Sensory nerves in the human cerebral circulation and trigeminal ganglion: role in primary headaches

Our knowledge of the nervous control of cerebral circulation has increased by the use of denervations and retrograde tracing in combination with immunohistochemical techniques. We have demonstrated that cerebral vessels are supplied with sensory nerve fibers containing a multiplicity of transmitter substances originating in the trigeminal ganglion. The majority of these transmitters are neuropeptides, but the gaseous signal substance, nitric oxide (NO), is also included. In primar headaches, calcitonin generelated peptide (CGRP) is released in parallel with the headache, while the parasympathetic nerve transmitter vasoactive intestinal peptide (VIP) is released in parallel with facial symptoms. Thus, the perivascular nerves participate in the pathogenesis of primary headaches. Current migraine drugs, e. g. triptans, act in part by inhibiting the release of CGRP from the sensory nerves.