2631-2581 2631-2581 S2631-25812020000100173 Portugal 00 04 2020 00 04 2020 29 1 173 174 Headache Classification Committee of the International Headache Society (IHS) 2018 38 1 1 1-211 2012 32 649-53 2017 18 1 1 9-19 2006 26 1234-7