Transcutaneous Electrical Nerve Stimulation: Too Experimental for PHN?

Transcutaneous electrical nerve stimulation, also known as TENS or TNS, involves placing tiny electrodes over the region experiencing pain. The electrodes deliver electrical impulses to nearby nerve pathways, relieving the pain (Mayo Clinic). Unfortunately, the process is very experimental: it does not work for everyone, and in fact can exacerbate the pain. The exact reason for relief is not known, although it is believed that the new electrical impulses trigger the release of endorphins, a natural painkiller.

On their website, Aetna lists the following as medically necessary for postherpetic neuraglgia (PHN): tricyclic antidepressants, gabapentin, pregabalin, opioids (oral), antivirals (oral), lidocaine patch, and intrathecal corticosteroids. However, it decrees TENS "experimental and investigational because their effectiveness for this indication has not been established" (Aetna clinical policy bulletin number 0725). According to the same site, there have been findings that report positive effects of TENS on some patients with PHN, but no validated, randomized and controlled study has been conducted. Additionally, in 1995 Reeve and Corabian evaluated evidence for clinical success of TENS on acute and chronic pain and found the results inconclusive.

Overall, TENS offers an interesting alternative to many PHN treatments; however, it raises the question, why use a treatment with significantly less conclusive results when you can use a less-questionable treatment? Admittedly, one positive reason to try TENS is its few side effects: it's not invasive, addictive, can be used for indeterminate amounts of time, and does not interfere with oral medications. It should not, however, be used with patients who have pacemakers because the electrical signals of the two devices could interfere with one another. The side effects that have been experienced with TENS include skin irritation from the electrode pads, and burns from extended exposure to stimulation. Yet, even with minor side effects, TENS has not proved to be any more revolutionary or helpful than other established treatments. Also, on a personal note, although I recognize that there are still many things about the body's processes that we do not understand, and this lack of comprehension does not prevent them from being effective, I would nevertheless favor a treatment that works through a known mechanism (particularly if it yields the same results).

But on the other hand, simply because we have not developed the treatment or the studies to their fullest extent does not mean we should dismiss it; there can be ample room for improvement. in an effort to give equal consideration to both sides of the TENS debate, it should be noted that although the treatment may be cumbersome and experimental, it nevertheless requires little effort from the patient and could be very manageable for people who do not need to travel much. And, of course, it would be very worthwhile if it eliminated PHN pain.

TENS can also be used to administer topical steroid medication through the skin to treat acute pain, because the electrical current it generates helps move the steroids into soft tissue, reducing inflammation. The TENS unit is battery-operated portable; it can be worn around the waist and can be turned on or off as needed for pain control. They can cost anywhere from approximately one hundred dollars, all the way up to six hundred dollars from the top manufacturers. The units are purchased or rented with a prescription, and a physical therapist should be consulted on the proper placement of the electrodes. Generally, TENS is used on a trial basis before being recommended as a long-term treatment. Of course, before using a TENS unit, be sure you have spoken to a physical therapist or doctor and know how to work the device and set the electrical signals at appropriate levels.