Concussion

Aka: Concussion, Concussion in Sports, Brain Concussion, Concussion Red Flags, Head Injury in Sports

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II. Definitions

  1. Concussion
    1. Synonymous with Mild Traumatic Brain Injury (preferred overall term) and Minor Head Injury
    2. Mildest form of Traumatic Brain Injury (see Mild Traumatic Brain Injury) in which GCS is 13-15
    3. Acute Trauma-induced mental function alteration (in contrast to structural abnormalities)
    4. Transient loss of consciousness variably present (10% overall, 40% of Emergency Department evaluations)

III. Epidemiology

  1. See Mild Traumatic Brain Injury
  2. Incidence
    1. Children: 1 in 220 annually (30-50% sports related, esp. football and soccer)
    2. Athletes All Ages: 1.6 to 3.8 Million in U.S. per year

IV. Pathophysiology

  1. Direct Head Trauma is not required to sustain a Concussion
    1. Acceleration, deceleration and rotational forces transmitted to the brain are sufficient to cause injury
  2. Concussion results in acute Neuron injury (esp. axonal Stretching and shearing)
    1. Leads to extracellular release of ions (esp. Potassium) and excitatory Neurotransmitters (esp. Glutamate)
  3. Increased energy demands (esp. ATP) to correct ion disruption (e.g. Sodium-Potassium ATP Pump)
    1. Yet decreased Blood Flow to injured tissue results in energy delivery deficit
  4. Metabolic derangements resolve over the course of weeks (corresponding to symptom improvement)
    1. Symptoms improve or resolve by 72 hours
    2. Recovery may approach 7 weeks (or longer in younger children)
      1. Adults may fully recover by 2 weeks in some studies, but other studies suggest as long as 3 months
      2. Children recover fully by one to three months (70-80%)
      3. In some cases, especially in young children, effects may persist longterm
      4. Kerrigan (2017) Childs Nerv Syst 33(10): 1669-75 [PubMed]

V. Risk Factors

  1. Active duty military deployed to combat regions
    1. Traumatic Brain Injury affected 15% U.S. troups involved in Iraq and Afghanistan
  2. Non-Sports related injury
    1. Falls (38%)
    2. Vehicle-related injuries (31%)
    3. Non-accidental Trauma (11%)
  3. Contact Sports Participation (highest risk)
    1. Football
      1. Most common cause of sports-related Concussion in U.S.
      2. Concussion in 20% of high school and 10% of college athletes each year
    2. Ice Hockey
    3. Soccer
      1. Second most common cause of Concussion in U.S. (especially in female athletes)
    4. Boxing
    5. Lacrosse
    6. Wrestling
    7. Basketball
    8. Rugby
    9. Softball
  4. Non-Contact Sports Participation
    1. Bicycling
    2. Playground-related injuries
    3. Gymnastics
    4. Skiing
    5. Sledding
    6. Ice Skating
    7. Inline Skating
    8. Horseback riding
  5. Female Gender
    1. Women are at higher risk of Concussions, secondary symptoms, Cognitive Impairment and prolonged recovery
    2. Women are more likely to be injured by contact with playing surface or equipment
      1. Contrast with men who are most often injured by player to player contact
    3. Covassin (2011) Clin Sports Med 30(1):125-31 [PubMed]

VI. Symptoms

  1. See Concussion Symptom Checklist
  2. Headache (75%, most common) or head pressure
  3. Blurred Vision (75%)
  4. Dizziness (60%)
  5. Nausea or Vomiting (54%)
  6. Double Vision (11%)
  7. Noise sensitivity or light sensitivity (4%)
  8. Slurred speech
  9. Irritability or sadness
  10. Altered sleep pattern
  11. Imbalance or Incoordination
    1. Typically lasts 3-5 days after Concussion
  12. Loss of consciousness
    1. Present in 10% of Concussions

VII. Signs: General

  1. Amnesia
  2. Disorientation
  3. Confusion
    1. Vacant stare
    2. Disorientation
    3. Delayed answers to questions
    4. Poor concentration
    5. Inattention
    6. Decreased verbal learning and memory

VIII. Signs: Red Flags for Severe Head Injury

  1. Mental status changes
    1. Loss if consciousness for more than 60 seconds
    2. Somnolence or confusion
    3. Disorientation
    4. Language or speech deficit
    5. Memory deficit
  2. Eye findings (Brainstem dysfunction)
    1. Visual disturbance
    2. Pupils unequal, fixed or dilated
    3. Extraocular Movements abnormal
  3. Deep Tendon Reflexes (Upper Motor Neuron dysfunction)
    1. Hyperreflexia
    2. Babinski Reflex present
  4. Muscle Strength
    1. See Motor Exam
    2. Decreased Muscle tone or weakness (especially asymmetric)
    3. Involuntary movements (consider Basal Ganglia or cerebellar injury)
  5. Sensory deficit
    1. See Sensory Exam
    2. Numbness or abnormal Sensation (consider dermatomal pattern for spinal root deficit)
  6. Incoordination or Balance problem (Cerebellar dysfunction)
    1. Romberg Sign positive
    2. Ataxic gait
    3. Postural instability (e.g. abnormal Balance Error Scoring System)
    4. Finger-to-Nose Test

IX. Differential Diagnosis

  1. See Altered Level of Consciousness Causes
  2. See Delirium
  3. Heat Illness
  4. Exertional Migraine
  5. Hypoglycemia

X. Grading

  1. See Concussion Grading

XI. Evaluation: Acute clinical

  1. See Head Injury
  2. Systematic evaluation (unless isolated Minor Head Injury)
    1. See Trauma Evaluation (includes Primary Survey)
    2. See Secondary Trauma Evaluation
  3. Neurologic evaluation
    1. See Emergency Neurologic Exam
    2. Glasgow Coma Scale (GCS)
    3. Complete Neurologic Exam
    4. Oculomotor testing
      1. Sensitive for minor Concussion
      2. Observe for Nystagmus, saccades, CN IV palsy, Anisocoria
  4. Assess for significant head and neck injuries
    1. Intracranial Hemorrhage (Epidural Hemorrhage, Subdural Hemorrhage)
    2. Skull Fracture
    3. Scalp Laceration with active bleeding (control bleeding as part of Primary Survey)
    4. Cervical Spine Injury (or Pediatric Cervical Spine Injury)
  5. Concussion is a clinical diagnosis
    1. Evaluation is focused on excluding associated Traumatic injuries
    2. No lab or imaging test defines Concussion
    3. However, sports related Concussion tools (or neuropsychiatric testing) may identify and monitor Concussions

XII. Evaluation: Sideline or in Sports Medicine Evaluation

  1. Sideline: Sport Concussion Assessment Tool ( SCAT6)
    1. Comprehensive - includes all other tests listed below
    2. Age 13 years old and older (SCAT6)
      1. https://bjsm.bmj.com/content/bjsports/57/11/622.full.pdf
    3. Age 8 to 12 years old (Child-SCAT6)
      1. https://bjsm.bmj.com/content/bjsports/57/11/636.full.pdf
  2. Office: Sport Concussion Office Assessment Tool (SCOAT6)
    1. Age 13 years old and older (SCOAT6)
      1. https://fittoplay.org/globalassets/documents/poster/scat6/scat6-english/scoat6.pdf
    2. Age 8 to 12 years (Child SCOAT6)
      1. https://bjsm.bmj.com/content/bjsports/57/11/672.full.pdf
  3. Tools included in Standardized Assessment of Concussion (SCAT5)
    1. Immediate On Field Assessment
      1. Red Flags (e.g. Altered Level of Consciousness, focal neurologic deficits, Seizures, Agitation, Neck Pain)
      2. Observable signs (e.g. Altered Level of Consciousness, neurologic deficits)
      3. Cervical Spine Assessment (pain at rest, active range of motion, extremity motor/sensory)
      4. Glasgow Coma Scale (15 points)
      5. Maddocks Score (5 points)
    2. Other testing in office, hospital or on field
      1. Concussion Symptom Checklist (22 points)
      2. Modified Balance Error Scoring System or MBess (30 points)
      3. Cognitive Screening of orientation, memory, recall, concentration
        1. Similar to Standard Assessment of Concussion
      4. Neuro screen exam (read aloud, cervical Neck Pain, coordination, Diplopia)
  4. Other tools
    1. Computer based Neuropsychological Testing (e.g. ImPACT)
      1. In some sports, baseline testing is performed
      2. Baseline testing is not recommended in young children (high variability)
    2. Postconcussive Symptom Scale
      1. http://www.hawaiiconcussion.com/pdf/post-concussion-symptom-scale.aspx

XIII. Imaging

  1. Head imaging indications
    1. Imaging is NOT indicated in uncomplicated Concussion without specific indications
      1. See Head Injury CT Indications in Adults (Canadian CT Head Rule, New Orleans Head CT Rule)
      2. See Head Injury CT Indications in Children (includes PECARN)
      3. Imaging evaluates for Intracranial Hemorrhage, NOT Concussion
    2. CT Head is indicated in all moderate and Severe Head Trauma (GCS <13)
      1. CT Head has a higher Test Sensitivity for Intracranial Hemorrhage than MRI Head
      2. Inform parents about CT-associated Radiation Exposure
    3. Other advanced imaging (MRI, SPECT) is not recommended routinely in children (cost, sedation)
    4. Skull XRays are not recommended (low Test Sensitivity: 63%)
  2. C-Spine imaging indications
    1. See Cervical Spine Imaging in Acute Traumatic Injury
    2. See NEXUS Criteria

XIV. Labs: TBI Biomarkers

  1. Precautions
    1. Little utility in emergency medical care
      1. Severe Traumatic Brain Injury (TBI) has the highest association with biomarkers
      2. However, Severe TBI patients are undergoing extensive head imaging regardless of biomarkers
      3. May be helpful in prognostication in the future
    2. Although biomarkers are FDA approved in adults as of 2023, not in general use
      1. High Test Sensitivity but poor Test Specificity
      2. Have not been studied against clinical gestalt or effective decision rules
    3. Pediatric head imaging decision rules would benefit most, but has not been validated in this age group
      1. Serum biomarkers are NOT recommended (beyond research) per pediatric mTBI working group
    4. References
      1. Marcolini and Swaminathan (2025) TBI Biomarkers, EM:Rap, 5/19/2025
  2. Current biomarkers
    1. Glial Fibrillary Acidic Protein (GFP)
    2. Ubiquitin C-terminal hydroxylase-L1 (UCHL1)
  3. Older biomarkers
    1. S100B
    2. Tau Protein

XV. Management: General

  1. See Head Injury
  2. See Management of Mild Head Injury
  3. See Cervical Spine Injury
  4. See Pediatric Cervical Spine Injury
  5. Precautions
    1. Immediately remove from play athlete with suspected Concussion or Head Injury
    2. Acute evaluation and management should follow Head Injury protocol
    3. Follow core Trauma tenets
      1. ABC Management
      2. Cervical Spine evaluation and stabilization
      3. Assess for focal neurologic deficits
      4. Consider higher level of care
        1. Sideline to emergency department
        2. Emergency department to Trauma Center
    4. Patient should not return to play until medical clearance
      1. See protocols as below
      2. See Return to Play after Concussion

XVI. Management: Disposition

  1. See Mild Head Injury Home Management
    1. Includes Head Injury Precautions (criteria for immediate follow-up)
  2. See Return to Play after Concussion
    1. Includes graduated (stepped) return to play protocol
  3. See Cognitive Deficit following Concussion
  4. See Postconcussion Syndrome
  5. Follow-up with medical provider
    1. Consider Concussion clinic (sports medicine) follow-up

XVII. Course

  1. Cognitive and physical rest are important in reducing the risk of prolonged symptoms
    1. See Mild Head Injury Home Management
    2. However, early activity return in children (as tolerated) speeds recovery
      1. Chauhan (2023) Pediatrics 151(5): e2022059592 [PubMed]
  2. Symptoms may evolve or worsen over the first few days after Concussion
  3. Symptoms may persist for weeks to months
  4. Common Symptoms typically resolve by 1 week in most cases
    1. Headache (most common)
    2. Dizziness
    3. Sleep disturbance (Daytime Somnolence, difficulty initiating and maintaining sleep)
  5. Cognitive Symptoms typically resolve by 2-4 weeks in most cases
    1. Impaired attention and memory
    2. Difficult Executive Function (e.g. organization, planning, reasoning)
  6. Prolonged course in a sizeable majority
    1. Anticipate resolution by 3 months (even in prolonged cases)
      1. In rare cases, symptoms persist years
    2. Postconcussion Syndrome (lasting 3 months)
      1. Identified on neurocognitive testing in up to 30% of children at 3 months
      2. Overall, more sensitive testing suggests >38% develop Postconcussion Syndrome
    3. Prolonged recovery is not consistently predicted by any specific factors
      1. Loss of consciousness and Amnesia do not consistently predict recovery period
      2. Some factors that are more predictive of prolonged recovery
        1. More severe symptoms at onset (Amnesia, Disorientation, mental status changes)
        2. Comorbidity (e.g. Migraine Headaches, ADHD, Sleep Disorders, Mood Disorders)
        3. Persistent neurocognitive deficit
        4. Prior Concussion
        5. Fatigue or fogginess
        6. Early onset Headache
        7. Younger age
        8. Women

XVIII. Complications

  1. Postconcussion Syndrome
  2. Recurrent Head Injury (especially if next Head Injury before recovery from the last)
    1. Second Impact Syndrome
    2. Cumulative neuropsychologic deficits
      1. See Cognitive Deficit following Concussion
    3. Chronic Traumatic encephalopathy
  3. Intracranial Hemorrhage
    1. Intracranial Hemorrhage is the most common cause of sports-related fatality
    2. Subdural Hematoma (most common)
      1. Acute Subdural Hematoma is often with low GCS on presentation (associated parenchymal injury)
      2. Chronic Subdural Hematoma may present late with persistent neurologic changes
    3. Epidural Hematoma
      1. Associated with Temporal BoneFracture in non-helmeted Head Injury
    4. Cerebral Parenchymal Hemorrhage
  4. Other Serious acute and subacute complications
    1. Cerebral edema
      1. See Second Impact Syndrome
    2. Posttraumatic Seizure
    3. Diffuse Axonal Injury
  5. Other longer lasting complications
    1. Migraine Headache
    2. Mood Disorder (depressed mood or Anxiety Disorder)
    3. Persistent cognitive deficit impact at school or work
      1. See Cognitive Deficit following Concussion

XIX. Prevention

  1. Measures that have significantly reduced sports-related Concussions in U.S. (28 to 64%)
    1. Youth Ice Hockey
      1. Bodychecking prohibition
      2. Mouth guards prevent dental injury, and mixed results on Concussion reduction
    2. American Football
      1. Reduced contact and collision frequency, duration and intensity
    3. Rugby
      1. On-field neuromuscular training warm-up program 3 times weekly
  2. CDC Heads Up Campaign
    1. https://www.cdc.gov/headsup/index.html

XX. References

  1. Dreis (2020) Crit Dec Emerg Med 34(7):3-21
  2. Raukar and Swaminathan in Herbert (2021) 21(3): 2-5
  3. (1997) Neurology 48:581-5 [PubMed]
  4. (1999) Pediatrics 104:1407-15 [PubMed]
  5. Cantu (1986) Phys Sportsmed 14(10):75-83 [PubMed]
  6. Hunt (2010) Clin Sports Med 29(1): 5-17 [PubMed]
  7. Kushner (2001) Am Fam Physician 64:1007-14 [PubMed]
  8. Lumba-Brown (2018) JAMA Pediatr 172(11):e182853 [PubMed]
  9. McCrory (2012) Br J Sports Med 47(5): 250-8 [PubMed]
  10. Putukian (2011) Clin Sports Med 30(1): 49-61 [PubMed]
  11. Patel (1010) Pediatr Clin North Am 57(3): 649-70 [PubMed]
  12. Scorza (2019) Am Fam Physician 99(7): 427-34 [PubMed]
  13. Scorza (2012) Am Fam Physician 85(2): 123-32 [PubMed]
  14. Whiteside (2006) Am Fam Physician 74(8):1357-62 [PubMed]

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