Medtronic’s RestoreADVANCED implant, traditionally used to manage chronic pain, helped spur voluntary muscle activity in patients who otherwise had no motor control, including 2 who had also lost physical sensation in their legs.
"We have uncovered a fundamentally new intervention strategy that can dramatically affect recovery of voluntary movement in individuals with complete paralysis even years after injury," the researchers wrote. "Future experiments with improved technology are needed expediently to take the most advantage functionally of these neurophysiological findings in people after severe spinal cord injury."
It’s not the first time that experiments have demonstrated success in overcoming paralysis with neurostimulation. Now-famous paralysis patient Rob Summers made headlines in 2011 after standing with the aid of the a stimulator. Summers was paralyzed from the waist down at the age of 20 after a hit-and-run accident, but was able to stand briefly on his own just 3 days after getting the implant.
Summers can now "feel soft touch, hard touch. I can feel pinpricks," he told NBC News. "I can feel the wind on my legs."
After years of training and observation, patients have been able to swing their legs, sit up without support and move their ankles. Some have also regained control over their bladders, bowels and sexual functions.
In the latest study, published this month in Brain; A Journal of Neurology, 4 new patients were able to move their ankles and toes on command while their implanted neurostimulators were activated. Three patients were able to demonstrate some movement between 4 and 11 days after implantation, while the 4th didn’t show any voluntary movement until 7 months after surgery.
The patients’ newly regained motor control wasn’t anything like what they were able to do prior to their injuries, providing only limited movement. The stimulation helped patients move only one leg at a time, requiring that the device be turned off and on again in order to move the other leg. Nevertheless, the result of new and previous studies have drawn a lot of attention from paralyzed people who have asked to participate in studies.
"In all 4 research participants, their ability to voluntarily move improved over time with daily epidural stimulation and voluntary training while also receiving stand or step training," the study authors wrote. "Although the exact mechanisms that enabled these surprising results cannot be definitively identified, the possibility of re-establishing functionally meaningful voluntary control in the presence of epidural stimulation places a high priority on reconsideration of the mechanisms contributing to paralysis in humans."
Future experiments may help better target and tailor stimulation, the authors noted. Another 8 patients are slated for implantation this year in a new study, although the researchers didn’t specify whether they would continue working with the Medtronic implant. The RestoreADVANCED neurostimulator used in the latest study was designed for managing chronic pain in the trunk or limbs.