There is no blood test or scan to diagnose migraine
Migraine is diagnosed by what the patient reports in his or her history. A healthcare provider arrives at a medical diagnosis of migraine after taking a careful health history and performing a thorough comprehensive physical exam. The exam should be normal with no neurological or ophthalmological deficits.
SYMPTOM CATEGORY A
The hallmark symptom of Migraine is, of course, the headache (typically lasting longer than four hours.) When this hallmark symptom is present, there are four additional primary criteria for diagnosing migraine:
SYMPTOM CATEGORY B
If at least two of the above symptoms are present, a diagnosis of migraine is possible. However, the patient must also answer yes to one of the following secondary criteria questions to make the diagnosis certain:
OTHER POSSIBLE CAUSES
Even if the patient experiences at least two of the primary criteria and at least one of the secondary criteria, their symptoms can still be consistent with one or more other primary headache disorders. A thorough examination of patient history is required to rule out all other possible contributing factors.
If the patient has had at least 5 attacks (migraine without aura) or at least 2 attacks (migraine with aura), no red flags are found in the history or exam, and the patient meets at least 3 of 6 criteria for migraine, then no additional labs, scans or other tests are required for a diagnosis of migraine.
Migraine attacks typically last 4-72 hours if left untreated. That means that if the headaches only last 3 hours without treatment, resolving spontaneously, they cannot be diagnosed as migraine headaches.