When to Send a Patient for Imaging in Migraines
Neuroimaging is not recommended for patients with typical migraine features and normal neurological examination, as the prevalence of significant intracranial abnormalities in these patients is approximately 0.2%, similar to the rate in asymptomatic individuals. 1, 2
Red Flags Requiring Neuroimaging
- Abnormal neurological examination - Any unexplained abnormal finding on neurological examination significantly increases the likelihood of identifying intracranial pathology 1, 2
- Thunderclap headache - Sudden onset, severe "worst headache of life" may indicate subarachnoid hemorrhage 1, 3
- New-onset headache in patients over 50 years - Raises suspicion for secondary headache including temporal arteritis 1
- Progressive headache pattern - Headache that worsens over time potentially indicates an intracranial space-occupying lesion 1
- Headache aggravated by Valsalva maneuver - May suggest increased intracranial pressure 1
- Headache that awakens patient from sleep - Possibly indicates increased intracranial pressure 1
- Marked change in previously stable headache pattern - Indicates possible new pathology 1
- Headache with focal neurological symptoms or signs - May indicate structural lesion 1
- Persistent headache following head trauma - Requires evaluation for traumatic brain injury 1
Additional Indications for Neuroimaging
- Unusual, prolonged, or persistent aura - Atypical presentations warrant investigation 4
- Migraine with brainstem aura - Previously called basilar-type migraine 4
- Migraine with confusion - Not typical of standard migraine 4
- Hemiplegic migraine - Migraine with motor manifestations 4
- Side-locked headache - Headache consistently on same side may indicate structural lesion 4
- Aura without headache - Particularly in older patients 4
- Posttraumatic headache - May indicate underlying structural damage 4
Secondary Signs Warranting Consideration of Imaging
- Unexplained fever - May indicate meningitis or other infectious process 1
- Neck stiffness - Possible indicator of meningitis or subarachnoid hemorrhage 1
- Weight loss associated with headache - Suggests possible malignancy 1
- Impaired memory, altered consciousness, or personality changes - May indicate structural lesion 1
- Uncoordination - Potentially indicates cerebellar pathology 1
Imaging Modality Selection
- MRI is generally preferred over CT due to higher resolution and absence of radiation exposure 1, 3
- CT without contrast is recommended when acute intracranial hemorrhage is suspected 1, 5
- Both MRI and CT have similar sensitivity for clinically significant pathology, though MRI may detect more clinically insignificant abnormalities 2
Common Pitfalls to Avoid
- Overutilization of imaging in patients with typical migraine features and normal neurological examinations 2
- Overlooking red flags that necessitate neuroimaging 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
- Ignoring incidental findings - Up to 8% of migraine patients may have clinically significant findings on MRI, particularly those over 40 years of age 6
- Unnecessary radiation exposure - Neuroimaging is not only rarely necessary in the diagnostic work-up of migraine but can be harmful due to radiation exposure with CT 3
- Creating patient anxiety - MRI can reveal clinically insignificant abnormalities (white matter lesions, arachnoid cysts, meningiomas), which can alarm patients and lead to unnecessary further testing 3
When Neuroimaging Is Not Warranted
- Typical migraine with normal neurological examination - These patients have a low prevalence of significant intracranial abnormalities 1, 2, 7
- Tension-type headache with normal neurological examination - Routine imaging not required 1
- Patients meeting strict definition of migraine without red flags 1, 4