What are the indications for head imaging in patients with migraines?

Indications for Head Imaging in Patients with Migraines

Neuroimaging should be considered in patients with migraine who have an unexplained abnormal finding on neurological examination, as this significantly increases the likelihood of identifying intracranial pathology. 1

Primary Indications for Neuroimaging

• Abnormal neurological examination findings, which increase the likelihood of intracranial pathology such as brain tumors, arteriovenous malformations, and hydrocephalus 1
• Thunderclap headache (sudden onset reaching maximum intensity within seconds to minutes), which may indicate subarachnoid hemorrhage 2
• Headache described as "worst headache of life," suggesting possible serious vascular pathology 2
• New-onset headache in patients over age 50, which raises suspicion for secondary headache including temporal arteritis 2
• Progressive headache that worsens over time, potentially indicating an intracranial space-occupying lesion 2
• Headache aggravated by Valsalva maneuver (coughing, sneezing, straining), which may suggest increased intracranial pressure 1, 2
• Headache that awakens the patient from sleep, possibly indicating increased intracranial pressure 1, 2
• Marked change in previously stable headache pattern 2
• Headache associated with focal neurological symptoms or signs 2
• Persistent headache following head trauma 2

Secondary Indications (Red Flags on Physical Examination)

• Unexplained fever, which may indicate meningitis 2
• Neck stiffness, a possible indicator of meningitis or subarachnoid hemorrhage 2
• Weight loss associated with headache, suggesting possible malignancy 2
• Impaired memory, altered consciousness, or personality changes 2
• Uncoordination, potentially indicating cerebellar pathology 2

When Neuroimaging Is Not Typically Warranted

• Patients with migraine and normal neurological examination (only 0.2% prevalence of significant intracranial abnormalities) 1
• Patients with typical features of migraine who meet the strict definition of migraine 1
• Patients with tension-type headache and normal neurological examination (though evidence is limited) 1

Imaging Modality Considerations

• No definitive recommendations exist regarding the comparative sensitivity of MRI versus CT for migraine evaluation 1
• MRI may be more sensitive than CT in identifying clinically insignificant abnormalities but not necessarily more sensitive for clinically significant pathology 1
• MRI is generally preferred due to higher resolution and absence of radiation exposure, except when acute intracranial hemorrhage is suspected, where CT without contrast is recommended 2

Important Clinical Considerations

• The prevalence of significant intracranial abnormalities in patients with migraine and normal neurological examination is approximately 0.2%, similar to the rate in asymptomatic volunteers (0.4%) 1
• Testing should be avoided if it will not lead to a change in management 1
• Testing is not recommended if the patient is not significantly more likely than the general population to have a significant abnormality 1
• False positive findings are more likely than true positive ones when pre-test probability is low, potentially leading to unnecessary concerns, further investigations, and procedures 1

Common Pitfalls

• Overlooking the need for neuroimaging when red flags are present 2
• Overutilization of imaging in patients with typical migraine features and normal neurological examinations 1
• Failure to recognize that certain features (headache worsened by Valsalva maneuver, headache awakening patient from sleep, new-onset headache in older patients) increase likelihood of significant intracranial pathology 1
• Not considering that imaging may occasionally be warranted in individual cases where patients are excessively worried about serious underlying causes, even when not clinically indicated 1

By following these evidence-based guidelines for neuroimaging in migraine patients, clinicians can appropriately identify those who require further investigation while avoiding unnecessary testing in those with typical migraine presentations.