Do I need to perform a head computed tomography (CT) scan or X-ray for a patient who had an unwitnessed fall?

Head CT Evaluation for Unwitnessed Falls

A head CT scan is usually not appropriate for patients with an unwitnessed fall unless specific risk factors are present according to validated clinical decision rules such as the Canadian CT Head Rule or New Orleans Criteria. 1

Clinical Decision Rules for Head CT After Falls

The American College of Radiology (ACR) Appropriateness Criteria provides clear guidance on when imaging is warranted after head trauma:

• Imaging is usually not appropriate for patients with mild head trauma (GCS 13-15) when not indicated by clinical decision rules 1
• Head CT is appropriate when clinical decision rules indicate the need for imaging 1

Canadian CT Head Rule - High Risk Factors (100% sensitive for neurosurgical intervention)

• Failure to reach GCS of 15 within 2 hours 2
• Suspected open skull fracture 1
• Any sign of basal skull fracture 1, 2
• Vomiting >2 episodes 1, 2
• Age >65 years 1, 2

Canadian CT Head Rule - Medium Risk Factors

• Amnesia before impact >30 minutes 2
• Dangerous mechanism of injury 1, 2

ACEP Clinical Policy Recommendations

• Level A recommendation: Head CT indicated with LOC/PTA if any of: headache, vomiting, age >60, intoxication, short-term memory deficits, trauma above clavicle, post-traumatic seizure, GCS <15, focal deficit, or coagulopathy 1
• Level B recommendation: Head CT should be considered with no LOC/PTA if any of: focal deficit, vomiting, severe headache, age ≥65, basilar skull fracture signs, GCS <15, coagulopathy, or dangerous mechanism 1

Special Considerations for Unwitnessed Falls

For unwitnessed falls specifically, consider:

• The Canadian CT Head Rule has been validated in patients with minimal head injury (no LOC or disorientation) with 100% sensitivity for detecting intracranial hemorrhage 3
• In elderly patients (≥65 years), falls are common but systematic CT scanning has shown low diagnostic yield (7.6% with traumatic lesions) 4
• Risk factors significantly associated with traumatic lesions include:
  • Male sex 4
  • Consciousness impairment 4
  • Focal neurological deficit 4
  • Past history of traumatic brain injury 4
  • Time interval >5 hours between trauma and CT (optimal for lesion detection) 4

Clinical Approach to Unwitnessed Falls

1. Assess for high-risk features:

   • Age >65 years 1, 2
   • Anticoagulation therapy (controversial but generally included) 1
   • Focal neurological deficits 1, 4
   • Altered mental status or GCS <15 1
   • Vomiting 1
   • Signs of basilar skull fracture 1

2. If no high-risk features are present:

   • CT imaging is generally not indicated 1
   • Observation may be appropriate 1

3. If any high-risk features are present:

   • Non-contrast head CT is the appropriate initial imaging study 1, 5
   • CT is highly sensitive for detecting neurosurgical lesions requiring intervention 1, 5

Common Pitfalls to Avoid

• Ordering CT scans for reassurance without clinical indications (cited by physicians as reasons in 24.6% of cases) 3
• Failing to apply validated clinical decision rules 1
• Overreliance on anticoagulation status alone (not statistically associated with increased risk in some studies) 4
• Using skull radiographs instead of CT (radiographs cannot characterize the full extent of fractures or intracranial pathology) 1
• Delaying imaging when indicated (optimal detection within 5 hours of injury) 4

Remember that CT remains the gold standard for detection of intracranial abnormalities in acute head trauma, offering rapid assessment and high sensitivity for neurosurgical lesions 5.