American Society for Peripheral Nerve

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Targeted muscle reinnervation improves residual limb pain, phantom limb pain, and limb function: a prospective study of 35 amputated limbs
Lauren Mioton, MD1, Gregory A Dumanian, MD2, Nikita Shah, B.A.3, Cecil Qiu, BA3, William J Ertl, MD, PhD4, Benjamin K. Potter, MD5, Jason M Souza, MD, PhD5, Scott M Tintle, MD6, George P. Nanos, MD7, Ian L. Valerio, M.D., M.S., M.B.A.8, Todd Kuiken, MD, PhD9, Jason H Ko, MD10 and Sumanas Jordan, MD, PhD3, (1)Northwestern Memorial Hospital, Chicago, IL, (2)Northwestern University, Chicago, IL, (3)Northwestern University, chicago, IL, (4)University of Oklahoma Medical Center, Oklahoma City, OK, (5)Walter Reed National Military Medical Center, Bethesda, MD, (6)Walter Reed National Medical Center, Bethesda, MD, (7)Department of Orthopaedics, Walter Reed National Military Medical Center, Bethesda, MD, (8)Department of Plastic Surgery, Ohio State University Wexner Medical Center, Columbus, OH, (9)The Shirley Ryan Ability Lab, chicago, IL, (10)Division of Plastic and Reconstructive Surgery, Northwestern University, Chicago, IL

Background: Targeted muscle reinnervation (TMR) is an emerging surgical technique for the treatment of neuroma pain. Sensory and mixed motor nerves are transferred to nearby redundant motor nerve branches. TMR was recently shown in a randomized-controlled trial (RCT) to provide significant reductions in post amputation pain relative to conventional neuroma excision and muscle burying. This study analyzes patient-reported outcomes for a cohort of TMR patients screened but not randomized into the RCT.

Methods: Patients who were ineligible for randomization, or refused to be randomized, and underwent TMR for pain or prostheses control were assembled for the present analysis. Data were collected prospectively from 2013 to 2017. The primary outcomes measured were the difference in residual limb pain (RLP) and phantom limb pain (PLP) before and one year after surgery, assessed by an 11-point Numerical Rating Scale (NRS). Secondary outcomes measured were change in Patient Reported Outcome Measurement System (PROMIS) pain measures and change in limb function, assessed by the Orthotics Prosthetics User Survey with Rasch conversion (OPUS Rasch) for upper limbs and Neuro-Quality of Life (Neuro-QOL) for lower limbs before and 1 year after surgery.

Results: Thirty-three patients comprising 35 limbs were included in the study. NRS scores for RLP decreased by a mean of 2.6, and PLP decreased by 2.2 1-year post TMR. Patients experiencing low pain at baseline (NRS 0-3) were more likely to experience worsening of both RLP and PLP after TMR compared to those with higher baseline pain (RLP: +0.5 vs -3.2, p<0.01; PLP: +0.7 vs -3.0, p<0.01). PROMIS pain intensity and pain interference scores both saw statistically significant improvements with respect to RLP and PLP (p≤0.01 for all comparisons). On functional assessment, OPUS Rasch scores improved by a mean of 2.7 points and Neuro-QOL improved by 2.2 points.

Conclusions:This prospective cohort of thirty-three amputees corroborates the results of a recently published RCT and additionally demonstrates improvement in RLP, PLP, and functional status.

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