1. Danish Headache Centre; Department of Neurology; Rigshospitalet Glostrup; University of Copenhagen; Glostrup Copenhagen Denmark
2. Department of Neurology; Headache Program; Mount Sinai Beth Israel; Icahn School of Medicine at Mount Sinai; New York NY USA
3. Pain Research and Nuffield Division of Anaesthetics; University of Oxford; The Churchill; Oxford UK
4. Department of Neuroscience; Norwegian University of Science and Technology; Trondheim Norway
5. Division of Brain Sciences; Imperial College London; UK