When is an MRI (Magnetic Resonance Imaging) of the brain recommended for patients with headaches?

When to Get MRI Brain for Headaches

MRI brain imaging is not typically warranted for patients with migraine or tension-type headache who have normal neurological examinations, but should be performed when specific "red flags" are present that suggest possible secondary causes of headache. 1, 2

Primary Indications for Neuroimaging

• Abnormal neurological examination findings - Unexplained abnormal findings on neurological examination significantly increase the likelihood of identifying intracranial pathology 1, 3
• Thunderclap headache - Sudden severe headache ("worst headache of life") suggests possible subarachnoid hemorrhage or other serious vascular pathology 1, 4
• New-onset headache in patients over age 50 - Raises suspicion for secondary headache including temporal arteritis 1, 2
• Progressive headache that worsens over time - Potentially indicates an intracranial space-occupying lesion 1, 5
• Headache aggravated by Valsalva maneuver - May suggest increased intracranial pressure 1, 6
• Headache that awakens patient from sleep - Possibly indicates increased intracranial pressure 1, 2
• Marked change in previously stable headache pattern - Suggests possible new pathology 1, 5
• Headache associated with focal neurological symptoms or signs - Requires neuroimaging to rule out structural lesions 1, 3
• Persistent headache following head trauma - May indicate traumatic brain injury complications 1, 4

Secondary Indications for Neuroimaging

• Unexplained fever with headache - May indicate meningitis or other infectious process 1
• Neck stiffness - Possible indicator of meningitis or subarachnoid hemorrhage 1, 7
• Weight loss associated with headache - Suggests possible malignancy 1
• Impaired memory, altered consciousness, or personality changes - May indicate structural brain lesions 1, 7
• Uncoordination - Potentially indicates cerebellar pathology 1, 3
• Immunocompromised state - Higher risk of CNS infections or malignancies 4, 6
• Pregnancy - Changes threshold for imaging due to specific concerns in this population 4, 1

When Neuroimaging Is Not Typically Warranted

• Typical migraine with normal neurological examination - The prevalence of significant intracranial abnormalities is only approximately 0.2%, similar to asymptomatic volunteers (0.4%) 3, 1, 2
• Tension-type headache with normal neurological examination - Low yield of clinically significant findings 3, 2
• Chronic stable headache pattern without red flags - Unlikely to reveal significant pathology 2, 8

Imaging Modality Considerations

• MRI vs CT - No definitive recommendations exist regarding comparative sensitivity for migraine evaluation 1, 2
• MRI advantages - Higher resolution and absence of radiation exposure; preferred for most non-emergency headache evaluations 1, 2
• CT advantages - Superior for detecting acute subarachnoid hemorrhage; faster and more readily available in emergency settings 2, 4

Common Pitfalls to Avoid

• Overlooking red flags - Missing important clinical indicators that warrant neuroimaging 1, 7
• Overutilization of imaging - Approximately 35% of patients may be imaged against guidelines, leading to unnecessary costs and potential false positives 8, 1
• Misdiagnosing "sinus headache" - Often actually migraine with cranial autonomic symptoms 2
• Failure to recognize concerning features - Such as headache worsened by Valsalva maneuver, headache awakening patient from sleep, or new-onset headache in older patients 1, 8

Decision-Making Algorithm

1. Assess for red flags (abnormal neurological exam, thunderclap onset, age >50 with new headache, etc.) 1, 5
2. If any red flags present → Proceed with appropriate neuroimaging 1, 4
3. If typical features of migraine or tension headache with normal neurological exam and no red flags → Neuroimaging not typically warranted 3, 2
4. For headaches associated with cough, exertion, or sexual activity → Consider MRI even without other red flags 5, 6
5. In emergency settings with suspected acute bleeding → CT without contrast is preferred 2, 4
6. For non-emergency evaluation of concerning headaches → MRI with and without contrast is generally preferred 1, 2