American Society for Peripheral Nerve

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Targeted Muscle Reinnervation Treats Neuroma and Phantom Limb Pain in Major Limb Amputees: A Randomized Clinical Trial
Gregory A Dumanian, MD1; Benjamin K Potter, MD2; Lauren Mioton, MD3; Jennifer E. Cheesborough, MD4; Jason M. Souza, MD2; Sumanas W Jordan, MD, PhD1; William J Ertl, MD, PhD5; Scott M Tintle, MD6; George P. Nanos, MD7; Ian L. Valerio, MD, MS, MBA8; Vania Apkarian, PhD9; Jason H Ko, MD10
1Northwestern University, Chicago, IL, 2Walter Reed National Military Medical Center, Bethesda, MD, 3Northwestern Memorial Hospital, Chicago, IL, 4Division of Plastic Surgery, Northwestern University, Chicago, IL, 5University of Oklahoma Medical Center, Oklahoma City, OK, 6Walter Reed National Medical Center, Bethesda, MD, 7Department of Orthopaedics, Walter Reed National Military Medical Center, Bethesda, MD, 8Department of Plastic Surgery, Ohio State University Wexner Medical Center, Columbus, OH, 9Northwestern University, Chicago, IL, 10Division of Plastic and Reconstructive Surgery, Northwestern University, Chicago, IL

Introduction: A majority of amputees suffer from pain isolated to the residual limb or pain perceived in the missing limb, known as phantom limb pain. End-neuromas are the leading cause of residual limb pain while the etiology of phantom limb pain is more complex. There are many surgical treatments for end-neuromas in the literature, highlighting the fact that no single treatment consistently works. Targeted Muscle Reinnervation (TMR) is a surgical procedure first developed to improve prosthesis control by transferring cut nerve endings to otherwise redundant motor nerves. It was incidentally found that patients undergoing TMR also had improvement in pain post-operatively. In this randomized clinical trial, we compare TMR as a treatment option for amputee-related pain to the current standard treatment for end-neuromas, which entails neurectomy and muscle-burying.

Materials and Methods: 28 major limb amputees suffering from neuroma-related pain were randomized to either standard therapy (14 patients, 15 limbs) or Targeted Muscle Reinnervation (14 patients, 15 limbs) across two sites. Pre-operative and post-operative residual limb and phantom limb pain outcomes were assessed using an eleven-point Numerical Rating Scale.

Results: At one-year post-surgery there was a greater reduction in phantom pain for patients receiving TMR compared to those receiving standard of care, [mean (adjusted CI) for difference in change scores = 3.4 (-0.1, 6.9), adjusted p = 0.060]. Specifically, the average change (SD) in phantom pain from pre-op to post-op was 3.2 (2.9) in the TMR cohort and -0.2 (4.9) in the standard group. In longitudinal mixed model analysis, the difference in change scores at one-year post-surgery was significantly greater in the TMR arm compared to standard care [mean (adjusted CI) = 3.5 (0.6, 6.3), adjusted p = 0.035]. There was a trend toward a greater decrease in average residual limb pain in the TMR group [mean (adjusted CI) for difference in change scores = 1.9 (-0.5, 4.4), adjusted p = 0.15]. The average change (SD) in residual limb scores from pre-op to post-op was 2.9 (2.2) in the TMR group and 0.9 (3.3) in the standard group. The mixed model results for the group comparison at one year yielded similar results [mean (adjusted CI) = 2.1 (-0.3, 4.6), adjusted p = 0.10].

Conclusions: Results from this randomized clinical trial reveal that Targeted Muscle Reinnervation provides long-term improvement in phantom limb pain and residual limb pain in major limb amputees compared to standard therapy.

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