Sports Concussion

Author(s): Timothy Tiu, MD , Rakhi Sutaria MD, Se Won Lee, MD

Originally published:11/15/2011

Last updated:05/05/2016



Sport-related concussions are a complex pathophysiological process affecting the brain, induced by acute traumatic biomechanical forces. Concussions typically result in short-lived neurological impairments that resolve spontaneously and most often do not involve loss of consciousness (LOC).1,2,3


Concussions are typically caused by a direct blow to the head, face, neck or elsewhere on the body with an “impulsive” force transmitted to the head from an opposing player, stationary object, or the ground.

Epidemiology including risk factors and primary prevention

There are an estimated 1.6-3.8 million sport-related concussions in the U.S. each year.4 Recent data suggest a trend of increased annual concussion rates over the past decade, which is speculated to be a result of the emphasis on concussion education and awareness leading to increased identification and reporting.5,6,7 Actual incidence may be higher, with studies showing up to 50% of concussions going unreported.8,9,10 Sports with the highest risk appear to be football and girl’s soccer. Other high-risk sports include ice hockey and lacrosse.11,12,13,14 History of a previous concussion is a clear risk factor. In sports with similar rules for each gender, the incidence is higher in females, but there is insufficient evidence to clearly state that females are at higher risk.1,2,3 Although it is felt that younger athletes may need more conservative management1,2,3, there is insufficient data to conclude that age is a risk factor for concussion.3


A concussion occurs from either a direct blow to the brain, or from an indirect blow that results in shearing forces diffusely across the brain. After the impact, a metabolic cascade ensues, including the release of excitatory neurotransmitters from the brain, which leads to a hypermetabolic state which lasts from days to weeks.16 Free radicals are produced and cerebral perfusion is decreased.

Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time)

The onset of symptoms following a concussion is typically immediate or within minutes after the initial impact. The most common reported symptoms are headache and dizziness. Acutely, the athlete may also describe a feeling of fogginess, complain of tinnitus, confusion, flashing lights, nausea, or amnesia. Other commonly reported symptoms are sensitivity to bright lights, altered sleep patterns, poor concentration, and irritability. In addition, an athlete may notice increasing fatigue and delayed reaction time with physical and mental tasks. Long-term effects might include neurobehavioral or cognitive impairments.1,2,3

Following a sports concussion, there is typically a step-wise gradual reduction in symptoms. The majority of concussions resolve within 7 to 10 days, but some cases may evolve to postconcussion syndrome (PCS) through a process that is poorly understood. PCS is defined as symptoms and signs of concussion that persist for weeks to months after the incident. Management is similar to acute concussion, and the foundation is time.1,2

Specific secondary or associated conditions and complications

Complications of a concussion in the absence of other significant medical diagnoses or injuries are usually related to cognitive impairments. The athlete may experience insomnia, emotional lability, memory impairments, depression, anxiety, fatigue, headache, and/or dizziness.



It is essential to understand that direct head trauma is not necessary for a concussion to occur. After a suspected concussion, the athlete should be questioned on the incident that caused the impact and what current symptoms he/she is experiencing. A graded symptoms checklist provides a tool for the initial assessment and tracking of symptoms over subsequent evaluations. Symptoms include somatic (eg: headache), cognitive (eg: feeling like in a fog), sleep disturbance (insomnia) and/or emotional (eg: lability).1 The patient may not be able to recall the incident so other spectators may need to be questioned or game tapes reviewed.

Physical examination

Initially, the on-field examination should focus on evaluating for emergent injuries. The cervical spine, skull and facial bones need to be palpated for any evidence of fracture. If the athlete is stable, a sideline assessment should be made. A thorough neurological evaluation needs to be performed that includes cranial nerves, sensation, strength, coordination, and balance. Maddocks questions are asked of the athlete, which test memory of details related to the current and past games. Cognitive assessment should be employed and should focus on immediate memory, concentration, and delayed recall. Standardized assessment tools are available, and they are designed to reduce the degree of subjectivity encountered by medical providers responsible for making a rapid and precise injury assessment and concussion diagnosis decision. When possible, sideline tests can be compared to a reliable preinjury baseline.2 Follow-up office examinations should include a graded symptom checklist, neurological exam, balance and coordination testing, as well as some form of cognitive assessment.

Functional assessment

The athlete will often have cognitive deficits after sustaining a concussion. The length of the deficits can be highly variable. Concentration, attention, mood, and sleep can be affected, which can further impact school, work, and daily activities. The athlete’s school performance should be closely followed after a concussion. A comprehensive neuropsychological evaluation can be used to identify subtle deficits.1

Laboratory studies

There are currently no recommendations for laboratory studies directly related to a concussion, unless there is concern for other clinically suspected pathology.


Neuroimaging is typically normal after a player has sustained a sport-related concussion, and is therefore not recommended. Computed tomography (CT) scan and magnetic resonance imaging (MRI) should be reserved for those athletes suspected of intracranial pathology. Findings that would warrant neuroimaging include worsening mental status, declining level of consciousness, focal neurological deficits, seizures, intractable vomiting, anisocoria (not present prior to injury), rhinorrhea, or otorrhea. The use of functional MRI has shown correlation with symptom severity and recovery, but is not recommended for routine evaluation. 4,17

Supplemental assessment tools

Multiple tools can be used in the acute phase after a concussion; the one most recommended is the Sport Concussion Assessment Tool 3 (SCAT3). SCAT3 utilizes a multifaceted standardized method to evaluate an athlete with either a known or suspected concussion. It incorporates the Maddocks questions and the Standardized Assessment of Concussion (SAC), with assessments of symptom evaluation, loss of consciousness, Glasgow Coma Scale, cognition, balance, and coordination. Balance testing in SCAT3 utilizes the Balance Error Scoring System (BESS) in which single-leg, double-leg, and tandem stance is evaluated. SCAT3 can be used sequentially to track an athlete’s recovery. While most concussions can be appropriately managed without a comprehensive instrumental neuropsychological evaluation, it can be used to identify subtle deficits and further guide management.1

Early predictions of outcomes

Many studies have looked at predictors of outcomes following sports concussions and studies have been disparate. Recently, separate studies have suggested that presence of post-traumatic amnesia and symptoms of fogginess are associated with prolonged recovery.18 Youth athletes may have a more prolonged recovery and are more susceptible to a concussion accompanied by a catastrophic injury. A greater number, severity, and duration of symptoms after concussion are predictors of a prolonged recovery.  History of pre-injury mood disorders, learning disorders, Attention Deficit Disorder/Attention Deficit Hyperactivity Disorder (ADD/ADHD), and migraine headache complicate diagnosis and management of concussion.2

Social role and social support system

Individuals may notice that attempting tasks in the home and at work/school often increase their concussive symptoms. For student athletes, teachers need to have the understanding that they may need additional time with homework or testing due to problems with attention and concentration. Cognitive rest is very important in the acute recovery from a concussion, and includes restrictions on cell phone use, texting, video games, physical activity and school work until symptoms abate.

Some athletes experience mood-related consequences including anxiety and depression. Contributing factors may include frustration over uncertain recovery time, isolation from teammates and sport, and lack of social support. Prior to pharmacologic or psychotherapy, treatment involves behavioral management interventions, such as regulated sleep schedule, proper nutrition and stress reduction. Helping the athlete to identify and talk about the etiology of the symptoms can be helpful.25

Professional Issues

Returning a concussed athlete back to activities too soon after injury is the situation that needs to be avoided. Thus, the physiatrist must have a process in place to prevent this from happening. If athletes are returned to play prior to full recovery, both cognitively and physically, they are at risk for worsening symptoms, an increased risk of suffering additional concussions, and in the worst cases, second impact syndrome which results in severe brain swelling, significant morbidity and often death.


Available or current treatment guidelines

The 3 main guidelines are from: the 4th International Conference on Concussion in Sport1, the American Medical Society for Sports Medicine2, and the American Academy of Neurology3. Return to play in sport is the key issue after a concussion and should occur only after medical clearance from a licensed health care provider trained in the evaluation and management of concussion. Return to play involves a 6-step program: 1. No activity, 2. Light aerobic exercise, 3. Sport specific exercise, 4. Non-contact training drills, 5. Full-contact practice, 6. Return to play. The athlete progresses to the next step when asymptomatic for 24 hours. If symptoms occur with activity, the progression should be halted and restarted at the preceding symptom-free step. Athletes should be off of medications that may mask or modify symptoms of concussion.1,2,3.

At different disease stages

On the sideline, the athlete should be removed from the field of play and not allowed to return if there a concussion suspected. The initial treatment after a concussion is physical and cognitive rest. The brain is in a hypermetabolic state after a concussion and physically demanding activities, in light of reduced cerebral perfusion, can increase symptoms and delay recovery.19 The athlete should avoid cognitive activities such as playing video games, watching television, and reading, as well as physically demanding activities which may exacerbate their symptoms. “Cognitive rest” with respect to academics may include a temporary leave of absence, shortened school days, reduced workloads, additional time for assignments and exams. Standardized testing during recovery is discouraged as scores may be lower than expected.4 Individuals should also avoid high-risk activities that may cause additional concussions and worsen symptoms even further. Over-the-counter melatonin may be prescribed for mild insomnia, or trazodone or amitriptyline for more severe cases. It is not uncommon for depression or anxiety to develop, for which prescribing an anti-depressant or anxiolytic can be considered if symptoms persist.

Coordination of care

The approach to an athlete with a sport-related concussion should integrate many individuals. A physician familiar with sports concussions should be directing care and decisions, often involving collaboration with physical/occupational therapists and neuropsychologists. Additionally, athletic trainers, family, coaching staff, teachers, and friends also need to be a part of the treatment process.

Patient & family education

The athlete, family, friends, teachers and coaches need to be educated on the effects of sport-related concussion. There needs to be an understanding of the injury in order to protect the athlete and support him/her through the recovery process.

Emerging/unique Interventions

Neuropsychological testing is the best measurement to evaluate cognitive impairment. This testing commonly utilizes computer-based programs that are simple and sensitive, but these are not substitutes for formal neuropsychologic testing1. These computerized tests evaluate an athlete’s visual memory, verbal memory, processing speed, and reaction time and can follow the resolution of cognitive deficits with serial testing.20  Although there is insufficient evidence to recommend the widespread routine use of baseline neuropsychological testing, this may be more important in high-risk athletes with a prior history of concussion, confounding conditions (learning disability, mood and attention disorders, migraine headaches), or those in high-risk sports.1,2

Translation into practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills

The most important aspect of sport-related concussions is the removal of athletes from sports activities as they are recovering. There are many useful tools for monitoring symptoms and cognition to help aid in the decision on when the athlete is ready to return to full participation. Although computer-based neuropsychological testing is becoming a cornerstone of concussion management, written tests are more comprehensive (and time consuming).


Cutting edge concepts and practice

Concussion legislation has been emerging in this country since the state of Washington passed the first concussion bill in 2009, the Lystedt Law, which required athletes to be removed immediately from athletic activities if it is suspected they have sustained a concussion. Within 5 years, all 50 states have passed a similar law.24 In order to return to play, athletes must be evaluated and receive written clearance from a health care provider trained in concussion assessment.

There is increasing concern that head impact exposure and recurrent concussions contribute to long-term neurologic sequelae such as chronic neurological impairment. Some studies have suggested an association between previous concussions and chronic cognitive dysfunction.2 Chronic Traumatic Encephalopathy (CTE) represents a distinct tauopathy with an unknown incidence in the athletic populations. A cause and effect relationship has not as yet been demonstrated between CTE and concussions or exposure to contact sports.1

A new emerging treatment for concussion is high dose omega-3 fatty acids, which may decrease neural inflammation caused by concussion. High dose fish oil administered to rats demonstrated a significant decrease in brain damage compared to rats that did not received supplementation.21 More studies are needed.

Vestibular rehabilitation has been demonstrated to decrease dizziness and lead to improvement in balance quicker than athletes who did not undergo vestibular rehabilitation.22

Genetic testing and blood tests for certain biomarkers to assist in treating concussions have some promise, but are not currently recommended for routine use. These include Apolipoprotein (Apo) E4, Tau polymerase, glial fibrillary acidic protein (GFAP), neuron specific enolase (NSE), and myelin basic protein (MBP).1


Gaps in the evidence-based knowledge

One of the major questions in sport-related concussion is a determination on when an athlete should retire from playing a respective sport due to multiple concussions. There are currently no evidenced-based guidelines for recommendation on retiring an athlete from their sport based on the number of concussions sustained.23

Direct focus on the musculoskeletal system pertains to both protective factors as well as risk of subsequent injury. A potential protective factor is neck strength, which has been shown to be a significant predictor of concussion26. Additional studies must be done to further investigate this, and to consider the effects of neck strengthening programs. Several studies have shown an increase in the risk musculoskeletal injuries following concussion27,28,29. These findings suggest that further investigations should be directed at return to play protocols as well as neuromuscular assessments to identify subtle deficits.

Additional research is needed to validate current assessment tools, further delineate the role of neuropsychologic and balance testing, validate return-to-play guidelines, and improve identification of those at risk for prolonged concussive symptoms. In addition to being a possible confounding variable in the assessment and management of concussions, ADHD has been identified as a potential risk factor30. Large-scale, epidemiological studies are needed to more clearly define risk factors and causation of any long-term neurological impairment.2


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Original Version of the Topic:

Ken Mautner, MD, Matthew Axtman, DO. Sports Concussion. Publication Date: 2011/11/15.

Author Disclosure

Timothy Tiu, MD
Nothing to Disclose

Rakhi Sutaria MD
Nothing to Disclose

Se Won Lee, MD
Nothing to Disclose

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