Abstract

BACKGROUND: Post-amputation phantom pain is notoriously persistent with few validated treatments. Cryoneurolysis involves the application of low temperatures to reversibly ablate peripheral nerves. We tested the hypothesis that a single cryoneurolysis treatment would decrease phantom pain 4 months later.METHODS: We enrolled patients with a lower-limb amputation and established phantom pain. Each received a single-injection femoral and sciatic nerve block with lidocaine and was subsequently randomized to receive either ultrasound-guided percutaneous cryoneurolysis or sham treatment at these same locations. The primary outcome was the change in average phantom pain intensity between baseline and 4 months as measured with a Numeric Rating Scale (0-10), after which an optional crossover treatment was offered. Investigators, participants, and clinical staff were masked to treatment group assignment with the exception of the treating physician performing the cryoneurolysis who had no subsequent participant interaction.RESULTS: Pretreatment phantom pain scores were similar in both groups, with a median [quartiles] of 5.0 [4.0, 6.0] for active treatment and 5.0 [4.0, 7.0] for sham. After 4 months, pain intensity decreased by 0.5 [-0.5, 3.0] in patients given cryoneurolysis (n=71) versus 0 [0, 3] in patients given sham (n=73): estimated difference (95% CI) -0.1 (-1.0, 0.7), P=0.759. Following our statistical gatekeeping protocol, we did not make inferences or draw conclusions on secondary endpoints. One serious adverse event occurred following a protocol deviation in which a femoral nerve cryolesion was induced just below the inguinal ligament-instead of the sensory-only saphenous nerve-which resulted in quadriceps weakness, and possibly a fall and clavicle fracture.DISCUSSION: Percutaneous cryoneurolysis did not decrease chronic lower extremity phantom limb pain 4 months following treatment. However, these results were based upon our specific study protocol; and since the optimal cryoneurolysis treatment parameters such as freeze duration and anatomic treatment location remain unknown, further research is warranted.

View details for DOI 10.1097/ALN.0000000000004429

View details for PubMedID 36512721