The main procedure for the measurement of diffuse noxious inhibitory controls (DNIC) function. A. On the Ashi-point of the knee, a 180-g von Frey filament is used to prick three to five times within a 1-cm-diameter circle at an angle of 45-degrees between the filament and the skin. The patients will be asked to rate the intensity of pain as VAS1. B.The patients will be asked to immerse the contralateral hand, including the wrist, into nociceptive cold water (10 to 12°C) for 1 minute, and the doctors will rate the intensity of the 180-g von Frey filament-induced pain at the Ashi-point as VAS2. DNIC = (VAS1-VAS2)/VAS1.