1. Department of Neurology; New York University School of Medicine; NYU Langone Medical Center and NYU Lutheran Headache Center; New York NY USA
2. Danish Headache Center; Department of Neurology; University of Copenhagen; Rigshospitalet Glostrup; Glostrup Denmark
3. Department of Neurology; Albert Einstein College of Medicine and Montefiore Headache Center; Bronx NY USA
4. Unit for Quality and Patient Safety; Capital Region of Denmark; Copenhagen Denmark