In a patient who fell, sustained a head injury, and now reports dizziness, what imaging study should be ordered?

Order a Noncontrast Head CT

In a patient who fell, hit their head, and is now complaining of dizziness, you should order a noncontrast head CT scan. Dizziness following head trauma is a concerning symptom that meets clinical decision rule criteria for imaging 1.

Clinical Decision Framework

The 2021 ACR Appropriateness Criteria provide clear guidance for this scenario 1:

When CT is Indicated After Head Trauma

For patients with head trauma without loss of consciousness (LOC) or post-traumatic amnesia (PTA), a noncontrast head CT should be ordered if any of the following are present:

• Focal neurologic deficit (dizziness can represent this)
• Vomiting
• Severe headache
• Age ≥65 years
• Physical signs of basilar skull fracture
• GCS score <15
• Coagulopathy
• Dangerous mechanism of injury (fall >3 feet or 5 stairs, motor vehicle ejection, pedestrian struck)

Why Dizziness Matters

Dizziness after head trauma is particularly concerning because:

• It may represent a focal neurologic deficit requiring imaging 1
• While isolated dizziness has low CT yield (2.2% positive findings), the context of acute head trauma changes the risk-benefit calculation 2
• CT is highly sensitive (essentially 100%) for detecting neurosurgical lesions that require intervention 1

Imaging Protocol

Noncontrast head CT with multiplanar reformatted images is the appropriate initial study 1:

• Multiplanar reformats increase diagnostic accuracy and should be included 1
• CT is the gold standard for detecting hemorrhage, herniation, and hydrocephalus in acute trauma 1
• CT can be performed rapidly in the acute setting

What NOT to Order Initially

The guidelines are explicit that these modalities have no role in initial acute head trauma evaluation 1:

• MRI (reserve for subacute/chronic unexplained deficits)
• CT angiography (unless vascular injury suspected)
• Skull radiographs (replaced by CT)
• PET, SPECT, MR spectroscopy, functional MRI, or DTI

Common Pitfalls to Avoid

1. Don't dismiss dizziness as "just vertigo" - In the context of acute head trauma, dizziness warrants imaging evaluation as it may represent a focal neurologic deficit 1

2. Don't delay imaging for clinical observation - The patient has already met criteria for CT based on the clinical decision rules 1

3. Don't order MRI first - CT is faster, more readily available, and more sensitive for acute hemorrhage requiring neurosurgical intervention 1

4. Consider additional risk factors - If the patient is on anticoagulants/antiplatelets, >60-65 years old, or has other concerning features, imaging is even more strongly indicated 1

Role of MRI

MRI may be considered as a second-line study only if 1:

• Head CT is negative but neurologic deficits persist
• Subacute or chronic symptoms develop
• There's clinical suspicion for subtle findings (small contusions, diffuse axonal injury) that might explain persistent symptoms

However, MRI has no role in the initial acute evaluation and does not change acute management in most cases 1.