What is Targeted Muscle Reinnervation (TMR)?
Unlike bone, muscle, blood vessels and skin, the nerve remains very much alive after an amputation. After transection, the nerves will germinate and grow into the surrounding scar tissue, forming a neuroma. This is one of the mechanisms of the peripheral nervous system that can contribute to neuropathic and phantom pain. Pain can be induced by spontaneous ectopic activity in these nerve endings or by chemical and mechanical stimulation. Although all severed nerves form neuromas, not all neuromas cause neuropathic or phantom pain.
With painful swellings at the end of nerves in an amputation stump or with nerve pain that cannot be treated with painkillers, a so-called “targeted muscle reinnervation” or “targeted nerve/muscle repair” surgery can be performed. This surgery involves carefully stitching nerves that control the forearm or lower leg muscles but have become inactive as a result of the amputation to the motor nerve unit of remaining muscles of the stump. In this way the idle nerve gets something to do again so that the signals fired in the brain get a purpose again. After decades of research into how neuromas can be treated, this is a promising development for people with amputations and nerve pain.