Implications of clinical subtypes of migraine with aura

To compare the clinical characteristics of familial hemiplegic migraine (FHM), sporadic hemiplegic migraine (SHM), and nonhemiplegic migraine with aura (NHMA) and further, to compare subtypes of NHMA.

To discover distinct underlying genetic and pathophysiological mechanisms it is crucial to drive clinical subdivision of migraine with aura as far as possible. The documentation of subtypes of migraine with aura depends on the clinical characteristics as the genetic mechanisms are unknown except for the dominantly inherited FHM.

Patients with FHM, SHM, or familial NHMA were recruited from specialist practice and diagnosed according to the International Classification of Headache Disorders (ICHD) in a validated interview by a physician. Patients with hemiplegic migraine had a physical and neurological examination. Patients with population-based NHMA from a previous Danish study were used for comparison.

We recruited 147 patients with FHM, 105 with SHM, and 362 with familial NHMA. FHM and SHM had similar aura and headache characteristics. Patients with FHM and SHM were more likely to experience two or more aura symptoms (100% vs. 31%, P < .0001), they more often had prolonged aura symptoms, they almost always had a headache associated with the aura (93% vs. 58%, P < .0001), and they more frequently had basilar-type symptoms (69% vs. 10%, P < .0001) than patients with population-based NHMA. Patients with familial NHMA were more likely to experience two or more aura symptoms than patients with population-based NHMA (61% vs. 32%, P < .0001). Within the subtypes of NHMA, patients with typical aura with migraine headache had an earlier age at onset (20 +/- 10 vs. 23 +/- 13 years, P= .044) and a higher co-occurrence of migraine without aura (43% vs. 22%, P= .002) than patients with typical aura with nonmigraine headache.

The present study proves that distinct subtypes of migraine with aura exist. It further underlines the phenotypic differences between the different subtypes of migraine with aura which likely are caused by different etiological mechanisms. In future studies FHM, SHM, and NHMA therefore should be analyzed as separate entities and patients with NHMA may be stratified by ICHD-2 subtype of NHMA.