What type of CT (Computed Tomography) scan is recommended for new onset or worsening migraines?

CT Head Without Contrast for New Onset or Worsening Migraines

For new onset or worsening migraines, CT head without IV contrast is the appropriate initial imaging modality when neuroimaging is indicated, though imaging is often not necessary if the neurologic examination is normal. 1

When to Image: Clinical Decision Algorithm

Neuroimaging IS Recommended:

• Abnormal neurologic examination - This is the strongest indication, as it increases likelihood of intracranial pathology including brain tumor, arteriovenous malformation, or hydrocephalus 1
• Atypical features or headaches that don't fulfill migraine criteria warrant a lower threshold for imaging 1

Red Flags That Increase Suspicion (Though Evidence is Insufficient for Firm Recommendations):

• Headache worsened by Valsalva maneuver 1
• Headache that awakens the patient from sleep 1
• New-onset headache in older patients 1
• Progressively worsening headache pattern 1

Neuroimaging NOT Usually Warranted:

• Patients with migraine and normal neurologic examination - The prevalence of significant intracranial abnormality is only approximately 0.2% in this population 1

Why CT Without Contrast Specifically

CT head without IV contrast is the first-line test because:

• Fast acquisition time - Critical in emergency settings 1
• Decreased safety screening requirements compared to MRI 1
• Excellent for detecting hemorrhage, mass effect, and hydrocephalus - the life-threatening emergencies that must be excluded 1

CT vs MRI: The Evidence Gap

The guidelines acknowledge insufficient evidence exists to definitively recommend CT versus MRI for comparative sensitivity in nonacute headache evaluation 1. However:

• The greater resolution of MRI appears to be of little clinical importance in evaluating nonacute headache 1
• MRI may be more sensitive for clinically insignificant abnormalities but no more sensitive than CT for clinically significant pathology 1

Contrast Enhancement Considerations

No data supports routine use of CT with contrast for migraine evaluation 1. Contrast-enhanced CT may be considered only if specific clinical concern exists for:

• Progression of intracranial infection (abscess, empyema) 1
• Tumor 1
• Inflammatory conditions 1

Common Pitfalls to Avoid

Do not reflexively order imaging on every migraine patient - Testing should be avoided if it won't lead to management changes, and patients with typical migraine and normal neurologic exams have extremely low yield (0.2% abnormality rate) 1

Beware of the "worried well" exception - While imaging is not normally recommended for typical migraine with normal exam, it may be reasonable in individual cases where patients are excessively worried about serious pathology, though this should be balanced against radiation exposure and cost 1

Don't assume "worst headache of life" always needs imaging in known migraineurs - Research shows that in patients with established migraine diagnoses presenting with "worst headache of life" but no other red flags (no intracranial pathology, cancer, immunocompromise, or recent trauma), the yield of CT is essentially zero 2