CALCA and Headache: The correlation between headache or migraine and etiology related with nasal and paranasal structures is interesting when we consider the trigeminal-vascular system, formed by the presence of trigeminal fibers around important central nervous system vessels, and when stimulated they produce inflammatory affections in these vessels, mediated by a peptide related with calcitonin gene (GGRP) and P substance, causing headaches .29