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Demystifying Sports-Related Concussions

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Duval County Medical Society CME Portal, October 2019

Demystifying Sports-Related Concussions

and Jennifer Maynard, MD, CAQSM
Mayo Clinic Florida

Address Correspondence to:

Timothy Dekker, MD
Mayo Clinic Florida
4500 San Pablo Road
Jacksonville, FL 32224
Telephone: (586) 202-9637

Date of Release: Oct. 1, 2019
Date Credit Expires: Oct. 1, 2021
Estimated Completion Time: 1 hour

The Duval County Medical Society (DCMS) is proud to provide its members with free continuing medical education (CME) opportunities in subject areas mandated and suggested by the State of Florida Board of Medicine to obtain and retain medical licensure. The DCMS would like to thank the St. Vincent’s Healthcare Committee on CME for reviewing and accrediting this activity in compliance with the Accreditation Council on Continuing Medical Education (ACCME). This month, the DCMS CME Portal includes an article, “Demystifying Sports-Related Concussions” authored by Timothy Dekker, MD and Jennifer Maynard, MD, CAQSM, which has been approved for 1 AMA PRA Category 1 credit.TM For a full description of CME requirements for Florida physicians, please visit


Timothy Dekker, MD, Resident Physician, Mayo Clinic Florida. Jennifer Maynard, MD, CAQSM, Program Director, Primary Care Sports Medicine Fellowship, Assistant Professor of Family Medicine, Mayo Clinic Florida.

Needs Assessment:

Concussion is a common condition that is often misdiagnosed and therefore mistreated. Healthcare providers may be unaware of the current guidelines for concussion diagnosis and treatment. Meanwhile, recommendations of acute management and options for therapies for subacute treatment are constantly evolving. Returning an athlete to school and play needs to be under the guidance of a clinician trained in concussion management. It is imperative for healthcare providers who are unfamiliar with concussions to know when and where to refer for specialized therapy.

  1. Define and explain the most up-to-date definition of sports related concussion (SRC) according to the Concussion in Sport Group consensus statement.
  2. Report epidemiology and common risk factors for sustaining an SRC.
  3. Discuss the five common domains of SRC symptoms, as well as specific symptoms of SRC.
  4. Discuss different assessment tools and recommendations for testing for SRC.
  5. Explain initial treatment and return to school and play protocol.
CME Credit Eligibility:

A minimum passing grade of 70% must be achieved. Only one re-take opportunity will be granted. If you take your test online, a certificate of credit/completion will be automatically downloaded to your DCMS member profile. If you submit your test by mail, a certificate of credit/completion will be emailed within 4 weeks of submission. If you have any questions, please contact the DCMS at 904-355-6561 or 

Faculty Disclosure:

Timothy Dekker, MD and Jennifer Maynard, MD, CAQSM report no significant relations to disclose, financial or otherwise with any commercial supporter or product manufacturer associated with this activity.

Disclosure of Conflicts of Interest:

St. Vincent’s Healthcare (SVHC) requires speakers, faculty, CME Committee and other individuals who are in a position to control the content of this educational activity to disclose any real or apparent conflict of interest they may have as related to the content of this activity. All identified conflicts of interest are thoroughly evaluated by SVHC for fair balance, scientific objectivity of studies mentioned in the presentation and educational materials used as basis for content, and appropriateness of patient care recommendations.

Joint Sponsorship Accreditation Statement:

This activity has been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education through the joint sponsorship of St. Vincent’s Healthcare and the Duval County Medical Society. St. Vincent’s Healthcare designates this educational activity for a maximum of 1 AMA PRA Category 1 credit.TM Physicians should only claim credit commensurate with the extent of their participation in the activity.

Sports-related concussion (SRC) is a popular topic as more is being discovered about the potential long-term negative effects. Meanwhile, it is also a confusing subject not well understood by the public and many clinicians. Many popular sports in the United States are contact sports where the future of the sport, and most importantly the health of athletes, could be determined by how well we understand, recognize, protect, and treat athletes with head injuries. Knowing the potential risk factors that predispose an athlete to concussion such as gender, age, level of competition, etc. can help coaches, trainers, and clinicians educate and protect those at risk. Once concussion is recognized, prompt removal of the athlete from play is essential. There are several sideline and subacute clinical assessment tools available; however, diagnosis of concussion remains a clinical decision. Physicians need to be aware of recommendations for acute management and returning an athlete to play needs to be under the guidance of a clinician training in concussion management. It is imperative for healthcare providers unfamiliar with concussions to know when and where to refer for specialized therapy

The term "concussion" is often used in the medical literature as a synonym for mild traumatic brain injury (mTBI), but is used more specifically to describe the characteristic symptoms and signs that an individual may experience after a mild TBI. The Concussion in Sport Group (CSIG) consensus statement defines a sport-related concussion (SRC) as a traumatic brain injury induced by biomechanical forces. The statement includes common findings that may be utilized in clinically defining the nature of a concussion:

  •  SRC may be caused either by a direct blow to the head or elsewhere on the body with an impulsive force transmitted to the head.
  •  SRC typically results in the rapid onset of short-lived impairment of neurological function that resolves spontaneously.
  •  SRC may result in neuropathological changes, but the acute clinical signs and symptoms largely reflect a functional disturbance rather than a structural injury.
  •  SRC may or may not involve loss of consciousness.1

A direct injury to the brain can occur from an object striking the head. Alternatively, rapid acceleration and deceleration (whiplash) imparts shear, tensile and compressive strains that mainly damage white matter connections by producing diffuse axonal and vascular injury.2 Release of excitatory neurotransmitters (acetylcholine, glutamate, and aspartate) and the generation of free radicals contribute to secondary injury. Mostly described in young boxers, phenomenon called “second impact syndrome,” described as cerebral edema that could lead to long-term sequelae or death, can occur if another impact occurs in a period of vulnerability before the brain has healed.3

In the United States (U.S.), the causes of TBI are as follows: motor vehicle accidents (20-45 percent), falls (30-38 percent), occupational accidents (10 percent), recreational accidents (10 percent), and assaults (5-17 percent).4 1.6–3.8 million concussions reported in the U.S. are attributed to sports participation.5


Most research shows that sports concussions occur more frequently in women, younger athletes, and those with a history of previous concussion.1 A meta-analysis showed high school women had a 1.5-3x higher concussion risk in similar ruled sports such as soccer and basketball when compared to men.6 Possible explanations include decreased neck strength and increased willingness to report injuries in women.7 Alternatively, studies of other sports have shown that males were at a greater risk.8 The authors explain that comparing different sport types-between sexes, introduces a bias as males tend to play high-collision sports with increased concussion risk and may take more risks within the same sport. Concussions can happen at any age, but children and adolescent athletes are thought to be more susceptible. Children also take longer to recover, have more significant memory and mental processing issues, and are more susceptible to rare and dangerous neurological complications, including death caused by a single or second impact.6 For instance, high school football players were at an increased concussion risk compared with collegiate players.7

There are other modifying factors that have been found to be associated with increased concussion risk. A prior concussion increased the risk of another concussion by 300 percent.9 Certain positions within sports have higher frequencies of concussions. For example, quarterbacks in American football had a 2-5x increase in concussion risk compared with other offensive positions; and goalies in soccer have a 3x decreased risk of concussion compared with the defense and forward units.10 Level of play also attributes to concussion rates. A study showed lower concussion rates in division one high school football compared to lower divisions. Explanations for this phenomenon include poorer quality of protective equipment, decreased skill levels, or players having to play both offensive and defensive positions.7 Low physical fitness also causes fatigue earlier in the game, leading to inability to react appropriately to the dynamic game environment and increasing injury risk, including concussions.11 Additionally, receiving a concussion increases future risk of lower extremity injuries including lateral ankle sprains, knee injuries, and muscle strains.12 

Signs and Symptoms

Most literature divides symptoms into five domains:

  • Physical signs and symptoms (headache, dizziness, nausea, vision alterations)
  • Cognitive (fogginess, amnesia, confusion, slurred speech, vacant stare)
  • Emotional (irritable, labile, anxious, depressed mood)
  • Sleep (trouble falling/staying asleep)
  • Balance alterations 

Amnesia almost always involves loss of memory of the traumatic event and frequently includes loss of recall for events immediately before (retrograde amnesia) and after (antegrade amnesia) the head trauma. An athlete with amnesia may be unable to recall details about recent plays in the game or details of current events. Amnesia also may be evidenced by the patient repeatedly asking a question that has already been answered. Loss of consciousness is not a requirement for diagnosing concussion, but is a clear indication that a concussion has occurred; in fact, loss of consciousness occurs in only 10 percent of concussions.13 The symptoms of concussion can be delayed but typically become evident in the first 48 hours following a head injury.



The Sport Concussion Assessment Tool (SCAT5) and the Child SCAT5 are the most well established and rigorously developed instruments available for sideline assessment. They were endorsed by the 5th International Consensus Statement on concussion in sport in 2016.1 The SCAT5 provides a detailed clinical assessment that includes a new section on immediate red-flag symptoms, review of subjective symptoms, the Glasgow Coma Scale (GCS), the cognitive assessment, and an evaluation of balance and coordination.

The King-Devick test is a vision-based performance measure in which an athlete with suspected concussion goes through a rapid series of number naming lists. The test can be useful as a “remove from play tool.” A player must have a baseline time for reading numbers on three lists in order to be compared to a post-injury score. The sensitivity and specificity were 86 percent and 90 percent for detecting a concussion; any worsening of baseline scoring indicates a 5x greater risk of concussion.14

Imaging is not typically done as standard brain scans are normal for someone with concussion. If concerned for a more severe head injury, head computed tomography (CT) without contrast, is the recommended test for patients with red-flag symptoms (focal neurologic signs, prolonged LOC, posturing, etc.). The Canadian CT head rule (CCHR), the New Orleans criteria (NOC), and the National Emergency X-Radiography Utilization Study II (NEXUS II) criteria can be used to determine if advanced imaging should be recommended.15 These advanced imaging tests can show diffuse axonal and vascular injuries. Gradient-echo and susceptibility weighted imaging can show microbleeds, which are a stable marker of white matter injury. Diffusion MRI can help predict clinical outcome and the extent of diffusion changes correlates with cognitive impairment in mTBI.16


Treatment and Return to Play

There are many different protocols for treatment and for determining when to return to play for athletes with concussions.1,17 Concussion management should be individualized given the heterogeneity of the responses and injuries. Any player with a suspected concussion should be immediately removed from play. The athlete should be referred to a healthcare professional trained in the management of concussions even if the symptoms resolve quickly.


According to the CSIG consensus statement, after an initial 24-72 hours of relative rest, the athlete may engage in sub-symptom activities.  Once symptoms have resolved and the athlete has obtained clearance by a physician, they may begin a supervised step-wise, graduated return to play.1 A player may proceed to the next step only after he has demonstrated tolerance of all activities in his current step without recurrence of signs or symptoms of concussion. If any step triggers recurrence of any signs or symptoms of concussion, those activities should be discontinued and the player returned to the prior step in the protocol. The American Academy of Pediatrics and the Concussion in Sport Group consensus statement states children and adolescents should remain at each stage of rehabilitation no less than 24 hours before advancing to the next level. Thus, a minimum of five days should pass before consideration of full return to competition.1,18 The exact return to play protocol detailed in the CSIG consensus statement is shown in Table 1. If symptoms are persistent, more than 10–14 days in adults or more than 1 month in children, the athlete should be referred to a healthcare professional who is an expert in the management of concussion. There are many emerging rehabilitation techniques such as cervical spinal manipulation, vestibular and oculomotor training, vision training, and pharmacological therapies that could become more routine in the future.


Table 1: Return to play protocol detailed in the CSIG consensus statement. Adapted from Reference 1.

If the player is able to tolerate all activities without recurrence of symptoms, the physician can conclude the athlete may safely return to play. It is important to be aware of your individual state’s concussion law regarding appropriate clearance for return to play. In the State of Florida, only a licensed physician (MD or DO) may sign the Florida High School Athletic Association AT-18 Post Head Injury/Concussion Initial Return to Participation form. This form can be accessed on the Florida High School Athletic Association’s website.19  

A concussion is a mild brain injury which typically results in physical, cognitive, emotional, sleep and/or balance symptoms. It is imperative to be able to recognize the signs and symptoms of a concussion, remove the athlete from play, and provide the appropriate principles of treatment, rest and rehabilitation, before returning a student or athlete to the athletic field. There are many different assessment tools for both the acute (sideline) evaluation, as well as follow up (clinic) evaluation. Continuing research on concussion diagnosis and management is essential. Breakthroughs are being made for improved diagnosis through sideline testing and potential chemical biomarkers. In addition, monitoring symptoms have improved during return to activity utilizing the Buffalo Concussion Treadmill Test. Emerging rehabilitation techniques are underway for those who are not recovering as expected.


This article was originally published in the Florida Family Physician.


  1. McCrory P, Meeuwisse W, Dvořák J et al. Consensus statement on concussion in sport-the 5th international conference on concussion in sport held in Berlin, October 2016. Br J Sports Med. 2017 Jun;51(11):838-47.
  2.  Browne KD, Chen, XH, Meaney DF, et al. Mild traumatic brain injury and diffuse axonal injury in swine. J Neurotrauma. 2011 Sep;28(9):1747–55.
  3.  McCrory P, Davis G, Makdissi M. Second impact syndrome or cerebral swelling after sporting head injury. Current Sports Med Rep. 2012 Jan-Feb;11(1):21–3.
  4. Jennett B, Frankovyski RF. The epidemiology of head injury. In: Braakman R, editor. Handbook of clinical neurology. New York: Elsevier; 1990. Vol 13, p. 1.
  5. Langlois JA, Rutland-Brown W, Wald MM. The epidemiology and impact of traumatic brain injury: a brief overview. J Head Trauma Rehabil. 2006 Sep-Oct;21(5):375–8.
  6. Pfister T, Pfister K, Hagel B, et al. The incidence of concussion in youth sports: a systematic review and meta-analysis. Br J Sports Med. 2016;50:292-7.
  7. Guskiewicz KM, Weaver NL, Padua DA, Garrett WE., Jr. Epidemiology of concussion in collegiate and high school football players. Am J Sports Med. 2000;28:643–650.
  8.  Abrahams S, Fie SM, Patricios J, et al. Risk factors for sports concussion: an evidence-based systematic review. Br J Sports Med. 2014 Jan;48(2):91-7.
  9. Annegers JF, Grabow JD, Kurland LT, et al. The incidence, causes, and secular trends of head trauma in Olmsted County, Minnesota, 1935–1974. Neurology. 1980 Sep;30(9):912–9.
  10. Pellman EJ, Powell JW, Viano DC, et al. Concussion in professional football: epidemiological features of game injuries and review of the literature—part 3. Neurosurgery. 2004 Jan;54(1):81–96.
  11. Kontos AP, Elbin RJ, Collins MW. Aerobic fitness and concussion outcomes in high school football. In: Slobounov S, Sebastianelli W, editors. Foundations of sport-related brain injuries. Boston (MA): Springer; 2005. p. 315–39.
  12. Gilbert FC, Burdette GT, Joyner AB, et al. Association between concussion and lower extremity injuries in collegiate athletes. Sports Health. 2016 Nov/Dec;8(6):561-7.
  13. Daneshvar DH, Nowinski CJ, McKee A, et al. The epidemiology of sport-related concussion. Clinics. 2011 Jan;30(1):1-17.
  14. Galetta KM, Liu M, Leong DF, et al. The King-Devick test of rapid number naming for concussion detection: meta-analysis and systematic review of the literature. Concussion. 2015 Sep 10;1(2):CNC8.
  15. Schachar JL, Zampolin RL, Miller TS, et al. External validation of the New Orleans Criteria (NOC), the Canadian CT Head Rule (CCHR) and the National Emergency X-Radiography Utilization Study II (NEXUS II) for CT scanning in pediatric patients with minor head injury in a non-trauma center. Pediatr Radiol. 2011 Aug;41(8):971-9.
  16. Cubon VA, Putukian M, Boyer C, et al. A diffusion tensor imaging study on the white matter skeleton in individuals with sports-related concussion. J Neurotrauma. 2011 Feb;28(2):189–201.
  17.  NFL Play Smart Play Safe. NFL return-to-participation protocol [Internet]. NFL Productions; 2017 Jun 20 [updated 2018 Jun; cited 2018 Nov]. Available from:
  18.  Halstead ME, Walter KD. Sport-related concussion in children and adolescents. Pediatrics. 2010 Sep;126(3):597.
  19. Florida High School Athletic Association. Post head injury/concussion initial return to participation [Internet].  FHSAA [updated 2018 Apr; cited 2018 Nov]. Available from:


To take the test and earn CME credit, click here.

1. What causes the most traumatic brain injuries in the United States?

a. Sports

b. Motor vehicle accident

c. Assault

d. Occupation injury

2.  Which of these risk factors is NOT associated with a higher risk of sport related concussions?

a. Older age

b. Higher level athletics (i.e. Division 1 high school football vs. Division 3)

c. Male gender

d. Previous concussion

3. Which of these below is NOT one of the five domains of concussion symptoms?

a. Hearing

b. Balance

c. Sleep

d. Emotional

e. Cognitive

4. In what percentage of SRC does loss of consciousness occur?

a. 10%

b. 25%

c. 50%

d. 75%

5.      What assessment tool can be used as both a sideline and clinical recovery tool?

a. PHQ9


c. SCAT5

d. New Orleans Criteria

6. After a suspected SRC has occurred, with no red flag symptoms, what is the best next step?

a. Remove the athlete from play for the rest of the game

b. Urgent evaluation in Emergency Department with imaging of the head

c. Rest until symptoms decrease and then resume play, perhaps the same day

d. Give Ibuprofen for the headache, and as long as athlete can play effectively, immediate return to play

7. During Return-to-Play protocol what should be done if an athlete gets a headache while exercising?

a. Push through the symptoms and determine what their current exercise limitations are

b. Take Ibuprofen and resume that same step once the athlete is feeling better

c. Stop the activity and try the same step tomorrow

d. Stop the activity and return to the previous step tomorrow if the athlete is symptom free at baseline

8. Which of these statements does NOT need to occur in order to start the Return-to-Play protocol?

a. Full participation in school

b. Normal head imaging (i.e. CT of the head)

c. Asymptomatic with activities of daily living

d. At least a delay of 24 hours from concussion

9.  Compared to adults, children with concussions on average have which of the following:

a. Fewer memory issues

b. Decreased risk of death from First or Second Impact Syndrome

c. Decreased risk for neurological injury

d. Slower recovery

10. What is a coup-countercoup injury with concussion?

a. A concussion with bilateral skull fractures

b. When the head is hit from two sides simultaneously

c. When there is a direct injury at the site of trauma, as well as the opposite site from the trauma due to brain motion within the skull (i.e. whiplash)

d. A penetrating skull injury with brain damage