Concussion is a mild traumatic brain injury manifesting with self-limited symptoms at the less severe end of the brain injury spectrum.

The Fifth International Conference on Concussion in Sport (2016) defines sports-related concussion as a traumatic brain injury induced by biomechanical forces caused either by a direct blow to the head, face, neck or elsewhere on the body with an impulsive force transmitted to the head. (However, this definition is also applicable to concussion in general.)

This injury results in the rapid onset of short-lived, spontaneously resolving neurological impairment. In some cases, signs and symptoms evolve over a number of minutes to hours.

Although neuropathological changes may result, the acute clinical signs and symptoms largely reflect a functional disturbance rather than brain structural injury, and therefore no abnormality is seen on standard structural neuroimaging studies.

A range of clinical signs and symptoms may develop that may or may not involve loss of consciousness.

Resolution of the clinical and cognitive features typically follows a sequential course, but in some cases symptoms may be prolonged.

The clinical signs and symptoms cannot be explained by drug, alcohol or medication use, other injuries (such as cervical injuries, peripheral vestibular dysfunction, etc.), or other comorbidities (e.g., psychological factors or coexisting medical conditions).


  • Mild traumatic brain injury (mTBI)

Epidemiology & Demographics


3.8 million sports- and recreation-related concussions occur each yr in the U.S. It is estimated that as many as 50% of concussions go unreported.


Each yr, U.S. emergency departments treat an estimated 135,000 sports- and recreation-related TBIs, including concussions, among children ages 5 to 18.

Predominant Gender and Age

  • •Children and teens are more likely to get a concussion and take longer to recover than adults.
  • •Limited studies have shown that in sports that are played by both men and women, women are at more risk of sustaining a concussion. In males the incidence is highest in football, followed by hockey, and in females, soccer. Player contact is the most common cause.

What increases the risk of Concussion?

  • •Participating in high-impact sports and recreational activities
  • •Previous history of concussion
  • •Athletes with a body mass index (BMI) >27 kg/m2 and those who train <3 hr/wk
  • •Individuals who sustain a sports-related concussion and continue playing immediately after the injury require nearly twice as much time to recover as those who are removed immediately

Physical Findings & Clinical Presentation

What are the Symptoms and Signs of Concussion

From Patel DR et al: Sports concussions in adolescents, Pediatr Clin N Am 57:652, 2010.

Mental Status Changes
Easily distracted
Excessive drowsiness
Feeling dinged, stunned, or foggy
Impaired level of consciousness
Inappropriate play behaviors
Poor concentration and attention
Seeing stars or flashing lights
Slow to answer questions or to follow directions
Physical or Somatic
Ataxia or loss of balance
Blurry vision
Decreased performance or playing ability
Double vision
Nausea, vomiting
Poor coordination
Ringing in the ears
Slurred, incoherent speech
Vacant stare/glassy-eyed
Behavior or Psychosomatic
Emotional lability
Low frustration tolerance
Personality changes
Nervousness, anxiety
Sadness, depressed mood

What causes Concussion?

  • •Occurs when rotational or angular acceleration forces are applied to the brain, resulting in shear strain of the underlying neural elements, including altered autonomic function and impaired control of cerebral blood flow
  • •May be associated with a blow to the skull; however, direct impact to the head is not required

Differential Diagnosis

  • •Migraine
  • •Cervical strain
  • •Posttraumatic vestibular injury

How is Concussion diagnosed?

  • •There is no definitive diagnostic test for concussion. A standardized protocol can help first responders identify more subtle mental status changes. Physical exam should include smooth pursuits (examiner moves finger horizontally across field of vision), saccades, gaze instability, near point of convergence, accommodation, and balance. Patients with loss of consciousness or posttraumatic convulsive seizures should be transported to the emergency department.

Standardized Assessment of Concussion

Goldman L, Shafer AI: Goldman-Cecil medicine, ed 26, Philadelphia, 2020, Elsevier.

TaskPossible Score
Month, date, day of week, year, time (1 point for each correct answer)0-5
Immediate Memory
Patient repeats a 5-word list spoken by examiner; 3 trials (1 point for each word correctly remembered)0-15
Digits backward; 3-, 4-, 5-, and 6-digit strings (1 point for each digit string correctly repeated backward)0-4
Months of the year in reverse order (1 point for repeating backward in correct sequence)0-1
Delayed Memory Recall
Patient repeats the 5 words from Immediate Memory test (1 point for each word correctly recalled)0-5
  • Sideline assessment:
    • 1.No athlete with a suspected concussion should return to play that day.
    • 2.Neurologic assessment using a standardized tool, such as s SCAT-3 (Sports Concussion Assessment Tool), which includes the BESS (Balance ErrorScoring System), Maddocks Questions, and SAC (Standardized Assessment of Concussion).
    • 3.Monitor for deterioration; no athlete should be left alone.
  • •Office assessment:
    • 1.History focused on current symptoms. Consider using Postconcussion Symptom Checklist. According to the Consensus Statement on Concussion in Sport issued by the Fifth International Conference on Concussion in Sport, the following domains should be investigated when considering a diagnosis of sports-related concussion. A problem in one domain in the proper historical context should raise concern for sports-related concussion.
      • a.Symptoms: Somatic (e.g., headache), cognitive (e.g., feeling like in a fog), and/or emotional symptoms (e.g., lability)
      • b.Physical signs (e.g., loss of consciousness, amnesia, neurological deficit)
      • c.Balance impairment (e.g., gait unsteadiness)
      • d.Behavioral changes (e.g., irritability)
      • e.Cognitive impairment (e.g., slowed reaction times)
      • f.Sleep/wake disturbance (e.g., somnolence, drowsiness)
    • 2.Neurologic exam
      • a.Gait/balance testing. Consider the Balance Error Scoring System (BESS)
      • b.Cerebellar coordination: Finger-to-nose testing (tested on SCAT-3 card)
      • c.Convergence of Accommodative Sufficiency
  • •Neurocognitive testing:
    • 1.Computer-based programs, such as ImPACT, ANAM, CogSport
    • 2.Neuropsychiatric testing administered by a neuropsychologist
  • •When used in combination, symptom assessment, balance assessment, and neurocognitive testing provide a sensitivity of >90% for the identification of concussion.
  • •Consider the Buffalo Concussion Treadmill Test, which identifies physiologic dysfunction in concussion, rules out other diagnoses, and can quantify a safe level of activity in concussion recovery.

Imaging Studies

  • •CT imaging is not universally indicated and should be considered on an individual basis. It is indicated in any athlete with a rapidly changing or focal neurologic exam or with a suspected intracranial bleed.
  • •Consider following PECARN guidelines.

 How is Concussion treated?

Acute General Treatment

  • •Removal from game
  • •Physical rest
    • 1.No return to play until asymptomatic for at least 24 hours.
    • 2.Follow the return-to-play guidelines

Graduated Return to Play Protocol

From Putukian M: The acute symptoms of sports-related concussion: diagnosis and on-field management, Clin Sports Med 30(58), 2011.

Rehabilitation StageFunctional Exercise at Each Stage of RehabilitationObjective of Each Stage
1.No activityComplete physical and cognitive restRecovery
2.Light aerobic exerciseWalking, swimming, or stationary cycling, keeping intensity <70% maximum predicted heart rate. No resistance trainingIncrease heart rate
3.Sport-specific exerciseSkating drills in ice hockey, running drills in soccer. No head impact activitiesAdd movement
4.Noncontact training drillsProgression to more complex training drills, e.g., passing drills in football and ice hockey. May start progressive resistance trainingExercise, coordination, and cognitive load
5.Full contact practiceAfter medical clearance, participate in normal training activitiesRestore confidence and assess functional skills by coaching staff
6.Return to playNormal game play
    • There is no evidence to support prolonged rest in concussed athletes longer than several weeks (see “ Postconcussive Syndrome ”). Prolonged inactivity after concussion has been linked to negative health effect. Light aerobic activity that avoids risk for reinjury decreases concussion symptoms, suggesting that low-level physical activity postconcussion might be beneficial.
  • •Cognitive rest to limit symptoms
    • 1.Limit screen time to less than 2 hours per day.
    • 2.Academic accommodations at school. Consider return to school for half-days when tolerating 2 hours of work at home.
    • 3.Encourage good sleep hygiene.


  • •Physiologic recovery is slower than symptomatic recovery. Protocols involving a symptom-free waiting period before return to play are warranted. The below table summarizes the American Academy of Neurology, American Medical Society for Sports Medicine, and International Conference on Concussion recommendations on returning to play after a concussion.
  • •If concussion symptoms occur with activity at one level, the athlete should stop the activity, rest until symptoms resolve, and then restart his or her progression at the level that did not elicit symptoms.
  • •There are no evidence-based guidelines for disqualifying or retiring an athlete from sport after a concussion. Each case should be individually considered.


Referral to sports-medicine physician, neuropsychology, or concussion center is indicated if there is concern about the timing of return to contact or collision sport.

Referral is also indicated in patients with preexisting neurologic disorders such as migraines, depression or anxiety, and in those who have had multiple concussions.


  • •Preparticipation evaluations for all athletes.
  • •Preparticipation neurocognitive and balance testing to establish a baseline.
  • •There is currently no evidence to support the use of concussion prevention headbands or mouth guards.
  • •Spontaneous recovery from acute concussion ranges from 1 to 2 wk in adults and up to 4 wk in adolescents.

Patient & Family Education

Centers for Disease Control and Prevention:

Suggested Readings

  • Centers for Disease Control and Prevention: Traumatic Brain Injury & Concussion. Available at
  • Elbin R.J., et al.: Removal from play after concussion and recovery time. Pediatrics 2016; 138(3): e20160910.
  • Grool A.M., et al.: Association between early participation in physical activity following acute concussion and persistent post-concussive symptoms in children and adolescents. JAMA 2015; 316: pp. 2504.
  • Halstead M.E., et al.: Sports-related concussion in children and adolescents. Pediatrics 2010; 126 (3): pp. 597-615.
  • Harmon K.G.: American Medical Society for Sports Medicine position statement: concussion in sport. Clin J Sport Med 2013; 23 (1-18):
  • Leddy J.J., et al.: Use of graded exercise testing in concussion and return-to-activity management. Curr Sports Med Rep 2013; 12 (6): pp. 370-376.
  • Master C.L., et al.: In the clinic: concussion. Ann Intern Med 2014; 160 (3):
  • McCrory P., et al.: Consensus statement on concussion in sport: the 4th International Conference on Concussion in Sport held in Zurich, November 2012. Br J Sports Med 2013; 47: pp. 250-258.
  • McCrory P., 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 2018; 51: pp. 838-847.
  • Mullally W.J.: Concussion. Am J Med 2017; 130: pp. 885-892.
  • Patel D.R., et al.: Sports related concussions in adolescents. Pediatr Clin North Am 2010; 57: pp. 649-670.
  • Putukian M.: The acute symptoms of sports-related concussion: diagnosis and on-field management. Clin Sports Med 2011; 30: pp. 49-61.

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