A recent study details how patients with complete paralysis can learn to make certain voluntary movements with the help of electrical stimulation of the spinal cord. The five patients in the study received transcutaneous stimulation delivering electrical current to the spinal cord via electrodes placed on the lower back. The research team was led by V. Reggie Edgerton, PhD, Professor of Integrative Biology and Physiology at University of California Los Angeles, and Yury Gerasimenko, PhD, Director of the Laboratory of Movement Physiology at the Pavlov Institute, St Petersburg, Russia. 1
Roughly 250,000 people in the US are currently living with spinal cord injuries of varying severity. These individuals usually have permanent and severe neurological deficits. Those diagnosed with “motor complete” injuries are currently very unlikely to regain voluntary control of movements. 2
Yet recent work in both animal models and human research has shown that the spinal circuitry below the level of injury may have greater functional recovery ability than was previously believed possible. This lends hope to improved outcomes for these patients in the future, even in those that have been paralyzed for many years. 1
Last year, Dr Edgerton and colleagues published a study in which four men with complete motor paralysis were able to perform some voluntary movements while receiving electrical stimulation to the spinal cord. In this case, an epidural stimulator was surgically implanted on the surface of the cord. Participants were able to voluntarily flex their toes, ankles, and knees while the stimulator was active. 3
This latest study follows up with a noninvasive transcutaneous strategy to perform electrical stimulation of the spinal cord. The research centered on five men with cervical or thoracic injury and paralysis of greater than two years. The subjects received a series of 45 minute sessions every week for approximately 18 weeks. 1
During these sessions, the men’s legs were suspended in braces hung from the ceiling (to allow for “step-like” movement in a gravity-neutral situation). At each session the subjects received transcutaneous electrical stimulations of the spinal cord. While receiving the stimulation, the subjects were asked to either try and move their legs or remain still. The subjects also received manual leg movement and physical conditioning each session. Additionally, the researchers took EMG readings from lower legs muscles at various points during the study. 1
In the last four weeks of the study, the subjects received the drug buspirone in place of electrical stimulation, a drug which has induced movement in mouse models of spinal cord injury. 1
Electrical stimulation caused step-like movement of the patients’ legs. At the beginning of the study, the subjects’ legs only moved when receiving this electrical stimulation. However, the men could significantly increase the range of leg movement if they attempted to move their leg while the stimulation was being applied. After four weeks of sessions, patients could double their range of motion in this fashion. 1
Remarkably, by the end of the study (while receiving buspirone) all of the subjects could move their legs while in the harness with no additional electrical stimulation. On average, the range of movement was about what it had been with the electrical stimulation. Also, the strength of EMG signals from the lower legs increased in magnitude over the course of the study. 1
The researchers believe that the stimulation period may have helped reestablish communication between the brain and spinal cord. “It’s as if we’ve reawakened some networks, so that once the individuals learned how to use those networks, they become less dependent and even independent of the stimulation,” said Dr Edgerton. The research findings were published as, “Noninvasive Reactivation of Motor Descending Control of Paralysis,” in Journal of Neurotrauma
this August. 4
In a follow up study, Dr Edgerton and colleagues plan to see whether these same men can be trained to fully bear their weight using transcutaneous stimulation (which has been achieved in some studies of surgically implanted stimulators). He is also hoping the technology can help individuals regain some autonomic functions, like bladder, bowel, and sexual control. 4
Going forward, Dr Edgerton believes researchers should continue to develop both noninvasive spinal stimulation techniques and surgically implanted devices, since these approaches may provide different benefits in specific clinical situations. 4
Roderic Pettigrew, MD, PhD, and director of the director of the National Institute of Biomedical Imaging and Bioengineering at the NIH, commented on the remarkable results. In an interview with Medscape Medical News
he said, "This is another very exciting step in our effort to treat paralysis due to spinal cord injury, a condition which just two years ago was thought to be permanent and carry with it a lifelong sentence of paralysis, but we don't have to view it that way anymore." 5
Gerasimenko YP, Lu DC, Modaber M, et al. Noninvasive reactivation of motor descending control after paralysis. J Neurotrauma. 2015 Aug 20. [Epub ahead of print] http://online.liebertpub.com/doi/pdf/10.1089/neu.2015.4008.
Chin, LS. Spinal Cord Injuries. Medscape. http://emedicine.medscape.com/article/793582-overview#show Updated July 7, 2015. Accessed August 29, 2015.
Spinal stimulation helps four patients with paraplegia regain voluntary movement. National Institutes of Health. http://www.nih.gov/news/health/apr2014/nibib-08.htm . April 8, 2014. Accessed August 29, 2015.
Paralyzed men move leg with new non-invasive spinal cord stimulation. National Institutes of Health. http://www.nih.gov/news/health/jul2015/nibib-30.htm. July 30, 2015. Accessed August 29, 2015.
Brooks M. Transcutaneous spinal cord stimulation helps paralyzed men move legs. Medscape Medical News. http://www.medscape.com/viewarticle/848951#vp_1. August 3, 2015. Accessed August 29, 2015.