Can the border of migraine with aura be safely extended?

We read with interest the article ‘Variability of clinical features in attacks of migraine with aura’ by Hansen et al. (1). The authors presented evidence that the clinical features of migrainous aura could vary ‘both among patients, and between attacks in an individual patient’, particularly if examined prospectively (1). Migraine with aura is a disorder codified in the ICHD-III beta version (2). Although the aura phenomenon is easily recognized by patients with chronic migraine with aura, the modification of its usual features, such as an increase in duration and/or frequency or the onset of new symptoms, particularly in patients with isolated visual disturbance, could provoke anxiety and result in presentation to an emergency department. These conditions are not dangerous in most patients, although ambiguous situations may occur with the subsequent risk of considering a potentially serious disorder as trivial.

A 41-year-old man had experienced attacks of migraine with aura from a young age, with a mean frequency of three to six attacks each year. The aura was characterized by visual disturbance followed by ascending paraesthesia limited to his right arm. As a consequence of the increasing frequency of his attacks, brain magnetic resonance imaging (MRI) was performed with normal results (Figure 1a and 1b). Two years later he experienced a prolonged aura affecting both his right limbs, which was followed by his usual headache. Brain MRI performed in the emergency department showed the presence of a cortical–subcortical haemorrhage in the left posterior parietal lobe (Figure 1c and 1d). In this patient, the extension of the sensory aura and the prolonged duration of the symptoms were considered to be suspicious and led to further investigations, resulting in the correct diagnosis.

Figure 1.

Brain MRI scans. (a) Axial fluid attenuated inversion recovery (FLAIR) image showing a normal result. (b) Coronal brain MRI T2-weighted image showing a normal result. (c) Axial FLAIR image showing a haemorrhage in the left parietal region. (d) Coronal T1-weighted image showing a haemorrhage in the left parietal region.

The suspicion of a possible symptomatic aura is essentially based on the availability of restricted diagnostic criteria for the definition of aura (2). However, recent papers on large series of patients (1,3–5) have documented the possibility of a qualitative and/or quantitative extension of the broad definition of the typical manifestations of aura. In particular, this could include: an increase in the frequency of aura; an extension in the duration of the symptoms (>60 minutes); onset at an older age; a change in the visual phenomena in the same patient during different attacks or during the same attack; or a high variability in the time relationship among aura symptoms or aura and the onset of headache.

If these features, some of them previously considered as red flags, are included in the definition of typical aura, then symptomatic patients will be more difficult to detect and, consequently, the elements that lead to the suspicion of a supervened secondary pathology should be fully revised. The extension of the diagnostic criteria for typical aura could undoubtedly reduce the requests for unnecessary diagnostic procedures, but, at the same time, could increase the risk of an under diagnosis of symptomatic patients, who are rare, but not exceptional. Therefore a possible modification of the diagnostic criteria requires a careful evaluation of risks and benefits and further studies are needed to determine which clinical features should be considered as red flags of a symptomatic aura.