1. Department of Anesthesiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
2. Interdisciplinary Pain Center, Keio University Hospital, Tokyo 160-0016, Japan
3. Department of Neuropsychiatry, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
4. Department of Pain Medicine, Fukushima Medical University School of Medicine, Fukushima 960-1295, Japan