1. Headache Group, Department of Basic and Clinical Neurosciences, King's College London, London, UK
2. Neurocenter of Southern Switzerland, Neurology clinic, Headache Center, Lugano, Switzerland
3. Headache Science Center, IRCCS Mondino Foundation, Pavia, Italy
4. Department of Pharmaceutical Sciences, University of Piemonte Orientale, Novara, Italy
5. Faculty of biomedical Sciences, Università della Svizzera Italiana, Lugano, Switzerland
6. NIHR-Wellcome Trust Clinical Research Facility, King's College Hospital, London, UK
7. Department of Brain and Behavioural Sciences, University of Pavia, Pavia, Italy