Version May 2024
INTRODUCTION — Concern over the effects of mild traumatic brain injury, or concussion, sustained during sport has grown substantially in recent decades. While the effects of sports-related concussions (SRCs) are usually benign and self-limited, medium and long-term sequelae have been described [1,2], and careful evaluation is needed.
This topic reviews the risks, prevention, and evaluation of concussion sustained by adolescents and adults while participating in athletic activities and whose initial medical evaluation reveals no sign of other significant structural injury such as intracranial hemorrhage, skull fracture, or cervical spine injury. The initial assessment and management of patients with significant head or other trauma are not discussed here. The treatment of older adolescents and adults with an SRC, and all other aspects of head trauma and brain injury, are reviewed separately:
●Clinic-based management of SRC (see "Clinic-based management of sports-related concussion in adolescents and adults")
●Trauma assessment (see "Initial management of trauma in adults" and "Trauma management: Approach to the unstable child")
●Traumatic brain injury in adults (see "Acute mild traumatic brain injury (concussion) in adults" and "Sequelae of mild traumatic brain injury" and "Management of acute moderate and severe traumatic brain injury")
●Children with concussion (see "Concussion in children and adolescents: Clinical manifestations and diagnosis" and "Concussion in children and adolescents: Management")
●Sports-related injury (see "Sideline evaluation of concussion" and "Evaluation of the collapsed adult athlete")
DEFINITION — A concussion is a complex, trauma-induced pathophysiological process affecting the brain. Further discussion of the definitions and pathophysiology associated with concussion is provided separately. (See "Sideline evaluation of concussion", section on 'Definition' and "Acute mild traumatic brain injury (concussion) in adults", section on 'Pathophysiology'.)
EPIDEMIOLOGY — The epidemiology of mild traumatic brain injury in general (including concussion) is discussed separately; specific information about the epidemiology of sports-related concussion (SRC) is provided below. (See "Acute mild traumatic brain injury (concussion) in adults", section on 'Epidemiology' and "Concussion in children and adolescents: Clinical manifestations and diagnosis", section on 'Epidemiology'.)
Each season, among athletes participating in organized sports, 2 to 15 percent experience SRC [3]. A 2020 systemic review of studies from multiple countries reported that sports-related traumatic brain injury (including SRC) comprised one-third of all traumatic brain injuries, and the incidence was highest among adolescents and young adults [4]. In a 2016 report using data from visits to United States emergency departments and clinics, and a high school injury surveillance system, researchers estimated that 1 to 1.8 million SRCs occur each year among children and adolescents 0 to 18 years old, with approximately 400,000 of these occurring in high school athletes [5].
Determining precise estimates of SRC incidence is challenging due to the varied settings where they occur; disparities in recognition skills among athletes, coaches, and parents/guardians; lack of uniform reporting; and variations across age, sex, sport, and level of competition [6]. While the incidence appears to be increasing, this may be due to higher reporting rates and improved knowledge among SRC stakeholders [6,7].
Not surprisingly, SRC rates are highest in contact and combat sports (figure 1) [8-10]. However, SRC occurs in nearly all sports and sometimes in training activities not directly related to sport participation (eg, weight room accidents) [8]. A meta-analysis of 83 international studies of various levels of sports participation published between 2001 and 2019 reports rugby to have the highest rate of SRC (28.25/10,000 athlete exposures) of any organized team sport [9]. Wrestling, ice hockey, and American football were classified as having medium risk, while relatively low-risk sports included football (soccer) and field hockey. Rates of SRC in non-team sports are less frequently reported, but a 2020 systematic review of 11 studies of sports-related traumatic brain injury reported annual rates per 100,000 participants [4].
Within particular sports, risk can vary significantly by activity, position, and types of play. A video analysis of National Football League (NFL) games during the 2015 to 2016 and 2016 to 2017 seasons found that cornerbacks sustained SRCs most often, followed by wide receivers, linebackers, and offensive linemen [11]. Across all sports, competitions are associated with significantly greater risk per athlete exposure than practices [9]. As an example, in rugby league and rugby union, the incidence of match-related SRCs exceeds that in training [12,13]. However, when considering the total number (as opposed to rate) of SRCs, in certain sports, practices (in particular, preseason training camp practices for American football) surpass games [14].
RISK FACTORS — The authors consider two sets of risk factors for sports-related concussion (SRC): general risk factors for sustaining any concussion and risk factors for sustaining a severe concussion (table 1).
General risk factors for sustaining a concussion — Potential factors associated with increased susceptibility for sustaining an SRC include the following:
●Previous concussion – According to prospective studies involving thousands of athletes, a prior concussion increases the risk for recurrent SRC and for prolonged recovery following such injury [15-18]. Data from the CARE Consortium (cohort of 10,604 military cadets) suggest that a previous concussion nearly doubled the risk of subsequent concussion (OR 1.98, 95% CI 1.73-2.01) [19]. Patients with unresolved symptoms from a prior injury are at greatest risk; recurrent injury is most likely to occur within the first 10 days after the initial injury [15,20-26].
●Age – The developing brain may be more susceptible to concussion. According to small observational studies, prepubescent athletes take longer to recover from a concussion [27-29]. While data are limited, the prevailing opinion among experts is that the increased risk of sustaining a concussion among younger athletes is more closely related to their stage of development than their chronologic age, with athletes who have yet to complete puberty being at higher risk [29]. There is additional observational evidence that teenagers may be most vulnerable to more severe concussion (higher symptom burden and persistent symptoms following an SRC) [30,31].
●Higher-risk sports – Combat sports (eg, boxing, mixed martial arts) and collision sports (eg, rugby, Australian football, American football, ice hockey, and boys' and men's lacrosse) have the highest concussion rates [9,17,32-36]. However, participants in girls' and women's soccer suffer among the highest number of concussions (in part due to the large number of participants).
●Sex – Some evidence suggests that females sustain more concussions than their male counterparts when playing the same sport under similar rules, with examples cited in soccer, basketball, lacrosse, and ice hockey. Data from the CARE Consortium reported that females had a significantly higher risk of SRC relative to their male counterparts (OR 1.38, 95% CI 1.07-1.78) [19]. The reasons for this discrepancy remain unclear but are likely multifactorial and may include relative neck muscle weakness, hormonal differences, style of play or coaching differences, and greater willingness to report symptoms [32,36-42].
While multiple earlier studies reported that females tend to have a higher symptom burden at the time of injury and during evaluation and take longer to recover from SRC than male counterparts [43,44], data from over 1000 concussions among United States college athletes reported by the CARE Consortium found no difference in recovery times between sexes [45]. Subsequent large, prospective cohort studies of college-aged athletes found no effect of sex on recovery [45,46]. Average days until athletes were able to return to exertion, remain symptom free, and return to full sport were the same in four sex-comparable sports (basketball, soccer, water polo, and rugby) [19,47].
●Impact density – Less time between multiple impacts may lower the threshold for concussion. In other words, sustaining multiple blows, particularly within 24 to 48 hours, and not just the magnitude of one particular impact, may increase concussion risk [48].
●Other factors – Many experts believe that the conditions listed below may increase risk by "lowering the threshold" for concussion. However, evidence is scant, and the purported role of these factors should be considered speculative:
•Dehydration
•Fatigue and sleep deprivation
•Concurrent illness involving fever or some other challenge/insult to the central nervous system
Risk factors for more severe concussion — For the purposes of this discussion, the severity of an SRC is determined by the initial symptom burden, duration of symptoms, and time to resolution and full medical clearance for return to sport. Multiple potential risk factors for more severe concussion have been described (table 1). These can be divided into "intrinsic" and "injury-specific" factors, as described below. Recognizing these factors can help clinicians with decision-making, patient counseling, and management.
Intrinsic risk factors — Factors intrinsic to the patient (ie, unrelated to the injury) that are associated with protracted recovery and a higher symptom burden include the following:
●Age – In general, prepubescent patients take longer to recover from concussions. Age and sex as risk factors for SRC are discussed above. (See 'General risk factors for sustaining a concussion' above.)
●Past medical history – Several medical conditions are associated with longer recovery following an SRC. However, these associations are drawn from limited evidence in many cases. Associated conditions include:
•Prior concussion(s) with protracted recovery
•History of vestibular dysfunction and motion sickness [49,50]
•History of ocular/oculomotor dysfunction
•Migraine, including personal or family history [19,43]
•Psychiatric comorbidities, including depression, anxiety, bipolar disorder, mood disorders, and post-traumatic stress disorder [43,44]
•Seizure disorder
Evidence about the relationship between SRC and learning disabilities and attention-deficit hyperactivity disorder (ADHD) is mixed. While some researchers believe that such conditions may be associated with prolonged recovery [51], a 2017 systematic review of 101 studies assessing factors associated with recovery from concussion found no such association, while noting large heterogeneity among the included articles [30,47,52-55]. Subsequently, a large, prospective cohort study of United States collegiate athletes found that male athletes (OR 1.47, 95% CI 1.20-1.81) and contact sport athletes (OR 1.40, 95% CI 1.16-1.70) previously diagnosed with ADHD experienced higher rates of SRC [56].
Injury-specific risk factors — Injury-specific risk factors for protracted recovery and a higher symptom burden fall into three general categories: injury mechanism, behaviors and symptoms immediately following injury, and specific findings identified by history and examination during the initial presentation.
●High-risk mechanisms – The relationship between mechanisms of injury and concussion risk is the subject of ongoing research and debate [57-61]. Nevertheless, we believe the mechanism is important, particularly when a reliable history or a video of the event is available.
•Double hit – Although high-quality evidence is lacking, in the authors' experience, a "double-hit" impact often leads to more severe injury. An example of such an impact might involve an ice hockey player who is checked by an opponent whose shoulder strikes the player's head (first hit), followed immediately by a fall in which the checked player's head strikes the ice (second hit).
•Rotational forces – Shearing forces from a rotational blow to the head are associated with an increased likelihood of SRC and often more severe dysfunction with prolonged recovery [62-64]. An example would be an American football player spun forcefully to the turf, causing the occiput to strike the ground as it is moving in an arc.
●Continued participation after initial injury/symptoms – Ongoing participation or play after sustaining an SRC (often unreported or unrecognized) may result in increased symptom burden and longer recovery [47,52,65,66].
Several observational studies have found that continued play in the immediate aftermath of an SRC can dramatically increase recovery times, typically on the order of doubling the time required for clearance to return to sport [52,65,67,68]. Further, continued participation or premature return (athletes with unresolved symptoms or impairment) has been implicated in second impact syndrome (SIS), a rare but often fatal neurologic injury described in pediatric and adolescent athletes [69]. (See "Sequelae of mild traumatic brain injury", section on 'Second impact syndrome' and "Concussion in children and adolescents: Management", section on 'Second impact syndrome'.)
●Delayed or no evaluation – Delayed presentation for evaluation is associated with protracted recovery and higher symptom burden. Ideally, athletes are evaluated and treated for SRC within a few days of the inciting injury. Neurocognitive test scores are lower among athletes who have sustained one or more previously undiagnosed concussions, suggesting possible long-term harm when SRC is not diagnosed promptly and managed appropriately [70]. There is a growing body of data, and strong consensus amongst experts, that early assessment and initiation of treatment can reduce the duration of symptoms and symptom burden [71].
●High early symptom burden – In a 2017 systematic review of over 100 articles related to recovery from SRC, the most consistent predictor of prolonged recovery was the severity of acute and subacute symptoms [30].
●Vestibular dysfunction – Vestibular dysfunction noted on initial examination and symptom checklist (particularly on-field "dizziness" and in-office "fogginess") may be associated with longer recovery times. Active treatment of vestibular dysfunction may shorten recovery [72]. (See 'Vestibular' below.)
PREVENTION AND PLANNING — The prevention of sports-related concussion (SRC) is of paramount importance and has a greater impact on reducing morbidity than treatment. A variety of interventions have been deployed to reduce the incidence and severity of SRC. Areas of focus include education and awareness campaigns, rule changes and enforcement of existing rules to prevent concussion, improvements in equipment, and changes in sports culture, coaching, and technique.
Education, awareness, and recognition — Education and awareness of activities and techniques associated with a high risk for SRC are the first steps in reducing concussion incidence [73]. If an injury does occur, mitigation of symptom burden and duration begins with prompt recognition of the potential injury. It is imperative to identify a potential concussion and remove the individual from activities that entail risk of further head trauma. This responsibility is shared among the injured athlete, teammates, coaches, parents/guardians, and medical staff. Accordingly, it is important to raise awareness among all parties about the symptoms and risks associated with concussion.
Concussion education and awareness resources favored by the authors include:
●BokSmart (South Africa; compulsory for anyone coaching or officiating rugby at any level) [74]
●RugbySmart (New Zealand) [75]
●SHRed (Canada)
●TeachAids CrashCourse (United States) [76]
●Centers for Disease Control and Prevention (CDC) HEADS UP (United States) [77]
●National Collegiate Athletic Association (NCAA) fact sheets for athletes and coaches (United States) [78]
●Heads-up football (United States) [79-82]
Clinicians should promote awareness among coaches, referees, parents, players, and other interested parties of the Concussion Recognition Tool 6 (CRT6), which is available for free.
Changes in rules and culture — To reduce the incidence of SRC, technique and instruction across sports should emphasize avoiding trauma sustained by or inflicted with the head. While repetitive head trauma continues to be relatively common in contact and collision sports such as rugby, American football, ice hockey, lacrosse, martial arts, boxing, and soccer, many sports bodies are acting to minimize such trauma. This has been addressed with a variety of rule changes from professional leagues to youth sports. One example is banning body checking in youth hockey. Studies of youth hockey leagues implementing such rule changes report substantial reductions in concussion rates. (See "Concussion in children and adolescents: Management", section on 'Prevention'.)
The National Football League (NFL) in the United States has made changes to rules, emphasizing player safety. As an example, in 2009, the return-to-play-from-concussion guideline was amended, and blows to the head of a defenseless receiver were prohibited. During the 2010 NFL season, there was increased discipline (increased enforcement, large fines, and possible suspensions) for helmet-to-helmet contact in violation of player safety rules and a change where the ball is immediately blown dead if a ball-carrier's helmet comes off during play. International rugby has taken a strong stand against high tackles and has guided referees to impose harsher sanctions on players making illegal tackles, including ones above shoulder height.
Repetitive head trauma below the threshold of concussion ("sub-concussive blows") may increase susceptibility for SRC, and evidence is growing that limiting contact, particularly head contact, during sports practice is valuable in this regard. Decreasing the number of contact practices and eliminating or decreasing the time spent in high-risk drills reduces head impacts and sub-concussive blows [73,83]. This approach has been associated with reductions in the rate of SRC (and other injuries) at youth, high school, college, and professional levels. Strategies limiting contact practices among secondary school American football teams are associated with a 64 percent reduction in the overall rate of practice-related concussions [84,85].
Attempts to change the culture and coaching of contact and collision sports are ongoing. Coaching mantras such as "don't hit the head, don't use the head" have become more common, and certain high-risk activities, such as kickoffs in football, heading the ball in youth soccer, and fighting in hockey, have been eliminated in some leagues.
Equipment
Helmets — Helmets help to prevent skull trauma and intracranial macrotrauma (including hemorrhage) but have not been proven to prevent concussions. In a systematic review of eight studies of youth rugby and football (soccer), use of soft-shell headgear was not associated with reduced rates of SRC or superficial head injury [86]. However, there is inconsistency among studies. In a large observational study of high school girls' lacrosse players, use of headgear was associated with a significant difference in SRC (25 versus 116 concussions) over three seasons [87]. Another observational study of over 3200 male, nonprofessional rugby players reported significantly lower concussion rates among players who consistently wore protective headgear during matches [21]. Nevertheless, these observational studies leave open the possibility that the observed effects associated with voluntary use of a helmet are the result of general risk-avoidant behavior rather than the helmet itself.
Appropriate helmet fit helps to reduce the incidence of concussion. The results of laboratory biomechanical studies of American football, hockey, and bicycle helmets and a variety of other sports-related protective headgear are available to clinicians and consumers, including in the following references [88-91].
Mouthguards — We strongly advocate the use of mouthguards in collision sports given the potential concussion protection, in addition to well-established dental and orofacial protection. Available evidence suggests that mouthguards reduce the risk of SRC. In a systematic review and meta-analysis of 192 studies of interventions to reduce the risk for SRC, mouthguards were associated with a 28 percent reduction of SRC in ice hockey and a 26 percent reduction in collision sports overall (IRR 0.74, 95% CI 0.64-0.89) [92].
Other devices — A novel collar device worn during play that purportedly reduces the effects of head impact has been approved by the US Food and Drug Administration (FDA). The premise for this collar is research suggesting that compression of the internal jugular vein causes increases in the volume of intracranial blood vessels, which may cushion the brain and prevent excessive movement during impact [93]. Evidence is insufficient to determine whether use of such devices can reduce the risk of sports-related brain injury [92].
Training and conditioning strategies. — Neuromuscular warm-up programs that include exercises for strength, balance, and proper movement are associated with reductions in the rate of SRC in rugby [92]. Research to date has been limited to male athletes. While evidence is limited, we advocate using neuromuscular warm-up programs for sports where SRC is a concern. The focus of such warm-ups is on strength, balance, body awareness and proprioception, and sound movement technique (eg, cutting, landing).
Stronger neck muscles may mitigate the effects of head impacts sustained in sports-related collisions, although evidence overall is mixed [94,95]. In a prospective study of over 6700 high school athletes (soccer, basketball, lacrosse), researchers found a significant association between poor neck strength and concussion [96]. A study of 225 professional rugby players reported a similar association [97].
General health, nutrition, and related measures — While there are no strong data, the authors believe that general wellness measures, specifically hydration, adequate sleep and recovery, and good nutrition, likely raise the threshold for sustaining an SRC. There is no compelling evidence that any nutritional supplement reduces risk. (See "Nutritional and non-medication supplements permitted for performance enhancement".)
Baseline testing — Many organizations recommend formal neurocognitive testing to establish a functional baseline and to assist with diagnosis and return-to-play decisions in athletes. We believe such testing may be useful but is not required for the evaluation of SRC [98]. Baseline testing in children and adolescent athletes is discussed in detail separately. (See "Concussion in children and adolescents: Clinical manifestations and diagnosis", section on 'Preparticipation assessment'.)
Ideally, baseline SRC testing is performed as part of a multimodal approach that includes the following:
●Symptom checklist
●Cognitive evaluation
●Formal testing of balance and vestibular/ocular motor function
SRC baseline testing programs can increase concussion awareness and may help to identify previously unknown deficits that may put an athlete at increased risk for injury or impair performance (eg, vestibular deficits, ocular motor dysfunction, visual deficits, mood disorders). However, testing can be costly and has inherent limitations. Test results can be affected by athlete effort and motivation, the testing environment, and normal developmental changes in the young brain that occur between the time of baseline testing and post-injury testing. An athlete's results may improve purely from learning about the test during repeat administration.
ACUTE EVALUATION OF ATHLETE WITH SUSPECTED CONCUSSION — Any athlete thought to have a concussion should be removed from play immediately. The safest and best approach when an athlete's status is unclear is to assume they are concussed. Any athlete with a clear or possible concussion should be restricted from any further play or practice and reassessed by a clinician familiar with sports-related concussion (SRC) within 48 hours of the injury. Failure to appreciate a potential concussion may result in further damage and protracted recovery [67,99].
Athletes who sustain significant head trauma must be carefully examined for possible intracranial and cervical injury in addition to possible SRC:
●Sideline assessment of the athlete with a possible SRC is discussed in detail separately. (See "Sideline evaluation of concussion".)
●Acute assessment of the patient with mild traumatic brain injury, including clinical evaluation and determinations about the need for diagnostic imaging and hospital admission, is discussed in detail separately. (See "Acute mild traumatic brain injury (concussion) in adults".)
Updated tools for the acute evaluation of SRC include the Sport Concussion Assessment Tool 6 (SCAT6), which was developed as part of the 6th International Conference on Concussion in Sport (Amsterdam 2022) [73,100].
CONCUSSION SYMPTOM CATEGORIES (CLINICAL DOMAINS)
Classification and terminology — Some sports medicine concussion specialists and specialty clinics have begun to apply classification schemes for sports-related concussion (SRC). The authors have found this approach to be useful for evaluating patients, tailoring treatment, and gauging prognosis [98,101-103]. The concept aligns with recommended multimodal clinical evaluation guidelines [104], as included in the newly developed Sport Concussion Office Assessment Tool 6 (SCOAT6), an important production from the 6th International Conference on Concussion in Sport (Amsterdam 2022) [73]. The SCOAT6, for use in athletes 13 years and older, is a multimodal clinical management tool to be used in the serial evaluation of athletes after an SRC and is aimed at assisting clinicians in an office-based environment [105]. Application of the SCOAT6 requires clinical expertise and provides for flexible application depending on the clinical context and time constraints.
For the purposes of clarifying the concept of multimodal assessment, we use the term "clinical domains" to describe categories of related history and findings caused by an SRC. Synonymous terms include concussion "subtypes," "clinical profiles," and "clinical trajectories." These terms are used to describe a constellation of findings, including medical history, symptoms, examination findings, and neurocognitive deficits, that are used to define an injury pattern.
Several models for the clinical domains of SRC have been proposed [98,101-103,106]. A model from the American Medical Society for Sports Medicine is found in the following reference [98]. The most common domains described in the literature are detailed below and listed here:
●Cognitive
●Headache/migraine
●Ocular/oculomotor
●Vestibular
●Mood/anxiety
●Sleep disturbance/fatigue
●Cervical/cervicogenic
It is important to note that most SRCs involve simultaneous impairment in multiple clinical domains and that the above list is not exhaustive. Some clinicians describe autonomic dysfunction as an important clinical physiologic subtype [106], while others prefer to describe cervical/cervicogenic and sleep disturbance as modifiers rather than stand-alone domains [101,102].
Cognitive — The cognitive domain involves impairment of cognition, including attention, concentration, reaction time, processing speed and performance, working memory, new learning, memory storage and retrieval, and organization of thoughts and behavior [101-103]. It is defined by self-reported symptoms and findings on neurocognitive testing (if performed). This is the most common clinical domain in adults and is more common in males [102]. Clinically, this domain is commonly seen when patients try to "push through" symptoms. It can be associated with a history of attention-deficit hyperactivity disorder (ADHD) and learning disabilities. Management of the cognitive effects of an SRC is discussed separately. (See "Clinic-based management of sports-related concussion in adolescents and adults", section on 'Treatment'.)
●Symptoms – Difficulty concentrating, focusing, and staying on task; fatigue; worsening symptoms at end of day; feeling slowed down; diffuse general headache, typically developing over the course the day.
●Examination findings – Deficits with neurocognitive testing and with assessments of recall, memory, and attention.
Headache and migraine — This domain is characterized by headache, often a migraine, and is often accompanied by a prodrome or aura and symptoms such as photophobia, phonophobia, or nausea. This is the most common domain for children and the most common domain experienced acutely (first three days) by adults and children [102]. Patients with a history of migraine are at increased risk. Inappropriately treated vestibular dysfunction can trigger migraines in SRC patients. (See "Post-traumatic headache".)
●Symptoms – Severe headache (often upon waking), nausea, photophobia, phonophobia, motion sensitivity, high symptom scores, self-medicating for headaches.
●Examination findings – Light-sensitivity, motion sensitivity.
Ocular/oculomotor — This domain involves impairment of the visual system, which may include both decrements in visual acuity and problems with oculomotor function. Visual acuity deficits often manifest as difficulty obtaining, processing, and responding to visual stimuli (images and colors). Oculomotor dysfunction involves impairment of the motor function of the eye, which can manifest as difficulty with tracking (objects, words, images), convergence and divergence, accommodation, and focus. The manifestations of cognitive and ocular dysfunction may overlap (eg, difficulty reading). (See "Sequelae of mild traumatic brain injury", section on 'Convergence insufficiency'.)
●Symptoms – Difficulty with visual activities (eg, using computer or cell phone screens, reading printed material, near work, writing, driving), eye strain and fatigue, problems with visual focus (including transitioning from near to far), photophobia, blurred vision, double vision, frontal headaches, eye pain/pressure, nausea, exacerbation of premorbid visual impairment, difficulty gauging distances, and feeling overwhelmed by environments with multiple stimuli.
●Examination findings – Slow/dyskinetic/fatigable saccadic eye movements during testing of extraocular motion, impaired accommodation, impaired convergence, esotropia/exotropia.
Specific treatment may include oculomotor rehabilitation and visual accommodations (eg, limiting screen time, allowing for audio participation preferentially over visual). (See "Clinic-based management of sports-related concussion in adolescents and adults", section on 'Ocular or vestibular dysfunction'.)
Vestibular — This domain involves impairment of the central vestibular system, leading to symptoms and dysfunction with movement and difficulty orientating the body in space. It involves dysfunction of the vestibulo-ocular, vestibulo-spinal, and oculomotor systems and gait. Vestibular dysfunction can provoke or exacerbate anxiety. (See "Sequelae of mild traumatic brain injury", section on 'Posttraumatic vertigo and dizziness'.)
●Symptoms – Dizziness, fogginess, lightheadedness, nausea, and disequilibrium. Symptoms are typically worse with dynamic movement and in busy environments. Untreated, patients can develop migraine-like symptoms, and recovery can be prolonged.
●Examination findings – Symptoms provoked by movement of the head, eye, or body.
Specific treatment includes vestibular rehabilitation exercises. (See "Clinic-based management of sports-related concussion in adolescents and adults", section on 'Ocular or vestibular dysfunction'.)
Mood/anxiety — This domain is characterized by increased anxiety and mood-related symptoms. It is common in patients with a history or predisposition to anxiety or other mood disorders. Symptoms are often exacerbated by inactivity or delayed presentation, and patients often present with a high symptom burden. Disturbed sleep is common.
●Symptoms – Often high symptom burden, including one or more of the following: nervousness, hypervigilance, feelings of being overwhelmed, sadness, feelings of hopelessness, increased emotionality, anger, hostility/irritability, loss of energy, fatigue.
●Examination findings – Emotionally labile; relatively normal objective neurocognitive testing.
Specific treatment can include counseling, psychotherapy, and pharmacotherapy. (See "Clinic-based management of sports-related concussion in adolescents and adults", section on 'Mood disorders and anxiety'.)
Sleep disturbance/fatigue — Sleep dysfunction is common with SRC [107]. (See "Sleep-wake disorders in patients with traumatic brain injury".)
●Symptoms – Problems falling asleep, problems staying asleep, disrupted/abnormal bedtime or awakening times, sleeping too much, sleeping too little, persistent fatigue.
●Examination findings – No specific findings.
Specific treatment in most cases includes education about proper sleep hygiene and possibly pharmacotherapy in more difficult cases. (See "Clinic-based management of sports-related concussion in adolescents and adults", section on 'Sleep disturbances'.)
Cervical/cervicogenic — Debate about whether this is a type of SRC or an associated injury is ongoing. This domain is characterized by symptoms and dysfunction from cervical injury (often cervical strain or muscle spasm).
●Symptoms – Neck pain, neck stiffness, decreased neck mobility, headache focused in occipital/suboccipital/cervical region.
●Examination findings – Decreased or painful cervical range of motion testing; tenderness and spasm at cervical paraspinal, occipital, suboccipital, and superior trapezius muscles. It is important to perform a thorough examination to exclude more serious pathology, including occult spine fracture and nerve impingement.
CLINIC EVALUATION
Overview and tools for performing evaluation — To capture all the symptoms and physical findings a patient may be experiencing from a sports-related concussion (SRC), the assessment should be performed in a systematic fashion. Tables and other tools to assist the examiner with each portion of the assessment are provided here:
●SRC history and examination checklist (table 2)
●Patient demographics and general information (table 3)
●History of acute and past head injury (table 4)
●Patient and family history of neurological and psychological conditions (table 5)
●Domain-based symptom assessment (table 6)
●General and head-neck examination (table 7)
●Neurologic examination (table 8)
●Posture and balance assessment (picture 1 and table 9)
●Vestibular and oculomotor screening (VOMS) (table 10)
●Memory and concentration testing (table 11)
The Sport Concussion Office Assessment Tool 6 (SCOAT6) is a comprehensive clinical assessment tool developed as part of the 6th International Conference on Concussion in Sport [73].
Preparation — The assessment of a potentially concussed athlete remains largely clinical given the absence of objective measures that are well studied and widely accepted. While tests for evaluating different aspects of brain function are available, comprehensive protocols to guide the diagnosis and management of the concussed athlete are lacking (although abbreviated clinical protocols have been described [108-110]).
Clinical teams likely to be caring for concussed athletes should prepare beforehand. Clinicians should be educated about mechanisms of injury, signs and symptoms, institutional protocols, and possible consequences of mismanagement [111]. Most concussions are managed primarily by primary care and sports medicine clinicians. Ideally, a multidisciplinary team should be available to manage aspects and potential complications when needed. This multidisciplinary team can include:
●Primary care and sports medicine clinicians
●Athletic trainers
●Physical therapists
●Neurologists
●Neuropsychologists and clinical psychologists
●Ophthalmologists and optometrists
●Otolaryngologists
●Psychiatrists
●Neurosurgeons
Additional help is often needed from the patient's family, friends, coaches, and academic support services.
Information about both normative and individual preinjury baseline function can be useful for assessing the athlete's status following an SRC [112]. This includes previous medical history (including any prior brain injury), school performance, neurocognitive assessments (including prior computerized testing), and other performance data such as assessments of eye tracking, balance, and vestibular function. Information from any sideline evaluation that was performed can be extremely helpful. (See "Sideline evaluation of concussion".)
Evaluation setting and equipment — The setting for the clinic examination should be a quiet, private office and examination room. It is best for as few people as possible to be present. In the case of minors, a parent/guardian may be present for the history but may be a distraction during the examination, and their presence could compromise accuracy.
The following equipment is useful:
●Chairs (examiner, patient, parent/guardian)
●Examination table
●Sphygmomanometer
●Flashlight
●Ophthalmoscope
●Snellen chart (figure 2 and picture 2)
●Stopwatch (for assessments with time component)
●Pins (for sensation assessment)
●3-meter line (for tandem gait assessment)
●Tape measure (for convergence measurement)
●Reflex hammer, ideally with ruler on handle
●512-Hz tuning fork
●Metronome (available as a phone app; for VOMS)
●Tongue depressor (or similar) with letter in newspaper-sized font (ie, size 9 or 10 font) glued to top or a commercially available product such as the Bernell Fixation Stick (for vision assessment) (picture 3)
Initial clinic evaluation — Often, the first thorough evaluation of an athlete with a suspected SRC is performed in an office or clinic a few days following the injury. The office evaluation should be sufficiently detailed to detect all potential presentations while allowing the clinician to focus on the clinical domains most severely affected [108,113]. Increasingly, research supports, and the authors recommend, a multimodal approach as outlined below [114,115].
Initial evaluation involves:
●Screening – Identify symptoms and signs from other conditions (eg, cervical spine injury) and distinguish these from symptoms and signs stemming from concussion.
●Evaluation – Assess all clinical domains potentially affected by SRC.
●Management – Initiate therapy based on the clinical domains affected and any comorbidities. Provide guidance about returning to school or work, driving, sport, and social life.
●Referral – Refer patient to appropriate specialists for diagnosis, treatment, and rehabilitation as indicated [116].
These goals are best achieved using a methodical approach that includes evaluation of all the clinical domains potentially affected by an SRC, including cognitive, headache and migraine, ocular, vestibular, mood, and sleep. (See 'Concussion symptom categories (clinical domains)' above.)
A brief, domain-based concussion evaluation tool, the Buffalo Concussion Physical Examination (BCPE) [117], has been described, and preliminary evidence suggests it is effective for detecting concussion, establishing recovery [108], and predicting risk of delayed recovery [118].
While the new Sport Concussion Assessment Tool 6 (SCAT6) is the appropriate tool for fieldside assessment of acute concussion (<72 hours), it does not include assessment of all domains that may present in a subacute setting (eg, VOMS is omitted) and may miss important concussion-related symptoms and signs if used beyond three days post-injury [119]. However, baseline material recorded on the SCAT, including preinjury information and a recent fieldside SCAT6, may be useful for assessing the evolution of symptoms and signs. (See "Sideline evaluation of concussion", section on 'Assessment instruments'.)
Bearing in mind the wide overlap between concussion and other conditions, the potential exacerbation of comorbidities by a head injury, and the potential for prolonged recovery in some cases, a comprehensive initial evaluation is warranted.
History and symptom assessment — The clinician should obtain a history and perform a systematic review of symptoms in each clinical domain potentially involved in an SRC. These domains are described above. (See 'Concussion symptom categories (clinical domains)' above.)
Should the initial evaluation detect symptoms or signs associated with a specific domain, further investigation is needed. Clinicians with expertise evaluating such problems can perform the workup themselves. If not, the patient should be referred to an appropriate specialist.
The initial assessment should include the following:
Demographic information — Basic demographic and historical information should be noted. A sample form for such information is provided (table 3), but clinicians and institutions may need to modify the questions included.
History of current injury — The clinician should note the date and time of the most recent injury and gather as much detail as possible about the mechanism of injury, how the player was managed on the field, and immediate subsequent events (table 4). Game video is useful when available.
Head injury history — The most significant risk factor for concussion is a prior concussion [120]. The recovery from any previous concussions and their management may affect subsequent risk for concussion and possibly musculoskeletal injury [121]. Hence, it is important to gather as much information as is available about the mechanisms of prior head injuries (eg, struck by another player, direct or indirect force to the head), acute presentation (eg, loss of consciousness, retrograde or anterograde amnesia, loss of balance), most prominent symptoms (eg, headache, sleep disturbances, vision problems), management, and any persistent effects (table 4).
Comorbidities and modifying factors — In addition to prior concussion, several medical and psychological conditions affect both predisposition to concussion and duration of recovery. The patient's past and present comorbidities should be noted. The risk factors for concussion are reviewed above. (See 'Risk factors' above.)
Other items that may affect symptoms and are important to note include:
●Situational and life stressors
●Past and current medications
●Family history of relevant medical (eg, migraine) and psychological (eg, depression) conditions (table 5)
Symptom assessment — The following table can be used to guide symptom assessment:
●Domain-based symptom assessment (table 6)
The number and severity of symptoms are important prognostic indicators for concussion recovery [122]. Moreover, certain initial symptoms are associated with specific outcomes [123]. As an example, higher somatic (physical) symptom scores predict that symptoms will be more easily provoked during VOMS [124], while headache predicts some degree of cognitive impairment [125].
In addition, many concussion symptoms overlap with those of other conditions, such as headache disorders, depression, anxiety, and learning disabilities [126]. An important challenge for the clinician is to distinguish symptoms caused by the SRC from those due to underlying comorbidities (eg, migraine, attention-deficit hyperactivity disorder [ADHD]). Symptoms of these chronic conditions may be exacerbated by the traumatic brain injury and require additional interventions such as adjusting medications and physical therapy.
Structured methods for recording symptoms are more accurate than "open" methods [127]. Documentation of the athlete's symptoms using a Likert scale of zero (none) to six (most severe) allows for comparison with symptoms recorded at the time of injury and subsequently during recovery. A table to assist with assessment and documentation is provided (table 6).
Grouping symptoms by clinical domain enables the clinician to see which areas need further evaluation. For instance, high scores in the mood domain can be assessed in greater detail with anxiety or depression questionnaires, while high scores in the cognitive domain can be assessed with a detailed neuropsychologic evaluation.
Abbreviated symptom checklists such as the Concussion Symptom Inventory have been suggested as being effective without compromising sensitivity or specificity [128]. This is a useful template, especially for clinicians with less experience in managing SRCs. A similar checklist is available in the following table (table 12). It is important to document whether symptoms are exacerbated by physical or cognitive activity.
Athletes presenting to clinicians' offices following SRC, especially those with persisting symptoms, may exhibit fear, anxiety, or depression. These could be caused by the concussion or stem from pre-existing or coexisting conditions. Clinicians have access to several free screening tools, such as the Sport Mental Health Assessment Tool 1, specific to athletes, that may provide insight into the athlete's mental health [129-132]. The SCOAT6 entails a more complete exploration of mental health symptoms and includes the Generalized Anxiety Disorder 7 (GAD-7) screen; the Patient Health Questionnaire 2 (PHQ-2) depression screen; and the Abbreviated Athlete Sleep Screen Questionnaire (ASSQ) as part of following concussion. (See "Generalized anxiety disorder in adults: Epidemiology, pathogenesis, clinical manifestations, course, assessment, and diagnosis", section on 'Screening' and "Screening for depression in adults", section on 'Screening tests'.)
Examination
Observation and general examination — Examination of the patient with a possible SRC begins with general observation and a screening examination looking for any sign of injury (table 2). Note the patient's affect, alertness, and cooperation. Are there signs of associated injury such as contusions or a limp?
Blood pressure and heart rate should be measured with the patient supine and standing. Abnormalities suggest possible autonomic disturbance. Cervical spine trauma is a relatively common injury associated with concussion. The patient's neck should be carefully examined, including midline palpation (table 7). Midline tenderness is concerning and typically warrants imaging. Assessment of the cervical spine following trauma is discussed in detail separately. (See "Evaluation and acute management of cervical spine injuries in children and adolescents" and "Cervical spinal column injuries in adults: Evaluation and initial management".)
Provided there is no concern for an unstable cervical spine injury, neck range of motion should be assessed, both actively and passively, noting any pain or dysfunction of the paravertebral muscles. Specific tests to assess the integrity of the alar and transverse ligaments have been described, as have clinical tests of muscle strength and endurance [133]. The temporomandibular joints should be palpated.
Posture, gait, and balance assessments — Posture is the orientation of the body relative to the vector of gravity; balance describes how the body maintains stability and avoids falling while moving. Posture, gait, and balance should be assessed as part of the SRC evaluation [134].
An assessment of posture should include an evaluation of neck and general muscle tone. Gait is a relatively complex motor task that may be impaired by an SRC [112,135]. Gait assessment should be sufficiently complex to display balance deficits caused by an SRC but not so complex that healthy individuals would be challenged to maintain their balance. Gait speed, stride length, and coordination should all be noted. During simple (ie, single-task) gait, the concussed patient may walk slower or with shorter strides than their uninjured counterparts [136]. By having the patient perform additional cognitive or motor functions while walking, clinicians may elicit deficits that are not detected using single-task assessments [137,138]. Examples of cognitive tests that can be performed while walking include:
●Spelling a five-letter word backward
●Subtracting by six or seven from a set of random two-digit numbers
●Reciting the months in reverse order, starting from a randomly chosen month
Especially during dual-task assessments, concussed athletes are more likely to take fewer steps per allocated time and to complete tasks more slowly than non-concussed controls. This has been demonstrated in adolescents diagnosed with SRC [139].
Assessment of balance may provide insight into functional disturbances associated with concussion, especially if compared with baseline measures. The Balance Error Scoring System (BESS) is a common method for assessing balance. It involves an unshod patient tested in three positions on two surfaces (ie, six total assessments) as follows (picture 1 and table 9):
●Double-leg stance (feet together) on firm and unstable (typically a foam pad) surfaces
●Single-leg stance (nondominant foot) on firm and unstable surfaces
●Tandem stance (nondominant foot behind) on firm and unstable surfaces
The patient holds each position and surface combination for 20 seconds with their eyes closed. The BESS score is calculated based on the number of deviations from the proper stance. If multiple errors occur at the same time, only one is counted. The maximum number of errors for any one combination is 10. Errors include:
●Taking hands off the iliac crests
●Opening eyes
●Taking a step, stumbling, or falling
●Abduction or flexion of the hip beyond 30 degrees
●Lifting the forefoot or heel off testing surface
●Remaining out of the proper testing position for >5 seconds
The number of errors for each of the six combinations are added together to obtain a total score (out of 60) [134,140,141].
A modified BESS (mBESS), which assesses the patient on the three stances but only the firm surface, has been described and is used in the SCAT6. As with the original BESS, the number of errors in each stance are added to obtain a total score (out of 30).
Assessment of complex tandem gait, measured as total errors of body sway while tandem walking forward five steps with eyes open, then five steps with eyes closed, followed by five steps backward with eyes open, and finally five steps backward with eyes closed, has shown promise in distinguishing concussed from non-concussed athletes [142,143]
Both BESS tests and the complex tandem gait test are brief and do not require special materials. Technology-assisted balance assessments do not produce more precise results than a combination of the mBESS and complex tandem gait tests [144].
Clinicians can use the standard Romberg test to help assess vestibular function [139]. For adolescents evaluated within 10 days following an SRC, abnormal performance on the Romberg test was independently associated with a longer duration of symptoms [145]. (See 'Neurologic examination' below.)
Neurologic examination — Although the presenting features of concussion are typically functional and may be subtle, it is important to perform a careful neurologic examination to identify signs of other serious neurologic pathology. The neurologic examination is discussed in detail separately; elements of particular importance for assessment of the patient with an SRC are reviewed below, and a checklist is provided (table 8). (See "The detailed neurologic examination in adults".)
Assessment should include:
●Observation and testing of facial symmetry, speech, and eye/eyelid movements
●Testing of visual acuity and visual fields (many SRC patients report blurred vision, difficulty focusing, and reduced peripheral vision)
●Testing of cranial nerve function
●Testing of strength and coordination, balance, and gait
Ocular assessment (including cranial nerves II, III, IV, and VI) can be performed as part of a vision screen that includes testing of visual acuity, smooth pursuit, saccades, near point of convergence, and nystagmus. However, in the context of an SRC, it is more appropriate to incorporate it as part of the more extensive VOMS using a validated VOMS protocol (movie 1) [146]. Vestibular and oculomotor impairment are common after SRC, and both are associated with increased disability and prolonged recovery [142,147-149].
The VOMS protocol is a brief battery of tests of vestibular and ocular function that requires no specialized equipment or training and distinguishes between healthy and concussed athletes with 90 percent accuracy (table 10) [150]. In addition, the protocol may be useful for tracking recovery from these impairments. Video clips showing preparation and performance of the VOMS tests follow:
●Guidance and equipment (movie 1)
●Vestibular & oculomotor function, including smooth pursuits (movie 2)
●Horizontal and vertical saccades (movie 3)
●Accommodation and convergence (movie 4)
●Vestibular-ocular reflex: Horizontal & vertical gaze stability (movie 5)
●Visual motor sensitivity (movie 6)
Memory and concentration — A 10-word recall test (included in SCAT6) can be used to assess memory. This test avoids the ceiling effect of the five-word test [151]. Immediate and delayed memory are assessed by having the patient repeat the list of words back immediately after they are told and again several minutes later. A number string test can also be used. A table to assist in the administration of these tests is provided (table 11).
Poor concentration can affect memory. Concentration can be assessed by asking the patient to (1) listen to a string of single-digit numbers and then say them backwards, and (2) recite the months of the year in reverse order.
Guidance for the word recall test:
●Ask the patient to say each word clearly, leaving one second between words
●Word order does not matter
●The word list is repeated three times in succession, recording the number of correct answers each time
Make a note when it is five minutes since the start of the start of the word recall tests and ask the athlete to repeat the word list (the athlete should not have been told that they will have to remember the words). Note the correct number of words recalled.
Guidance for the number string test:
●Ask the patient to say the numbers from a list selected at random, spoken one second apart
●Ask the patient to repeat these numbers in reverse order
●Should the sequence be correct, move on to the next higher sequence (a new list with one additional number)
●If the sequence is incorrect, the patient is allowed one further opportunity using a different sequence with the same number of digits
Preinjury baseline scores are useful for both tests, but it is also helpful to compare scores achieved at successive visits during recovery.
ANCILLARY NEUROCOGNITIVE TESTING — A small subset of patients require more specialized testing performed by specialists. Such testing may include the interventions listed below.
Executive function — Clinicians may want to perform or refer for more detailed testing of cognitive function to determine the full effects of a sports-related concussion (SRC), especially when function at school or work has been impaired for longer than four weeks. Many of these tests are typically performed by clinicians with specific expertise, such as neuropsychologists. Clinicians performing such tests should be familiar with their uses, indications, and limitations. Validated tests that can be conducted in an office setting include:
●Trail Making Test A and B – The Trail Making Test is a neuropsychologic test of visual attention and task switching. It provides information about visual search speed, scanning, speed of processing, visual spatial skill, attention, mental flexibility, and executive functioning [152,153].
●Verbal fluency test – Verbal fluency tests, particularly initial letter fluency, are widely used to assess executive dysfunction and help establish diagnoses such as attention-deficit hyperactivity disorder (ADHD) and neurodegenerative diseases [154]. Participants must produce as many words as possible from a category within a given time (usually 60 seconds). This category can be semantic, including objects such as animals or fruits, or phonemic, including words beginning with a specified letter. Individuals with concussion have been shown to produce fewer words and make more errors than non-concussed controls [154,155].
●Auditory – Functional listening skills, such as the ability to understand speech within noise, and the capability to sustain performance over time in taxing auditory conditions (ie, environments with significant ambient noise) may be compromised following a concussion [156,157]. Such impairments may exacerbate cognitive and academic challenges and should be considered in return-to-learn and return-to-play decisions. Auditory impairment of this type is difficult to measure, and referral to an audiologist may be needed. However, the primary clinician should ask about such problems, especially if a patient is performing suboptimally in school or at work.
Computerized cognitive tests — Computerized neurocognitive tests are not typically used to diagnose an SRC but rather for management and decisions about returning to sport. These standardized assessments measure such things as reaction time, memory, and information processing speed and allow comparisons with preinjury baseline scores or normative values. Examples include Axon Sports/CogState, ImPACT, ANAM, and HeadMinder. The use of such neurocognitive testing to establish a preinjury baseline and for post-injury management of children and younger adolescents is reviewed separately. (See "Concussion in children and adolescents: Clinical manifestations and diagnosis", section on 'Preparticipation assessment'.)
Cognitive deficits may resolve independently of symptoms, with the computerized test deficits typically outlasting symptoms by an average of two to three days [158]. The tests are most useful in the context of a thorough clinical evaluation and still have value when no individual baseline exists for comparison. In such circumstances, results can be compared with age-matched norms [112]. Assessments should be appropriately supervised, conducted in a quiet, controlled environment, and not be used as the sole basis for making a return-to-sport decision [159].
Specialized evaluation and referral — Depending upon which clinical domains are affected and to what extent, additional specialized assessments may be needed. These may include assessments of the patient's physical, mental, and social wellbeing, possibly including evaluation for depression, anxiety, and sleep disorders. When making such determinations, clinicians should remember that symptoms thought to stem from an SRC may be due to other injuries and conditions. An appropriate history and examination should be performed to rule out such conditions.
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Sports-related concussion" and "Society guideline links: Minor head trauma and concussion".)
SUMMARY AND RECOMMENDATIONS
●Epidemiology – Sports-related concussions (SRCs) comprise one-third of traumatic brain injuries. Incidence is highest among adolescents and young adults. Combat sports (eg, boxing) and collision team sports such as rugby, American football, and ice hockey pose the greatest risk. (See 'Epidemiology' above.)
●Risk factors – Individual risk factors for sustaining a concussion include prior concussion, younger age (prepubescent athletes), female sex, and impact density (ie, multiple head impacts within brief period). Factors associated with prolonged or more severe symptoms include intrinsic (eg, specific comorbidities) and injury-specific (eg, high-risk mechanism, continued play after injury, severe early symptoms) factors. (See 'Risk factors' above.)
●Prevention – Education, sport rules (eg, prohibition of checks or tackles to the head) and culture that protect against head injury, proper equipment (eg, headgear, mouthguard) and training (eg, neuromuscular warm-up), and good general health practices all play a role in helping to reduce the risk for SRC. (See 'Prevention and planning' above.)
●Initial evaluation – The initial clinic visit should include a thorough medical evaluation looking for possible concurrent injuries (eg, cervical spine injury), systematic assessment of symptoms and signs due to SRC, initiation of appropriate therapy, and referral to specialists as indicated. Preparation and tools needed for such assessment are described in the text. SCOAT6 is a useful clinical guide and evaluation checklist. (See 'Clinic evaluation' above.)
●History and symptom assessment – In addition to a careful history of the injury (table 4), including mechanism, acute presentation (eg, retrograde amnesia, loss of balance), and prominent symptoms, clinicians should perform a systematic history of all the major domains that may be affected by an SRC (table 6), including:
•Cognitive (see 'Cognitive' above)
•Headache/migraine (see 'Headache and migraine' above)
•Ocular/oculomotor (see 'Ocular/oculomotor' above)
•Vestibular (see 'Vestibular' above)
•Mood/anxiety (see 'Mood/anxiety' above)
•Sleep disturbance/fatigue (see 'Sleep disturbance/fatigue' above)
•Cervical/cervicogenic (see 'Cervical/cervicogenic' above)
●Physical examination – Examination begins with general observation and screening for any sign of injury (table 2). Cervical spine trauma is a relatively common injury associated with SRC. The patient's neck should be carefully examined (table 7). Other important elements include assessment of posture, gait, and balance (picture 1 and table 9); neurologic examination (table 8 and table 10); and assessment of memory and concentration (table 11). (See 'Examination' above.)
●Ancillary neurocognitive testing – More detailed testing of cognitive function to determine the full effects of an SRC may be needed, especially when function at school or work has been impaired for longer than four weeks. Many of these tests are typically performed by clinicians with special expertise (eg, neuropsychologist). (See 'Ancillary neurocognitive testing' above.)
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