1Department of Psychiatry and Behavioral Sciences and Department of Rehabilitation Medicine, University of Washington School of Medicine, 1959 NE Pacific St., Room BB1517a, Box 356560, Seattle, WA 98195-6560, USA
2John and Emma Bonica Professor of Anesthesiology & Pain Research, Department of Anesthesiology, University of Washington School of Medicine, Seattle, WA, USA
*Corresponding author. Tel.: +1 206 543 3997; fax:+1 206 685 1139.
☆The authors have no financial or other relationships that might lead to a conflict of interest.