[1] Univ Essen Gesamthsch, Dept Neurol, DE-45147 Essen, Germany
[2] Bayer Vital GmbH, Cologne, Germany
[3] Pain Clin, Kiel, Germany
[4] Michael Balint Clin, Konigsfeld, Germany
[5] Bayer AG, D-5090 Leverkusen, Germany
[6] Univ Regensburg, Dept Neurol, D-8400 Regensburg, Germany
[7] Pain Relief Ctr, Goppingen, Germany