How Doctors Diagnose Migraine Disorders

There is no blood test for migraine. No brain scan that lights up in a characteristic pattern. No biomarker that confirms the diagnosis with certainty. Migraine is diagnosed clinically, meaning through a careful conversation between a patient and a clinician, guided by established diagnostic criteria and supported by a thorough headache history.

This reality has consequences. It means that the quality of the diagnosis depends heavily on the quality of the information the patient provides. It means that a brief appointment with an unprepared patient produces a less reliable diagnosis than one with a patient who arrives with weeks of detailed headache data. And it means that migraine remains underdiagnosed at a rate that researchers have consistently described as a significant problem in neurological care.

Understanding how migraine is diagnosed helps people with headache disorders become more effective participants in their own care.

The Diagnostic Criteria

The foundation of migraine diagnosis is the International Classification of Headache Disorders, third edition, published by the International Headache Society. This document provides specific, operationalized criteria for every recognized headache disorder, including migraine without aura, migraine with aura, chronic migraine, and their subtypes.

For migraine without aura, the criteria require at least five attacks lasting four to seventy-two hours untreated, with at least two of the following characteristics: unilateral location, pulsating quality, moderate or severe intensity, or aggravation by routine physical activity. At least one of the following must also be present during the headache: nausea or vomiting, or sensitivity to both light and sound.

For migraine with aura, the criteria require at least two attacks with aura symptoms that are fully reversible, develop gradually over five or more minutes, last between five and sixty minutes, and are followed by or accompanied by headache.

These criteria were developed through decades of clinical research and are used by neurologists and headache specialists worldwide.

The Headache History

The clinical diagnosis of migraine begins with the headache history, and it is the most important part of the evaluation. A thorough headache history covers attack frequency, duration, typical severity, location and quality of pain, associated symptoms, potential triggers, response to medications, family history of migraine, and the impact of headache on daily functioning.

This is a substantial amount of information to collect and communicate accurately from memory. Most people cannot reliably recall the details of attacks that occurred weeks or months ago, particularly when those attacks are frequent. Research has shown that retrospective headache recall is subject to significant bias and inaccuracy, which means that a headache history reconstructed from memory alone may not accurately represent the patient's true pattern.

This is the primary reason neurologists and headache specialists consistently recommend that patients keep a prospective headache diary before their appointment. A diary that documents attacks as they occur produces a far more accurate headache history than recall alone.

The Physical and Neurological Examination

A complete evaluation for migraine includes a physical examination with neurological components. The neurological examination assesses cranial nerve function, motor strength, sensory function, coordination, reflexes, and cognitive function. In the context of migraine evaluation, the purpose of the neurological examination is primarily to detect signs that would suggest a secondary headache cause.

A normal neurological examination is the expected finding in primary migraine. Abnormalities on examination may prompt further investigation including brain imaging.

The Role of Brain Imaging

Brain imaging is not routinely required for the diagnosis of migraine in the absence of red flag features. The diagnosis of primary migraine is clinical, and a normal MRI does not confirm migraine while an abnormal one does not rule it out.

Red flag features that may prompt brain imaging include new or significantly changed headache pattern, progressively worsening headache over weeks, headache that wakes from sleep, headache associated with fever or neck stiffness, new neurological symptoms, headache in a person with known cancer or immunosuppression, or headache following head trauma.

Why Migraine Is Underdiagnosed

Despite the availability of clear diagnostic criteria and effective treatments, migraine remains underdiagnosed in the general population. Research from the American Migraine Prevalence and Prevention Study found that a substantial proportion of people meeting diagnostic criteria for migraine had never received the diagnosis.

Several factors contribute to this. People with migraine frequently minimize their symptoms, having internalized the cultural message that headaches are not a serious medical concern. Appointments may be too brief to allow a complete headache history. And migraine can present differently in different populations, including in men, in older adults, and in children, in ways that may not match the classic presentation.

Preparing for a Diagnostic Appointment

The most useful thing a person can do before a headache evaluation is to keep a prospective headache diary for at least four to six weeks before the appointment. This diary should document every headache day, not just severe attacks, and should capture onset time, duration, severity, location, associated symptoms, medications taken, and potential triggers.

Bringing a record of all medications tried for headache, including over-the-counter analgesics, triptans, and any preventive treatments, along with the outcome of each, gives the clinician the context needed to make informed treatment decisions rather than repeating approaches that have already failed.