A standard MRI of someone with migraine almost always looks normal. The scan will not display the headache itself, and there is no “migraine lesion” a radiologist can point to as proof of diagnosis. Current guidelines from the American Headache Society state that neuroimaging is unnecessary for patients whose headaches fit a migraine pattern and whose neurological exam is normal. Yet that is only part of the story. Research-level imaging has revealed a surprising amount happening inside the migraine brain, from small bright spots in the white matter to shifts in blood flow and changes in gray matter volume. The gap between what a clinical scan shows and what scientists can detect with specialized techniques is where most of the confusion lives.
Why Your Doctor Probably Will Not Order an MRI
Migraine is diagnosed by its symptoms, not by a scan. The American Headache Society’s evidence-based guideline assigns a Grade A recommendation against routine neuroimaging in patients with headaches consistent with migraine who have a normal neurological examination and no red flags.1PubMed. Neuroimaging for Migraine: The American Headache Society Systematic Review and Evidence-Based Guideline In other words, if your headaches behave like textbook migraine and your doctor’s examination is normal, an MRI is unlikely to change anything about your care.
The reason is partly mathematical. Studies looking at what happens when large groups of headache patients get scanned show that meaningful brain findings are uncommon. In one study of 500 patients scanned for headache, only about 6% had any form of brain tissue abnormality, while the most common finding was sinus inflammation, not a brain problem at all.2PubMed Central. Evaluation of CT and MRI Findings among Patients Presented with Chief Complaint of Headache in Central India Another study of 150 chronic headache patients found that only about a quarter had positive intracranial findings, with tumors accounting for roughly 7% of the total sample.3PubMed Central. Magnetic resonance imaging in chronic headache: our experiences and perspectives Most of those abnormal findings occurred in patients who already had other warning signs.
The guideline does carve out specific situations where imaging makes sense. These include headaches with unusual or prolonged aura, migraine with motor weakness on one side, a first or worst-ever headache, headache with brainstem symptoms, late-onset migraine with aura features, headache that always stays on the same side, and post-traumatic headache.1PubMed. Neuroimaging for Migraine: The American Headache Society Systematic Review and Evidence-Based Guideline A structured checklist of red flags known as the SNNOOP10 list helps clinicians identify headaches that could signal something more dangerous, though the authors of that review note that many red flags still lack strong prospective data on how well they actually predict secondary causes.4PubMed Central. Red and orange flags for secondary headaches in clinical practice: SNNOOP10 list
White Matter Bright Spots
Even though a clinical MRI does not “show” migraine, it often does show something in people who have it. Small bright spots in the brain’s white matter, called white matter hyperintensities, appear at higher rates in migraine patients than in the general population. A meta-analysis pooling data across multiple studies found these spots in roughly 44% of migraine patients overall, 45% of those with aura, and 38% of those without aura.5PubMed Central. Prevalence and clinical characteristics of white matter hyperintensities in Migraine: A meta-analysis They tend to cluster in the frontal lobe and in the deeper layers of white matter beneath the cortex.5PubMed Central. Prevalence and clinical characteristics of white matter hyperintensities in Migraine: A meta-analysis
These bright spots are not unique to migraine. They show up in healthy aging, high blood pressure, and many other conditions, which is why radiologists often call them “nonspecific.” But in migraine patients, their presence correlates with how long someone has had the disease and how frequently attacks occur. A study of 186 migraine patients found that those with white matter hyperintensities had lived with the disease significantly longer (about 20 years versus 14 years) and had more frequent attacks per month than those without the spots.6PubMed Central. Risk factors of migraine-related brain white matter hyperintensities: an investigation of 186 patients Above the 20-year mark, nearly half of patients in that study had white matter changes, compared to about a quarter with shorter disease duration.6PubMed Central. Risk factors of migraine-related brain white matter hyperintensities: an investigation of 186 patients
Less commonly, bright spots appear in the brainstem and cerebellum. One population-based study found brainstem or cerebellar hyperintensities in about 4.4% of migraine patients compared to under 1% of controls, mostly located in the base of the pons.7PubMed. Brain stem and cerebellar hyperintense lesions in migraine Cerebellar lesions consistent with tiny areas of ischemia were found in about 8.5% of migraine patients in another study, compared to 4% of controls.8PubMed Central. Cerebellar function and ischemic brain lesions in migraine patients from the general population People with frequent aura appear to carry a higher risk of posterior circulation lesions, possibly driven by episodes of reduced blood flow in the back of the brain during prolonged aura.9PubMed. Crossed cerebellar diaschisis during migraine with prolonged aura: a possible mechanism for cerebellar infarctions
Should You Worry About Those Spots?
In elderly people without migraine, white matter hyperintensities are linked to a higher risk of stroke, cognitive decline, and dementia. That association understandably causes alarm when a migraine patient in their 30s or 40s sees similar-looking spots on their own scan. But the evidence suggests the spots in migraine brains behave differently. The CAMERA-2 study, a major longitudinal investigation, found no association between deep white matter lesion burden in migraine patients and changes in cognitive test scores over time. Broader longitudinal research has also found no evidence that a history of migraine increases the risk of dementia, and some studies have even noted slightly better cognitive performance in people with migraine.10The American Journal of Pathology. Pathophysiology of Migraine-Related White Matter Lesions The underlying biology of these lesions may differ from the vascular damage seen in aging or hypertension, though the exact mechanism behind them remains an open question.
Still, the appearance of these bright spots can be unsettling. As one review noted, nonspecific white matter hyperintensities cause uncertainty for physicians and anxiety for patients.11PubMed. Migraine and white matter hyperintensities A radiologist reading the scan may describe them in cautious language, and the patient may leave the appointment more worried than they were before the MRI. This is one of the practical downsides of scanning patients whose headaches already have a clear clinical explanation.
Telling Migraine Spots Apart from Multiple Sclerosis
One of the most anxiety-producing scenarios is when a migraine patient’s MRI shows white matter lesions that look like they could be multiple sclerosis. Both conditions can produce small, bright spots scattered through the brain’s white matter, and in some cases the overlap in appearance is enough to trigger an MS workup in someone who actually has migraine.
Researchers have been developing ways to distinguish the two. One promising approach uses a feature called the “central vein sign.” MS lesions tend to form around a small vein running through their center, which is visible on certain MRI sequences. A study comparing the two populations found that when more than 35% of a patient’s white matter lesions had a central vein sign, there was a 97% sensitivity and 86% specificity for an MS diagnosis rather than migraine.12PubMed. The “central vein sign” to differentiate multiple sclerosis from migraine MS lesions also tended to be much larger in volume.
Advanced MRI techniques can further separate the two. Using spectroscopy and relaxation-time measurements, researchers found that migraine lesions and MS lesions have measurably different chemical and tissue-water signatures. In particular, a chemical marker called myo-inositol could distinguish MS lesions from migraine lesions with roughly 87% sensitivity and 82% specificity.13PubMed Central. Differentiation of hemispheric white matter lesions in migraine and multiple sclerosis with similar radiological features using advanced MRI These tools are not yet part of routine clinical practice, but they offer reassurance that the two conditions are becoming easier to tell apart when there is genuine diagnostic uncertainty.
What Functional MRI Captures During and Before Attacks
The imaging that has reshaped scientists’ understanding of migraine is not the standard structural MRI you get at a hospital. It is functional MRI, which tracks changes in blood flow and brain activity in real time. This kind of imaging is almost entirely a research tool, but its findings explain why migraine is now understood as a brain disorder rather than simply a “bad headache.”
The most dramatic observations have come during migraine aura. Using high-field functional MRI, researchers captured a wave of increased blood-oxygen-level signals slowly spreading across the visual cortex at about 3.5 millimeters per minute, closely matching the visual disturbances the patient was experiencing. This wave was followed by a period of reduced signal, consistent with the brain phenomenon known as cortical spreading depression.14PubMed Central. Mechanisms of migraine aura revealed by functional MRI in human visual cortex That work provided direct evidence in living human brains for a process that had previously only been documented in animals.
Even more interesting is what happens before a migraine starts. A review of premonitory-phase imaging found consistent activation in the hypothalamus, midbrain, and limbic system in the hours before headache onset, supporting the idea that migraine attacks are initiated deep in the brain rather than starting with blood vessel problems.15PubMed Central. Neuroimaging in the pre-ictal or premonitory phase of migraine: a narrative review A study of menstrually related migraine pinpointed robust hypothalamic activation in the 48 hours before headache onset, with no equivalent activation seen in healthy controls during the same menstrual phase.16PubMed. Neuronal Dynamics of Menstrually Related Migraine: A Longitudinal Task-Based fMRI Study
A longitudinal study that scanned three migraine patients every weekday for four weeks found that brainstem activity was similar to controls between attacks but changed dramatically in the 24 hours before a migraine. Activity surged in the spinal trigeminal nucleus and dorsal pons, the brainstem regions where head and face pain signals first arrive.17PubMed Central. Brainstem functional oscillations across the migraine cycle: A longitudinal investigation These findings collectively paint a picture of migraine as a cyclical brain event with a detectable pre-attack signature, though the sample sizes in some of this work remain small.
Blood Flow Shifts Visible on Specialized Scans
Specialized blood-flow MRI techniques called arterial spin labeling can pick up perfusion changes during migraine attacks. In children with migraine with aura, these scans have shown reduced blood flow in the brain regions corresponding to the child’s aura symptoms. One study found hypoperfusion in all nine pediatric patients scanned within 24 hours of symptom onset, and in a separate study, the pattern of reduced flow visually matched the expected brain territory based on each child’s neurological symptoms in nearly every case.18PubMed Central. Perfusion imaging by arterial spin labeling in migraine: A literature review In adults, a study of migraine without aura found that blood flow in the dorsolateral pons, on the same side as the pain, increased by about 14% during attacks compared to outside attacks.19PubMed Central. Glutamate levels and perfusion in pons during migraine attacks: A 3T MRI study using proton spectroscopy and arterial spin labeling
These blood flow findings are relevant for a practical reason as well. When a child arrives at an emergency room during a severe aura episode, reduced perfusion on imaging could be mistaken for a stroke. The fact that diffusion-weighted imaging in these migraine cases typically shows no signs of tissue damage from oxygen deprivation is what helps distinguish the two.18PubMed Central. Perfusion imaging by arterial spin labeling in migraine: A literature review The blood flow drops during aura, but the brain tissue survives.
Gray Matter and Microstructural Changes
Beyond white matter bright spots, research MRI has revealed subtler differences in the brain tissue of migraine patients. A systematic review and meta-analysis of gray matter studies found that migraine patients tend to have reduced gray matter volume in the frontal lobes and the cingulate gyrus, a region involved in processing pain and emotional responses. The severity of these reductions correlated with headache frequency.20PubMed Central. Grey matter alterations in migraine: A systematic review and meta-analysis Chronic migraine patients specifically showed gray matter reductions in the cerebellum, temporal lobe, amygdala, and visual cortex compared to healthy controls.21PubMed Central. Cerebral gray matter volume in patients with chronic migraine: correlations with clinical features
Diffusion tensor imaging, which maps the microstructure of white matter tracts by tracking how water molecules move through tissue, has shown differences between chronic and episodic migraine. One study found changes across 38 white matter regions in chronic migraine patients compared to those with episodic migraine, with the extent of change correlating with how long someone had been in the chronic phase.22PubMed Central. White matter changes in chronic and episodic migraine: a diffusion tensor imaging study A separate study found that migraine patients had measurably different white matter organization in the occipital regions and cerebellum.23PubMed. Microstructural differences in migraine: A diffusion-tensor imaging study Whether these changes are a consequence of repeated attacks or a pre-existing feature of the migraine brain is an important unresolved question.
Children with Migraine on MRI
Parents often wonder whether their child should have a brain scan for recurring headaches. The answer tracks closely with the adult guideline: if the headaches fit a migraine pattern and the neurological exam is normal, imaging is generally not recommended. But when scans are done, they do show findings.
White matter lesions have been identified in roughly 11% of children with migraine in one study, compared to none of the children in the control group.24PubMed. MRI white matter lesions in pediatric migraine A smaller study of 20 pediatric migraine patients found a higher rate, with 50% showing abnormal MRI findings, though most of those were small white matter lesions.25PubMed Central. Investigating Brain MRI Findings in Children with Headache In terms of brain structure, pediatric migraine patients have shown gray matter differences in the frontal and temporal lobes that are part of the brain’s pain-processing network, even early in the disease course. The fact that these differences existed in children whose disease was relatively new, and did not correlate with disease duration, led the authors to suggest these may be an inborn feature of the migraine brain rather than damage from repeated attacks.26PubMed. Structural brain MRI abnormalities in pediatric patients with migraine
Imaging During Pregnancy
Migraine frequently changes during pregnancy, often improving in the second and third trimesters but sometimes worsening or appearing for the first time. When a pregnant person develops a new headache pattern or worsening symptoms, the challenge is ruling out secondary causes like cerebral venous thrombosis or preeclampsia-related complications without exposing the fetus to radiation. MRI without contrast is considered safe in pregnancy and is the preferred imaging tool in these situations. A systematic review on headache and pregnancy noted that brain MRI and MR angiography can be used to exclude secondary causes, and that contrast agents should be used only when strictly necessary.27PubMed Central. Headache and pregnancy: a systematic review The threshold for ordering a scan is generally lower in pregnant patients with new or atypical headache, because the conditions being ruled out carry serious risks for both mother and fetus.
The Cost of Scanning Everyone
Despite guidelines advising against routine imaging for uncomplicated migraine, a lot of scans still happen. Between 1995 and 2010 in the United States, the proportion of headache-related visits that included neuroimaging nearly tripled, rising from about 5% to nearly 15% of all headache visits. Total neuroimaging spending over a four-year period was estimated at $3.9 billion, with $1.5 billion of that coming from migraine visits alone.28JAMA Internal Medicine. Headaches and Neuroimaging: High Utilization and Costs Despite Guidelines
One older analysis modeled the cost of detecting clinically significant findings by MRI in patients with non-focal headache and came up with a cost of roughly $34,500 per meaningful case detected.29PubMed Central. Economic and outcomes assessment of magnetic resonance imaging in the evaluation of headache The drivers behind this overuse are not simple. A review in the neuroradiology literature pointed to fear of missing a significant lesion, litigation risk, patient expectations, financial incentives, and simple habit as reasons why clinicians continue ordering scans they know are unlikely to change the diagnosis.30American Journal of Neuroradiology. Headache and Neuroimaging: Why We Continue to Do It For the patient, the harm is not just financial. A scan that reveals an incidental finding or nonspecific white matter changes can set off a cascade of follow-up testing and worry, with no benefit if the original diagnosis was correct all along.
Ultra-High-Field MRI and the Glymphatic System
The frontier of migraine imaging involves ultra-high-field MRI machines running at 7 Tesla, roughly double the field strength of most clinical scanners. These machines can resolve structures that are invisible at standard resolutions. A recent 7T study comparing migraine with aura, migraine without aura, and healthy controls found evidence of impaired glymphatic function in migraine with aura. The brain’s glymphatic system is its waste-clearance network, and patients with aura showed enlarged perivascular spaces and a lower drainage index compared to controls and to migraine-without-aura patients. Iron deposits in the amygdala were also associated with these drainage measures, hinting at a link between metal accumulation and fluid clearance in the migraine brain.31PubMed Central. Subcortical nuclei and glymphatic system alterations in migraine with aura: a comparative 7T multimodal MRI analysis This line of research is brand new, but it illustrates how much more the migraine brain has to reveal as imaging technology advances. Whether any of this eventually translates into a clinical diagnostic test remains to be seen.