Targeted Muscle Reinnervation for the Treatment of Complex Regional Pain Syndrome: a Case Series
Stephanie E. Shin, MS1, Zoë K. Haffner, BS2, Brian L. Chang, MD2; Grant M. Kleiber, MD2
1Georgetown University School of Medicine, Washington, DC, 2Department of Plastic and Reconstructive Surgery, MedStar Georgetown University Hospital, Washington, DC
Background: Complex Regional Pain Syndrome (CRPS) is a debilitating condition, characterized by severe pain with vascular, motor, or trophic changes. Targeted muscle reinnervation (TMR) has been shown to improve neuroma and phantom limb pain (PLP) in amputees. The objective of this case series was to characterize TMR as a treatment for CRPS.
Methods: A retrospective review was performed of patients receiving TMR for CRPS by a single surgeon from 2018-2021. Demographics, operative details, and functional outcomes were collected and compared pre- and post-operatively. Pain was evaluated using Numerical Pain Rating Scale (NRS). Function was used as a proxy for pain interference, and assessed qualitatively based on reported activity. Measures of central tendency were reported for appropriate variables.
Results: 13 patients were identified; all were female, with an average age of 42.1±14.5 years and pre-TMR NRS of 6±3. All were diagnosed with CRPS, with traumatic or post-surgical etiology. Patients were otherwise healthy, with exception of 3 active smokers, Sjogren's syndrome, and Ehler’s Danlos. All patients had previous or concurrent interventions for pain, including previous nerve blocks (n=9; 69.2%), spinal cord stimulation (n=3; 23.1%), and lower extremity amputation (n=6; 46.2%). Patients 1, 2, and 3 received their CRPS diagnosis less than 1 year before TMR. Patient 1 had CRPS of the lower extremity and no previous nerve operations. She reported resolution of pain at last follow-up after below knee amputation with concurrent TMR. Patient 2 had a tibial nerve coaptation and saphenous neurectomy during previous amputation. She endorsed generalized pain, but denied PLP at last follow-up. Both patients 1 and 2 could independently ambulate at 2 and 3 months postoperatively, reporting improved pain allowed them to tolerate a prosthetic. Patient 3 was unable to tolerate “any touch” in her upper extremity before TMR, yet reported resolution of neuropathic paresthesia and ability to handwrite at last follow-up. The remaining 10 patients received TMR more than 1 year after pain diagnosis (Patients 4-13 had CRPS for 24-128 months). Excluding patient 7, all patients had unchanged or reduced pain and average NRS improvement of 3.2±2.15 at last follow-up.
Conclusion: Chronic pain is a complex disorder with a variety of treatments. TMR may be useful for plastic surgeons to improve pain in patients with CRPS. We observe that earlier intervention may yield better clinical results. Future studies may include prospective trials that assess the role of TMR in the management of chronic pain.
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