Roderic I. Pettigrew, Ph.D., M.D., is the first Director of the NIH's National Institute of Biomedical Imaging and Bioengineering (NIBIB). Prior to his appointment at the NIH, Dr. Pettigrew was Professor of Radiology, Medicine (Cardiology), at Emory University and Bioengineering at the Georgia Institute of Technology and Director of the Emory Center for MR Research, Emory University School of Medicine, Atlanta, Georgia. He is known internationally for his pioneering work involving four-dimensional imaging of the cardiovascular system using magnetic resonance imaging (MRI). His current research focuses on integrated imaging and predictive biomechanical modeling of coronary atherosclerotic disease.
Is paralysis a major health problem?
Yes, it is. The Christopher Reeve Foundation published a study in 2009 that found far more Americans are paralyzed than originally thought. The study indicated that 5.6 million (1 in 50) Americans are paralyzed to some degree and that 1.275 million of those cases resulted from spinal cord injury. This is five times the previous estimate.
What does this new study mean for the average paralyzed person?
Spinal stimulation therapy is still in the research phase. This means that before it can become available to the average person, its safety and effectiveness will have to be established in a large number of patients, and it will need to be approved by the FDA. In addition, the technology used in this study has limitations because it was designed for another purpose, to suppress back pain. Researchers are currently working to develop an optimized stimulator that could help patients achieve more controlled movements. That said, the results from this study challenge the conventional wisdom that patients with complete paralysis have almost no chance of meaningful recovery. Now for paralyzed patients, there is more hope than ever.
What surprises you most about the study?
The fact that the spinal stimulation therapy was able to generate voluntary movement in four out of four patients with complete paralysis is truly remarkable. The researchers initially expected that only patients with the ability to experience sensation below their injury would be able to benefit from the therapy. That notion was thrown out the window when the first patient, who had no sensation below his injury, moved almost immediately in the presence of stimulation. Statistically, the fact that all four men regained some voluntary movement of their lower extremities suggests that many other patients with spinal cord injuries are also likely to benefit. Another impressive outcome was that all four patients also experienced improvements in involuntary nervous system function. This included control of blood pressure, body temperature regulation through sweating, and return of bladder, bowel, and sexual function.
Do you think people who have been paralyzed for years may someday walk again?
That is our hope, and that is what we are working toward. However, it will take more research. The spinal stimulation and physical therapy approach to rehabilitation used in this most-recent study is the product of decades of NIH-funded research on the spinal cord, carried out by Dr. V. Reggie Edgerton (UCLA) and his collaborators. Walking is a complicated process that requires multiple muscles to produce controlled contractions in both legs and in a specific pattern. This will require more extensive recovery than was realized in this initial study, but it is now conceivable that this can be achieved in the future.
And what about those people who can't use their arms and hands? How much research is being done for them?
NIBIB is also supporting Dr. Edgerton and his colleagues to determine whether spinal stimulation can be used to help patients with paralysis of the upper limbs.
Do you see any benefits from this research flowing to people with Parkinson's disease or other neurological disorders?
The mechanism of dysfunction in spinal cord injury is not completely understood but is believed to be different from that in Parkinson's and some of the other neurological disorders. Consequently, it is difficult to predict how many types of populations will ultimately benefit from this therapy. This will require further research.
What other breakthroughs do you see happening in the next few years?
In addition to optimizing the spinal stimulator, researchers are working to develop a new device that can deliver electrical stimulation through the skin, so that the stimulator doesn't have to be surgically implanted. A non-invasive spinal stimulator will make it easier to reach patients in remote settings, away from large medical centers.
Besides spinal stimulation, there are other technologies being developed with support from NIBIB that show promise for helping patients with paralysis perform essential activities of daily living. For example, researchers have developed and are now evaluating an implantable Networked Neuroprosthesis (NNP) to restore hand grasp in those with tetraplegia. This next generation Functional Electrical Stimulation (FES) neuroprosthesis couples sensors—implanted in the muscle that interprets the intention to move—with more intense stimulators that electrically activate the nerves controlling the target muscles. Researchers are also developing Brain-Computer Interfaces (BCI) that allow patients to control a computer and other devices such as a robotic arm using only their thoughts. Another NIBIB-funded researcher has developed a system that allows patients to control devices and even navigate a wheelchair using only tongue movements.
Do you believe there will ever be a cure for paralysis?
This report of remarkable recovery in 4 of 4 patients with long-standing, complete motor paralysis is a medical milestone that has been reached; but it is not the end of the research. The more we learn about the mechanisms of spinal cord injury and dysfunction, the better we will be able to innovate and craft definitive treatments. It is my belief that this systematic process will eventually lead us to a cure.