What are the PECARN (Pediatric Emergency Care Applied Research Network) head injury rules for determining the need for a CT (Computed Tomography) scan in patients with minor head trauma?

PECARN Head Injury Rules

Overview and Risk Stratification Framework

The PECARN (Pediatric Emergency Care Applied Research Network) head injury rules are the most extensively validated clinical decision tools for determining CT scan necessity in children with minor head trauma, stratifying patients into very low, intermediate, and high-risk categories with exceptional sensitivity (99-100%) for identifying clinically important traumatic brain injuries. 1, 2

The rules are age-stratified into two distinct algorithms: one for children <2 years old and another for children ≥2 years old. 1

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Children ≥2 Years Old

Very Low Risk (CT NOT indicated)

Children meeting ALL of the following criteria can safely forgo CT imaging with <0.05% risk of clinically important traumatic brain injury: 1, 2

• Glasgow Coma Scale (GCS) of 15 1
• Normal mental status 1
• No clinical signs of basilar skull fracture 1
• No loss of consciousness 1
• No vomiting 1
• No severe mechanism of injury 1
• No severe headache 1

The negative predictive value is 99.9% with 96.8% sensitivity, validated in over 25,000 children. 1

Intermediate Risk (CT may be considered)

Children with GCS 15 and normal mental status BUT with any of: 1, 2

• Loss of consciousness 1
• Vomiting 1
• Severe mechanism of injury 1
• Severe headache 1

Risk of clinically important traumatic brain injury is approximately 0.8%. 2, 3 Clinical observation is a reasonable alternative to immediate CT scanning for this group, as every additional hour of emergency department observation decreases CT utilization without delaying diagnosis of significant injury. 3

High Risk (CT strongly indicated)

Immediate CT is warranted for children with: 1, 2

• GCS of 14 or other signs of altered mental status 1
• Signs of basilar skull fracture 1

Risk of clinically important traumatic brain injury is approximately 4.3%. 2, 3

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Children <2 Years Old

Very Low Risk (CT NOT indicated)

Children meeting ALL of the following criteria can safely forgo CT imaging with <0.02% risk of clinically important traumatic brain injury: 1, 4

• GCS of 15 1, 4
• Normal mental status 1, 4
• No palpable skull fracture 1, 4
• No nonfrontal scalp hematoma 1, 4
• Loss of consciousness ≤5 seconds 1, 4
• No severe mechanism of injury 1, 4
• Acting normally per parents 1, 4

The negative predictive value is 100% with 100% sensitivity, validated in over 14,000 children <2 years old. 1

Intermediate Risk (CT may be considered)

Children with GCS 15 and normal mental status BUT with any of: 1, 4

• Loss of consciousness >5 seconds 1, 4
• Severe mechanism of injury 1, 4
• Not acting normally per parent 1, 4
• Nonfrontal scalp hematoma 1

Risk of clinically important traumatic brain injury is approximately 0.9%. 4, 3 Clinical observation versus CT should be considered based on parental preference, multiple risk factors, worsening symptoms during observation, or difficulty assessing young infants. 2

High Risk (CT strongly indicated)

Immediate CT is warranted for children with: 1, 4

• GCS of 14 or other signs of altered mental status 1, 4
• Palpable skull fracture 1, 4

Risk of clinically important traumatic brain injury is approximately 4.4%. 3

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Validation and Performance

The PECARN rules have been validated across multiple international studies with consistently superior performance compared to other clinical decision rules (CATCH, CHALICE, NEXUS). 1, 2

• A large Australian/New Zealand validation study of over 15,000 children confirmed 99-100% sensitivity and 100% negative predictive value across both age groups. 1, 2
• Multiple smaller validation studies of 1,000-2,400 children demonstrated 100% sensitivity for very low-risk criteria. 1
• External validation in Italy showed 100% safety (all ciTBI cases identified) with 92.3% efficacy (avoiding unnecessary CTs). 5
• A Dutch cohort study demonstrated that PECARN rules would reduce CT rates from 44% to 24-28% without missing clinically important injuries. 6

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Critical Pitfalls to Avoid

Do NOT apply PECARN criteria to suspected non-accidental trauma (child abuse) cases, as these require separate evaluation protocols. 1, 3, 7 A Japanese validation study found that PECARN sensitivity dropped from 100% to 85.7% in children <2 years when physically abused children were included, with two abused children with ciTBI incorrectly classified as very low risk. 7

Do NOT obtain skull radiographs as the primary imaging modality, as up to 50% of intracranial injuries occur without fracture, making plain films insufficient for ruling out traumatic brain injury. 1, 2, 3

Do NOT use IV contrast for acute trauma CT, as contrast may obscure subtle hemorrhages. 2, 3

Do NOT routinely obtain CT scans in very low-risk patients who meet all PECARN criteria, as this exposes them to unnecessary radiation without clinical benefit. 1, 2, 3

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Imaging Technical Specifications

When CT is indicated: 2, 3

• Perform non-contrast CT head 2, 3
• Use pediatric-specific, size-adjusted protocols following ALARA (as low as reasonably achievable) radiation dose reduction principles 2, 3
• Include multiplanar and 3D reconstructions to increase sensitivity for fractures and small hemorrhages 3
• Avoid sedation when possible, as CT acquisition is rapid 3

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Disposition Decisions

Patients meeting very low-risk criteria without CT imaging, or those with negative CT scans and normal neurologic examinations, can be safely discharged. 2, 4

Hospitalization is required for: 2, 4

• Positive CT findings showing intracranial injury 2, 4
• Abnormal neurologic examination 2, 4
• Patients on anticoagulation or antiplatelet therapy 2, 4

Discharge instructions must be provided in both written and verbal form, written at 6th-7th grade reading level, with font size ≥12 points, educating parents about postconcussive symptoms and warning that 18% of patients who deteriorate do so between days 2-7. 4