[The window into headache research : what have we learned from functional and structural neuroimaging].

Current functional neuroimaging studies in headache patients have demonstrated that changes in vascular function are not the primary cause for the pain in migraine. Especially in headache research, functional imaging revealed for the first time important information on the pathophysiology of idiopathic syndromes beyond mere anatomical attribution. Several independent studies have reinforced the crucial role of the brainstem in migraine resulting in primary dysfunction of the endogenous antinociceptive systems, including the periaqueductal grey and the dorsal raphe nucleus (DRN) in the midbrain as well as areas involved in the neuronal regulation of cerebral blood flow (DRN and locus coeruleus). The hypothalamus on the other hand is involved in the fundamental processes leading to the acute attacks of cluster headache. These data have been repeatedly replicated by several groups and led to a new understanding of the pathophysiology of these syndromes and specifically the central role of the brain. The recent studies investigating the structural changes in migraine, chronic tension-type headache and cluster headache are not yet clear in their relevance but raise important questions and promise increasing knowledge of one of the most frequent symptoms in humans.