The Migrainous Brain: What You See Is Not All You Get?

M igraine is an episodic brain disorder [1] that affects about 15 percent of the population [2,3]. The disorder can be highly disabling [4], and has been estimated to be the most costly neurological disorder in the European Community, costing more than 27 billion per year [5]. Two clinical forms are commonly seen: migraine with aura and migraine without aura [6]. Aura in this context is defi ned as a recurrent disorder manifesting in attacks of reversible focal neurological symptoms, usually developing gradually over a period of fi ve to 20 minutes and lasting for less than 60 minutes. These symptoms are typically visual [7], and are often described as bright jagged lines (fortifi cation spectra) that move across the visual fi eld, often followed by visual loss (scotoma). The phenomenon of migraine has been known since antiquity. Now there are new data on anatomical alterations in the visual motion-processing regions. Do these new data shed light on aura, or perhaps illuminate more basic principles about the migrainous brain? Is the traditional view—that the migrainous brain is structurally normal—incorrect? In a new study published in PLoS Medicine, Granziera and colleagues [8] used magnetic resonance imaging to perform high-resolution measurements of cortical thickness and diffusion tensor imaging to study the anatomy of the motion-processing network in patients with migraine and in healthy controls. The authors found signifi cant differences between patients and controls in MT+ and V3A, both motion-processing visual cortical regions [9]. These differences were seen both in patients who experienced migraine with aura and patients who experienced migraine without aura. These data need to be considered in the light of recent structural imaging suggesting, in a study of a random sample of patients with migraine, that those with aura may be particularly at risk for brain lesions on magnetic resonance imaging [10]. The data also need to be seen in the context of no detected change in voxel-based morphometry (a computational approach to neuroanatomy that measures differences in local concentrations of brain tissue) in the brains of patients with migraine [11]. However, voxel-based morphometry is probably not as sensitive as the technique used by Granziera and colleagues in their new study. The authors of the new study suggest that the fi ndings may be used as a biomarker. Certainly the fi ndings will not be useful as diagnostic tools, since they overlap with healthy controls, and it still remains …