Arkansas Neurosurgeon Studies New High-Frequency Implant to Ease 'Phantom Pain'

Nov 25, 2018

A neurosurgeon with the University of Arkansas for Medical Sciences is helping with a study on a high-frequency device similar to a pacemaker that can help ease amputation pain.

The study is part of clinical trials at up to 25 sites nationally.  Dr. Erika Petersen, a neurosurgeon and researcher, will lead the local study for UAMS.  Amputees will undergo surgery to be implanted with the device, which they can then activate for pain relief on an as-needed basis.

DR. PETERSEN: So amputation pain is interesting because there's two different kinds of pain that people who have lost a leg will tell you about. They have pain, which is at the stump where their leg now ends, and that makes it hard for them to wear a false leg or a prostethis.  It makes it just hard to get comfortable, because of where the scar is and where the leg was removed.

Dr. Erika Petersen and patient Jared Jackson discuss the nerve block device
Credit UAMS

The other piece is the pain from what we call 'phantom pain.'  That is, even though part of their leg is mssing, it hurts as if it's still there. I have patients who lost their leg below the knee who tell me that their toes feel like they are being stabbed with a poker, for example.  We think what's happening is that the brain is looking for what used to be there and filling in that information from nerves that are damaged from the surgery or the trauma that caused the leg to be amputated. And filling it in in a way that is frankly very stramge or bizarre or painful to that person.

ARKANSAS PUBLIC MEDIA: With her patients experiencing that kind of pain, Petersen was eager to begin the study.

DR. PETERSEN: You know, there's two things about it.  One is that there's not a lot of solutions to this kind of chronic, nerve damage-related pain that work for everybody. You can try medications, you can try doing additional surgery to see if that might help the tissue that is healed from the amputation in some way, but those don't work for everyone.  And a lot of people who are in chronic pain - they are already disabled from the loss of a limb, potentially, and the pain makes it to where they can't recover.  They can't rehabiliate, they can't resume life or work the way that they want to.

ARKANSAS PUBLIC MEDIA: The device itself is very small and is activated by the patient when he or she experiences pain.

A sample Altius High Frequency Nerve Block
Credit Ann Kenda / ARKANSAS PUBLIC MEDIA

DR. PETERSEN: It's radio, but I have a demo I could show you. The implanted battery pack is about the size of a box of tic-tacs or a little bit thinner than that, so about two inches by about an inch and a half in dimension.  It sits about an inch or so deep underneath the skin and there's a wireless device that communicates through the skin to activate it so patients can get a treatment to relieve pain. That signal, when the treatment is activated, is sent down a little electrical wire that runs under the skin of the leg and wraps around the nerves in the leg just above where the amputation has been.

ARKANSAS PUBLIC MEDIA: And the high-frequency nerve blocker is not an opioid.

DR, PETERSEN: Oh, that's absolutely for the best.  You know, there's been a lot of discussion about what an opioid epidemic we have, particularly here in Arkansas, and if we are able to reduce the dependence of patients on opioid medications, that also reduces the risk of having potentially life-threatening complications or overdoses.  Or having people in their families get access to those medicines and have harm from them as well. And so in this instance, avoiding those medications by using an alternative could be a true benefit.

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