Flexible spinal implant heals paralysis in rats
Graham Templeton
January 12, 2015
When electrical signals leave the brain on their way to the body’s extremities, they are all funneled through a bottleneck in the actualneck. Even further down the spine, when a portion of our nervous commands have already peeled off toward their individual destinations, the nervous system has a severe lack of redundancy; sustain damage to your spine, and you lose access to whole fractions of your body. That’s why the body keeps the spine pretty well protected — it’s on your back, for one, studded with bone, flanked by thick slabs of back muscle, and sheathed in a protective sleeve called the dura mater (which also extends upward to help protect the brain).
These protections, which make so much sense from an evolutionary perspective, tend to make life more difficult for doctors and biomedical engineers, however, and recent successes granting movement to paralyzed rats were undercut by negative side-effects. Now, thanks to a truly next-generation spinal implant, a solution may be on the way.
Last year, an implant very similar to the one in this study was used to reconnect both sides of a severed spinal cord, and received some well-deserved attention in return. However, less thrilling was the fact that the rodents whose legs had become usable again quickly suffered major spinal injuries — the dura mater, in particular, seemed incapable of dealing with having such an alien piece of technology inside it.
This led to intense research on improved fabrication of the implant (which seemed to work, at least in principle) so it could have all the same capabilities in a softer, more flexible form. Now, thanks to input from researchers all over the world, comes e-dura, a flexible spinal implant that carries both electrical and chemical signals without seeming to cause any additional damage to the spine it’s assisting.
The rats in this experiment were fitted with the implants for long periods of time, up to several months in some cases. This shows that the system could be viable in the extreme long term, especially since this is just a first attempt. Also, since the dura mater extends into the cranium, it’s possible that this technology could assist with powered implants on or near the brain. E-dura‘s ability to ferry chemical signals as well as electrical (a big part of its success in actually restoring some movement ability) could also be used for localized drug delivery, which would also be doubly useful in the context of long-term brain implants.
It’s remarkable that research has now reached the refinement stage for re-routing the spinal cord, that the simple fact of the endeavor is no longer enough to impress. We’re not at the point of bringing the principle together with the practical, a process that’s usually longer than we’d like but still quite short on the whole. In that spirit, human trials are a proximate goal now.
Note that all this really is, is a way of jumping neural signals from one place to another, and there’s no specific reason that it need only be applied to the spine. Sufferers of extreme epilepsy are sometimes forced to undergo horrifically destructive surgical procedures to control the storms of neural energy in their brains, but perhaps a patient could be fitted with a smart implant that replaced a severed corpus colosseum except during a seizure. Perhaps a nucleus of neurons found to be firing incorrectly and causing chronic pain could have its signals redirected to nowhere.
These are of course very long-term applications, if they’re possible at all, but they are the sorts of application that are becoming possible enough to intrigue real researchers. With tools like e-dura at their disposal (assuming human testing goes ahead successfully), doctors and engineers will have some incredible opportunities before them. As much as this is a direct attempt to solve the paralysis, it is also a general ability to direct neural information precisely where we want it to go. How such an ability might be applied, I’d challenge anyone to predict.
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