Neurologists diagnose migraines primarily through your medical history and a structured clinical interview, not through brain scans or blood tests. There is no single test that confirms a migraine. Instead, your neurologist matches your symptom pattern against established diagnostic criteria, performs a neurological exam to rule out other causes, and orders imaging only when something in your history or exam raises concern about a more serious condition.
The Clinical Interview Comes First
The most important diagnostic tool is the conversation. Your neurologist will ask detailed questions about what your headaches feel like, how long they last, how often they occur, and what other symptoms accompany them. They’re listening for a specific pattern. To meet the formal diagnostic criteria used worldwide, you need to have experienced at least five attacks that each lasted between 4 and 72 hours (untreated). In children and adolescents, episodes as short as 2 hours can qualify.
Beyond duration, the headache itself needs to have at least two of these four features: pain on one side of the head, a pulsating or throbbing quality, moderate to severe intensity, or pain that gets worse with routine physical activity like walking or climbing stairs. On top of that, during the headache you must also experience either nausea or vomiting, or sensitivity to both light and sound. These criteria come from the International Classification of Headache Disorders, the standard reference neurologists use globally.
A quick screening method that works well in practice looks at five features, sometimes called the POUND criteria: pulsating quality, duration of 4 to 72 hours, one-sided location, nausea or vomiting, and disabling intensity. When four or more of these are present, the likelihood of migraine is very high. Interestingly, adding photophobia or phonophobia to this checklist doesn’t improve its accuracy, because those five features alone capture the pattern so effectively.
What Happens During the Neurological Exam
After the interview, your neurologist performs a hands-on physical exam. This isn’t to confirm the migraine. It’s to make sure nothing else is causing your headaches. The exam typically takes 15 to 30 minutes and involves several components.
Your doctor will check your cranial nerves, the twelve pairs of nerves that control functions like vision, facial sensation, and eye movement. This might involve shining a light into your eyes to examine the optic nerve, asking you to follow a finger with your gaze, touching different areas of your face, or having you bite down so they can assess the muscles involved in chewing. They’ll test your reflexes with a small hammer at your knees, elbows, and other joints. They may check your coordination by asking you to touch your nose with your eyes closed, walk in a straight line, or tap your fingers rapidly. Sensation testing with a dull pin or tuning fork checks whether you can feel and distinguish different types of touch. They’ll also briefly assess your mental status through conversation, checking that your speech is clear and your awareness is intact.
In a straightforward migraine case, this entire exam comes back normal. That’s actually the point. A normal neurological exam, combined with a history that fits the criteria, is what confirms the diagnosis.
Red Flags That Change the Approach
Neurologists are trained to watch for warning signs that suggest a headache might be caused by something other than migraine, such as a blood vessel problem, increased pressure in the brain, or an infection. They use a checklist of red flags organized by the mnemonic SNOOP4.
- Systemic signs: Fever, night sweats, unexplained weight loss, or an underlying condition like a compromised immune system.
- Neurological symptoms: New weakness in an arm or leg, numbness that’s not typical for you, or unusual visual changes. Primary headaches like migraine don’t usually come with neurological deficits outside of aura.
- Onset that’s sudden: A headache that reaches maximum intensity within seconds, sometimes called a thunderclap headache, can signal a vascular emergency like an aneurysm and requires immediate evaluation.
- Older age: New headaches starting after age 50 are more likely to have a secondary cause.
- Progression: A headache pattern that’s clearly getting worse over time, becoming more severe or more frequent in a steady trajectory rather than fluctuating.
- Papilledema: Swelling of the optic nerve visible during the eye exam, which can indicate elevated pressure around the brain.
- Positional changes: Pain that shifts in intensity when you move from standing to lying down, or that’s triggered by coughing or straining.
- Pregnancy: New headaches during or shortly after pregnancy warrant evaluation for vascular or hormonal complications.
If none of these red flags are present and the history fits, your neurologist can confidently diagnose migraine without any imaging at all.
When Brain Scans Are Ordered
MRIs and CT scans don’t show migraines. A migraine brain looks normal on imaging. So neurologists order scans not to confirm migraine, but to rule out other conditions when something in the clinical picture is concerning.
Specific scenarios that justify imaging include a sudden-onset severe headache (MRI is preferred over CT for this), a new headache accompanied by focal neurological deficits or optic nerve swelling, new headaches in someone over 50, headaches in immunocompromised or cancer patients, positional headaches, and headaches that worsen with coughing or exertion. If there’s suspicion of an artery tear in the neck, a specialized scan of the blood vessels (CT or MR angiography) may be added. After head trauma, CT without contrast is the standard first step.
If you’ve had stable migraines for years that fit the typical pattern, a scan is unlikely to change your diagnosis or treatment. Many patients expect imaging as part of the process, but ordering it routinely in clear-cut migraine cases adds cost without benefit.
Distinguishing Migraine From Other Headache Types
Part of the diagnostic process involves making sure your headaches aren’t a different primary headache disorder. The two most common alternatives are tension-type headache and cluster headache, and each has a distinct profile.
Cluster headaches overlap with migraines more than most people realize. Both can cause one-sided pain, tearing, eye redness, and nasal congestion. The key differences are behavioral: during a migraine, you want to lie down in a dark, quiet room. During a cluster headache, people become agitated and restless, often pacing or rocking. Cluster headaches also tend to be shorter (15 minutes to 3 hours versus 4 to 72 hours for migraine) and localize strictly to one side, usually around the eye or temple. Migraine pain can shift sides or involve the entire head. Duration and the rest-versus-agitation distinction are the two most reliable features neurologists use to separate them.
Episodic Versus Chronic Migraine
Once migraine is diagnosed, your neurologist classifies it as either episodic or chronic. The dividing line is 15 headache days per month. If you have headaches on 15 or more days per month, and at least 8 of those days meet migraine criteria, you’re classified as having chronic migraine. This distinction matters because it changes treatment strategy, and chronic migraine qualifies for certain preventive therapies that insurers may not cover for episodic migraine.
Vestibular Migraine
If your primary complaint is dizziness or vertigo rather than head pain, your neurologist may evaluate you for vestibular migraine. This variant requires at least five episodes of moderate to severe vestibular symptoms (vertigo, dizziness, or balance problems) lasting between 5 minutes and 72 hours. At least half of those episodes must overlap with typical migraine features: one-sided pulsating head pain, light and sound sensitivity, or visual aura. You also need a current or past history of migraine.
Episode duration varies widely. Roughly a third of vestibular migraine patients have episodes lasting minutes, another third experience hours-long attacks, and another third deal with episodes spanning several days. Some patients have brief seconds-long bursts triggered by head movement that recur over a longer period. Full recovery from a single episode can occasionally take up to four weeks, though the core attack rarely exceeds 72 hours.
How to Prepare for Your Appointment
You can make the diagnostic process faster and more accurate by tracking your headaches before you see a neurologist. One approach recommended by specialists at Mayo Clinic is a simple “stoplight diary”: mark each day on a calendar as green (mild impact on your daily function), yellow (moderate impairment), or red (severe, potentially bedbound). Also note when you take medication to treat an attack.
Come prepared to describe what the pain feels like, what other symptoms accompany it (nausea, light sensitivity, fatigue), and how disabling your attacks are on a scale of 1 to 10. Bring a list of every medication and supplement you’ve tried for headaches, including dosages, how long you used them, side effects, and whether they helped. Even treatments that failed are useful information, because they guide your neurologist away from approaches that won’t work for you and toward options that might.
One thing you don’t necessarily need to stress over: trigger tracking. While many patients arrive with detailed logs of potential triggers, some headache specialists find this approach more stressful than helpful. It can lead to unnecessary avoidance behaviors and puts blame on the patient rather than the disease. The stoplight diary captures the information your neurologist needs most: how often your migraines happen and how much they affect your life.