1. From the Neurology Department (R.B., A.D.), Montpellier University Hospital, France
2. Neurology Department, Nantes University Hospital, France (S.d.G.)
3. Department of Medical Information (C.D., G.M.), Montpellier University Hospital, France
4. Emergency Headache Centre (J.M., C.B., C.R., U.F.), Lariboisière Hospital, Assistance Publique–Hôpitaux de Paris, France.
5. Neurology Department (M.-G.B.), Lariboisière Hospital, Assistance Publique–Hôpitaux de Paris, France.