Breakthroughs in Treating Spinal Cord Injury

Sep 15, 2014, 9:00 AM, Posted by Roderic Pettigrew

Roderic I. Pettigrew, PhD, MD, is director of the National Institute of Biomedical Imaging and Bioengineering (NIBIB) at the National Institutes of Health (NIH). He was a member of the inaugural class of the Robert Wood Johnson Foundation (RWJF) Harold Amos Medical Faculty Development Program.

On a fateful day in 2006, 20 year-old Rob Summers, a standout collegiate baseball pitcher at Portland State with aspirations to play in the big leagues, was a victim of a hit-and-run accident while standing in his own driveway. His injuries left him paralyzed below the chest, and his doctors informed him he would never move his legs again.

I first met Rob at NIBIB’s ten-year anniversary celebration. It had been just four years since his accident, and he had already broken new ground in spinal cord injury recovery. During the event, Rob shared his incredible story about the experimental procedure he had recently undergone as part of an NIBIB-funded research trial. In the trial, Rob became the first human to have an electrical stimulator implanted on his spinal cord with the goal of restoring some function to previously paralyzed muscles.  

Rob spoke about how, in just weeks after implantation, the stimulation enabled him to hold himself in a standing position for the first time since his injury. In addition, he began to sense when he was uncomfortable in his wheelchair. Rob went on to describe how, seven months into the trial, he discovered he was able to move his toes, ankles, and legs on command, a feat that shocked the researchers, as they never expected Rob to regain voluntary movement. 

Rob also began to regain important involuntary functions impaired by paralysis, such as the ability to sweat, regulate blood pressure, and even control bladder and bowel, and regain sexual function. Over time, these functions remained even when the stimulator was turned off. Rob expressed that these improvements gave him back his independence; they have also allowed him to participate in the activities he loves such as coaching baseball (without the ability to sweat, Rob wasn’t able to stay out in the heat for more than a few minutes).

The Path to Progress

While the effects of the spinal stimulation were immediate, Rob’s medical breakthrough didn’t happen at the flick of a switch. Instead, it was the culmination of decades of NIH-funded research on the spinal cord led by Reggie Edgerton, PhD, a distinguished professor of integrative biology and physiology at UCLA.

For years, Edgerton had been conducting research on animals with spinal cord injuries, experimenting with ways to tap into the spinal cord’s local circuitry in order to restore movement despite interrupted input from the brain. Edgerton found that cats whose spinal cords had been severed could regain the ability to stand or step following a period of locomotor training on a treadmill while suspended from a harness. Later, he and colleagues showed that paralyzed rats could also regain movement with locomotor training, but they required an extra boost either with drugs or electrical stimulation to the spinal cord.

In 2009, the stage was set to determine whether a similar approach could also restore movement in humans with spinal cord injury. Leading up to this point, Rob had been receiving daily locomotor training overseen by Susan Harkema, PhD, director of rehabilitation research at the Kentucky Spinal Cord Injury Research Center at the University of Louisville. After two years of training, Rob underwent surgery to have an epidural stimulator—normally used for the suppression of back pain—implanted on his spinal cord.

The goal of the stimulation was to increase the excitability of local neurons in the spinal cord. While not strong enough to directly induce muscle activation, the researchers believed the stimulation could lead to movement when combined with sensory input from the locomotor training. The combination of physical training and stimulation did just that and more; it enabled Rob to move his previously paralyzed limbs on command.

Following the tremendous success of this first study in man, many questions remained. Would others benefit from spinal stimulation? Could Rob have moved on command earlier if he had been prompted? How does the stimulation restore voluntary movement? In regards to the last question, the researchers hypothesized that perhaps the stimulator’s success hinged on the fact that Rob had some sensation left below his injury.

With NIBIB funding, a second study involving three additional patients was initiated, and this time the patients were tested for voluntary movement immediately after implantation. The patient first chosen for the new trial, Kent Stephenson, also had no movement or sensation below his chest. According to the researchers, Kent was meant to serve as a control, as they assumed some sensation was needed for the therapy to be effective.

Amazingly, several days after turning his stimulator on, Kent regained some voluntary control of previously paralyzed muscles. The other two participants, one similar to Rob in that he had some sensation below his injury and one without any sensation, also regained some voluntary control almost immediately upon stimulation. The three new patients also reported recovered autonomic functions similar to Rob.

Moving Forward

Since the results from the most recent study were published in April 2014, NIBIB and the researchers together have received thousands of emails from individuals with paralysis and their family members, asking for information about spinal stimulation and wanting to know how they too can become research participants. With such promising results from a technology that is already making a huge difference in several patients’ lives, there is an urgent need to develop the spinal stimulation technology so that it can be quickly and safely adopted by others.

In answer to the overwhelming community response and the desire to continue the momentum, NIBIB is currently working to create a consortium of leaders from industry, academia and philanthropic communities who share an interest in accelerating the spinal stimulation research. 

In addition, NIBIB is supporting research that aims to optimize the spinal stimulation technology. Because the current stimulator was developed for the suppression of back pain, it has limited flexibility for changing the patterns that are used to stimulate the spinal cord. Edgerton is now working to develop a new high-density, 27 electrode array in rats to determine if it can provide finer, more robust control of locomotion.

NIBIB is also supporting Edgerton and collaborators for research to determine whether spinal stimulation can be used to help patients with upper limb paralysis.  In addition these researchers are developing a technology that can deliver stimulation through the skin, which could eliminate the need for surgical implantation.

NIH/NIBIB- Supported Research

While exciting progress is being made using spinal stimulation, there are other technologies in development that show promise for assisting individuals with paralysis. For example, researchers have developed and are now evaluating an implantable networked neural prosthesis  to restore hand grasp in those with tetraplegia. Researchers are also developing brain-computer interfaces  that allow patients to control a computer and other devices such as a robotic arm using only their thoughts. Another system allows patients to control devices and even navigate a wheelchair using only tongue movements.

Through a combination of direct NIH research support and collaboration with leaders in industry, academia and philanthropy, NIBIB is highly committed to advancing the pace of scientific and technological advancement that will improve the quality of life of individuals with spinal cord injury and other movement disorders. This commitment is continuously strengthened by the untiring dedication of the researchers, the courage of the research participants, and the millions of affected individuals and their families who wait patiently for progress.

This commentary originally appeared on the RWJF Human Capital Blog. The views and opinions expressed here are those of the authors.