1. Headache Centre and Cerebrovascular Disease Department
2. Department of Neurology, Regensburg University, Regensburg, Germany
3. Department of Neurosurgery, Istituto Nazionale Neurologico Carlo Besta, Milano
4. Department of Neurology, Mayo Clinic, Scottsdale Arizona
5. The New England Center for Headache, Stamford, CT, USA
6. Institute of Neurology, The National Hospital for Neurology and Neurosurgery, London, UK
7. Neurology and Neuroanatomy, University of Liege, Headache Research Unit, CHR Citadelle, Liege, Belgium
8. Department of Neurology, University of Napoli, Napoli, Italy