The research of Reggie Edgerton, Susan Harkema, Wise Young and others has shown that epidural stimulation in combination with locomotor training can lead to restoration of a number of important functions, including bowel, bladder, sexual function, temperature regulation and more. Electrical stimulation is also an excitatory stimulus. It follows that another logical possibility for further research is to explore the potential of epidural stimulation by itself.
The obvious upside of epidural stimulation by itself is that it would appeal to a much larger percentage of chronic SCI survivors, who would benefit more or less immediately. Those who want to follow up with locomotor training could then do so at the pace and commitment level that is most practical for their individual lifestyle.
Unite to Fight Paralysis advocates for more inclusive research that focuses on more readily achievable, partial recovery of function. Matthew Rodreick, executive director of U2FP, is working with the research community to include the priorities of the SCI community in clinical trials. “It seems the scientific community has been obsessively focused on walking in most of their SCI trials. Most of the studies have paired locomotor training with other ‘tools’ to gain recovery in walking. But a number of studies have now shown that bowel and bladder and other important functions are being regained, mainly as a kind of side effect. So why can’t that now be the major aim of studies?”
Rodreick has organized a quarterly conference call attended by a dozen or so major researchers so they can share information. He sees a change happening where more studies are focusing on priorities other than walking (see Research Matters, for more on this topic). He has also been instrumental in advocating for funding for specific projects. One such project is a clinical trial still in progress, conducted by Dr. David Darrow, a Minneapolis neurosurgeon.
The study involves 12 chronic SCI survivors, female and male, that focuses on restoring bladder and bowel function using epidural stimulation. So far 10 subjects have been fitted with stimulators, and the results are impressive. The design of the trial is structured to make restoration of function less onerous. Stimulators are implanted in a day surgery, and participants are sent home to try various pre-programmed stimulator settings that are activated by an innovative smart phone app that Darrow and a colleague have created. In this way, optimum results can be achieved from the participants’ homes. The range of testing also allows data not previously targeted to be collected, like heart rate, blood pressure, and other information important to overall health.
So what’s next? More trials involving greater numbers. Perhaps further research in separate trials could also combine epidural stimulation with untethering surgery, which has already been shown to increase the incidence of bladder and bowel restoration in the Kunming trials.
Q&A with Dr. David Darrow
Tim Gilmer: Why focus on epistim by itself in your study — with no locomotor training?
David Darrow: We already know the importance of the central pattern generator and intensive rehab/LT, but we don’t know what is the primary stimulus that activates the restoration of movement. We are targeting the entire lumbar-sacral area with a single 16-contact “paddle” and tracking outcomes of various settings.
TG: What if there’s damage to cord in that area?
DD: Interesting question. So far, people have to have an MRI that shows they don’t have damage in that area. But it’s hard to predict outcomes. We are concentrating on subjects with primarily thoracic injuries, C7-T10. So far we have implanted people up to 17 years post-injury, some 50 or 60 years old. In the future I see no reason why people with damage in the T11-L2 area couldn’t be implanted. You never know what is possible until you try it.
TG: What about higher cervical injuries?
DD: We are excited and looking forward to including quads in another trial. We are funded and may be enrolling, hopefully, by the end of the year. It will be more difficult. We’ll have to build on what we are learning and it will require more electrode paddles placed in different locations, perhaps two or three. We want to learn what works best for a range of quad issues.
TG: How do you track and collect data from the different settings?
DD: With an app that we created. We had to write our own app in order to monitor not only the best settings for bowel and bladder, but also other factors that are affected by SCI, like cardio, spasticity, autonomic dysreflexia and BP, etc. And the purpose of collecting the data is so we can learn what settings work best for different uses. We need different programs for different outcomes, so patients’ treatment can be individualized. The results can be transmitted to us wirelessly.
TG: What about transcutaneous stim? Are you interested in doing that?
DD: Yes, of course, if you can do it, it would be better than surgery. But we don’t know if we can tailor it like we can with epidural stim, where we can shift paddle placement by monitoring results during the operation according to the individual injury. Electrically it is further from the cord, so we don’t know if it will be comparable … yet.
Right now our approach is to target people who don’t have the time, money or ability to dedicate themselves to months and months of intensive rehab, but who might benefit more or less immediately and be able to do this in their homes. We are seeing a range of beneficial results converge in three to six months — bowel, bladder, sexual function and more. We want to facilitate it so people in rural areas can do this and maybe improve strength and bone building for later specialized locomotor training, if they have the opportunity. We want to minimize the burden on the person with SCI. We don’t think our approach is better or that LT is not needed, we are just hopeful that our work complements what everyone else is doing.
TG. Wise Young has talked about the need for SCI research scientists to not only do clinical trials, but to design them in such a way that the treatments can be applied in an affordable and practical way for as many people as possible. Sounds like that is a philosophy the two of you share.
DD: Absolutely. I’m not a scientist per se, I’m a surgeon. I work with patients all the time and I want to help them get better. So far the biggest gains, according to the patients’ own responses, are with bowel management and spasticity. One hundred percent have seen benefits with spasticity. And spending less time in the bathroom is a big deal for so many SCI survivors. We are finding out how important working with patients is and getting to know them as individuals.