[1] Citadelle Hosp, Headache Res Unit, Neurol, CHU Liege, Liege, Belgium
[2] Rigshosp Glostrup, Danish Headache Ctr, Glostrup, Denmark
[3] Leiden Univ, Med Ctr, Leiden, Netherlands
[4] Kings Coll London, Headache Grp, London, England
[5] Sungkyunkwan Univ, Samsung Med Ctr, Sch Med, Seoul, South Korea
[6] Univ Essen Gesamthsch, Dept Neurol, Essen, Germany
[7] Mayo Clin, Dept Neurol, Scottsdale, AZ USA
[8] CHU Nice, Neurosurg, Nice, France
[9] UCL, Inst Neurol, London, England
[10] Univ Krankenhaus Eppendorf, Syst Neurosci, Hamburg, Germany
[11] Behaviorial Analyt, Vector Psychometr Grp, Chapel Hill, NC USA
[12] Dartmouth Hitchcock, Dept Neurol, Lebanon, NH USA