1. Nashville Neuroscience Group, PC, and Vanderbilt University School of Medicine, Nashville, TN
2. Sjolyst Medical Centre, Oslo, Norway
3. Helsinki Headache Centre, Helsinki, Finland
4. Headache Care Center, Springfield, MO
5. The City of London Migraine Clinic, London
6. Thomas Jefferson University Hospital, Philadelphia, PA, USA
7. Vernalis Development Ltd, Winnersh, UK