Guidelines for Head CT Scans in Suspected Head Injuries
Noncontrast head CT is the most appropriate initial imaging study for patients with head trauma when indicated by clinical decision rules, with specific criteria based on trauma severity.1
Clinical Decision Rules for Mild Head Trauma (GCS 13-15)
For patients WITH loss of consciousness (LOC) or post-traumatic amnesia (PTA):
- Noncontrast head CT is indicated if ANY of these risk factors are present:1, 2
- Headache
- Vomiting
- Age >60 years
- Drug or alcohol intoxication
- Short-term memory deficits
- Physical evidence of trauma above the clavicle
- Post-traumatic seizure
- GCS score <15
- Focal neurologic deficit
- Coagulopathy
For patients WITHOUT loss of consciousness or post-traumatic amnesia:
- Noncontrast head CT should be considered if ANY of these factors are present:1, 2
- Focal neurologic deficit
- Vomiting
- Severe headache
- Age ≥65 years
- Signs of basilar skull fracture
- GCS score <15
- Coagulopathy
- Dangerous mechanism of injury (e.g., ejection from vehicle, pedestrian struck by vehicle, fall >3 feet or 5 stairs)
Imaging Recommendations Based on Trauma Severity
- Mild head trauma (GCS 13-15): Imaging is usually not appropriate when not indicated by clinical decision rules1
- Moderate head trauma (GCS 9-12): Noncontrast head CT is always appropriate as the initial imaging study1, 2
- Severe head trauma (GCS 3-8): Noncontrast head CT is always appropriate as the initial imaging study1, 2
- Penetrating head trauma: Noncontrast head CT is always appropriate as the initial imaging study1
Follow-up Imaging Considerations
Noncontrast head CT is appropriate for short-term follow-up in patients with:1
- Positive findings on initial imaging with unchanged neurologic examination
- New or progressive neurologic deficits
For patients with severe head injury (GCS ≤8), routine repeat head CT may be indicated even without neurologic changes, as findings might lead to intervention3
For mild to moderate head injuries, repeat head CT is only indicated with neurologic deterioration3
Special Considerations
For patients with suspected intracranial vascular injury due to trauma:1, 2
- Head and neck CTA is appropriate for suspected arterial injury
- Head CTV is appropriate for suspected venous injury
For subacute or chronic head trauma with persistent unexplained cognitive or neurologic deficits:1, 2
- Noncontrast brain MRI or noncontrast head CT are appropriate options
- MRI is more sensitive for subtle findings and small white matter lesions
Common Pitfalls to Avoid
- Ordering head CT for all minor head trauma patients without applying clinical decision rules leads to unnecessary radiation exposure1, 2
- Failing to recognize that patients on anticoagulants may require imaging even with minimal trauma1
- Relying on skull radiographs, which have been replaced by CT due to superior sensitivity for neurosurgical lesions1, 4
- Using advanced neuroimaging techniques (MR spectroscopy, functional MRI, diffusion tensor imaging) for initial evaluation, as these are still research tools and not routine clinical practice1, 5
Risk Factors for Clinical Deterioration
Patients with these findings on initial CT have higher risk of deterioration and may benefit from closer monitoring:6
- Lower GCS score at admission
- Abnormal international normalized ratio (INR)
- Presence of midline shift
- Effaced basal cisterns
- Multiple hemorrhagic lesions