Migralepsy and related conditions: Advances in pathophysiology and classification

Basic and clinical neuroscience research findings suggest that cortical spreading depression (CSD) and epileptic foci may facilitate each other; furthermore, the threshold required for the onset of CSD has been suggested to be lower than that required for an epileptic focus. These data may explain the prevalence of epilepsy in migraine populations (ranging from 1% to 17%) and the frequency of migraine in epileptic populations (ranging from 8.4% to 20%). There is currently a considerable amount of confusion regarding this topic in both headache and epilepsy classifications (ICHD-II and ILAE). The ICHD-II includes "migraine-triggered seizure" (coded as "1.5.5") (so-called "migralepsy") among the "complications of migraine", and defines "hemicrania epileptica" ("7.6.1") as an "ictal headache" (ipsilateral to the ictal EEG discharge) that occurs "synchronously" with a seizure (partial epileptic seizure) recognized by ILAE classification. However, neither "migralepsy" nor "hemicrania epileptica" are terms used in the current ILAE classification. On the basis of data reported in the literature and our recent findings, we suggest that the terms "migraine-triggered seizure" and "migralepsy" be deleted until unequivocal evidence of the existence of these conditions emerges. "Ictal epileptic headache" (IEH) should be used to classify those rare events in which headache represents the sole ictal epileptic manifestation. On the other hand, the term "hemicrania epileptica" should be maintained in the ICHD-II and introduced into the ILAE, and be used to classify all cases in which an "ictal epileptic headache" "coexists" and is associated synchronously or sequentially with other ictal sensory-motor events.