1. Department of Neurology, Vanadzor Medical Center, Vanadzor, Armenia
2. Department of Neurology, Erebouni Medical Center, Yerevan, Armenia
3. Danish Headache Center, Department of Neurology, Rigshospitalet-Glostrup, Faculty of Health and Medical Sciences, University of Copenhagen, Glostrup, Denmark
4. Department of Neurology and Neurosurgery, Avdalbekyan National Institute of Health, Yerevan, Armenia, Somnus Neurology Clinic, Yerevan, Armenia