What are the criteria for diagnosing a concussion?

Concussion Diagnostic Criteria

The four prevalent and consistent indicators of concussion are: observed and documented disorientation or confusion immediately after the event, impaired balance within 1 day after injury, slower reaction time within 2 days after injury, and impaired verbal learning and memory within 2 days after injury. 1

Core Diagnostic Indicators

Immediate Indicators

• Disorientation or confusion immediately following a potential concussive event (PCE) is one of the most reliable immediate indicators of concussion 1
• This may manifest as confusion about game details, opponent, score, or time in sports-related injuries 1

Early Physical Indicators (Within 24 Hours)

• Impaired balance is a significant indicator when assessed within the first day post-injury 1
• Balance testing should be performed using standardized assessment tools such as the Balance Error Scoring System (BESS) or Sensory Organization Test (SOT) 1, 2

Early Cognitive Indicators (Within 48 Hours)

• Slower reaction time measured within 2 days of injury is a consistent indicator of concussion 1
• Impaired verbal learning and memory within 2 days of injury provides objective evidence of cognitive dysfunction 1

Concussion Subtypes Classification

Current evidence supports five predominant concussion subtypes that should be evaluated during assessment 1:

1. Cognitive subtype

   • Characterized by difficulty concentrating, memory problems, and slowed processing speed 1
   • Objectively measured through neurocognitive testing 2

2. Ocular-motor subtype

   • Involves abnormalities in eye movement, tracking, and convergence 1
   • Assessment should include evaluation of smooth pursuit, saccades, and convergence 2

3. Headache/migraine subtype

   • Characterized by post-traumatic headaches that may mimic migraine features 1
   • Often one of the most common and persistent symptoms 3

4. Vestibular subtype

   • Involves dizziness, vertigo, and balance problems 1
   • Can be assessed through vestibular-ocular reflex testing and dynamic balance assessments 2

5. Anxiety/mood subtype

   • Includes emotional symptoms such as irritability, anxiety, and mood disturbances 1
   • May develop immediately or emerge later in the recovery process 1

Associated Conditions

• Sleep disturbance is commonly associated with concussion and should be evaluated 1
• Cervical strain often accompanies concussion but has insufficient research data for prevalence estimates 1, 4

Important Clinical Considerations

• Multiple concussion subtypes may contribute to a patient's clinical presentation; they are not mutually exclusive 1
• The predominant subtype may change over time following injury 1
• There is currently no objective biomarker or imaging test that definitively diagnoses concussion 1, 5
• Diagnosis remains primarily clinical, based on history and examination findings 5, 6

Common Pitfalls to Avoid

• Overreliance on loss of consciousness (LOC) - LOC is not required for concussion diagnosis and occurs in a minority of cases 1
• Failure to assess all domains - A comprehensive assessment should evaluate all potential subtypes rather than focusing on only the most obvious symptoms 2
• Delayed evaluation - The most reliable indicators are present within the first 48 hours; delayed assessment may miss critical diagnostic features 1
• Inadequate follow-up - While most concussions resolve within 2-4 weeks, some patients develop persistent post-concussive symptoms requiring ongoing evaluation 4, 6

The evidence base for concussion diagnosis continues to evolve, but these criteria represent the most consistent and prevalent indicators supported by high-quality research to date 1.