[1] Pfizer Inc, New York, NY 10017 USA
[2] Pfizer Ltd, Tadworth, Surrey, England
[3] Pfizer Global Res & Dev, Sandwich, Kent, England
[4] Univ Glasgow, Pain Clin Gartnavel Gen Hosp, Glasgow G12 8QQ, Lanark, Scotland
[5] Univ Calgary, Hotchkiss Brain Inst, Dept Clin Neurosci, Calgary, AB, Canada
[6] Aarhus Univ Hosp, Dept Neurol, Danish Pain Res Ctr, DK-8000 Aarhus, Denmark
[7] Amphia Hosp, Pain Clin, Breda, Netherlands