Continuous postoperative regional analgesia by nerve sheath block for amputation surgery--a pilot study. A pilot study of continuous postoperative regional analgesia by nerve sheath block for lower limb amputation is presented. At the time of exposure of sciatic or posterior tibial nerve trunks during above- or below-knee amputations in 11 patients with ASA physical status III or IV, a catheter was introduced directly into the transected nerve sheath for continuous infusion of 0.25% bupivacaine at a rate of 10 mL/h for 72 h. Effective amputation stump analgesia was obtained, significantly reducing the need for on-demand narcotic analgesics during this time to a mean dose equivalent of 1.4 mg of morphine compared with a retrospective control group who received the equivalent of a mean dose of 18.4 mg of morphine (P less than 0.0001). No complications related to the technique were observed. A follow-up of the group receiving continuous postoperative regional analgesia for up to 12 mo showed a total absence of phantom pain despite the presence of preoperative limb pain. 