• Brian M Ilfeld, Bahareh Khatibi, Kamal Maheshwari, Sarah J Madison, EsaWael Ali SakrWASOutcomes Research Consortium, Cleveland, OH, United States.Departments of General Anesthesia and Outcomes Research, the Cleveland Clinic, Cleveland, OH, United States., Edward R Mariano, Michael L Kent, Steven Hanling, Daniel I Sessler, James C Eisenach, Steven P Cohen, Edward J Mascha, Chao Ma, Jennifer A Padwal, Alparslan Turan, and PAINfRE Investigators.
• Department of Anesthesiology, University of California San Diego, San Diego, CA, United States.
• Pain. 2021 Mar 1; 162 (3): 938955938-955.

AbstractPhantom limb pain is thought to be sustained by reentrant neural pathways, which provoke dysfunctional reorganization in the somatosensory cortex. We hypothesized that disrupting reentrant pathways with a 6-day-long continuous peripheral nerve block reduces phantom pain 4 weeks after treatment. We enrolled patients who had an upper- or lower-limb amputation and established phantom pain. Each was randomized to receive a 6-day perineural infusion of either ropivacaine or normal saline. The primary outcome was the average phantom pain severity as measured with a Numeric Rating Scale (0-10) at 4 weeks, after which an optional crossover treatment was offered within the following 0 to 12 weeks. Pretreatment pain scores were similar in both groups, with a median (interquartile range) of 5.0 (4.0, 7.0) for each. After 4 weeks, average phantom limb pain intensity was a mean (SD) of 3.0 (2.9) in patients given local anesthetic vs 4.5 (2.6) in those given placebo (difference [95% confidence interval] 1.3 [0.4, 2.2], P = 0.003). Patients given local anesthetic had improved global impression of change and less pain-induced physical and emotional dysfunction, but did not differ on depression scores. For subjects who received only the first infusion (no self-selected crossover), the median decrease in phantom limb pain at 6 months for treated subjects was 3.0 (0, 5.0) vs 1.5 (0, 5.0) for the placebo group; there seemed to be little residual benefit at 12 months. We conclude that a 6-day continuous peripheral nerve block reduces phantom limb pain as well as physical and emotional dysfunction for at least 1 month.Copyright © 2020 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the International Association for the Study of Pain.

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