Targeted muscle reinnervation at the time of amputation in the management of complex regional pain syndrome of the lower extremity.

Abstract

Complex regional pain syndrome (CRPS) is a chronic, posttraumatic condition defined by severe pain and sensorimotor dysfunction. In cases of severe CRPS, patients request amputation, which may cause phantom limb pain (PLP) and residual limb pain (RLP). Targeted muscle reinnervation (TMR) reduces the risk of PLP and RLP. This report describes the use of TMR at the time of amputation in a series of patients with CRPS. Four patients (ages 38-71 years) underwent TMR at the time of amputation for CRPS between April 2018 and January 2019. Three patients had a history of trauma and surgery to the affected limb. All patients attempted pharmacologic and interventional treatments for 1-7 years before requesting amputation. Three patients underwent below-knee amputations (BKA) and one had an above-knee amputation (AKA). Target muscles included the soleus, gastrocnemius, and flexor hallucis longus (BKA), and semitendinosus, biceps femoris, and vastus medialis (AKA). Postoperative phantom and residual limb pain symptoms were collected via a telephone survey adapted from the Patient-Reported Outcomes Measurement Information System (PROMIS). There were no complications related to the TMR procedure. Average follow-up time was 12.75 months. Patients reported varied outcomes: two had RLP and PLP, one had RLP only, and one had PLP only. All patients reported successful prosthetic use. TMR may be performed at the time of amputation for CRPS. Further study is necessary to determine the effect of TMR on pain, pain medication use, prosthesis use, and other domains of function.