New international classification of migraine with aura (ICHD-2) applied to 362 migraine patients

The International Classification of Headache Disorders 2nd edition (ICHD-2) subdivides migraine with aura (MA) differently from the ICHD-1 and includes new diagnostic criteria. The aim of the present study was to evaluate how the new classification works in practice and in comparison with the ICHD-1. The patients were recruited from a screen of the Danish National Patient Registry and from Danish neurologists. We included 362 patients diagnosed with MA according to the ICHD-1 in a validated semistructured physician-conducted interview. According to the ICHD-2, 89% (322 of 362) had MA and 11% (40 of 362) had probable MA. The MA patients had one or more ICHD-2 subtype of MA: 54% (173 of 322) had typical aura with migraine headache (MA-MH), 40% (129 of 322) had typical aura with non-migraine headache (MA-NMH), 37% (120 of 322) had aura without headache (MA-WOH), and 7% (26 of 322) had basilar-type migraine (MA-B). Of patients with MA-MH 34% (59 of 173) had co-occurrence of MA-WOH, 9% (16 of 173) had co-occurrence of MA-B and 5% (8 of 173) had co-occurrence of both MA-WOH and MA-B. Of patients with MA-NMH 27% (35 of 129) had co-occurrence of MA-WOH. Only 6% (18 of 322) of the MA patients had exclusively MA-WOH and <1% (2 of 322) had exclusively MA-B. Patients with MA-MH had an earlier age at onset (P = 0.044), an increased lifetime number of MA attacks (P = 0.054) and a higher co-occurrence of migraine without aura (P = 0.002) than patients with MA-NMH. Patients with MA-B tended to have an earlier age at onset and more severe attacks and patients with MA-WOH had a higher age at onset and less severe attacks than patients with MA-MH. The variations between ICHD-2 subtypes of MA indicate that patients with similar subtype of MA share phenotype and very likely have similar underlying aetiology.