In order to understand the nature of the relationship between cerebral blood flow (CBF) and primary
headaches, we have conducted a literature review with particular emphasis on the role of perivascular
neurotransmitters. Primary
headaches are in general considered complex polygenic
disorders (genetic and environmental influence) with pathophysiological neurovascular alterations. Identified candidate
headache genes are associated with neuro- and gliogenesis, vascular development and diseases, and regulation of vascular tone. These findings support a role for the vasculature in
primary headache disorders. Moreover, neuronal hyperexcitability and other abnormalities have been observed in primary
headaches and related to changes in hemodynamic factors. In particular, this relates to
migraine aura and spreading depression. During
headache attacks, ganglia such as trigeminal and sphenopalatine (located outside the blood-brain barrier) are variably activated and sensitized which gives rise to vasoactive
neurotransmitter release. Sympathetic, parasympathetic and sensory nerves to the cerebral vasculature are activated. During
migraine attacks, altered CBF has been observed in brain regions such as the somatosensory cortex, brainstem and thalamus. In regulation of CBF, the individual roles of
neurotransmitters are partly known, but much needs to be unraveled with respect to
headache disorders.