CALCA and migraine disorder: Edvinsson et al. (44) recently examined the relationship between those neurons in the trigeminal ganglion expressing CGRP in unmyelinated sensory C-fibers and CGRP receptors found on myelinated Aδ sensory fibers, as it had been theorized that anti-migraine drugs might act to prevent CGRP binding to trigeminal Aδ-fibers in the periphery.