What are the risks and benefits of a head CT scan after head trauma in an 18-month-old?

Risk-Benefit Assessment of Head CT in an 18-Month-Old After Head Trauma

The decision to obtain a head CT in an 18-month-old after head trauma should be based on validated PECARN risk stratification criteria, which can safely identify children who can forgo CT imaging (very low risk), those who may benefit from observation versus CT (intermediate risk), and those who require immediate CT (high risk). 1

Risk Stratification Framework

Very Low Risk - CT NOT Indicated

An 18-month-old can safely forgo CT imaging if ALL of the following criteria are met: 1

• Glasgow Coma Scale (GCS) of 15 1
• Normal mental status 1
• No palpable skull fracture 1
• No nonfrontal scalp hematoma 1
• Loss of consciousness ≤5 seconds (or none) 1
• No severe mechanism of injury 1
• Acting normally per parents 1

The risk of clinically important traumatic brain injury in this group is <0.02%, with 100% sensitivity and 100% negative predictive value validated in over 4,000 children under 2 years of age. 1 These children should NOT undergo CT imaging. 1

High Risk - CT Strongly Recommended

Immediate CT is strongly indicated if ANY of the following are present: 1, 2

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

The risk of clinically important intracranial injury in high-risk children under 2 years is approximately 4.4%. 1 CT has excellent sensitivity for acute intracranial hemorrhage and fractures with rapid acquisition time. 1, 2

Intermediate Risk - Clinical Judgment Required

CT may be considered (versus careful observation) if the child has GCS 15 and normal mental status BUT has: 1

• Loss of consciousness >5 seconds 1
• Severe mechanism of injury 1
• Not acting normally per parent 1

The risk of significant injury in intermediate-risk children under 2 years is approximately 0.9%. 1 CT may be considered in lieu of observation based on: 1

• Parental preference 1
• Multiple risk factors present 1
• Worsening clinical symptoms during observation 1
• Young infant age where observational assessment is challenging 1

Benefits of CT Imaging

When indicated, CT provides critical diagnostic information: 1, 2

• Rapid acquisition (minutes vs. hours for MRI) 1, 2
• Excellent sensitivity for acute intracranial hemorrhage requiring intervention 1, 2
• High sensitivity for skull fractures 1
• No sedation required (unlike MRI in this age group) 1
• Identifies the 0.1% of children requiring neurosurgery 3

Risks of CT Imaging

The primary risk is radiation-induced malignancy: 3

• Lifetime cancer risk from pediatric head CT is estimated at 1 in 1,000-5,000 scans 3
• Children are more radiosensitive than adults and have longer life expectancy for cancer development 3
• Risk must be balanced against benefit of detecting treatable intracranial injury 3

Facilities should use pediatric-specific, reduced-dose CT protocols following ALARA principles ("as low as reasonably achievable"). 2

Clinical Observation as Alternative Strategy

For intermediate-risk patients, clinical observation can effectively reduce unnecessary CT utilization: 2

• Every additional hour of emergency department observation is associated with decreased CT use without delay in diagnosis of significant traumatic brain injury 2
• Clinical deterioration during observation warrants immediate CT imaging 2

Critical Pitfalls to Avoid

Common errors in management include: 2

• Obtaining CT in very low-risk patients who meet all PECARN criteria for safe discharge 1
• Relying on clinical characteristics alone without systematic risk stratification 2
• Using skull radiographs, which miss up to 50% of intracranial injuries 1
• Considering MRI in the acute setting, which is impractical due to length of examination and frequent need for sedation in 18-month-olds 1

If CT is obtained and shows intracranial injury, maintain adequate cerebral perfusion by avoiding hypotension and hypoxia. 4