When is imaging recommended for patients presenting with headaches?

Neuroimaging for Headache Patients

Neuroimaging is not recommended for patients with typical primary headaches (migraine or tension-type) and a normal neurological examination, but should be performed when "red flags" or abnormal neurological findings are present.

When to Order Neuroimaging

Red Flags Requiring Imaging

• Sudden severe headache ("thunderclap" or "worst headache of my life") 1, 2
• New headache in patients over 50 years old 2
• Headache worsened by Valsalva maneuver or causing awakening from sleep 1, 2
• Rapidly increasing frequency or severity of headaches 1
• Headache with focal neurological deficits 1, 2
• Headache following head trauma 1
• Headache associated with seizures or cognitive changes 3
• Headache in immunocompromised patients 4
• Headache in cancer patients 4
• Headache in pregnant patients 4
• Headache with papilledema or optic disc edema 2, 5
• Headache with neck stiffness (possible meningitis) 5
• Headache that is positional or activity-related 2, 4

Neurological Examination Findings

• Any unexplained abnormal neurological finding significantly increases the probability of finding intracranial pathology 1
• Focal neurological signs 1
• Altered mental status 1
• Signs of increased intracranial pressure 1

Imaging Modality Selection

For Acute/Emergency Situations

• CT brain without contrast is recommended as initial imaging for:
  • Sudden severe headache (to rule out subarachnoid hemorrhage) 1, 5
  • Headache following trauma 1
  • When rapid assessment is needed 6

For Non-Emergency Situations

• MRI brain with and without contrast is preferred for:
  • Most non-emergent evaluations 2
  • Suspected infection (meningitis, encephalitis) 1
  • Headache attributed to prior remote trauma 1
  • Suspected intracranial neoplasm 7

Special Imaging Considerations

• CT venography or MR venography should be considered if cerebral venous thrombosis is suspected 2
• MRI with specific sequences (diffusion-weighted imaging, SWI/GRE) for suspected infection or prior hemorrhage 1
• For suspected vascular abnormalities, CTA or MRA may be appropriate 1

Evidence on Imaging Yield

• The probability of finding significant abnormalities on neuroimaging in patients with migraine and normal neurological examination is only 0.2% (2/1086), which is not higher than in asymptomatic individuals (0.4%) 1
• For tension-type headache with normal neurological examination, studies show 0% (0/83) yield of significant abnormalities 1
• For chronic headache (not further defined) with normal neurological examination, the yield is approximately 0.5% (7/1445) 1

Common Pitfalls to Avoid

• Unnecessary imaging in patients with typical primary headache patterns and normal neurological examination leads to:

  • Radiation exposure (with CT) 1
  • False positive findings requiring additional workup 1
  • Increased healthcare costs without clinical benefit 2
  • Potential allergic reactions to contrast agents 1

• Relying solely on patient request for imaging without clinical indication 2

• Missing secondary causes by not recognizing atypical features or red flags in headache presentation 3

• Failing to consider CT-negative causes of serious headache (arterial dissection, encephalitis, vasculitis, cerebral venous thrombosis) that may require MRI or lumbar puncture 3

By following these evidence-based guidelines for neuroimaging in headache patients, clinicians can appropriately identify those who require further investigation while avoiding unnecessary testing in patients with benign primary headache disorders.