CALCA and Headache: Meanwhile, in a retrospective study of 112 adolescents (mean age:15.9 yrs) with refractory chronic headache disorders (83.9% CM), treated with an anti-CGRP/rec mAb (86.6% erenumab), 30% had a “significant benefit” defined as \documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\ge$$\end{document}≥ one third reduction in headache frequency, intensity or duration for at least 1 month, and 40% had “some benefit”.