A review of pain outcomes following targeted muscle reinnervation in lower extremity limb pain

Approximately 75%experience phantom(PLP),residual(RLP),or general(GLP)limb pain following lower extremity amputation.Targeted muscle reinnervation(TMR)is a peripheral nerve transfer that reroutes amputated nerves to motor endplates that can prevent or treat limb pain.This systematic review summarizes pain outcomes following primary and secondary treatment of lower extremity PLP,RLP,and GLP.Primary literature review of three databases-PubMed,EMBASE,MEDLINE-were used for all articles related to TMR and lower extremity limb pain,querying the same keywords:“targeted muscle reinnervation”AND“pain”.Citations were then reviewed and eliminated if only upper extremities were studied or the study lacked pain outcomes.Citations were categorized as primary or secondary TMR.Pain outcomes,including Numerical Rating Scales(NRS)and Patient-Reported Outcome Measurement Information System(PROMIS)Pain scores,were aggregated when appropriate.Ten studies met all inclusion and exclusion criteria after formal review for a total of 431 extremities,of which 79.1%(n=341 limbs)were lower extremities.Average primary TMR PROMIS scores for PLP and RLP were lower than amputees without primary TMR.Average NRS scores and PROMIS Pain scores in secondary TMR demonstrated improvements in PLP,RLP,and GLP.Primary and Secondary TMR does prevent and improve PLP,RLP,and GLP;however,a minority of studies report quantifiable pain outcomes.All future TMR studies should include validated pain outcomes to better quantify the expected pain and quality of life improvements after lower extremity TMR.

Efficacy of targeted muscle reinnervation for treating and preventing postamputation pain-a systematic review

Aim:Targeted muscle reinnervation(TMR)is a procedure pioneered to improve control of myoelectric prostheses and was fortuitously found to improve postamputation pain by transferring residual nerve ends from an amputated limb to reinnervate motor nerve units in denervated muscles.This study sought to perform a systematic review of the literature regarding the postamputation pain-related outcomes following TMR.Methods:PubMed database was queried using the key term“targeted muscle reinnervation”.Articles were chosen based on the following criteria:(1)clinical studies on TMR;(2)greater than one subject;(3)studies were case-controls,comparative cohort analyses,controlled trials,or randomized controlled trials;and(4)studies included one or more outcomes of interest:prosthetic use and functionality,improvement or persistence of pain,indications,complications,donor nerves,and technical aspects of TMR.Results:Overall,9 studies including 101 upper extremity and 252 lower extremity nerve transfers were analyzed,with nerve transfer type,amputation location,and specific neurotizations reported.Four studies assessed the efficacy of TMR in addressing phantom limb pain(PLP)and residual limb pain(RLP),with 3 out of 4 studies reporting significant improvements in PROMIS(Patient Reported Outcome Measurement Information System)scores in TMR subjects compared to controls.Five additional studies did not analyze PROMIS scores but reported subjective improvements in pain outcomes.Conclusion:Included studies demonstrated TMR had lower maximal pain and pain intensity,behavior and interference compared to the standard of care.Secondary TMR used to treat patients with established painful neuromas also reported improvement in pain compared to baseline.