1. Department of Neurology, University Hospital, Gentofte, Denmark
2. Migraine Clinic, Koenigstein, West Germany
3. Hôpital d'Instruction des Armées Laveran, Marseille, France
4. Institut für Anaesthesiologie, Ludwig-Maximilians-Universität-München, Munich, West Germany
5. Department of Neurology, Oldchurch Hospital, Romford, Essex UK
6. Artzin für Anaesthesiologie, Heidelberg, West Germany