How a new implant could treat pain without opioids


At one time or another, we all experience physical pain. We cross it or turn to medicine, from aspirin to opioids. New research published in the journal Science highlights a more mechanical alternative: a biodegradable implant that cools a nerve to block pain signals.

It looks like a small transparent rubber band with tiny channels winding through it. Marketplace’s Kimberly Adams spoke with John Rogers, a biomedical engineer from Northwestern University who led the research and design of the device. He explained how the technology works and the challenges of managing chronic and acute pain. The following is an edited transcript of their conversation.

John Rogers: If you’ve ever been outside on a cold day without gloves, your fingers are going numb in many cases. And this is a consequence of the cooling effect on the propagation of signals through the sensory nerves of the fingertips. We are exploiting this same type of effect, but applied to peripheral nerves which are deep inside the body and which carry pain signals from a particular region of the body to the brain. By providing this local cooling effect, we can block these signals. And we can do it in a reversible and controllable way that could provide an alternative to drug or pharmaceutical approaches to pain management in the future.

Kimberly Adams: This is such an important point. Many people are prescribed opioids for pain, which in many ways has fueled opioid addiction. Is this a potential future solution to some of these issues?

Roger: Well, we hope so. I’m a biomedical engineer, and we’re thinking about device and technology-based approaches to meeting patient needs, ultimately. And pain management is an important part of patient care. And we realized the challenge of opioids, addiction and all the bad consequences of this kind of approach to pain management and decided that as engineers maybe we could come up with an alternative device-based. And so this device is very focused. It is placed in a specific place on the body. It is deterministically controlled, unlike drugs which pass through the body uncontrollably in many cases. And it also has a switch and a dial, which allows us to turn the painkiller effect on and off. And we can adjust its magnitude. So it’s quite different from a drug-based approach, and we think it could offer significant benefits.

Adam: If you cool the nerves enough to stop the pain signals, how do you also avoid stopping the nerve signals that, for example, make your muscles move?

Roger: So it turns out that there is a range of temperatures where you can block these pain signals without blocking the motor signals that are needed to control the muscles of the body. So it turns out that if you control temperature very tightly, you can block out pain without affecting motor behaviors.

Adam: Since you already knew that applying cold to a specific nerve could potentially numb or reduce pain, what about the distance between the surface of the skin and the location of the sore spot that makes it difficult to bring of this chill where you are? try to go?

Roger: Ultimately, the goal here is to deliver cooling power locally to a region of interest, but nowhere else. And so any kind of approach that doesn’t offer this ability will lead to cooling in unwanted places in the body. And in some cases, this cooling can be excessive in the sense that it can damage adjacent tissues. And so our device and our ability to create this evaporative cooling effect only at the location of the peripheral nerve that we want to induce pain blockage is a key feature of how we assemble the device.

Adam: Opioids are often used to treat chronic pain. And it seems like what you’re mostly talking about here is more acute pain, like that related to surgeries and things like that. Is there a rollout of this technology for chronic pain, such as that often treated with opioids?

Roger: That’s certainly one of our goals, is to use this development as perhaps a starting point for the treatment of chronic pain. We initially decided to focus on this acute postoperative pain opportunity because the device is an implantable system. And the way it’s set up right now, it requires access to external hardware—pump systems and access to those coolants, for example—for it to work properly. So I think that kind of postoperative hospital care and in an acute setting is a natural starting point based on certain engineering characteristics. But that does not mean that one could perhaps not envisage a fully implantable version of this device, with a recirculation pump in miniaturized form, which can be inserted into the body, in which case one could easily imagine that it is used to treat chronic forms of pain. This will require significant additional technical development work, but it is something we are very interested in.

Adam: How far are we from having this as part of regular patient care, if at all?

Roger: There is additional work that needs to be done around biological effects; in particular, the time and duration of this cooling which can be imposed on a nerve without any sort of irreversible adverse effect on the tissue itself. We need to do more of this kind of work and more of this kind of study in larger animal models. This is something to keep in mind. The other is that a device of this type represents a general class of technology that the [Food and Drug Administration] has not been processed in the past. And so there are associated uncertainties that come with that in terms of the regulatory process, but that’s another kind of wild card to kind of predict when this device would be available for widespread use with humans.

An illustration of the implantable device inside an arm. The red oval indicates pain. The device gently wraps around the peripheral nerve to silence signals to the brain. (Courtesy of Northwestern University)

Rogers said one of the benefits of this new device is that once you’re done using it, it dissolves in the body in about 50 days. here is a short video showing what it looks like.

While Rogers said the current device is best suited for acute pain, such as during surgery, he said the implant could one day, with some improvements, be used to treat chronic pain and replace opioid treatments.

For now, there are other technological options for treating chronic pain. In November, the FDA endorsed a virtual reality home program that treats chronic lower back pain.

While we’re on the subject of VR, here’s an interview my colleague Meghan McCarty Carino did in April about how VR is being used not just to treat pain, but to help diagnose certain ailments. So I guess the doctor is going to see you now – in your helmet.


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