Peripheral Nerve Blocks as a Predictor of Nerve Reconstruction Success After Major Limb Amputation

Postamputation pain is a spectrum of debilitating sensations that impacts millions of people in the United States. While the development of postamputation pain, including phantom limb pain (PLP), is multifactorial, it has been associated with disorganized axonal sprouting, resulting in a neuroma and subsequent central nervous system changes. Nerve reconstruction surgeries, such as regenerative peripheral nerve interface (RPNI) and targeted muscle reinnervation (TMR), provide transected nerve fibers with proper target organs for reinnervation and have been shown to significantly reduce PLP. This case series aims to describe perioperative peripheral nerve blocks as a diagnostic tool for identifying patients who would benefit from RPNI or TMR. We conducted a retrospective search of patients who underwent major extremity amputation and who received a diagnostic peripheral nerve block before undergoing reconstructive nerve surgery (TMR and/or RPNI). Six patients (58-80 years old) with below-knee amputations (BKA) were examined. All patients experienced a reduction in postamputation pain (PAP), specifically PLP, after a diagnostic peripheral nerve block (PNB). The average time between amputation and revision surgery was approximately two years (Mean: 22.35 months). Following surgical intervention, all patients reported a reduction in PLP episodes after nerve reconstruction surgery. Two patients no longer reported PLP. Ambulation rates also improved following revision (50% vs 83%). PNBs can be used as an effective diagnostic tool to identify patients that will significantly benefit from amputation revisions with TMR or RPNI.