Relationship between serum levels of VIP, but not of CGRP, and cranial autonomic parasympathetic symptoms: A study in chronic migraine patients

Background Cranial autonomic parasympathetic symptoms (CAPS) appear in at least half of migraine patients theoretically as a result of the release of peptides by the trigemino-vascular system (TVS). Cranial pain pathways become sensitised by repeated episodes of TVS activation, leading to migraine chronification. Objective The objective of this article is to correlate the presence of CAPS with serum levels of vasoactive intestinal peptides (VIP) and calcitonin gene-related peptide (CGRP). Patients and methods Patients with chronic migraine (CM) were asked about the presence - during migraine attacks - of five CAPS, which were scored from 0 to 10 by using a quantitative scale. Serum VIP and CGRP levels were determined by ELISA. Results We interviewed 87 CM patients (82 females; mean age 44.710.6 years). Seventeen had no CAPS, while 70 reported at least one CAPS. VIP levels ranged from 20.8 to 668.2pg/ml (mean 154.5 +/- 123.2). There was a significant positive correlation between scores in the CAPS scale and VIP levels (Spearman correlation coefficient=0.227; p=0.035). VIP levels were significantly higher in CM patients by at least one point in the scale vs those with 0 points (p=0.002). Analysing symptoms individually, VIP levels were numerically higher in those patients with symptoms, though they were significantly higher only in those patients with lacrimation vs those without it (p=0.013). There was no significant correlation between CGRP levels and the score in the CAPS scale. Conclusions Serum VIP, but not CGRP, levels seem to reflect the rate of activation of the parasympathetic arm of the TVS in migraine.