Sciatic Block in Contralateral Limb Phantom and Residual Limb Pain

Sciatic Block in Contralateral Limb for Treatment of Refractory Phantom and Residual Limb Pain; a Triple-Blind Randomized Crossover Controlled Trial

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.

Inclusion Criteria:

• 1. Age greater than 18 years of age at day of enrollment
• 2. Lower extremity amputation performed more than 12 months before study enrollment
• 3. PLP/RLP in affected amputated limb > 4 on numeric rating scale 26 (NRS26)
• 4. Pain duration of more than 6 months despite a trial of conservative therapies for at least 2 months, including oral medications, topical medicines, physical therapy, and physical modalities (i.e., heat, cold, transcutaneous electrical nerve stimulation, phonophoresis)
• 5. Willingness to undergo image guided diagnostic nerve block

Exclusion Criteria:

• 1. Refusal / inability to participate or provide consent
• 2. Contraindications to diagnostic nerve block
• 3. Non-neurogenic source of PLP/RLP
• 4. Current opioid use > 50 morphine milligram equivalents per day
• 5. Any interventional pain treatment in the residual limb within the last 30 days
• 6. Severe uncontrolled medical condition (i.e., hypertensive crisis, decompensated hypothyroidism)
• 7. Use of investigational pain drug within past 30 days or other concurrent clinical trial enrollment