1. Emergency Headache Center, Department of Neurology, GH Saint-Louis-Lariboisière, Assistance Publique des Hôpitaux de Paris APHP, Université Paris Denis Diderot and DHU NeuroVasc Sorbonne Paris-Cité; Paris France (J. Mawet)
2. Institut National de la Santé et de la Recherche Médicale (INSERM) U897 Epidemiology and Biostatistics and Department of Neurology, Bordeaux University Hospital; Bordeaux France (S. Debette)
3. Department of Neurology; GH Saint-Louis-Lariboisière, Assistance Publique des Hôpitaux de Paris APHP, Université Paris Denis Diderot and DHU NeuroVasc Sorbonne Paris-Cité; Paris France (M.-G. Bousser)
4. Department of Neurology; Montpellier University Hospital and Montpellier University; Montpellier France (A. Ducros)