TMRpni: Combining Two Peripheral Nerve Management Techniques

Abstract

Summary: Amputee patients suffer high rates of chronic neuropathic pain, residual limb dysfunction, and disability. Recently, targeted muscle reinnervation (TMR) and regenerative peripheral nerve interface (RPNI) are 2 techniques that have been advocated for such patients, given their ability to maximize intuitive prosthetic function while also minimizing neuropathic pain, such as residual and phantom limb pain. However, there remains room to further improve outcomes for our residual limb patients and patients suffering from symptomatic end neuromas. “TMRpni” is a nerve management technique that leverages beneficial elements described for both TMR and RPNI. TMRpni involves coaptation of a sensory or mixed sensory/motor nerve to a nearby motor nerve branch (ie, a nerve transfer), as performed in traditional TMR surgeries. Additionally, the typically mismatched nerve coaptation is wrapped with an autologous free muscle graft that is akin to an RPNI. The authors herein describe the “TMRpni” technique and illustrate a case where this technique was employed.

A Consensus Approach for Targeted Muscle Reinnervation in Amputees

“…There are a number of combination TMR/RPNI techniques that have been described, attempting to harness the power of TMR and capturing any potential escaping axons using the strategy for RPNI. [41][42][43] The rationale for these techniques lies in the size mismatch of the donor and recipient nerves for "standard" TMR, and the desire to provide a functional destination for all regenerating axons-even those that might escape from the smaller recipient motor nerve target. It is not known if the provision of these techniques improves outcomes compared with traditional TMR.…”

Demystifying Targeted Muscle Reinnervation: A Systematic Review of Nerve Transfers for the Lower Extremity

“…Ten original reports described donor nerve dissection and target muscles at the transfemoral level (Table 2; Supplemental Digital Content 1, http://links.lww.com/ PRSGO/C457). 2,3,[12][13][14][15][16][17][18][19] Agnew et al performed the initial anatomic study to advance transfemoral TMR. Landmarks for motor branch clusters to all muscles of the thigh were identified.…”

The Peripheral Nerve Surgeon’s Role in the Management of Neuropathic Pain

“…Interestingly, combinations of these techniques with each other and with other NP therapies have been reported. 104,105 Like improved diagnosis, the expansion of these surgical techniques may enable the generation of personalized therapies, engaging with individual pathophysiology more effectively. In addition to techniques, PRS Global Open • 2023 surgical devices are poised to take on a greater role in the management of NP.…”