American Society for Peripheral Nerve
ASPN Home ASPN Home Past & Future Meetings Past & Future Meetings

Back to 2023 Posters


Combined TMR and RPNI in a Vasculopathy Patient
Logan Grant Galbraith, BA1; James Gatherwright, MD2
1Northeast Ohio Medical University, Rootstown, OH; 2Cleveland Clinic, Cleveland, OH

Intro/Background
TMR (Targeted Muscle Reinnervation) or RPNI (Regenerative Peripheral Nerve Interface) have been the accepted route for managing nerve injuries. TMR allows the injured nerve to join that of innervated muscle. Literature supports this method as it prevents post operative pain and expands the capabilities of intuitive electronic prosthetics. RPNI has been used to decrease pain after nerve transection, a procedure which directs the injured nerve into a de-innervated muscle graft.
Case
The patient was a 75-year-old female undergoing left above the knee amputation. In efforts to reduce phantom pain and neuroma formation, a combined TMR-RPNI approach was utilized. Specifically, the saphenous, peroneal sciatic, and the tibial component sciatic (2 in fig. 1) were spliced into the gastrocnemius muscle (4 in fig. 1) with a free muscle graft (3 in fig. 1) wrapping around their connection. After the connections were complete, an electric stimulator (1 in fig. 1) was used to confirm the transmission of a neuronal signal. Notably the patient suffered from peripheral vasculopathy and chronic kidney disease. The patient did experience delayed wound healing; however, the phantom pain was rated as acceptable and nerve pain was nonexistent.
Discussion
While TMR lowers the incidence of phantom and nerve pain, there remain areas of the technique that can go awry. As stated, the biggest challenge remains nerve size mismatch and axonal escape. These axons can be kept contained using a biological nerve wrap (3 in fig. 1) that gives escape axons a place to invade instead of allowing their progression to neuroma formation (1 in fig. 2). This muscle wrap works based on the accepted mechanism for RPNI. The patient in this case reported no nerve pain and minimal phantom pain.
Conclusion
With more extensive research and data collection, the recommendations for universal TMR-RPNI technique may soon be clear. However, this procedure remains straight forward with no obvious complications or risks to the patient. With these things in mind, the benefits of such a simple procedure should be considered whenever feasible for a patient undergoing amputation or another nerve damaging event.


Back to 2023 Posters