress‐related traits

Emerging evidence suggests that mild traumatic brain injury (mTBI) resulting from blast exposure may contribute to the occurrence of posttraumatic stress disorder (PTSD) and related affective sequelae, such as anxiety and depression. Many studies have used survey techniques to describe blast exposure leading to comorbid mTBI and related persistent postconcussive symptoms (PPCS) with PTSD in military populations. Despite this, there is a lack of literature that examines possible biological mechanisms by which blast exposure contributes to the development of PTSD sequelae. This Mini‐Review addresses the current literature on potential neurophysiological changes that may contribute to PTSD‐like traits as a result of a single or multiple exposures to blast events. Evidence from clinical blast‐induced mTBI populations and animal models of blast‐induced mTBI was evaluated with an emphasis on behavioral and physiological symptoms similar to those seen in PTSD populations and models. From the analysis, we propose potential mechanisms that merit further investigation for better understanding of how blast exposures may produce a higher rate of comorbid PPCS, PTSD, and affective phenomena. An improved understanding of PTSD‐like outcomes resulting from blast exposure will ultimately help facilitate the development of future treatments and contribute to a better understanding of PTSD sequelae that develop from physical trauma. © 2015 Wiley Periodicals, Inc.     

Cross-validation of a method for predicting wechsler memory scale-revised index scores

Abstract

Equations for prorating Wechsler Memory Scale-Revised General Memory (GM) and Delayed Recall (DR) index scores (Woodward & Axelrod, 1995) were confirmed in clinical samples of patients who were seen for comprehensive neuropsychological testing with (1) moderate or severe closed-head injuries (n = 53); (2) mild head injury/concussion (n = 47); and (3) patients with intractible seizures who were seen for neuropsychological testing prior to neurosurgical resection (n = 24). Fifty-one of the closed-head injury (CHI) patients were involved in litigation related to their injury at the time of this evaluation. Predicted GM and DR index scores fell within 6 points of the obtained scores for 91% and 92%, respectively, of the CHI sample, and 100% of the seizure resection sample. This is well within the standard error of measurement of these index scores. There were no significant differences in accuracy of estimated index scores between litigants and non-litigants or between levels of head injury severity. These findings confirm the earlier cross-validation results reported by Axelrod et al. (1996) in a mixed sample of traumatic brain injury and other neurological insult.