Abstract
Since the original descriptions of postconcussive pathophysiology, there has been a significant increase in interest and ongoing research to study the biological underpinnings of concussion. ...The initial ionic flux and glutamate release result in significant energy demands and a period of metabolic crisis for the injured brain. These physiological perturbations can now be linked to clinical characteristics of concussion, including migrainous symptoms, vulnerability to repeat injury, and cognitive impairment. Furthermore, advanced neuroimaging now allows a research window to monitor postconcussion pathophysiology in humans noninvasively. There is also increasing concern about the risk for chronic or even progressive neurobehavioral impairment after concussion/mild traumatic brain injury. Critical studies are underway to better link the acute pathobiology of concussion with potential mechanisms of chronic cell death, dysfunction, and neurodegeneration. This “new and improved” article summarizes in a translational fashion and updates what is known about the acute neurometabolic changes after concussive brain injury. Furthermore, new connections are proposed between this neurobiology and early clinical symptoms as well as to cellular processes that may underlie long-term impairment.
PURPOSE OF THE STATEMENT: ▸ To provide an evidence-based, best practises summary to assist physicians with the evaluation and management of sports concussion. ▸ To establish the level of evidence, ...knowledge gaps and areas requiring additional research.
▸ Sports medicine physicians are frequently involved in the care of patients with sports concussion. ▸ Sports medicine physicians are specifically trained to provide care along the continuum of sports concussion from the acute injury to return-to-play (RTP) decisions. ▸ The care of athletes with sports concussion is ideally performed by healthcare professionals with specific training and experience in the assessment and management of concussion. Competence should be determined by training and experience, not dictated by specialty. ▸ While this statement is directed towards sports medicine physicians, it may also assist other physicians and healthcare professionals in the care of patients with sports concussion.
▸ Concussion is defined as a traumatically induced transient disturbance of brain function and involves a complex pathophysiological process. Concussion is a subset of mild traumatic brain injury (MTBI) which is generally self-limited and at the less-severe end of the brain injury spectrum.
▸ Animal and human studies support the concept of postconcussive vulnerability, showing that a second blow before the brain has recovered results in worsening metabolic changes within the cell. ▸ Experimental evidence suggests the concussed brain is less responsive to usual neural activation and when premature cognitive or physical activity occurs before complete recovery the brain may be vulnerable to prolonged dysfunction.
▸ It is estimated that as many as 3.8 million concussions occur in the USA per year during competitive sports and recreational activities; however, as many as 50% of the concussions may go unreported. ▸ Concussions occur in all sports with the highest incidence in football, hockey, rugby, soccer and basketball. RISK FACTORS FOR SPORT-RELATED CONCUSSION: ▸ A history of concussion is associated with a higher risk of sustaining another concussion. ▸ A greater number, severity and duration of symptoms after a concussion are predictors of a prolonged recovery. ▸ In sports with similar playing rules, the reported incidence of concussion is higher in female athletes than in male athletes. ▸ Certain sports, positions and individual playing styles have a greater risk of concussion. ▸ Youth athletes may have a more prolonged recovery and are more susceptible to a concussion accompanied by a catastrophic injury. ▸ Preinjury mood disorders, learning disorders, attention-deficit disorders (ADD/ADHD) and migraine headaches complicate diagnosis and management of a concussion.
▸ Concussion remains a clinical diagnosis ideally made by a healthcare provider familiar with the athlete and knowledgeable in the recognition and evaluation of concussion. ▸ Graded symptom checklists provide an objective tool for assessing a variety of symptoms related to concussions, while also tracking the severity of those symptoms over serial evaluations. ▸ Standardised assessment tools provide a helpful structure for the evaluation of concussion, although limited validation of these assessment tools is available.
▸ Any athlete suspected of having a concussion should be stopped from playing and assessed by a licenced healthcare provider trained in the evaluation and management of concussions. ▸ Recognition and initial assessment of a concussion should be guided by a symptoms checklist, cognitive evaluation (including orientation, past and immediate memory, new learning and concentration), balance tests and further neurological physical examination. ▸ While standardised sideline tests are a useful framework for examination, the sensitivity, specificity, validity and reliability of these tests among different age groups, cultural groups and settings is largely undefined. Their practical usefulness with or without an individual baseline test is also largely unknown. ▸ Balance disturbance is a specific indicator of a concussion, but not very sensitive. Balance testing on the sideline may be substantially different than baseline tests because of differences in shoe/cleat-type or surface, use of ankle tape or braces, or the presence of other lower extremity injury. ▸ Imaging is reserved for athletes where intracerebral bleeding is suspected. ▸ There is no same day RTP for an athlete diagnosed with a concussion. ▸ Athletes suspected or diagnosed with a concussion should be monitored for deteriorating physical or mental status.
▸ Neuropsychological (NP) tests are an objective measure of brain-behaviour relationships and are more sensitive for subtle cognitive impairment than clinical exam. ▸ Most concussions can be managed appropriately without the use of NP testing. ▸ Computerised neuropsychological (CNP) testing should be interpreted by healthcare professionals trained and familiar with the type of test and the individual test limitations, including a knowledgeable assessment of the reliable change index, baseline variability and false-positive and false-negative rates. ▸ Paper and pencil NP tests can be more comprehensive, test different domains and assess for other conditions which may masquerade as or complicate assessment of concussion. ▸ NP testing should be used only as part of a comprehensive concussion management strategy and should not be used in isolation. ▸ The ideal timing, frequency and type of NP testing have not been determined. ▸ In some cases, properly administered and interpreted NP testing provides an added value to assess cognitive function and recovery in the management of sports concussions. ▸ It is unknown if use of NP testing in the management of sports concussion helps prevent recurrent concussion, catastrophic injury or long-term complications. ▸ Comprehensive NP evaluation is helpful in the post-concussion management of athletes with persistent symptoms or complicated courses.
▸ Students will require cognitive rest and may require academic accommodations such as reduced workload and extended time for tests while recovering from a concussion.
▸ Concussion symptoms should be resolved before returning to exercise. ▸ A RTP progression involves a gradual, step-wise increase in physical demands, sports-specific activities and the risk for contact. ▸ If symptoms occur with activity, the progression should be halted and restarted at the preceding symptom-free step. ▸ RTP after concussion should occur only with medical clearance from a licenced healthcare provider trained in the evaluation and management of concussions. SHORT-TERM RISKS OF PREMATURE RTP: ▸ The primary concern with early RTP is decreased reaction time leading to an increased risk of a repeat concussion or other injury and prolongation of symptoms. LONG-TERM EFFECTS: ▸ There is an increasing concern that head impact exposure and recurrent concussions contribute to long-term neurological sequelae. ▸ Some studies have suggested an association between prior concussions and chronic cognitive dysfunction. Large-scale epidemiological studies are needed to more clearly define risk factors and causation of any long-term neurological impairment.
▸ There are no evidence-based guidelines for disqualifying/retiring an athlete from a sport after a concussion. Each case should be carefully deliberated and an individualised approach to determining disqualification taken.
▸ Greater efforts are needed to educate involved parties, including athletes, parents, coaches, officials, school administrators and healthcare providers to improve concussion recognition, management and prevention. ▸ Physicians should be prepared to provide counselling regarding potential long-term consequences of a concussion and recurrent concussions.
▸ Primary prevention of some injuries may be possible with modification and enforcement of the rules and fair play. ▸ Helmets, both hard (football, lacrosse and hockey) and soft (soccer, rugby) are best suited to prevent impact injuries (fracture, bleeding, laceration, etc.) but have not been shown to reduce the incidence and severity of concussions. ▸ There is no current evidence that mouth guards can reduce the severity of or prevent concussions. ▸ Secondary prevention may be possible by appropriate RTP management.
▸ Legislative efforts provide a uniform standard for scholastic and non-scholastic sports organisations regarding concussion safety and management.
▸ Additional research is needed to validate current assessment tools, delineate the role of NP testing and improve identification of those at risk of prolonged post-concussive symptoms or other long-term complications. ▸ Evolving technologies for the diagnosis of concussion, such as newer neuroimaging techniques or biological markers, may provide new insights into the evaluation and management of sports concussion.
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 aim of this study was to update our original systematic review of return to sport rates following anterior cruciate ligament (ACL) reconstruction surgery.
Electronic databases were searched from ...April 2010 to November 2013 for articles reporting the number of patients returning to sport following ACL reconstruction surgery. Return to sport rates, physical functioning and contextual data were extracted and combined using random-effects meta-analyses. Data from the original review (articles published up to April 2010) were combined with data from the updated search.
Sixty-nine articles, reporting on 7556 participants, were reviewed. On average, 81% of people returned to any sport, 65% returned to their preinjury level of sport and 55% returned to competitive level sport after surgery. Symmetrical hopping performance (d=0.3) and the contextual factors of younger age (d=-0.3), male gender (OR=1.4), playing elite sport (OR=2.5) and having a positive psychological response (d=0.3) favoured returning to the preinjury level sport. Receiving a hamstring tendon autograft favoured returning to competitive level sport (OR=2.4), whereas receiving a patellar tendon autograft favoured returning to the preinjury level sport (OR=1.2).
Returning to sport varied according to different physical functioning and contextual factors, which could warrant additional emphasis in postoperative rehabilitation programmes to maximise participation.
Chronic traumatic encephalopathy (CTE) is a progressive neurodegenerative disorder linked to repetitive traumatic brain injury (TBI) and characterized by deposition of hyperphosphorylated tau at the ...depths of sulci. We sought to determine the presence of CTE pathology in a brain bank for neurodegenerative disorders for individuals with and without a history of contact sports participation. Available medical records of 1721 men were reviewed for evidence of past history of injury or participation in contact sports. Subsequently, cerebral cortical samples were processed for tau immunohistochemistry in cases with a documented history of sports exposure as well as age- and disease-matched men and women without such exposure. For cases with available frozen tissue, genetic analysis was performed for variants in
APOE
,
MAPT
, and
TMEM106B
. Immunohistochemistry revealed 21 of 66 former athletes had cortical tau pathology consistent with CTE. CTE pathology was not detected in 198 individuals without exposure to contact sports, including 33 individuals with documented single-incident TBI sustained from falls, motor vehicle accidents, domestic violence, or assaults. Among those exposed to contact sports, those with CTE pathology did not differ from those without CTE pathology with respect to noted clinicopathologic features. There were no significant differences in genetic variants for those with CTE pathology, but we observed a slight increase in
MAPT
H1 haplotype, and there tended to be fewer homozygous carriers of the protective
TMEM106B
rs3173615 minor allele in those with sports exposure and CTE pathology compared to those without CTE pathology. In conclusion, this study has identified a small, yet significant, subset of individuals with neurodegenerative disorders and concomitant CTE pathology. CTE pathology was only detected in individuals with documented participation in contact sports. Exposure to contact sports was the greatest risk factor for CTE pathology. Future studies addressing clinical correlates of CTE pathology are needed.
Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease associated with repetitive mild traumatic brain injury. It is defined pathologically by the abnormal accumulation of tau in a ...unique pattern that is distinct from other tauopathies, including Alzheimer’s disease (AD). Although trauma has been suggested to increase amyloid β peptide (Aβ) levels, the extent of Aβ deposition in CTE has not been thoroughly characterized. We studied a heterogeneous cohort of deceased athletes and military veterans with neuropathologically diagnosed CTE (
n
= 114, mean age at death = 60) to test the hypothesis that Aβ deposition is altered in CTE and associated with more severe pathology and worse clinical outcomes. We found that Aβ deposition, either as diffuse or neuritic plaques, was present in 52 % of CTE subjects. Moreover, Aβ deposition in CTE occurred at an accelerated rate and with altered dynamics in CTE compared to a normal aging population (OR = 3.8,
p
< 0.001). We also found a clear pathological and clinical dichotomy between those CTE cases with Aβ plaques and those without. Aβ deposition was significantly associated with the presence of the
APOE
ε4 allele (
p
= 0.035), older age at symptom onset (
p
< 0.001), and older age at death (
p
< 0.001). In addition, when controlling for age, neuritic plaques were significantly associated with increased CTE tauopathy stage (
β
= 2.43,
p
= 0.018), co-morbid Lewy body disease (OR = 5.01,
p
= 0.009), and dementia (OR = 4.45,
p
= 0.012). A subset of subjects met the diagnostic criteria for both CTE and AD, and in these subjects both Aβ plaques and total levels of Aβ1-40 were increased at the depths of the cortical sulcus compared to the gyral crests. Overall, these findings suggest that Aβ deposition is altered and accelerated in a cohort of CTE subjects compared to normal aging and that Aβ is associated with both pathological and clinical progression of CTE independent of age.
OBJECTIVE:To determine the degree to which preinjury and acute postinjury psychosocial and injury-related variables predict symptom duration following sport-related concussion.
METHODS:A total of ...2,055 high school and collegiate athletes completed preseason evaluations. Concussed athletes (n = 127) repeated assessments serially (<24 hours and days 8, 15, and 45) postinjury. Cox proportional hazard modeling was used to predict concussive symptom duration (in days). Predictors considered included demographic and history variables; baseline psychological, neurocognitive, and balance functioning; acute injury characteristics; and postinjury clinical measures.
RESULTS:Preinjury somatic symptom score (Brief Symptom Inventory–18 somatization scale) was the strongest premorbid predictor of symptom duration. Acute (24-hour) postconcussive symptom burden (Sport Concussion Assessment Tool–3 symptom severity) was the best injury-related predictor of recovery. These 2 predictors were moderately correlated (r = 0.51). Path analyses indicated that the relationship between preinjury somatization symptoms and symptom recovery was mediated by postinjury concussive symptoms.
CONCLUSIONS:Preinjury somatization symptoms contribute to reported postconcussive symptom recovery via their influence on acute postconcussive symptoms. The findings highlight the relevance of premorbid psychological factors in postconcussive recovery, even in a healthy athlete sample relatively free of psychopathology or medical comorbidities. Future research should elucidate the neurobiopsychosocial mechanisms that explain the role of this individual difference variable in outcome following concussive injury.
Purpose To describe an arthroscopic technique for decompression of a prominent anterior inferior iliac spine (AIIS) leading to extra-articular hip impingement and to provide short-term outcome after ...this procedure. Methods We retrospectively reviewed office charts, imaging studies, operative reports, arthroscopic images, preoperative and postoperative hip flexion range of motion, and preoperative and postoperative modified Harris Hip Scores in a consecutive series of 10 male patients who had arthroscopic decompression of symptomatic AIIS deformities leading to extra-articular hip impingement. The procedure was performed through standard anterolateral and mid-anterior hip arthroscopy portals that were also used to explore the joint and address concomitant intra-articular pathologies. Results The mean age was 24.9 years, with 8 of 10 patients aged younger than 30 years. In 9 patients, an anterior cam lesion was identified and decompressed before the AIIS decompression. The mean follow-up time was 14.7 months (range, 6 to 26 months). Hip flexion range of motion improved from 99° ± 7° before surgery to 117° ± 8° after surgery ( P < .001). The modified Harris Hip Score improved from 64 ± 18 before surgery to 98 ± 2 at latest follow-up after surgery ( P < .001). Conclusions Arthroscopic decompression of a symptomatic AIIS deformity is a reproducible procedure that can provide excellent outcomes at short-term follow-up. As opposed to using an open approach for decompressing a prominent AIIS, an arthroscopic approach may be of particular value in patients with mixed intra- and extra-articular sources of hip dysfunction, because it enables the surgeon to address all pathologies with a single arthroscopic procedure. Level of Evidence Level IV, therapeutic case series.
Clinically it is understood that rapid increases in training loads expose an athlete to an increased risk of injury; however, there are no systematic reviews to qualify this statement.
The aim of ...this systematic review was to determine training and competition loads, and the relationship between injury, illness and soreness.
The MEDLINE, SPORTDiscus, CINAHL and EMBASE databases were searched using a predefined search strategy. Studies were included if they analysed the relationship between training or competition loads and injury or illness, and were published prior to October 2015. Participants were athletes of any age or level of competition. The quality of the studies included in the review was evaluated using the Newcastle-Ottawa Scale (NOS). The level of evidence was defined as strong, 'consistent findings among multiple high-quality randomised controlled trials (RCTs)'; moderate, 'consistent findings among multiple low-quality RCTs and/or non-randomised controlled trials (CCTs) and/or one high-quality RCT'; limited, 'one low-quality RCT and/or CCTs, conflicting evidence'; conflicting, 'inconsistent findings among multiple trials (RCTs and/or CCTs)'; or no evidence, 'no RCTs or CCTs'.
A total of 799 studies were identified; 23 studies met the inclusion criteria, and a further 12 studies that were not identified in the search but met the inclusion criteria were subsequently added to the review. The largest number of studies evaluated the relationship between injuries and training load in rugby league players (n = 9) followed by cricket (n = 5), football (n = 3), Australian Football (n = 3), rugby union (n = 2),volleyball (n = 2), baseball (n = 2), water polo (n = 1), rowing (n = 1), basketball (n = 1), swimming (n = 1), middle-distance runners (n = 1) and various sports combined (n = 1). Moderate evidence for a significant relationship was observed between training loads and injury incidence in the majority of studies (n = 27, 93 %). In addition, moderate evidence exists for a significant relationship between training loads and illness incidence (n = 6, 75 %). Training loads were reported to have a protective effect against injury (n = 9, 31 %) and illness (n = 1, 13 %). The median (range) NOS score for injury and illness was 8 (5-9) and 6 (5-9), respectively.
A limitation of this systematic review was the a priori search strategy. Twelve further studies were included that were not identified in the search strategy, thus potentially introducing bias. The quality assessment was completed by only one author.
The results of this systematic review highlight that there is emerging moderate evidence for the relationship between the training load applied to an athlete and the occurrence of injury and illness.
The training load applied to an athlete appears to be related to their risk of injury and/or illness. Sports science and medicine professionals working with athletes should monitor this load and avoid acute spikes in loads. It is recommended that internal load as the product of the rate of perceived exertion (10-point modified Borg) and duration be used when determining injury risk in team-based sports. External loads measured as throw counts should also be monitored and collected across a season to determine injury risk in throwing populations. Global positioning system-derived distances should be utilised in team sports, and injury monitoring should occur for at least 4 weeks after spikes in loads.
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