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Basic Information ⬇

AUTHOR: Joseph S. Kass, MD, JD, FAAN

Definition

Concussion is a mild traumatic brain injury (TBI) 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 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 neurologic impairment. In some cases, signs and symptoms evolve over several minutes to hours. Although neuropathologic 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).

Synonym

Mild traumatic brain injury (mTBI)

ICD-10CM CODES
S06.0Concussion
S06.0X0AConcussion without loss of consciousness, initial encounter
S06.0X0DConcussion without loss of consciousness, subsequent encounter
S06.0X0SConcussion without loss of consciousness, sequela
S06.0X1AConcussion with loss of consciousness of 30 minutes or less, initial encounter
S06.0X9AConcussion with loss of consciousness of unspecified duration, initial encounter
Epidemiology & Demographics
Incidence

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.

Prevalence

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 Sex & 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.
Risk Factors

  • 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 h/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
  • Military personnel
Physical Findings & Clinical Presentation

Common neurologic examination findings include nystagmus, changes in gait, balance abnormalities, truncal ataxia, gait ataxia, increased posture sway, saccadic eye movements with smooth pursuit, memory deficits, amnesia, disorientation, and emotional lability (Table 1).

TABLE 1 Common Symptoms of Sports-Related Concussion

SomaticCognitiveNeurobehavioral
Headache
Dizziness
Photophobia
Phonophobia
Blurred vision/diplopia
Nausea		Disorientation/confusion
Feeling “in a fog” or “hazy”
Lack of attention/focus
Distractibility
Memory deficits		Lethargy/fatigue
Drowsiness
Hypersomnia/insomnia
Sadness/depression
Anger
Nervousness/irritability
“Not feeling right”
PhysicalCognitiveNeurobehavioral
Loss of consciousness
Loss of awareness
Blank stare/dazed look
Seizure
Vomiting
Dysarthria/slurred speech
Ataxia/discoordination		Disorientation/confusion
Memory impairment
Slowed reaction time or processing speed
Attention deficit
Impaired comprehension
Problems with concentration		Personality changes
Irritability/violent outburst
Depression
Emotional lability

From Jankovic J et al: Bradley and Daroff’s neurology in clinical practice, ed 8, Philadelphia, 2022, Elsevier.

Etiology

  • 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

Diagnosis ⬆ ⬇

Differential Diagnosis

  • Migraine
  • Cervical strain
  • Posttraumatic vestibular injury
Workup

  • There is no definitive diagnostic test for concussion. A standardized protocol (Table 2) 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. Concussions are graded according to the severity of symptoms: Presence or absence of loss of consciousness and time (more or less than 15 minutes) for resolution of symptoms (Table 3).
  • Sideline assessment:
    1. No athlete with a suspected concussion should return to play that day.
    2. Neurologic assessment using a standardized tool, such as SCAT-3 (Sports Concussion Assessment Tool), which includes the BESS (Balance Error Scoring 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.
      1. Symptoms: Somatic (e.g., headache), cognitive (e.g., feeling like in a fog), and/or emotional symptoms (e.g., lability)
      2. Physical signs (e.g., loss of consciousness, amnesia, neurologic deficit)
      3. Balance impairment (e.g., gait unsteadiness)
      4. Behavioral changes (e.g., irritability)
      5. Cognitive impairment (e.g., slowed reaction times)
      6. Sleep/wake disturbance (e.g., somnolence, drowsiness)
    2. Neurologic exam
      1. Gait/balance testing. Consider the Balance Error Scoring System (BESS)
      2. Cerebellar coordination: Finger-to-nose testing (tested on SCAT-3 card)
      3. 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.

TABLE 2 Standardized Assessment of Concussion

TaskPossible Score
Orientation
Month, date, day of week, yr, 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
Concentration
Digits backward; 3-, 4-, 5-, and 6-digit strings (1 point for each digit string correctly repeated backward)0-4
Months of the yr 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
TOTAL SCORE0-30

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

TABLE 3 Grading of Concussion

GradeCantu SystemAmerican Academy of Neurology System
  1. (Mild)
A. PTA <30 minA. Transient confusion
B. No LOCB. No LOC
C. Symptoms resolved in <15 min
  1. (Moderate)
A. LOC <5 min, or B. PTA >30 minAs above, but symptoms last >15 min (still no LOC) (PTA is common)
  1. (Severe)
A. LOC ≥5 min, or B. PTA ≥24 hAny LOC, whether brief (seconds) or prolonged

LOC, Loss of consciousness; PTA, posttraumatic amnesia.

From Jankovic J et al: Bradley and Daroff’s neurology in clinical practice, ed 8, Philadelphia, 2022, Elsevier.

Imaging Studies

  • Computed tomography (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.

Treatment ⬆ ⬇

Acute General Rx

  • Removal from game
  • Physical rest
    1. No return to play until asymptomatic for at least 24 h.
    2. Follow the return-to-play guidelines (Table 4).
    3. 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 h/day.
    2. Academic accommodations at school. Consider return to school for half-days when tolerating 2 h of work at home.
    3. Encourage good sleep hygiene.

TABLE 4 Guidelines for the Management of Sport-Related Concussion∗

SymptomsFirst ConcussionSecond Concussion
Grade 1: No loss of consciousness, transient confusion, resolution of symptoms and mental abnormalities in <15 min†Remove from play
Examine at 5-min intervals
May return to play if symptoms disappear and results of mental function examination return to normal within 15 min		Allow return to play after 1 wk if there are no symptoms at rest or with exertion
Grade 2: As above but with mental symptoms for ≥15 minRemove from play and disallow play for rest of day
Examine for signs of intracranial lesion at sidelines and obtain further examination by a trained person on same day
Allow return to play after 1 wk if neurologic examination is nonconcerning		Allow return to play after 2-wk period of no symptoms at rest or with exertion
Remove from play for season if imaging shows abnormality
Grade 3: Any loss of consciousnessPerform thorough neurologic examination in hospital and obtain imaging studies when indicated
Assess neurologic status daily until postconcussive symptoms resolve or stabilize
Remove from play for 1 wk if loss of consciousness lasts seconds or for 2 wk if it lasts minutes; must be asymptomatic at rest and with exertion to return to play		Withhold from play until symptoms have been absent for at least 1 mo

∗These guidelines reflect consensus opinion, are not evidence-based, and are under revision. Adapted from the American Academy of Neurology guidelines.

† Testing includes orientation, repetition of digit strings, recall of word list at 0 and 5 min, recall of recent game events, recall of current events, pupillary symmetry, finger-to-nose and tandem-gait tests, Romberg test, and provocative testing for symptoms with a 4-yd (3.5-m) sprint, five push-ups, and five knee bends.

From Jankovic J et al: Bradley and Daroff’s neurology in clinical practice, ed 8, Philadelphia, 2022, Elsevier.

Chronic Rx

See “Postconcussive Syndrome.”

Disposition

  • Physiologic recovery is slower than symptomatic recovery. Protocols involving a symptom-free waiting period before return to play are warranted. Table 4 summarizes recommendations on returning to play after a concussion. CDC protocols for managing return to activities after concussion are described in Table 5. Physical and cognitive rest are the cornerstones of initial concussion management, with subsequent gradual return to school and physical activities. Repeated concussions, especially within days or weeks, carry a significant risk of permanent brain injury (second impact syndrome).
  • 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.

TABLE 5 Protocol for Return to Sport After Concussion.

Return-to-play protocol follows a stepwise progress with each step taking ≥24 h. The athlete should continue to the next level if asymptomatic at the current level.
  1. Back to regular activities such as school.
  2. Light aerobic exercise such as walking or stationary cycling; no weight lifting.
  3. Moderate activity such as jogging, brief running, moderate-intensity stationary biking, moderate-intensity weightlifting (less than their prior weightlifting routine).
  4. Heavy, noncontact physical activity such as sprinting/running, regular weightlifting routine, noncontact sport specific drills.
  5. Practice and full contact.
  6. Competition.

From Centers for Disease Control and Prevention: Managing return to activities, 2018. https://www.cdc.gov/headsup/providers/return_to_activities.html.

Referral

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.

Pearls & Considerations ⬆ ⬇

Prevention

  • 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: https://www.cdc.gov/TraumaticBrainInjury/get_the_facts.html.

Related Content

Concussion (Patient Information)

Postconcussion Syndrome (Related Key Topic)

Traumatic Brain Injury (Related Key Topic)

Suggested Readings ⬆

    1. Centers for Disease Control and Prevention: Traumatic brain injury & concussion. Available at www.cdc.gov/TraumaticBrainInjury/get_the_facts.html.
    2. Elbin R.J. : Removal from play after concussion and recovery timePediatrics. ;138(3), 2016.
    3. Grool A.M. : Association between early participation in physical activity following acute concussion and persistent post-concussive symptoms in children and adolescentsJ Am Med Assoc. ;316, 2015.
    4. Halstead M.E. : Sports-related concussion in children and adolescentsPediatrics. ;126(3):597-615, 2010.
    5. Leddy J.J. : Use of graded exercise testing in concussion and return-to-activity managementCurr Sports Med Rep. ;12(6):370-376, 2013.
    6. Master C.L. : In the clinic: concussionAnn Intern Med. ;160(3), 2014.
    7. McCrory P. : Consensus statement on concussion in sport: the 4th International Conference on Concussion in Sport held in Zurich, November 2012Br J Sports Med. ;47:250-258, 2013.
    8. McCrory P. : Consensus statement on concussion in sport: the 5th International Conference on Concussion in Sport held in Berlin, October 2016Br J Sports Med. ;51:838-847, 2018.
    9. Mullally W.J. : Concussion, Am J Med. ;130:885-892, 2017.
    10. Patel D.R. : Sports related concussions in adolescentsPediatr Clin North Am. ;57:649-670, 2010.
    11. Putukian M. : The acute symptoms of sports-related concussion: diagnosis and on-field managementClin Sports Med. ;30:49-61, 2011.