1. Department of Neurology Rutgers Robert Wood Johnson Medical School New Brunswick New Jersey USA
2. Department of Neuroscience University of Pittsburgh Pittsburgh Pennsylvania USA
3. Department of Neurological Sciences University of Vermont Larner College of Medicine Burlington Vermont USA
4. Department of Neurology, Danish Headache Center Copenhagen University Hospital—Rigshospitalet Copenhagen Denmark
5. Danish Knowledge Center on Headache Disorders Glostrup Denmark
6. Department of Clinical Medicine, Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark