What is the preferred initial imaging modality, CT (Computed Tomography) head or head XR (X-ray), for an elderly patient with a minor head injury after a fall?

CT Head is the Preferred Imaging Modality for Elderly Patients with Minor Head Injury

Non-contrast CT head is the recommended first-line imaging study for elderly patients with minor head injury after a fall, as skull X-rays are no longer recommended and have been replaced by CT, which is more sensitive for detecting neurosurgical lesions. 1

Rationale for CT Head over X-ray

• Head CT has revolutionized the management of acute head trauma with its ability to detect neurosurgical lesions such as hemorrhage, herniation, and hydrocephalus 1
• The American College of Radiology (ACR) explicitly states that skull radiography is no longer recommended as first-line imaging for head trauma 2
• CT provides rapid assessment of potentially life-threatening intracranial injuries without the need for contrast administration 2
• CT is highly sensitive for detecting findings that may require neurosurgical intervention in the acute setting 1

Special Considerations for Elderly Patients

Elderly patients (≥65 years) are at higher risk for intracranial injury after minor head trauma:

• Age >65 years alone is considered a high-risk factor in the Canadian CT Head Rule 3
• Older age increases the risk of intracranial hemorrhage even with minor trauma due to:
  • Brain atrophy creating more space for bridging veins to stretch and tear
  • Higher prevalence of anticoagulant/antiplatelet medication use
  • Increased vascular fragility

Clinical Decision Rules for CT in Elderly Patients

Several validated clinical decision rules can help determine the need for CT in elderly patients with minor head trauma:

1. Canadian CT Head Rule 3 - 100% sensitive for predicting need for neurosurgical intervention

   • High-risk criteria (any one indicates need for CT):
     • Age >65 years
     • GCS <15 at 2 hours post-injury
     • Suspected open or basal skull fracture
     • Vomiting >2 episodes

2. New Orleans Criteria 4 - 100% sensitive for detecting intracranial injuries

   • Any one of these findings indicates need for CT:
     • Headache
     • Vomiting
     • Age >60 years
     • Drug/alcohol intoxication
     • Short-term memory deficits
     • Physical evidence of trauma above clavicles
     • Seizure

3. CTHEAD Rule 5 - Specifically developed for older adults (≥65 years)

   • Consider CT if any of these are present:
     • High-risk mechanism of injury
     • Vomiting
     • Witnessed loss of consciousness
     • Anterograde amnesia

Imaging Protocol Recommendations

When performing CT for elderly patients with minor head trauma:

• Non-contrast CT is recommended as the initial study 1, 2
• Multiplanar reformatted images should be included as they increase diagnostic accuracy 1
• Contrast-enhanced CT is not recommended for initial evaluation as it may obscure subtle hemorrhages 2

When to Consider Alternative or Additional Imaging

• If CT is negative but neurological symptoms persist unexplained, consider MRI 1
• MRI is more sensitive for detecting:
  • Subtle findings adjacent to the calvarium or skull base
  • Small cortical contusions and subdural hematomas
  • Small white matter lesions in traumatic axonal injury 1

Common Pitfalls to Avoid

1. Delaying CT imaging in elderly patients with loss of consciousness significantly increases morbidity and mortality risk 2
2. Administering contrast before initial non-contrast CT can obscure hemorrhage and lead to missed diagnosis 2
3. Relying on skull X-rays which have been replaced by CT due to superior sensitivity for neurosurgical lesions 1, 2
4. Failing to recognize that a normal CT with normal neurologic examination has a very low risk (0.006%) of deterioration 1

In conclusion, non-contrast CT head is clearly superior to skull X-ray for evaluating elderly patients with minor head injury after a fall. The evidence strongly supports CT as the first-line imaging modality due to its high sensitivity for detecting clinically significant intracranial injuries that may require intervention.