Stimulation of the spinal cord can alleviate “phantom” pain for people who have had a limb amputated, suggests a new study.
Researchers found an electrical pulse delivered to the spinal cord of amputees from their prosthetic limb “significantly” reduced pain coming from the missing limb.
The ‘exciting’ new study revealed that these pulses also improved amputees’ balance.
The treatment could provide relief for millions of sufferers around the world, as current methods such as painkillers are unable to treat the phenomenon.
A collaborative research team led by the University of Pittsburgh School of Medicine sought to offer a solution to pain frequently experienced by amputees – of whom there are more than 1.5 million in the United States alone.
Eight out of ten amputees are said to experience some degree of chronic pain perceived as coming from their missing limb, known as phantom pain, at some point in their lives.
This affliction can begin occurring within mere days of a limb being amputated, doesn’t respond to medication and can dramatically impair a sufferer’s quality of life.
Additionally, as even the most technically sophisticated prosthetics are not equipped with sensory feedback functionality, amputees remain prone to balance deficits and falls which further limit their mobility.
Typical stimulation systems shut down pain neurons by overriding them with another sensory signal – such as scratching or rubbing a painful area of our bodies.
The team behind the study, published in the journal Nature Biomedical Engineering and led by Dr. Lee Fisher, leveraged existing spinal cord stimulation technology to restore sensory feedback by replacing the severed connections between sensory neurons in the missing foot and the central nervous system.
To modulate the intensity of sensations in response to varying pressure on a prosthetic foot whilst walking, a pair of thin electrode strands implanted over the top of the spinal cord in the lower back were connected to a mobile phone-sized stimulation device delivering electric pulses varying in frequency and amplitude.
The leads were implanted for one to three months and removed after the trial ended.
The researchers were able to exert active control of spinal cord stimulation parameters whilst participants walked or stood with their prosthetic legs.
They found that as well as observing meaningful improvement in balance control and gait – even in the most challenging conditions such as standing on a moving platform with their eyes closed – the study participants reported an average reduction in phantom pain of 70 per cent.
“We are using electrodes and stimulation devices that are already frequently used in the clinic and that physicians know how to implant,” said Dr. Fisher, an associate professor of physical medicine and rehabilitation at the University of Pittsburgh.
“We are leveraging those technologies to produce meaningful improvement in function and reduction of pain.
“That’s exciting and we’ve been building it for a while.”
The new technology used was also found to be versatile; demonstrating its ability to work with extensive nerve damage caused by chronic conditions including diabetes and in those with traumatic amputations.
It also doesn’t require costly, custom-made electrodes or uncommon surgical procedures.
“We are able to produce sensations as long as the spinal cord is intact,” Dr. Fisher added.
“Our approach has the potential to become an important intervention for lower-limb amputation and, with proper support from industry partners, translated into the clinic in the next five years.”
Produced in association with SWNS Talker
