1 Department of Neurology, Dizziness and Vertigo Center Essen, West-German Headache Center, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
2 Center for Translational Neuro- and Behavioral Sciences, University of Duisburg-Essen, Essen, Germany.
3 Department of Neurology, Martin-Luther-University Halle-Wittenberg, Halle/Saale, Germany.
4 Department of Neurology, Weser-Egge Hospital Höxter, and University of Duisburg-Essen, Essen, Germany.