• Posted December 15, 2023

Spinal Cord Stimulation Eases Pain, Boosts Function for People With Prosthetic Legs

People who've lost a leg due to injury or disease are often plagued by what's known as phantom limb pain -- discomfort arising in the area, despite the absence of the limb.

Now, researchers report that people who wear a prosthetic leg after amputation may have that pain eased, as well as improved sensation in their new foot, using spinal cord stimulation.

“We are using electrodes and stimulation devices that are already frequently used in the clinic and that physicians know how to implant,” said study senior author Lee Fisher, of 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 technology involves special pressure sensors that are placed on the prosthetic's foot. These sensors trigger signals that are sent to the person's spinal cord. The technology appears to ease pain and help users walk better, the research team said.

If proven successful, the spinal stimulation technology might help a wide range of people dealing with an amputation -- those whose leg was amputated due to trauma, as well as those who fell prey to the nerve damage of advanced diabetes.

“We are able to produce sensations as long as the spinal cord is intact,” said Fisher, an associate professor of physical medicine and rehabilitation at Pitt. “Our approach has the potential to become an important intervention for lower-limb amputation."

According to background information in a Pitt news release, over 1.5 million Americans now live with a lower-limb amputation. About eight of every 10 say they suffer from phantom limb pain in the missing leg and/or foot. Most of this pain does not respond to medication.

As well, many prosthetics don't include the kind of sensory feedback functionality used by Fisher's group. That makes balance more difficult when using a prosthetic.

The new technology essentially replaces severed connections between the spinal cord and the foot with the new cord-stimulation technology.

"A pair of thin electrode strands implanted over the top of the spinal cord in the lower back was connected to a cell phone-sized stimulation device delivering electric pulses of varying amplitude and frequency," the researchers said.

Using this technology, Fisher's team was able to help study participants walk or stand in real time over the three-month course of the study.

The participants appeared to gain real improvement in balance control, Fisher's team reported Dec. 14 in the journal Nature Biomedical Engineering. That was true even under challenging conditions -- for example, standing with eyes closed on an unstable, moving platform.

As a welcome bonus, participants also reported an average 70% reduction in their phantom limb pain, the investigators said.

How soon until patients everywhere might benefit? According to Fisher, with "proper support from industry partners, [this could be] translated into the clinic in the next five years.”

Researchers at Carnegie Mellon University and the University of Chicago collaborated on this research.

More information

Find out more about phantom limb pain at the Cleveland Clinic.

SOURCE: University of Pittsburgh, news release, Dec. 14, 2023