News on the pathomechanism of migraine: spreading depression, a vascular factor, and cortical excitability

Abstract

The mechanisms underlying headache, aura, and photophobia in migraine are still not fully understood, although migraine is the most prevalent neurological disorder and a lot of research has been done in that field. In 1944 the famous Brazilian physiologist A.A. Leao described spreading depression of activity in the cerebral cortex for the first time. Although this has been discussed for many decades as the underlying mechanism of the aura in migraine, it is still not clear how cortical spreading depression is related to headache. In the first study summarized in this month’s Journal Club, an activation of central trigeminovascular neurons by cortical spreading depression was found in rats. This elegantly links cortical spreading depression, aura, and headache in migraine. In the second article, a novel highresolution direct magnetic resonance angiography imaging technique was used to measure the arterial circumference of extracranial and intracranial arteries before and during a migraine attack. These data show that migraine without aura is associated with dilatation of extracranial and intracranial arteries and that contraction of extracerebral and not intracerebral arteries is associated with amelioration of headache by sumatriptan. In the third article, a PET study of photophobia during spontaneous migraine attacks, it is shown that ictal photophobia is linked with visual cortex hyperexcitability. All in all, these findings deepen our knowledge of the pathophysiology of migraine aura and headache in favor of cortical spreading depression. Finally, as a good introduction to the topic, in Table 1 an overview of the clinical features of migraine is given. Activation of central trigeminovascular neurons by cortical spreading depression