Do You Need an MRI for Migraines?

It is one of the most common questions people with migraine ask their doctor, and one of the most common sources of confusion when the answer is no. If the pain is severe enough to be disabling, if it has been happening for years, if it is disrupting work and family and every plan made for the future, then surely something should be visible on a scan. Surely an image of the brain would show what is wrong.

The answer to whether an MRI is needed is more nuanced than yes or no, and understanding it requires knowing what an MRI can and cannot show, which headache features prompt imaging, and what the evidence says about routine imaging in people with established migraine.

What an MRI Can and Cannot Show

Magnetic resonance imaging produces detailed images of brain structure. It can detect tumors, vascular malformations, areas of infarction, white matter changes, hydrocephalus, and structural abnormalities. These are all secondary causes of headache, meaning headaches produced by an underlying structural condition rather than by primary migraine disorder.

What an MRI cannot show is migraine itself. There is no structural abnormality visible on MRI that confirms a migraine diagnosis. A person with decades of disabling migraine will typically have a normal MRI. The disorder is neurological and functional rather than structural.

This is important context for understanding why an MRI is not routinely ordered for migraine. A normal MRI does not rule out migraine, because migraine does not produce MRI abnormalities. And an abnormal MRI does not confirm migraine, because the abnormalities found are typically either incidental or indicative of a different diagnosis.

When Imaging Is Indicated

The decision to order brain imaging in the context of headache is guided by the presence or absence of red flag features. The American Headache Society and the American College of Radiology have published evidence-based guidelines on appropriate imaging for headache.

Imaging is generally recommended for a thunderclap headache reaching maximum intensity within seconds to minutes, a new or significantly changed headache pattern in someone with a previously established migraine history, progressively worsening headache over days to weeks, headache associated with fever and neck stiffness, neurological symptoms that persist beyond the typical duration and pattern of migraine aura, headache in a person with known malignancy or immunosuppressive condition, and headache following head trauma.

In the absence of these red flag features, in a person with a stable, established headache pattern that meets the clinical criteria for migraine, routine brain imaging is not recommended by major clinical guidelines.

Incidental Findings and What They Mean

One consequence of MRI in people with migraine is the discovery of incidental findings. In the migraine population, the most common incidental finding is white matter hyperintensities, small bright spots visible on certain MRI sequences that appear at higher rates in people with migraine than in the general population.

Research has shown that white matter hyperintensities are more common in women with migraine with aura and in people with high attack frequency. Their clinical significance in the context of migraine is not fully established. They do not appear to be associated with cognitive impairment or significantly increased stroke risk in most people with migraine.

The challenge of incidental findings is that they can produce significant anxiety in patients who are told that something was found on their scan, even when the clinical significance is low.

The Value of a Clinical Diagnosis

A clinical diagnosis of migraine, made by an experienced clinician using the established ICHD-3 criteria and a detailed headache history, is reliable. Research has found that the diagnostic criteria perform well in distinguishing migraine from other headache disorders and from secondary headache causes in the absence of red flag features.

The value of that clinical diagnosis is not diminished by the absence of an imaging study. A normal MRI adds no diagnostic information for a patient who meets clinical criteria for migraine without red flag features.

What to Ask the Clinician

Anyone being evaluated for headache who wonders whether they need an MRI should ask their clinician directly whether any features of their headache pattern suggest a secondary cause that warrants imaging. If the answer is no, asking what clinical features would change that assessment in the future is useful. If the answer is yes, asking what specific condition is being evaluated for and what the imaging result will mean for management gives the person the context needed to understand the recommendation.

These are reasonable questions that a well-prepared clinician will welcome, because they reflect an engaged patient who wants to understand their care rather than simply comply with it.