Introduction
Targeted muscle re-innervation (TMR) is the practice of transferring a nerve to a muscle for a purpose other than the normal function of the nerve or muscle. It has some application in prosthetics for major amputations, but the most common application is in the setting of painful neuromas.
Indications
Neuromas are painful balls of nerve fibres occurring after nerve injury or amputation. Although the symptoms of some will settle with time and physiotherapy, others cause long-term discomfort. Simply removing the neuroma will only result in another neuroma forming, as the underlying cause is the divided nerve ending. TMR addresses this problem by giving the nerve a target to regenerate into. By transferring the nerve to the muscle, the nerve should branch out and avoid forming the painful neuroma.
Preoperative Instructions
TMR for neuroma pain is done as either day surgery or with an overnight stay, depending on the circumstances. Anticoagulant medication should be stopped in consultation with your doctor. The hospital will be in contact regarding admission and fasting times.
Procedure
The problematic nerve and neuroma are identified and the neuroma is removed. The nerve is then dissected, so it can be moved to repair it to the recipient nerve. A redundant or unimportant motor nerve is identified and divided and the neuroma nerve repaired to it as close to the muscle as possible.
Postoperative Instructions
The site of the surgery, be it an amputation stump or a hand, is immobilized as much as possible for 2 weeks. Physiotherapy then starts to avoid resulting stiffness, and desensitization exercises are often helpful. Although there is often some immediate relief from the neuroma pain, it can take several months to feel the benefit of the TMD procedure as the nerve slowly grows into the muscle.
Risks
There is still some risk of the neuroma recurring, and if a motor nerve to a functional muscle is used, there could be some loss of strength in that muscle.
Treatment Alternatives
Simple excision of the neuroma or excision of the neuroma and burying the nerve in a bone tunnel are more traditional treatments of neuroma that you can discuss.