C J Schankin1, F Puledda2,3, P J Goadsby2,3. 1. Department of Neurology, Inselspital, University Hospital Bern, University of Bern, Bern, Switzerland. 2. Headache Group, Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK. 3. NIHR-Wellcome Trust King's Clinical Research Facility, SLaM Biomedical Research Center, King's College London, London, UK.