Migraine classification, diagnostic criteria, and testing

The need for operational diagnostic criteria led to the development of the International Headache Society classification, including the diagnostic criteria for migraine. This is a valid, reliable, and comprehensive diagnostic system. Although its acceptance is high, it is still not used sufficiently. Patients fulfilling its criteria for migraine rarely need additional diagnostic testing. Electroencephalography studies are not indicated except when there is altered mental status or the suspicion of a seizure disorder. Results of MRI and CT are almost always normal in migraineurs except for white matter abnormalities (WMAs). WMAs have been variably reported in 12% to 46% of migraineurs compared with 2% to 14% of controls. The cause of these WMAs is not certain. Other disorders, such as antiphospholipid antibody syndrome, vasculitis, and MS, can also cause WMAs. Imaging may be indicated when there are atypical headache features, focal neurologic symptoms or signs, or a history of seizures. Patients with late-life migraine accompaniments may require diagnostic testing to exclude the numerous causes of transient ischemic events. Lumbar puncture may be indicated in migraine for the first or worst migraine to exclude subarachnoid hemorrhage, infection, and, in some cases, MS. Lumbar puncture is also essential in the diagnosis of idiopathic intracranial hypertension or headache disorders associated with CNS infections. This article reviews the diagnostic possibilities and relevant testing in the examination of patients with headache. Although it is necessary to distinguish primary headaches from those that are secondary to other causes, it is equally important to correctly diagnose the type of primary headache, because treatments may differ.