Extended activity-based training with epidural stimulation resulted in ability to stand and move without stimulation.

Andrew Meas, a research participant at the University of Louisville with a complete spinal cord injury, who had lost motor function below the level of the injury, has regained the ability to move his legs voluntarily and stand six years after his injury.

A study published in the journal Scientific Reports describes the recovery of motor function in a research participant who previously had received long-term activity-based training along with spinal cord epidural stimulation (scES). In the article, senior author Susan Harkema, PhD, professor and associate director of the Kentucky Spinal Cord Injury Research Center at the University of Louisville, and her colleagues report that over the course of 34.5 months following the original training, the participant recovered substantial voluntary lower-limb motor control and the ability to stand independently without the use of scES.

“Activity-dependent plasticity can re-establish voluntary control of movement and standing after complete paralysis in humans even years after injury,” Harkema said. “This should open up new opportunities for recovery-based rehabilitation as an agent for recovery, not just learning how to function with compensatory strategies, even for those with the most severe injuries.”

Previous research at KSCIRC involving four participants with chronic clinically motor-complete spinal cord injury found that activity-based training with the use of scES – electrical signals delivered to motor neurons in the spine by an implanted device – allowed the participants to stand and to perform relatively fine voluntary lower limb movements when the scES device was activated. Andrew Meas was one of the four participants in that study.

The original training protocol included daily, one-hour, activity-based training sessions with the aid of epidural stimulation. During these sessions, the participant trained on standing activity for several months, followed by several months of training on stepping.

After completing a nine-month training program in the lab, Meas continued activity-based stand training at home. After a year of independent training, he returned to the lab to train for three months in a revised activity-based training schedule. The revised training called for two, daily one-hour training sessions and included both stand and step training each day, all with the aid of epidural stimulation.

After that training, Meas was able to voluntarily extend his knees and his hip flexion was improved. In addition, using his upper body and minimal additional assistance to reach a standing position, he was able to remain in a standing position without assistance, and even stand on one leg, without the use of epidural stimulation.

“We observed that in participants we have worked with so far, eight months of activity-based training with stimulation did not lead to any improvement without stimulation,” said Enrico Rejc, PhD, assistant professor in the UofL Department of Neurological Surgery and the article’s first author. “This participant kept training at home and, after several months, he came back to the lab and we tried a different training protocol. After a couple of months of training with the new protocol, we surprisingly observed that he was able to stand without any stimulation – with two legs and with one leg – using only his hands for balance control.”

The authors suggest that several mechanisms may be responsible for Meas’ recovery of mobility, including the sprouting of axons from above the point of injury into areas below the lesion. Another possible explanation may be that the activity-based training with scES promoted remodeling of connections among neurons in the spinal cord.

In addition, they suggest that the participant’s own effort at voluntary movement may have