Migraine: How it's diagnosed and what that means

When a doctor makes a diagnosis, many people expect proof. Migraine doesn’t offer that.

Yet the diagnosis can still be definitive — just not in the way you might expect, says neurologist Dr. Paul Rizzoli, clinical director of the Graham Headache Center at Harvard-affiliated Brigham and Women’s/Faulkner Hospital.

Nearly 16% of Americans are affected by migraine, which strikes women at nearly twice the rate as men. While doctors now understand far more about the nerve pathways involved in the headache disorder, migraine is still a bit of a mystery.

Advanced imaging still can’t diagnose migraine, which is defined by patterns of migraine symptoms rather than a blood test, scan, or biopsy. And pain is only one part of the picture, Dr. Rizzoli says.

“There are tests that eliminate other causes of headache (see “What imaging tests rule out”), but there’s no test that documents it’s migraine,” he says. “Typically, someone’s history is where all the information is — and it’s usually so convincing for migraine that we end up not needing much in the way of further evaluation.”

What is migraine?

While imaging scans have become increasingly sensitive, doctors still can’t use them to prove a migraine diagnosis. Why? Because migraine doesn’t create a visible brain abnormality that scans can capture.

“We don’t actually know yet what migraine is,” Dr. Rizzoli explains. “We just suspect something is genetically different between migraine and non-migraine people that creates a sensitive or reactive brain. With that in place, features of the environment can act as migraine triggers — such as weather, stress, sleep, food, or hormonal changes — in individual events.”

Migraine symptoms doctors look for

Despite the limitations of testing, pinpointing migraine is surprisingly straightforward. The condition is characterized by a recurring constellation of symptoms that may include

• one-sided, pulsing, or stabbing head pain
• pain that gets worse with movement
• nausea
• sensitivity to light and sound.

A repeated, recognizable pattern of headaches — interspersed with periods of feeling normal — is key, Dr. Rizzoli says. With those parameters, “it can’t really be anything else besides migraine,” he says. “There’s no other illness that affects you for years in intermittent fashion, leaving you normal in between.”

Wide variation in symptoms

That said, migraine symptoms are far from cookie-cutter. One person might experience severe, throbbing pain; another, visual disturbances, dizziness, or nausea. Yet another person may have mild headaches but profound sensitivity to light.

Doctors must also push past fallacies about migraine that can muddy diagnosis, such as the following:

• Migraine always affects one side of the head.
• It always brings severe pain. “The most common report is that headaches are mild to moderate in intensity, so that’s the biggest misconception,” Dr. Rizzoli says.
• Sensory, visual, or speech changes (called migraine aura) always occur.

“There are not only variations from one patient to another, but within a patient,” he says. “Headaches can disappear and recur. I liken it to variations on a theme in a piece of music — even though there’s a significant amount of variation, you can sort of hear the migraine underneath.”

Connecting the dots

The main challenge of diagnosing migraine is that doctors must do it solely through reported symptoms. Dr. Rizzoli asks patients a series of questions such as the following:

• How many days are “headache days” in a given month?
• How many hours — or days — do symptoms during an episode typically last?
• What other symptoms are you having?
• What seems to trigger episodes?
• Do you have a family history of headaches or migraine?

“Think through your headache — what’s happening?” he says. “I’m interested in features like the time of day it starts; if there’s any warning beforehand; what happens first, then next; how long it lasts; what symptoms go with it; what sets one off; what you’re usually doing when you have one; and if you’re able to complete daily activities when you have a headache.”

What happens after a migraine diagnosis?

After determining that migraine is the culprit, doctors usually tailor treatments to each individual’s history and symptom pattern.

Mainstay therapy typically involves a combination of preventive and therapeutic medications — those designed to prevent the onset of a migraine or ease symptoms once it occurs.

“In patients who regularly have four or more per month, we discuss prevention,” Dr. Rizzoli says. “One reason is to get control of the syndrome, but the larger reason is to forestall the development of chronic headache syndrome — 15 or more headaches per month.”

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