Is a head X-ray (X-ray of the head) necessary?

Head X-rays Are Not Appropriate for Head Trauma Evaluation

X-ray imaging of the head is not appropriate for evaluating head trauma as it has been replaced by CT and MRI due to its extremely poor sensitivity for detecting clinically important traumatic brain injuries. 1

Current Imaging Recommendations for Head Trauma

First-line Imaging

• Non-contrast head CT is the recommended first-line imaging modality for:
  • Moderate to severe head trauma (GCS 9-12 or 3-8) 1
  • Mild head trauma (GCS 13-15) when indicated by clinical decision rules 1
  • Patients with skull fractures or clinical signs of intracranial injury 1
  • Patients with risk factors for intracranial bleeding (anticoagulant use, coagulopathy) 1

When CT is Indicated

• Signs of altered mental status
• Focal neurological deficits
• Loss of consciousness
• Palpable skull fracture (especially in children under 2 years) 2
• Scalp hematoma (important predictor in children under 2 years) 2
• Suspected vascular injury

Why X-rays Are Obsolete for Head Trauma

Poor Diagnostic Performance

• Skull X-rays have extremely low sensitivity (0.00-0.38) for detecting intracranial hemorrhage 3
• Up to 50% of intracranial injuries occur without skull fracture 2
• X-rays only show bone structures and cannot visualize brain tissue or bleeding 3

Evidence Against X-ray Use

• A retrospective study of 1,938 patients with mild head trauma found that skull X-rays had 0% sensitivity and 94% specificity compared to CT scans 3
• Even when skull fractures were detected on X-ray, they were often false positives 3
• Another study of 566 cases found that management decisions were not altered by skull radiography results in any cases 4

Appropriate Imaging Modalities

CT Benefits

• Rapid assessment for hemorrhage, herniation, and hydrocephalus 2
• Can visualize scalp, bone, extra-axial hematomas and parenchymal injury 5
• Usually performed without contrast enhancement 5
• Appropriate for emergency situations with multiple monitors in place 5

MRI Role

• More sensitive than CT for parenchymal injuries 2
• Better for detecting subtle contusions and diffuse axonal injury 1
• Indicated when:
  • CT does not explain clinical presentation 5
  • Persistent neurological deficits remain unexplained after CT 1
  • Subacute or chronic head trauma with unexplained cognitive deficits 1

Special Considerations

Pediatric Patients

• CT should not be routinely obtained for mild head injuries in children 2
• Lower threshold for imaging is recommended in children under 2 years 2
• ALARA principle should be followed with weight and size-based CT parameters to minimize radiation exposure 2

Vascular Imaging

• CTA or MRA should be considered when there is clinical suspicion of vascular injury 2
• Particularly important with fractures extending through skull base vascular channels 2

Common Pitfalls to Avoid

• Relying on skull X-rays to rule out intracranial injury (extremely poor sensitivity)
• Unnecessary radiation exposure from CT in low-risk patients
• Delaying appropriate imaging in moderate to severe head trauma
• Failing to consider MRI for unexplained neurological deficits after normal CT

In conclusion, skull X-rays have no role in modern head trauma evaluation and have been completely replaced by CT and MRI, which provide significantly better visualization of both bony structures and intracranial contents.