aDepartment of Neurology, Danish Headache Center, Rigshospitalet Glostrup, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
bDepartment of Neurology, Albert Einstein College of Medicine, New York, NY, United States
cDepartments of Neurology and Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States
*Corresponding author. Danish Headache Center, Department of Neurology, University of Copenhagen, Rigshospitalet-Glostrup, Valdemar Hansens Vej 5, 2600 Glostrup, Denmark. Tel.: +45 3863 2062. Address: E-mail address: [email protected] (H.W. Schytz).
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H.M. Al-Khazali and H. Ashina contributed equally to this work.