1. Headache Group-Department of Neurology, University of California, San Francisco, San Francisco, CA, USA
2. Department of Oral and Maxillofacial Pathology, Radiology and Medicine, New York University College of Dentistry, New York, NY, USA
3. Department of Neural and Pain Sciences, University of Maryland Baltimore, Baltimore, Maryland, MD, USA
4. Headache Group, Department of Basic and Clinical Neuroscience, Institute of Psychology, Psychiatry and Neuroscience, King’s College London, London, UK
5. NIHR-Wellcome Trust King’s Clinical Research Facility, King’s College Hospital, London, UK