P J Slotty1, G Bara2, L Kowatz2, A Gendolla3, C Wille4, S Schu2, J Vesper2. 1. Department of Functional Neurosurgery and Stereotaxy, Neurosurgical Clinic, Heinrich-Heine University Düsseldorf, Germany slotty@hhu.de. 2. Department of Functional Neurosurgery and Stereotaxy, Neurosurgical Clinic, Heinrich-Heine University Düsseldorf, Germany. 3. Headache and Pain Center, Germany. 4. Neurochirurgische Praxis-Klinik, Germany.