Calcitonin gene-related peptide in cervicogenic headache.

Trigeminovascular activation is involved in the pathophysiology of migraine and cluster headache. The marker evaluated best for trigeminovascular activation is calcitonin gene-related peptide (CGRP) in the cranial circulation. It is unknown whether trigeminovascular activation plays any role in cervicogenic headache (CEH). The objective of this study was to investigate CGRP plasma levels in CEH patients in relation to headache state. To compare plasma CGRP levels between the peripheral and the cranial circulation. Blood from both external jugular veins and from the antecubital vein was drawn from 11 patients with CEH. Plasma CGRP levels were measured by radioimmunoassay. No difference was found between CGRP levels assessed on days with and without headache. There was no difference between CGRP levels from the symptomatic and the asymptomatic external jugular vein and the antecubital vein. There is no evidence for an activation of the trigeminovascular system in CEH. In certain cases, clinical differentiation between CEH and migraine without aura is difficult. Plasma CGRP levels might serve as a biological marker to distinguish the two headache entities.