Abstract

Phantom 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 0-12 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 versus 4.5 (2.6) in those given placebo (difference (95% CI) 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 appeared 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.

View details for DOI 10.1097/j.pain.0000000000002087

View details for PubMedID 33021563