Let’s revisit the epidural stimulation story that broke in May. It was impossible to miss this, with all the major news outlets and networks offering coverage. Rob Summers, a college baseball player paralyzed five years ago by a hit and run driver (he had some sensation but no muscle function below his chest – categorized as ASIA B) was implanted with a stimulator device on his lower spinal cord. Summers, when stimulated, was able to stand unassisted for a short time and when suspended on a treadmill could take robust steps. For the background facts, see FAQ
or this overview
A big surprise that really gives this story a jolt -- and credibility as a meaningful breakthrough -- is that after seven months, Summers, while stimulated, could voluntarily move his toes, ankles, knees and hips. The research team speculates that his voluntary recovery of function may have been caused by the epidural stim awakening spinal nerves that were alive but not fully active. Recovery may also have come about due to nerve regeneration or sprouting as a result of repetitive activity and training.
But even when the stim was turned off, Summers reported better bladder control, the return of sweating and temperature regulation, and near normal sexual function. Clearly, there’s more going on than stimulation; something biological happened too, perhaps including brain circuit remodeling.
It was remarkable to see and, to be sure, newsworthy. There’s an archive of coverage here
. Media coverage was, on the whole, reasonable and responsible. The headline writers often had issues separating a science story from a clinical “breakthrough.” This was not a treatment, it was not a cure. Was it a breakthrough? From the science side, absolutely. Note the words paradigm shift
, from the paper: “These results suggest that epidural stimulation has potential as a clinical intervention in combination with task-specific training for the recovery of function … These findings open the possibility of a paradigm shift in the perception of possible interventions that could be used to improve function for a range of neuromotor disorders.”
Here are a handful of questions that came in to the Reeve Foundation on the epidural stimulation experiment.
Haven’t people been standing and stepping with stimulation for 30 years or more?
Yes. But you’re thinking of functional electrical stimulation, or FES, which has been around for a long time, even commercially. This is not FES. The muscles in Summers’ legs were not activated by external electrical charges. He was able to animate his lower extremities because the stimulation made the spinal cord itself more sensitive to sensory cues. If you watch the videos of Summers as he is fired up with the stimulator, he must lean forward in his chair and load some weight on his feet before the activity of standing can occur. This weight-bearing is the sensory cue that initiates the pattern that leads to standing motion. Granted, Summers partly pulled himself up to standing using his arms on a frame for support. But once on foot, he was for a while on his own, doing the work himself; wired-up muscles weren’t doing the work for him.
How is this different from the Parastep system of several years ago? That was an external electrical stimulation system that took a lot of effort.
Same as above. Parastep
, a commercially available FES walking system, uses electrical signals directly on the legs of paralyzed individuals to affect a walking motion. It does take an effort to don and doff the gear and it’s suboptimal for long distance ambulation. Summers’ activity was related to movement patterns wired in to the spinal cord and elicited by the combination of epidural stimulation and intensive Locomotor Training.
Some people might be OK with an electronic band-aide but this will actually set back money for real regeneration work.
This comment appeared in various forms on the Reeve website and on Internet discussion boards elsewhere. Underneath the question is the notion that anything other than a biologic treatment won’t be a true cure. There is something about an on-off switch that puts some folks off. Well, let’s suppose real regeneration, in this context, means there has been success growing or replacing axons lost to trauma; this is, of course, the goal of many research projects and remains a significant part of the Reeve research portfolio. Regeneration research is difficult science; some approaches have shown promise in animal studies and are leading to clinical trials. Moving from trials to treatments – this is new territory for the SCI field. Tough, expensive decisions will have to be made.
Three points here: early regeneration trials will likely result in patients who become more incomplete, or if you like, less complete – that is, people might recover some motor and sensory function over a couple of spinal cord segments. These people will then become even better candidates for something like epidural stimulation, able to use technology to boost biology.
Second: the work on epidural stimulation doesn’t have to justify itself within the fully competitive world of science. It is not funded out of proportion to its significance and by no means does this work siphon funds from numerous biological experiments to repair spinal nerves.
Third: it’s hard to see how the changes in Summers’ bladder, autonomic and sexual function can be anything other than biologic. His nervous system appears to have been modified; some sort of plasticity or regenerative response has occurred.
So what. This research has not changed Summers’ daily life one iota.
Are you kidding? Ask Summers if it was a big deal: “This procedure has completely changed my life. For someone who for four years was unable to even move a toe, to have the freedom and ability to stand on my own is the most amazing feeling. To be able to pick up my foot and step down again was unbelievable, but beyond all of that my sense of well-being has changed. My physique and muscle tone have improved greatly, so much that most people don’t even believe I am paralyzed."
I’ve met Summers a couple of times since the hoopla of the epidural stim announcement. He lives in Los Angeles now, having moved in with his girlfriend, who he met last December in Louisville, KY the night before he was surgically implanted with the stimulator. Somebody got the idea the research project might make an interesting documentary. A friend of Summers’ from Oregon knew just one person with a connection to the movie business. She agreed to come to Louisville from LA thinking the story might indeed have possibilities. She got the scoop and more: she fell in love with Summers, and vice versa, which of course might have life-changing implications in a totally non-scientific realm.
But I digress. Summers still turns the stim on for two hours a day, stands in a frame, and spends at least an hour a day “practicing” flexing his toes/etc. He tells me he’s getting stronger and improving in voluntary motor control. What’s been remarkably understated in all of this is what happens when the stim is off: Summers says he can now feel when he needs to use the bathroom; he can sweat now; and in the sexual department, he reports that should the issue arise, he is now able to address it “in the normal way.” Draw your own conclusion whether or not that is a life-changer.
I bet that the epidural stim (even if improved drastically) won’t be rolled out as a therapy to the general SCI public.
You mean like cars that will get 100 miles per gallon but we don’t ever see them because the oil industry bought all the patents? There is a lot more to do before epidural stimulation is more than an experimental procedure, let along part of routine clinical SCI care. But there is no reason whatsoever to suspect it will be mothballed.
This technology will really only help the 10 to 15 percent of people with spinal cord injury who are basically about to regain the ability to walk a short distance using walkers or braces.
This comment understates the potential population that could benefit from epidural stim. It came from a prominent M.D., Ph.D. in the SCI field who makes reference to the cohort of very incompletely injured ASIA C and D folks who are already close to walking, assuming that they would benefit -- right now -- from epidural stim implants. While it may be the case that a stim unit could hasten their walking, the potential benefits extend well beyond the small number of almost-walking folks. Summers, for one, is ASIA B.
He’s incomplete. So what?
Exactly. Summers had sensation below his injury. But no motor function. There are obvious limits to this case study of one; what if he were ASIA A, no motor, no sensation…? The Louisville team has another patient just about ready for stimulator implant and at least three more to test in coming months. Others will need to replicate the work to assure validity. Suspend judgment until more data comes along but expect to hear much more about epidural stim as the mysteries of spinal cord circuitry are revealed.