The Responses to CGRP in the Territory of the Posterior Cerebral Artery in Migraine

Abstract

Calcitonin gene-related peptide (CGRP) is important in trigeminovascular (TMV) sensitization with neurogenic inflammation which might be involved in CGRP-induced headache (CGRP-IH). Distribution of white matter lesions, migraine aura, and functional neuroimaging indicate that posterior circulation is especially exposed to TMV sensitization. The transcranial Doppler (TCD) is able to detect changes in the posterior cerebral artery (PCA) during CGRP stimulation. Thus, we studied CGRP-induced hemodynamic changes in PCA and frequency of CGRP-IH. Twenty healthy subjects and 20 patients with migraine participated in our study. TCD was used to monitor mean arterial velocity in posterior cerebral artery (vmPCA). Simultaneously, end-tidal carbon dioxide (Et-CO2), mean arterial pressure (MAP), and heart rate (HR) were measured. During the experiment, we monitored the frequency of CGRP-IH. We determined the values of vmPCA, Et-CO2, MAP, and HR and calculate the response of vmPCA, Et-CO2, MAP, and HR to CGRP. To test the differences and relationships, statistical methods were applied using SSPS. We found significant decrease in vmPCA in migraine and control groups and found the vmPCA response to be significantly lower in migraine ( $p=0.018$ ). Et-CO2 decreases in both groups, and it is significantly lower in migraine ( $p<0.001$ ). MAP is significantly higher in migraine ( $p=0.001$ ), while HR is not significantly higher in migraine ( $p=0.570$ ). CGRP-IH is significantly associated with vmPCA responses ( $p=0.003$ ) and migraine ( $p<0.001$ ). We concluded that hemodynamic changes in PCA are significantly related to CGRP-IH. The TMV sensitization might be pronounced in posterior circulation explaining clinical and morphologic issues in migraine.