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Leaving Vagus: From The Vagina to The Relief of Chronic Pain

Taking the vagus out of vague.

A recent article in the journal "Pain Medicine" described the relief of treatment-resistant fibromyalgia via stimulation of the vagus nerve, that serpentine cranial nerve which allows even female victims of complete spinal nerve injury to experience orgasm.

The small pilot study reported in this article involved 14 women diagnosed with fibromyalgia, who had not responded adequately to treatments such as nonsteroidal anti-inflammatories, tricyclic antidepressants, and anticonvulsants. These subjects underwent surgical implantation with a vagus nerve stimulation (VNS) device, and subsequently underwent a two-week stimulation adjustment period during which VNS intensity was increased to deliver the highest tolerable current.

Subjects experienced the same side effects seen with VNS treatment of epilepsy and depression, including voice alteration, neck pain, nausea, shortness of breath, dry mouth, and fatigue.

Nevertheless, the therapeutic effect documented appears to overshadow such adverse events, at least at this preliminary stage of investigation: The primary efficacy outcome was a composite of pain, overall well-being, and physical function. Interestingly, five of the 14 subjects had significant improvement in these parameters, and two actually ceased to fulfill fibromyalgia diagnostic criteria for pain and tenderness. Moreover, it was found that eight months beyond the conclusion of this three-month study, seven participants were now found to have significant improvement, and there was improvement in the classic widespread pain of fibromyalgia.

If anything, this small study is thought-provoking. After all, the vagus nerve conveys sensory information about the state of the body's organs to the brain; approximately 90% of this nerve's fibers are sensory nerves. The Latin word "vagus" means "wandering" (think of all the words that use the same root: vagrant, vagabond, vague, to name a few); I cannot tell you how often a fibromyalgia patient has described to me the generalized vagueness of the pain experienced, the wandering nature of the noxious discomfort.

And the vagus nerve can be activated during emotional stress and sexual excitement, both of which stimuli can result in fainting as a result of a sudden drop in blood pressure. It would certainly be interesting to have a psychometric evaluation if further studies are undertaken with VNS for fibromyalgia, particularly in light of the great body of literature dealing with the emotional and psychological impacts on fibromyalgia severity and responsiveness to treatment.

As always, in such a small trial, the potential impact of the placebo effect will cast doubt on results. The truth might be found in future and larger studies.

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