Sciatic Block in Contralateral Limb Phantom and Residual Limb Pain

Participants with chronic, refractory phantom limb pain (PLP) or residual limb pain (RLP) for more than 6 months will be enrolled in this clinical trial. Aim: Define the attributable pain relief and functional improvement in participants with PLP/RLP after contralateral limb sciatic nerve block. Also, contribute to the basic science understanding of the crossed-withdraw reflex by demonstrating a known animal model phenomenon in human participants. Hypothesis: Contralateral limb sciatic nerve anesthetic block with 2% lidocaine provides immediate clinically meaningful pain reduction, defined as the proportion of patients with at least 50% improvement in numeric rating scale (NRS) pain score in PLP/RLP when compared to sham.