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Concussion (Mild Traumatic Brain Injury)

Concussion (Mild Traumatic Brain Injury) is a topic covered in the 5-Minute Clinical Consult.

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  • Concussion (or mild traumatic brain injury [mTBI]) is defined as a complex pathophysiologic process affecting the brain, induced by traumatic biomechanical forces. This can be direct (blow to the head) or indirect (impulsive force is then transmitted to the head).
  • Concussion may or may not involve loss of consciousness (LOC). There is currently no widely accepted classification system for concussions.
  • The most prevalent and consistent indicators are (1):
    • Immediate confusion or disorientation
    • Impaired balance within 1 day
    • Slowed reaction times within 2 days of event
    • Impaired verbal learning and memory within 2 days

Pediatric Considerations
Resolution of symptoms and return to neurocognitive baseline often take longer in pediatric and adolescent athletes (<18 years).


  • The CDC estimates 1.6 to 3.8 million concussions occur every year, although many go unreported.
  • >1 million ER visits every year are due to TBIs (falls, MVAs, assault, sports, others); >1/2 of these visits are by children aged 5 to 18 years.
  • High school (HS) and college athlete concussion rates have increased in the past 30 years, likely in part due to increased reporting.
  • NCAA from 2009 to 2014 reported 1,670 concussions. Highest incident sports: football, hockey, rugby, soccer, basketball
  • Concussions more likely in games than practices
  • Female athletes have more reported concussions than male athletes in similar sports and more frequently suffer cognitive impairment.

  • The most common cause of TBI in the elderly (>65 years of age) is falls.
  • Up to 1/3 of all sports-related concussions may go unreported or undiagnosed (2)[B].
  • Sports (numbers per 1,000 athlete exposures, defined as one athlete playing in one game or practice)
    • Football: college 0.61 (0.39 in practice, 3.02 in games); HS 0.47 (0.21 in practice, 1.55 in games)
    • Basketball (college): males 0.16; females 0.22
    • Ice hockey (college): males 0.41, females 0.91
    • Lacrosse (college): males 0.26, females 0.25
    • Soccer: college males 0.49, HS males 0.22; college females 0.63, HS females 0.36
    • Skiing and snowboarding: 0.005 and 0.004, respectively. Snowboarders have a higher incidence of severe brain injuries than skiers.

Etiology and Pathophysiology

  • Direct or indirect injury to the head
    • Falls
    • Sports-related injuries
    • Motor vehicle accidents
    • Assaults
  • Identifiable metabolic changes include alterations in intra-/extracellular potassium, calcium, and glutamate with subsequent neuron dysfunction. Microtearing of cerebral blood vessels and a relative decrease in cerebral blood flow also occurs. An increased requirement for glucose by the brain, coupled with decreased blood flow, may result in cellular dysfunction and increased susceptibility to subsequent brain insults. Other biochemical changes are currently being studied.
  • Structural abnormalities of the brain are typically absent based on imaging studies.

Risk Factors

  • Patients at high risk for falls: elderly, intoxication
  • History of previous concussion
  • Young adolescents, female gender
  • Contact sports (particularly football): activities such as bicycling, cheerleading, skiing, and snowboarding; organized sports > leisure physical activity
  • There are no incidences of concussion associated with heading a soccer ball in a 6-year study.
  • Severity predictor
    • Retrograde amnesia is better predictor than LOC for acute neuropsychological deficits (3).
    • Longer recovery in mood disorders, learning disabilities

General Prevention

  • Educate athletes, coaches, parents, and officials about signs and symptoms of concussions.
  • Preparticipation exams to identify at-risk athletes
  • Strength and conditioning (athletes and elderly)
  • Rule enforcement in sports (e.g., penalties for spearing or head-to-head contact) and teaching athletes correct sports-specific techniques
  • Protective equipments, such as helmets and mouth guards, decrease fractures, bleeds, lacerations but have not been shown to decrease concussion rates.

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Stephens, Mark B., et al., editors. "Concussion (Mild Traumatic Brain Injury)." 5-Minute Clinical Consult, 27th ed., Wolters Kluwer, 2019. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816763/all/Concussion__Mild_Traumatic_Brain_Injury_.
Concussion (Mild Traumatic Brain Injury). In: Stephens MB, Golding J, Baldor RA, et al, eds. 5-Minute Clinical Consult. 27th ed. Wolters Kluwer; 2019. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816763/all/Concussion__Mild_Traumatic_Brain_Injury_. Accessed April 25, 2019.
Concussion (Mild Traumatic Brain Injury). (2019). In Stephens, M. B., Golding, J., Baldor, R. A., & Domino, F. J. (Eds.), 5-Minute Clinical Consult. Available from https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816763/all/Concussion__Mild_Traumatic_Brain_Injury_
Concussion (Mild Traumatic Brain Injury) [Internet]. In: Stephens MB, Golding J, Baldor RA, Domino FJ, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2019. [cited 2019 April 25]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816763/all/Concussion__Mild_Traumatic_Brain_Injury_.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Concussion (Mild Traumatic Brain Injury) ID - 816763 ED - Stephens,Mark B, ED - Golding,Jeremy, ED - Baldor,Robert A, ED - Domino,Frank J, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816763/all/Concussion__Mild_Traumatic_Brain_Injury_ PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -