[1] Urals State Med Univ, Dept Neurol & Neurosurg, Ekaterinburg, Russia
[2] Europe Asia Int Headache Ctr, Ekaterinburg, Russia
[3] New Hosp Med Union, Ekaterinburg, Russia
[4] Urals Fed Univ, Grad Sch Econ & Management, Dept Econometr & Stat, Ekaterinburg, Russia
[5] Univ Copenhagen, Glostrup Hosp, Dept Neurol, Danish Headache Ctr, Copenhagen, Denmark