Redefining types of migraine aura

To the Editor:

We read with great interest the invitation by the Headache Classification Committee leadership to comment on ICHD-3 (1) and suggest changes that will improve the future ICHD-4. While discussions about criteria for the distinction between episodic and chronic migraine or criteria for the duration of the prodrome phase are a “hot topic” among Society members, abundant heterogeneous symptoms during migraine aura (2–4) seem to be unspecified and neglected in the current ICHD-3. Also, terminology in some cases could be misleading.

For instance, one of the criteria for typical aura is reporting “sensory symptoms”, referring to pins and needles sensations or numbness that affect a greater or smaller part of one side of the body, face and/or tongue. Knowing that the term “sensory” represents sensory systems, such as visual, tactile or vestibular, using that term only for tactile sensations can lead to unclear terminology. For the reason of better clarity, we suggest that the term “sensory” should be replaced with the term “somatosensory”.

Further, criteria for migraine with typical aura include only speech/language symptoms, besides visual and somatosensory symptoms, although more than half of patients also report other higher cortical dysfunctions (HCD) during the aura (2–6), such as memory disturbances, prosopagnosia, dyscalculia, manual dyspraxia, etc. Therefore, we suggest that the term “speech/language symptoms” should be replaced with the term “higher cortical disturbances” or “symptoms of higher cortical dysfunction”. Moreover, we found that patients who suffer from migraine with typical aura accompanied by symptoms of HCD, with regards to those without HCD, exhibit differences in cerebral cortical morphology and thickness (7), white matter integrity (8), and detection of interictal microembolic signals in the middle cerebral artery (9). These specific structural and cerebrovascular findings may either be associated with an increased propensity to experience disturbances of higher cortical functions during the aura or be the consequence of this clinical phenotype. All the above are questioning whether these two subgroups of patients should be classified as one group labeled as migraine with typical aura or the current diagnostic criteria and classification should be modified. The answer to this question is important because identifying subtypes of migraine with typical aura might lead to more individualized therapy (10). Hereby, we invite Society members to discuss and test this hypothesis.

Finally, the proper classification of patients who have migraine with typical aura could be achieved with the recently proposed Migraine Aura Complexity Score (11). Moreover, the score could be used in neuroimaging or clinical studies to better achieve a stratification and homogenization of patients who have migraine with aura (12).