Today I was working with one of my pudendal neuralgia patients and noted that she had these stimulation pads on her left foot. These are common in PTNS, or posterior tibial nerve stimulation. I asked her who she was working with that was doing PTNS?
She replied "oh my acupuncturist said these were the acupuncture points to help with pudendal neuralgia and recommended that I do TENS at these points."
It is always interesting when we see the intersection between allopathic and complementary medicine. In Chinese medicine, it is known that stimulation of these points helps with bladder spasticity, and apparently they use it for PN type pain as well. It is also known by me that the same stimulation will help with pudendal neuralgia, because it neuromodulates S2, which is part of the pudendal nerve.
What is fascinating is that in Chinese medicine this is explained through system of energy meridians, rather than though the neuroanatomy and physiology that we understand in allopathic medicine.
In Pre-Copernican times, there was a model of the heavens that put the earth in the center of the solar system. It had complex mathematics that involved certain bodies changing directions at certain times. It was quite accurate in predicting where the heavenly bodies would be in the sky. That said, it was completely wrong.
I often think that Chinese medicine is like this model. Much of what it predicts is correct, but not for the reason they say. I don't believe there are measurable energy meridians throughout the body that can be manipulated with needles and nerve stimulation. But I do believe that stimulation of peripheral nerves will cause a neuromodulatory effect, and may cause an effect in another part of the body that seems completely unrelated, though in actually they are related neurologically.
I suspect that every effective use of acupuncture is working this way, and if one really looked at the nerve patterns involved we would see a similar relationship to what we see in this case.
In this specific case, the pudendal nerve is made up of S2, S3, and S4 fibers. With PTNS stimulation, there is a peripheral neuromodulation signal effecting S2. We also know that given enough voltage, a neuromodulatory signal can jump several nerve roots, probably conducted through the sympathetic chain which bridges the different roots. As such, she was receiving indirect pudendal nerve neuromodulation.
As such, I think the acupuncturist was making a great recommendation to my patient, suggesting TENS at these points. She calls it acupuncture point electrical stimulation, I call it PTNS.
With this particular patient, she did experience moderate relief when she turned the unit on at these locations. I may suggest this further to other PN patients, as it is inexpensive, harmless, and may improve their quality of life.
The other thing about this is that in a patient who experiences some relief with PTNS, I think there is a very good chance they will experience ever more relief with a DRG implant at S2 or S3. PTNS is stimulating a peripheral nerve, but that signal has to be conducted all the way up the leg to the Dorsal Root Ganglia to cause its action. The DRG is the cell body, where all the action happens. The rest of the nerve is really just cable.
A DRG stimulator puts the electrode directly on top of the DRG. With an electrode so close, one can create a powerful neuromodulatory signal with very low voltage. This is better than peripheral stim because to achieve the same effect with peripheral stim, one would require a voltage that would be painful to administer. But with a wire right on the DRG, a very low voltage can have a large effect.
The use of DRG is really a very high tech version of what is being accomplished with the PTNS, but has the opportunity to be even more effective. At this point it is experimental in pudendal neuralgia, but early data are promising.
Nicholas Fogelson, MD