Should a CT (Computed Tomography) scan with or without contrast be performed after a fall on the head?

CT Without Contrast is the Appropriate Imaging Choice After Head Trauma

Non-contrast head CT is the recommended first-line imaging study for patients with acute head trauma, as it provides rapid assessment of potentially life-threatening intracranial injuries without the need for contrast administration. 1, 2

Initial Imaging Approach for Head Trauma

Non-contrast Head CT

• Non-contrast head CT is the gold standard for initial evaluation of head trauma due to its:
  • High sensitivity for detecting acute intracranial hemorrhage
  • Ability to identify skull fractures
  • Rapid acquisition time (critical in trauma settings)
  • Capability to detect mass effect requiring urgent intervention 1, 2

When to Perform Head CT

The American College of Radiology (ACR) Appropriateness Criteria provides clear guidance:

• For mild head trauma (GCS 13-15): Non-contrast head CT when indicated by clinical decision rules 1
• For moderate (GCS 9-12) or severe (GCS 3-8) head trauma: Non-contrast head CT is always appropriate 1
• For follow-up imaging of patients with positive initial findings: Non-contrast head CT 1
• For patients with new or progressive neurologic deficits: Non-contrast head CT 1

Why Contrast is NOT Recommended

Contrast-enhanced CT is specifically not recommended for initial head trauma evaluation because:

1. It may obscure subtle hemorrhages due to contrast enhancement 2
2. There is no relevant literature supporting the added value of contrast-enhanced brain MRI or CT in the initial imaging evaluation of head trauma 1
3. Administering contrast before initial non-contrast CT can lead to missed diagnoses of hemorrhage 2

Special Considerations

Elderly Patients

• Falls in elderly patients have shown only 7.6% have traumatic lesions on CT, but those with consciousness impairment, focal neurological deficits, or past history of traumatic brain injury are at higher risk 3
• Male sex and a time interval of approximately 5 hours between trauma and CT scan are associated with higher detection rates of lesions 3

Mechanism of Injury

• While falls from standing are more common (76%), falls on stairs (19%) or from height (5%) are more likely to result in abnormal CT findings 4
• An abnormal neurological examination significantly increases the risk for requiring neurosurgical intervention (risk ratio 11.5) 4

Follow-up Imaging

If initial non-contrast CT is negative but clinical suspicion remains high:

• MRI with gradient echo (GRE) or susceptibility-weighted imaging is recommended as it is more sensitive for detecting small bleeds, particularly in the posterior fossa or brainstem 2
• MRI is superior for detecting subacute and chronic subdural collections 2

Pitfalls to Avoid

1. Delaying CT imaging in patients with loss of consciousness after head trauma, which increases morbidity and mortality risk 2
2. Using contrast-enhanced CT as first-line imaging, which may obscure subtle hemorrhages 2
3. Relying on skull radiographs, which have been replaced by CT as the standard of care 2, 5
4. Missing small hemorrhages in the posterior fossa, which can be difficult to detect on non-contrast CT 2

Non-contrast head CT remains the cornerstone of initial evaluation for head trauma, providing the best balance of sensitivity, speed, and accessibility for detecting clinically significant injuries requiring intervention.