Targeted muscle reinnervation and regenerative peripheral nerve interfaces for pain prophylaxis and treatment: A systematic review

Objective: Nerve pain frequently develops following amputations and peripheral nerve injuries. Two innovative surgical techniques, targeted muscle reinnervation (TMR) and regenerative peripheral nerve interfaces (RPNI), are rapidly gaining popularity as alternatives to traditional nerve management, but their effectiveness is unclear. Literature Survey: A review of literature pertaining to TMR and RPNI pain results was conducted. PubMed and MEDLINE electronic databases were queried. Methodology: Studies were included if pain outcomes were assessed after TMR or RPNI in the upper or lower extremity, both for prophylaxis performed at the time of amputation and for treatment of postamputation pain. Data were extracted for evaluation. Synthesis: Seventeen studies were included, with 14 evaluating TMR (366 patients) and three evaluating RPNI (75 patients). Of these, one study was a randomized controlled trial. Nine studies had a mean follow-up time of at least 1 year (range 4–27.6 months). For pain treatment, TMR and RPNI improved neuroma pain in 75%–100% of patients and phantom limb pain in 45%–80% of patients, averaging a 2.4–6.2-point reduction in pain scores on the numeric rating scale postoperatively. When TMR or RPNI was performed prophylactically, many patients reported no neuroma pain (48%–100%) or phantom limb pain (45%–87%) at time of follow-up. Six TMR studies reported Patient-Reported Outcomes Measurement Information System (PROMIS) scores assessing pain intensity, behavior, and interference, which consistently showed a benefit for all measures. Complication rates ranged from 13% to 31%, most frequently delayed wound healing. Conclusions: Both TMR and RPNI may be beneficial for preventing and treating pain originating from peripheral nerve dysfunction compared to traditional techniques. Randomized trials with longer term follow-up are needed to directly compare the effectiveness of TMR and RPNI with traditional nerve management techniques.