[1] Copenhagen Univ Hosp, Rigshospitalet, Danish Headache Ctr, Dept Neurol, Copenhagen, Denmark
[2] Danish Knowledge Ctr Headache Disorders, Glostrup, Denmark
[3] Univ Copenhagen, Fac Hlth & Med Sci, Dept Clin Med, Copenhagen, Denmark
[4] Inst Psychiat, Wolfson Ctr Age Related Dis, Psychol & Neurosci, London, England
[5] Kings Coll Hosp London, NIHRWellcome Trust Kings Clin Res Facil, SLaM Biomed Res Ctr, London, England
[6] Harvard Med Sch, Beth Israel Deaconess Med Ctr, Dept Anaesthesia Crit Care & Pain Med, Boston, MA 02115 USA
[7] Copenhagen Univ Hosp, Dept Brain & Spinal Cord Injury, Rigshosp, Copenhagen, Denmark
[8] Univ Otago, Dept Pharmacol & Toxicol, Dunedin, New Zealand
[9] Harvard Med Sch, BIDMC Comprehens Headache Ctr, Beth Israel Deaconess Med Ctr, Dept Neurol, Boston, MA USA
[10] Harvard Med Sch, Beth Israel Deaconess Med Ctr, Dept Anesthesia Crit Care & Pain Med, Boston, MA USA
[11] Univ Puerto Rico Med Sci Campus, San Juan, PR USA
[12] Univ Pavia, Dept Brain & Behav Sci, Pavia, Italy
[13] IRCCS Mondino Fdn, Headache Sci & Neurorehabil Ctr, Pavia, Italy
[14] Mayo Clin, Dept Neurol, Scottsdale, AZ USA
[15] Univ Copenhagen, Fac Hlth & Med Sci, Danish Headache Ctr, Dept Neurol,Rigshospitalet Glostrup, Valdemar Hansen Vej 5, DK-2600 Glostrup, Denmark