What is Peripheral Nerve Stimulation?
If you ever bump your elbow, the first thing you might do is rub it to make it feel better. This idea of reducing your elbow pain is based on the Gate Theory of Pain, first described by R. Melzack and P. Wall in 1965. By rubbing your injured elbow, you are increasing the normal touch sensory input and essentially overriding the sensation of pain through the spinal cord and brain. A transcutaneous electrical nerve stimulation (TENS) unit works in the same way. Several adhesive electrodes are placed over the painful area and electrical impulses are delivered through the skin and subcutaneous tissues to stimulate the nerves and block the pain signals from reaching the brain.
A TENS unit has several disadvantages, however. It might not be strong enough to effectively reduce your pain, and if it is, you may experience a buzzing, tingling, or prickling sensation that can be uncomfortable. Also, TENS should only last for 30 minutes at a time and it is common for the pain to return as soon as the unit is switched off. These characteristics tend to make TENS a cumbersome and often ineffective way to treat chronic pain.
Peripheral nerve stimulation (PNS) is an FDA-cleared system that takes TENS therapy to the next level, actually, down a level – to the nerve itself. Under fluoroscopic (X-ray) guidance, a small wire is placed through a needle to lie directly adjacent to the nerve suspected to be transmitting the bulk of your pain signals. This allows for much more potent stimulation of the nerve, as compared to TENS. There is also a carry-over effect, meaning your pain relief will typically extend beyond just when the device is active. Once implanted, the wire is activated and controlled by an external wearable antenna assembly. Although results may vary, many patients report only needing to wear the antenna assembly for approximately 4 hours to yield 2-3 days’ worth of pain relief. When not wearing the antenna assembly, nobody can see you have a wire under your skin. You are unlikely to even see or feel it yourself. Therefore, you can still experience pain relief in the shower, in the pool, when exercising, or simply when sporting your favorite outfit on the town. In summary, this minimally invasive, implantable technology offers a convenient, long-lasting, drug-free alternative to treat your chronic pain.
Who Might Benefit from Peripheral Nerve Stimulation?
In general, patients who might benefit from PNS are those with severe pain who want to avoid surgery (i.e., knee replacement surgery, etc.) or whose recovery from surgery (or injury) has been complicated by chronic pain otherwise refractory to more conservative treatments, such as rest, oral analgesics, anti-inflammatories, and chiropractic or physical therapy. Common pain syndromes that are amenable to this technology include shoulder pain (suprascapular nerve), low back pain (superior cluneal nerve), sacroiliac (SI) joint pain (middle cluneal nerve), knee pain (genicular nerve), and foot/ankle pain (tibial nerve), among others.
What Does the Process Involve?
Once you have been identified as someone who might benefit from PNS, you will be scheduled to undergo a diagnostic ‘block’ of the specific nerve in question. This involves essentially injecting the nerve with lidocaine or other anesthetics with the purpose of numbing the area the nerve supplies. If your typical pain is significantly better during the anesthetic period (up to 2 hours), likely that the nerve is indeed responsible for your pain, and so this qualifies you for a PNS trial.
A PNS trial involves inserting the wire through a needle to lie directly adjacent to the nerve. This is a relatively innocuous outpatient procedure and so local anesthetic really is all that is required. Once the wire is in the right place, the needle is removed, leaving behind a ‘tail’ coming out of the skin. This leftover wire is coiled up and secured with a bandage over the skin. Once in recovery, you are fit with an external wearable antenna assembly and the wire is activated and programmed. Often, patients will experience significant pain relief right away. For some, a few programming adjustments will be required. After 1 week, you follow up in the clinic and the wire is easily removed. If during that first week, you achieved meaningful and significant pain relief, then we will proceed with the permanent implantation of the PNS device.
Permanent implantation of the PNS device involves all the same steps as the trial, except instead of leaving a tail hanging out, that residual wire is routed at an angle and affixed under the skin. This allows the whole wire to be buried in your skin and secured against movement, or migration. You will then follow up in the clinic after 10-12 days for device activation. Throughout the whole process, you are followed closely by your physician and PNS representative. This ensures that your questions are being answered and your path to success is without complication.
Does Insurance Pay for PNS?
PNS is covered by Medicare and most major commercial insurance companies, although Blue Cross Blue Shield is the notable exception at this time.
Dustin Leek, MD
Updated 1/27/2023