Consensus Statement on Concussion in Sport: The 4th International Conference on Concussion in Sport, Zurich, November 2012

This paper is a revision and update of the recommendations developed following the 1st (Vienna 2001), 2nd (Prague 2004), and 3rd (Zurich 2008) International Consensus Conference on Concussion in Sport and is based on the deliberations at the 4th International Conference on Concussion in Sport held in Zurich, November 2012.1–3The new 2012 Zurich Consensus statement is designed to build on the principles outlined in the previous documents and to develop further conceptual understanding of this problem using a formal consensus-based approach. A detailed description of the consensus process is outlined at the end of this document under the "Background" section. This document is developed for use by physicians and health care professionals who are primarily involved in the care of injured athletes, whether at the recreational, elite, or professional level.While agreement exists pertaining to principle messages conveyed within this document, the authors acknowledge that the science of concussion is evolving, and therefore, management and RTP decisions remain in the realm of clinical judgment on an individualized basis. Readers are encouraged to copy and distribute freely the Zurich Consensus document, the Pocket Concussion Recognition Tool (CRT), the Sports Concussion Assessment Tool version 3 (SCAT3), and the Child SCAT3 card (Appendix), and none is subject to any restriction, provided it is not altered in any way or converted to a digital format. The authors request that the document and the accompanying tools be distributed in their full and complete format.This consensus paper is broken into a number of sections:The Zurich 2012 document examines sport concussion and management issues raised in the previous Vienna 2001, Prague 2004, and Zurich 2008 documents and applies the consensus questions from Section 3 to these areas.1–3Panel discussion regarding the definition of concussion and its separation from mild traumatic brain injury (mTBI) was held. There was acknowledgement by the Concussion in Sport Group (CISG) that, although the terms mild traumatic brain injury (mTBI) and concussion are often used interchangeably in the sporting context and particularly in the US literature, others use the term to refer to different injury constructs. Concussion is the historical term representing low-velocity injuries that cause brain "shaking," resulting in clinical symptoms, and which are not necessarily related to a pathologic injury. Concussion is a subset of TBI, and the term concussion will be used in this document. It was also noted that the term commotio cerebri is often used in European and other countries. Minor revisions were made to the definition of concussion and it is defined as follows: Concussion is a brain injury and is defined as a complex pathophysiological process affecting the brain, induced by biomechanical forces. Several common features that incorporate clinical, pathologic, and biomechanical injury constructs that may be utilized in defining the nature of a concussive head injury include:The majority (80% to 90%) of concussions resolve in a short (7–10 day) period, although the recovery timeframe may be longer in children and adolescents.2The diagnosis of acute concussion usually involves the assessment of a range of domains including clinical symptoms, physical signs, cognitive impairment, neurobehavioral features, and sleep disturbance. Furthermore, a detailed concussion history is an important part of the evaluation, both in the injured athlete and when conducting a preparticipation examination. The detailed clinical assessment of concussion is outlined in the SCAT3 and Child SCAT3 forms, which are appendices to this document.The suspected diagnosis of concussion can include 1 or more of the following clinical domains:If any 1 or more of these components is present, a concussion should be suspected and the appropriate management strategy instituted.When a player shows any features of a concussion:Sufficient time for assessment and adequate facilities should be provided for the appropriate medical assessment, both on and off the field, for all injured athletes. In some sports, this may require rule change to allow an appropriate off-field medical assessment to occur without affecting the flow of the game or unduly penalizing the injured player's team. The final determination regarding concussion diagnosis and fitness to play is a medical decision based on clinical judgment.Sideline evaluation of cognitive function is an essential component in the assessment of this injury. Brief neuropsychological test batteries that assess attention and memory function have been shown to be practical and effective. Such tests include the SCAT3, which incorporates the Maddocks questions,4,5 and the Standardized Assessment of Concussion (SAC).6–8 It is worth noting that standard orientation questions (eg, time, place, person) have been shown to be unreliable in the sporting situation when compared with memory assessment.5,9 It is recognized, however, that abbreviated testing paradigms are designed for rapid concussion screening on the sidelines and are not meant to replace comprehensive neuropsychological testing, which should ideally be performed by trained neuropsychologists who are sensitive to subtle deficits that may exist beyond the acute episode; nor should they be used as a standalone tool for the ongoing management of sports concussions.It should also be recognized that the appearance of symptoms or cognitive deficit might be delayed several hours after a concussive episode and that concussion should be seen as an evolving injury in the acute stage.An athlete with concussion may be evaluated in the emergency room or doctor's office as a point of first contact after injury or may have been referred from another care provider. In addition to the points outlined above, the key features of this exam should encompass:In large part, the points above are included in the SCAT3 assessment.A range of additional investigations may be used to assist in the diagnosis or exclusion of injury. Conventional structural neuroimaging is typically normal in concussive injury. Given that caveat, the following suggestions are made. Brain computed tomography (CT; or where available, magnetic resonance imaging [MRI]) contributes little to concussion evaluation but should be employed whenever suspicion of an intracerebral or structural lesion (eg, skull fracture) exists. Examples of such situations may include prolonged disturbance of conscious state, focal neurological deficit, or worsening symptoms.Other imaging modalities, such as functional MRI (fMRI) demonstrate activation patterns that correlate with symptom severity and recovery in concussion.10–14 While not part of routine assessment at the present time, they nevertheless provide additional insight to pathophysiologic mechanisms. Alternative imaging technologies (eg, positron emission tomography, diffusion tensor imaging, magnetic resonance spectroscopy, functional connectivity), while demonstrating some compelling findings, are still at early stages of development and cannot be recommended other than in a research setting.Published studies, using both sophisticated force-plate technology, as well as those using less sophisticated clinical balance tests (eg, Balance Error Scoring System), have identified acute postural stability deficits lasting approximately 72 hours after sport-related concussion. It appears that postural-stability testing provides a useful tool for objectively assessing the motor domain of neurologic functioning and should be considered a reliable and valid addition to the assessment of athletes suffering from concussion, particularly where symptoms or signs indicate a balance component.15–21The significance of apolipoprotein (Apo) E4, ApoE promotor gene, tau polymerase, and other genetic markers in the management of sports concussion risk or injury outcome is unclear at this time.22,23 Evidence from human and animal studies in more severe traumatic brain injury demonstrates induction of a variety of genetic and cytokine factors, such as insulin-like growth factor-1 (IGF-1), IGF binding protein-2, fibroblast growth factor, Cu-Zn superoxide dismutase, superoxide dismutase-1 (SOD-1), nerve growth factor, glial fibrillary acidic protein (GFAP), and S-100. How such factors are affected in sporting concussion is not known at this stage.24–31 In addition, biochemical serum and cerebrospinal fluid biomarkers of brain injury (including S-100, neuron specific enolase [NSE], myelin basic protein [MBP], GFAP, tau, etc) have been proposed as means by which cellular damage may be detected if present.32–38 There is currently insufficient evidence, however, to justify the routine use of these biomarkers clinically.Different electrophysiologic recording techniques (eg, evoked response potential, cortical magnetic stimulation, and electroencephalography) have demonstrated reproducible abnormalities in the postconcussive state; however, not all studies reliably differentiated concussed athletes from controls.39–45 The clinical significance of these changes remains to be established.The application of neuropsychological (NP) testing in concussion has been shown to be of clinical value and contributes significant information in concussion evaluation.46–51 Although in most cases, cognitive recovery largely overlaps with the time course of symptom recovery, it has been demonstrated that cognitive recovery may occasionally precede or more commonly follow clinical symptom resolution, suggesting that the assessment of cognitive function should be an important component in the overall assessment of concussion and, in particular, any RTP protocol.52,53 It must be emphasized, however, that NP assessment should not be the sole basis of management decisions. Rather, it should be seen as an aid to the clinical decision-making process in conjunction with a range of assessments of different clinical domains and investigational results.It is recommended that all athletes should have a clinical neurological assessment (including assessment of their cognitive function) as part of their overall management. This will normally be done by the treating physician, often in conjunction with computerized NP screening tools.Formal NP testing is not required for all athletes; however, when this is considered necessary, then it should ideally be performed by a trained neuropsychologist. Although neuropsychologists are in the best position to interpret NP tests by virtue of their background and training, the ultimate RTP decision should remain a medical one in which a multidisciplinary approach, when possible, has been taken. In the absence of NP and other (eg, formal balance assessment) testing, a more conservative RTP approach may be appropriate.Neuropsychological testing may be used to assist RTP decisions and is typically performed when an athlete is clinically asymptomatic. However, NP assessment may add important information in the early stages after injury.54,55 There may be particular situations where testing is performed early to assist in determining aspects of management (eg, return to school in a pediatric athlete). This will normally be best determined in consultation with a trained neuropsychologist.56,57Baseline NP testing was considered by the panel and was not felt to be required as a mandatory aspect of every assessment. However, it may be helpful or add useful information to the overall interpretation of these tests. It also provides an additional educative opportunity for the physician to discuss the significance of this injury with the athlete. At present, there is insufficient evidence to recommend the widespread routine use of baseline NP testing.The cornerstone of concussion management is physical and cognitive rest until the acute symptoms resolve and then a graded program of exertion before medical clearance and RTP. The current published evidence evaluating the effect of rest after a sport-related concussion is sparse. An initial period of rest in the acute symptomatic period after injury (24–48 hours) may be of benefit. Further research to evaluate the long-term outcome of rest and the optimal amount and type of rest is needed. In the absence of evidence-based recommendations, a sensible approach involves the gradual return to school and social activities (before contact sports) in a manner that does not result in a significant exacerbation of symptoms.Low-level exercise for those who are slow to recover may be of benefit, although the optimal timing after injury for initiation of this treatment is currently unknown.As described above, the majority of injuries will recover spontaneously over several days. In these situations, it is expected that an athlete will proceed progressively through a stepwise RTP strategy.58The RTP protocol after a concussion follows a stepwise process as outlined in Table 1.With this stepwise progression, the athlete should continue to proceed to the next level if asymptomatic at the current level. Generally, each step should take 24 hours, so that an athlete would take approximately 1 week to proceed through the full rehabilitation protocol once asymptomatic at rest and with provocative exercise. If any postconcussion symptoms occur while in the stepwise program, then the patient should drop back to the previous asymptomatic level and try to progress again after a further 24-hour period of rest has passed.It was unanimously agreed that no RTP on the day of concussive injury should occur. There are data demonstrating that, at the collegiate and high school level, athletes allowed to RTP on the same day may demonstrate NP deficits postinjury that may not be evident on the sidelines and are more likely to have delayed onset of symptoms.59–65Persistent symptoms (>10 days) are reported in 10%–15% of concussions. In general, symptoms are not specific to concussion, and it is important to consider other conditions. Cases of concussion in sport where clinical recovery falls outside the expected window (ie, 10 days) should be managed in a multidisciplinary manner by health care providers with experience in sports-related concussion.Psychological approaches may have potential application in this injury, particularly with the modifiers listed below.66,67 Physicians are also encouraged to evaluate the concussed athlete for affective symptoms such as depression and anxiety, as these symptoms are common in all forms of traumatic brain injury.58Pharmacologic therapy in sports concussion may be applied in 2 distinct situations. The first of these situations is the management of specific or prolonged symptoms (eg, sleep disturbance, anxiety). The second situation is where drug therapy is used to modify the underlying pathophysiology of the condition with the aim of shortening the duration of the concussion symptoms.68 In broad terms, this approach to management should be considered only by clinicians experienced in concussion management.An important consideration in RTP is that concussed athletes should not only be symptom free but also should not be taking any pharmacologic agents or medications that may mask or modify the symptoms of concussion. Where antidepressant therapy may be commenced during the management of a concussion, the decision to RTP while still on such medication must be considered carefully by the treating clinician.Recognizing the importance of a concussion history and appreciating the fact that many athletes will not recognize all the concussions they may have suffered in the past, a detailed concussion history is of value.69–72 Such a history may pre-identify athletes who fit into a high- risk category and provides an opportunity for the health care provider to educate the athlete in regard to the significance of concussive injury. A structured concussion history should include specific questions as to previous symptoms of a concussion and length of recovery, not just the perceived number of past concussions. It is also worth noting that dependence upon the recall of concussive injuries by teammates or coaches has been demonstrated to be unreliable.69 The clinical history should also include information about all previous head, face, and cervical spine injuries, as these may also have clinical relevance. It is worth emphasizing that in the setting of maxillofacial and cervical spine injuries, coexistent concussive injuries may be missed unless specifically assessed. Questions pertaining to disproportionate effect versus symptom-severity matching may alert the clinician to a progressively increasing vulnerability to injury. As part of the clinical history, it is advised that details regarding protective equipment employed at time of injury be sought, both for recent and remote injuries.There is an additional and often unrecognized benefit of the preparticipation physical examination insofar as the evaluation allows for an educative opportunity with the player concerned as well as consideration of modification of playing behavior if required.A range of modifying factors may influence the investigation and management of concussion and, in some cases, may predict the potential for prolonged or persistent symptoms. However, in some cases, the evidence for their efficacy is limited. These modifiers would be important to consider in a detailed concussion history and are outlined in Table 2.The role of female sex as a possible modifier in the management of concussion was discussed at length by the panel. There was not unanimous agreement that the current published research evidence is conclusive enough for this to be included as a modifying factor, although it was accepted that sex may be a risk factor for injury or influence injury severity (or both).73–75In the overall management of moderate to severe traumatic brain injury, duration of loss of consciousness (LOC) is an acknowledged predictor of outcome.76 While published findings in concussion describe LOC associated with specific early cognitive deficits, it has not been noted as a measure of injury severity.77,78 Consensus discussion determined that prolonged (>1-minute duration) LOC would be considered as a factor that may modify management.There is renewed interest in the role of posttraumatic amnesia and its role as a surrogate measure of injury severity.64,79,80 Published evidence suggests that the nature, burden, and duration of the clinical postconcussive symptoms may be more important than the presence or duration of amnesia alone.77,81,82 Further, it must be noted that retrograde amnesia varies with the time of measurement postinjury and hence is poorly reflective of injury severity.83,84A variety of immediate motor phenomena (eg, tonic posturing) or convulsive movements may accompany a concussion. Although dramatic, these clinical features are generally benign and require no specific management beyond the standard treatment of the underlying concussive injury.85,86Mental health issues as have been reported as a of all of traumatic brain injury, including sports-related concussion. studies using that a after concussion may an underlying pathophysiological with a of While such health issues may be in nature, it is recommended that the treating physician consider these issues in the management of concussed evaluation and management recommendations can be applied to children and to the of that children concussion symptoms different from and would require symptom as a component of assessment. An additional consideration in assessing the or athlete with a concussion is that the clinical evaluation by the health care professional may to include both patient and and and school when A SCAT3 has been developed to assess concussion for those decision to use NP testing is the same as the assessment although there are some of testing may in to assist in school and management. If cognitive testing is then it must be sensitive until to the ongoing cognitive that during this period in the of to the baseline or to In this it is more important to consider the use of trained pediatric neuropsychologists to interpret assessment particularly in children with or who may more sophisticated assessment was agreed by the panel that no return to sport or should occur before the or athlete has managed to return to school In addition, the of was with to a to exertion with activities of that may symptoms. and activities may also to be to of symptoms. should not be to sport until clinically symptom which may require a longer timeframe than for of the different response and longer recovery after concussion and specific (eg, related to head during and a more conservative RTP approach is It is appropriate to the amount of time of asymptomatic rest or the length of the graded exertion in children and It is not appropriate for a or athlete with concussion to RTP on the same day as the injury, of the level of Concussion modifiers more to this than and may more RTP athletes, of level of should be managed using the same treatment and RTP The and in concussion evaluation are of more importance in determining management than a separation and athlete management. Although formal NP testing may be beyond the of many sports or it is recommended that, in all sports, consideration be to this cognitive evaluation, of the or level of to be of the potential for long-term in the management of all athletes. 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