1. Headache Center Berlin at the Sankt Gertrauden Krankenhaus Berlin, Germany.
2. MEDAS Ostschweiz, Interdisciplinary Medicine, Kornhausstr. 3, 9000 St. Gallen, Switzerland.
3. Neurological Guided Pain Centre, Kiel, Germany.
4. Institute of Medical Psychology and Medical Sociology, Medical Faculty, University of Rostock, Germany.