New way to prevent phantom limb pain in amputees

Scientists have found that rerouting nerves during amputation can reduce debilitating phantom limb and stump pain in amputees even before it starts.

Doctors at Ohio State University in the US are pioneering the use of primary targeted muscle reinnervation (TMR) to prevent or reduce phantom limb pain -- a condition which causes an amputee to feel pain in the missing limb.

TMR was first developed to allow amputees better control of upper limb prosthetics. Traditionally doctors perform the surgery months or years after the initial amputation.

A study published in the journal Plastic and Reconstructive Surgery showed that primary TMR -- the rerouting of nerves cut during amputation into surrounding muscle -- greatly reduces phantom limb and residual limb pain.

The research describes how to perform this technique in below-the-knee amputations and documents the benefits of primary TMR for preventing pain.

"This paper provides a blueprint for improving patient outcomes and quality of life following amputation," said K Craig Kent, dean of The Ohio State University.

Over the course of three years, the surgeons performed 22 TMR surgeries on below-the-knee amputees, 18 primary and four secondary. None of the patients have developed symptomatic neuromas and only 13 per cent of patients who received primary TMR reported having pain six months later.

"A significant amount of pain in amputees is caused by disorganized nerve endings, ie symptomatic neuromas, in the residual limb. They form when nerves are severed and not addressed, thus they have nowhere to go," said Ian Valerio, division chief of Burn, Wound and Trauma in Ohio State.

"Attaching those cut nerve endings to motor nerves in a nearby muscle allows the body to re-establish its neural circuitry. This alleviates phantom and residual limb pain by giving those severed nerves somewhere to go and something to do," said Valerio.

Patients who have had TMR significantly reduce or sometimes stop using narcotics and other nerve pain related medications, which can greatly improve their quality of life.

"TMR has been shown to reduce pain scores and multiple types of pain via a variety of validated pain surveys. These findings are the first to show that surgery can greatly reduce phantom and other types of limb pain directly," Valerio said.

The researchers believe primary TMR is a reliable technique to prevent the development of disorganised nerve endings and to reduce phantom and other limb pain in all types of amputations.

When done at the time of initial amputation, there is minimal health risk and recovery is similar to that of traditional amputation surgery.