Concussion in Sport : Current Sports Medicine Reports

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Concussion in Sport

Moreland, George MD; Barkley, Lisa C. MD, FAAFP, FACSM, FSAHM

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Current Sports Medicine Reports 20(4):p 181-182, April 2021. | DOI: 10.1249/JSR.0000000000000825
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Background and Epidemiology

A concussion is caused by a traumatic force to the head that leads to immediate symptoms and cognitive impairments (1). Sports-related concussions are a subtype of mild traumatic brain injury (TBI) (2). It is a subjective diagnosis that is made through cognitive evaluation, motor evaluation, and self-reported symptoms. The most common symptoms reported include headache, dizziness, and confusion (1). Other signs and symptoms include the following clinical domains:

  1. Somatic, cognitive, or emotional (i.e., emotional lability)
  2. Physical (i.e., visual problems, light and noise sensitivity)
  3. Balance impairment (i.e., unsteady gait)
  4. Behavioral changes (i.e., irritability)
  5. Cognitive impairment (i.e., delayed responses) and sleep/wake disturbance (i.e., drowsiness) (2,3).

The Centers for Disease Control and Prevention estimates that in the United States, 10% of all sport athletes suffer from a concussion yearly (4). In children, 45% of sports- and recreation-related TBIs came from collision or contact sports (5). Some sports with the highest incidences include football, soccer, and basketball (5). Children ages 10 to 14 have the most emergency department visits due to sports-related TBIs (2). Females have been noted to have higher risk in sustaining sports-related TBI. Some postulations as to why these groups have higher risk include lower neck strength and hormonal fluctuations (6).

A full recovery from a sports-related concussion usually takes about 1 to 2 weeks; however, some symptoms may last longer. Professional athletes overall recover the quickest, and then collegiate athletes, followed by high school athletes, and lastly children. Good aerobic conditioning is thought to minimize recovery time (2). One of the most significant risk factors for prolonged recovery is an athlete with a history of concussions. Other risk factors for prolonged recovery include those with learning disabilities, sleep and mood disorders, or preexisting head trauma (2). The symptoms observed at the time of injury, such as amnesia or loss of consciousness, also may predict the risk for prolonged recovery. A variety of diagnostic systems that evaluate the length of symptoms and severity of impairment related to prolonged recovery may be used to diagnose post-concussive syndrome.

Pathophysiology

There is no clear pathophysiologic definition of a concussion (4). Some of the primary theories for pathophysiology include tauopathy, axonal shearing, neuronal electrolyte imbalances, and reduced perfusion (4,6). In concussion trauma, there is an unusual accumulation of a tau protein in the cortical sulci. This protein is hyper phosphorylated which leads to neurofibrillary lesions and disruptions in the neuronal connectivity. Tau phosphorylation not only is seen in normal aging, but also is seen in early ages in athletes who suffer from concussions (4). Shearing and electrolyte imbalances lead to increased metabolic stress and depletion of energy stores, which leads to necrosis. The neurotransmitter glutamate is released immediately after a concussion along with potassium efflux and calcium influx which results in increased glucose metabolism. The increase in calcium is thought to facilitate cell death (7).

Sideline Screening

Sideline suspicion is important because 90% of second concussions happen within 7 to 10 d of the first one (2). Players suspected of sports-related concussion should be removed from the game and evaluated on the sideline. In addition to a physical examination, the sideline assessment should include neurological, memory, and attention function assessment. Due to the lack of evidence on the efficacy of sideline tests, expert consensus is the guiding source of sideline management and the Sport Concussion Assessment Tool 5 (SCAT-5) is the most established, developed, and studied sideline assessment tool at this time (8).

Management

Prevention is the cornerstone of management. Equipment should fit properly, preseason conditioning should be optimized, and participants should be taught sport-specific collision techniques. Overall, sports programs at every level have had more emphasis and awareness of concussions. Programs have instituted contact limitations and rule changes in sports such as football to decrease the number of sports-related concussions (9).

The American Academy of Neurology has suggested that baseline neuropsychological assessments allow better interpretation of post-concussion scores (7). Having baseline scores helps assess those individuals who may have already had difficulties prior to concussion symptoms and more accurately determine a return to baseline function after injury.

Clinical management of sports-related concussions emphasizes cognitive and physical rest. Activities such as computer, phone, tablets, and video games, and reading all involve mental exercise and should be limited (7). School-aged athletes should have a return to school strategy (3). Athletes should be completely asymptomatic at rest and on exertion to be cleared to return to sports. Return to play prior to resolution of symptoms may prolong recovery time (2). The graduated return to sport strategy is widely used to allow athletes to gradually introduce themselves back into contact sports. The stages are as follows:

  1. Daily activities that do not cause symptoms
  2. Light aerobic exercise
  3. Sport-specific exercise
  4. More intense, noncontact training exercises
  5. Full contact practice
  6. Return to normal game play (3)

The authors declare no conflict of interest and do not have any financial disclosures.

References

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2. Conder RL, Conder AA. Sports-related concussions. N. C. Med. J. 2015; 76:89–95.
3. 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; 51:838–47.
4. Satarasinghe P, Hamilton DK, Buchanan RJ, Koltz MT. Unifying pathophysiological explanations for sports-related concussion and concussion protocol management: literature review. J. Exp. Neurosci. 2019; 13:1179069518824125.
5. Chen Y, Herrold AA, Gallagher VT, et al. Cutting to the pathophysiology chase: translating cutting-edge neuroscience to rehabilitation practice in sports-related concussion management. J. Orthop. Sports Phys. Ther. 2019; 49:811–8.
6. Hall EE, Ketcham CJ, Crenshaw CR, et al. Concussion management in collegiate student-athletes: return-to-academics recommendations. Clin. J. Sport Med. 2015; 25:291–6.
7. Patricios J, Fuller GW, Ellenbogen R, et al. What are the critical elements of sideline screening that can be used to establish the diagnosis of concussion? A systematic review. Br. J. Sports Med. 2017; 51:888–94.
8. Waltzman D, Womack LS, Thomas KE, Sarmiento K. Trends in emergency department visits for contact sports-related traumatic brain injuries among children—United States, 2001–2018. Morb. Mortal Wkly. Rep. 2020; 69:870–4.
9. Rivara FP, Tennyson R, Mills B, et al. Consensus statement on sports-related concussions in youth sports using a modified Delphi approach. JAMA Pediatr. 2020; 174:79–85.
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