PROCESS guided case series of primary targeted muscle reinnervation and regenerative peripheral nerve interfaces in the prevention of post amputation and phantom limb pain

Lower limb amputations have a prevalence of about 26 per 100,000 in the United Kingdom. A significant proportion of these patients suffer from chronic pain and/or phantom limb pain. Targeted muscle reinnervation (TMR) and regenerative peripheral nerve interfaces (RPNI) have been found to help improve these symptoms, however these are usually used as a treatment as opposed to prevention. These techniques work on the principle of giving the nerves somewhere to go and something to do, but it is not yet standard practice. Central neural reorganisation and adaptation to chronic/phantom limb pain suggest that preventing the symptom in the first place could yield a superior result to treatment after the problem has arisen. We present a series of 24 cases of where TMR and/or RPNI were performed primarily at the time of initial amputation. Patients were followed up approximately one year after procedure and assessed their pain scores according to a numerical rating scale (NRS) and the PROMIS Pain Interference Short form 6b Significant improvements of pain scores were found for these patients when compared to patients without previous TMR or RPNI. PLP is a debilitating, life limiting and an economic burden on patients who have undergone limb amputations, and with no clear medical or surgical intervention yet widely accepted to offer a definitive management option for this problem, TMR and RPNI may be able to fill a void. This is a good proof of principle showing promising results, and suggests that further investigations with randomised control studies are warranted.