When is a CT (computed tomography) scan of the head recommended for a patient presenting with vertigo and headaches?

CT of Head for Vertigo and Headaches

CT scans of the head are not routinely indicated for patients with isolated vertigo without focal neurological deficits, but should be performed when vertigo is accompanied by severe headache, age >60 years, vomiting, drug/alcohol intoxication, short-term memory deficits, trauma above the clavicle, seizures, or focal neurological deficits. 1

Clinical Decision Making for Neuroimaging in Vertigo and Headaches

When to Order CT for Vertigo:

• CT has very low sensitivity (28.5%) for central causes of vertigo 2
• Only 6.9% of CT scans show clinically significant findings in patients with vertigo without focal neurological abnormalities 3
• The American Academy of Otolaryngology-Head and Neck Surgery recommends against routine imaging for peripheral vestibular disorders 4

Indications for Head CT in Patients with Vertigo and Headaches:

1. Presence of "red flag" symptoms:

   • Severe headache (especially sudden onset)
   • Vomiting
   • Age >60 years
   • Drug or alcohol intoxication
   • Deficits in short-term memory
   • Physical evidence of trauma above the clavicle
   • Seizures
   • GCS score <15
   • Focal neurological deficits
   • Coagulopathy

2. Suspected central causes of vertigo:

   • Vertebrobasilar insufficiency
   • Stroke
   • Intracranial hemorrhage
   • Space-occupying lesions

Diagnostic Approach Algorithm:

1. Initial Assessment:

   • Determine if vertigo is positional or spontaneous
   • Check for nystagmus characteristics (direction, fatiguability)
   • Perform HINTS examination (Head Impulse, Nystagmus, Test of Skew) for acute vestibular syndrome 4

2. Decision for CT Imaging:

   • If HINTS exam suggests central cause → CT head
   • If any red flag symptoms present → CT head
   • If normal neurological exam and typical peripheral vertigo pattern → No imaging needed

3. Consider MRI instead of CT when:

   • Posterior fossa pathology suspected (MRI has higher sensitivity)
   • Persistent unexplained symptoms despite normal CT
   • Suspected cerebellopontine angle lesion

Limitations and Considerations

CT Limitations:

• Low sensitivity (28.5%) for detecting central causes of vertigo 2
• Poor visualization of posterior fossa structures
• Cost-benefit concerns: 90% of radiological tests show no findings related to vertigo 5

MRI Considerations:

• Higher sensitivity (79.8%) than CT for central causes 2
• Better for posterior fossa visualization
• Still misses approximately 20% of strokes if performed early 2
• More expensive and less readily available than CT

Common Pitfalls to Avoid

1. Overreliance on imaging:

   • Neuroimaging should not be the only tool for ruling out stroke in acute dizziness/vertigo 2

2. Inappropriate imaging:

   • Routine CT scanning for typical BPPV or other clear peripheral vertigo 4

3. Missing central causes:

   • Failing to perform HINTS examination in acute vestibular syndrome
   • Relying solely on normal CT to rule out posterior circulation stroke

4. Delayed diagnosis:

   • Not considering MRI when clinical suspicion for central cause remains high despite normal CT

By following these guidelines, clinicians can make appropriate decisions about when to order head CT for patients with vertigo and headaches, balancing diagnostic yield with resource utilization and patient safety.