Migraine with brainstem aura: defining the core syndrome.

Migraine with brainstem aura is a rare subtype of migraine with aura. Although this entity has been known for many years, its diagnosis and even its existence are still a matter of debate. Previous studies demonstrated that current diagnostic criteria for migraine with brainstem aura are too open and brainstem symptoms may originate within the cortex and not in the brainstem. The aims of the present study were to analyse whether aura from the brainstem exists, how prevalent such a core syndrome is, to analyse if current diagnostic criteria define such a core syndrome and, if necessary, to develop new diagnostic criteria that define only the core syndrome. We analysed all migraine with brainstem aura cases described in detail in the literature, clinical cases from the Danish Headache Center (DHC) and our large sample of telephone interviewed cases with migraine with aura. We selected the 20 most convincing cases from the literature and convincing cases from the DHC. Of 79 migraine with brainstem aura cases described in detail in the literature, 44 fulfilled the diagnostic criteria for migraine with brainstem aura of the International Classification of Headache Disorders, 3rd edition (ICHD-3). In the DHC after face-to-face interview, neurological examination and imaging, four migraine with brainstem aura of 293 cases with migraine with aura (1.37%) were found, corresponding to 0.04% of the general population. The 20 most convincing cases had symptoms that likely originated in the brainstem. Our telephone-interviewed cohort included 1781 subjects with a diagnosis of migraine with aura or probable migraine with aura. Of these, 228 fulfilled the diagnostic criteria for migraine with brainstem aura of the ICHD-3. Thus, using telephone interview diagnosis according to current diagnostic criteria results in too many cases of migraine with brainstem aura being diagnosed. Therefore, we developed stricter diagnostic criteria in an attempt to include only those rare cases that definitely have aura originating from the brainstem. Migraine with brainstem aura does exist, but it is very rare. Existing diagnostic criteria are too unspecific, but it was possible to develop tighter criteria that define a core syndrome probably caused by brainstem dysfunction.