Asghar and collaborators35 examined the diameter of extracranial and intracranial vessels in subjects suffering from migraine without aura, seeking to avoid a premature dismissal of vascular mechanisms. A novel high-resolution direct MRA imaging technique was used to measure arterial circumference of the extracranial
MMA and the intracranial middle cerebral artery (MCA). The study found dilation of both MMA and MCA during migraine attack. Sumatriptan administration caused amelioration of headache and contraction of MMA, but the MCA remained unchanged. Exploratory analysis revealed www.selleckchem.com/p38-MAPK.html that in attacks with unilateral headache, there was only dilation of the ipsilateral Selleckchem CP673451 and no dilation of the contralateral MMA and of the MCA. In bilateral headache, bilateral vasodilation of both MMA and MCA became apparent. These data suggest that migraine without aura is accompanied by dilation of extracerebral and intracerebral arteries and that the headache location correlates with the location of the vasodilation. Furthermore, contraction of extracerebral, and not intracerebral arteries, is associated with amelioration of headache. Taken together,
these observations support a role for vasodilation and potential perivascular release of vasoactive substances in migraine generation. Functional Correlates.— With improved neurophysiological and functional MCE公司 imaging techniques, it became evident that migraine is associated with distinct patterns of neuronal and glial activation.36 The correct interpretation of imaging data, however, relies on distinguishing the signal alterations induced by migraine from those of a general pain response. One way of achieving this is to compare areas of activation and deactivation present during the migraine attack, to signal changes occurring after effective abortive therapy.7 The areas responsible for pain are expected to change following
effective therapy. Persistence of hyperactivity in an area represents evidence in favor of its role as a migraine-triggering site (see Table 2 for a list of neuroimaging findings during migraine attack). In several studies after sumatriptan administration, for example, the dorsal pons remained activated.37-39 An important early PET study from Weiller and collaborators39 demonstrated specific changes in blood flow during migraine attacks that do not follow a neurovascular distribution and are distinct from the patterns of blood flow seen during other primary headache disorders. Increased blood flow was found during spontaneous attacks in the brainstem and in the cingulate, auditory, and visual association cortices. Only contalateral brainstem activation, however, persisted after sumatriptan injection had induced complete relief from headache and phonophobia and photophobia.