A summary of the Commentary by Melissa A. Farmer “What is special about the vulvar vestibule?” Copyright 2015 by the International Association for the Study of Pain, March 2015, Volume 156, Number 3
If you were to take a mirror and take a look at the opening of your external genitalia, you would be looking at your vulvar vestibule. The vulvar vestibule (or “entrance way” to the vagina) includes from the clitoris to the urethral opening (for urinating) to the vaginal opening as well as portions of the inner lips on either side of the vaginal opening. Many incorrectly refer to the whole area as “the vagina”. Actually the skin of the vestibule lies between the vaginal lining and the outside hair bearing skin. If you need a little help on vocab and anatomy - check out this blog.
It is also really important to realize that the most common reason for entrance pain with intercourse, tampon use, vaginal speculum or just light touch from clothing is the common condition known as vulvar vestibulitis or better called vulvar vestibulodynia. (“itis” means inflammation and “dynia” means pain).
So back to looking in the mirror. You’ve probably never whispered “you’re special” to your vulvar vestibule. But it is. Not just for its role in the reproduction of life, but because the external tissues in that area are actually very different from other mucosal surfaces in the body. Mucosal surfaces are those bodily tissues that excrete mucus like the inside of your mouth and the inside of your nose. The difference is in the “profile” of the immune cells in that area, meaning the type and the amount of the cells of the immune system. Given how important the external genitalia is to the reproduction of life, we would suspect that it would indeed be a place that needs some extra immune system defense. This same observation holds true for other species as well, not just humans.
We also know that one of the methods the immune system uses to attack what it identifies as a threat to the system is inflammation. And as a result of inflammation we often feel pain. It makes sense then that pain brought on by inflammation at the vulvar vestibule would be different than the pain brought on by inflammation at other mucosal sites. Recent research seems to indicate that pain felt in this area is determined by 1) the amount (not simply the presence alone) of low grade inflammation, 2) altered vulvar nerve innervations, meaning an abnormality in the distribution of impulses of the nerves in that area, and 3) genetic susceptibilities that contribute to abnormal inflammatory cascades (chemical messengers that ramp up the immune system and cause a domino effect).
Vagina! (You are definitely more complicated than we thought!!!)
Just making sure you’re still with me here, this information is dense but it’s how we know persistent genital, sexual, and pelvic pain has a MEDICAL and SCIENTIFIC explanation.
Ok, back to the mirror. We know that the vulvar vestibule is derived (or made from) the endoderm. When we were just embryos in the womb, the inner-most layer of that embryo is called the endoderm. Do you know what else was derived from the endoderm? The bladder and urethra and also the gastrointestinal tract. It is possible that these other structures also have unique immune profiles, similar to that of the vulvar vestibule.
Let’s briefly recap: The vulvar vestibule has a unique immune profile compared with that of other mucosal sites. An immune/inflammation response at the vulvar vestibule isn’t enough to cause pain. Pain is determined by the magnitude of the immune response/inflammation. The vulvar vestibule, the bladder, and urethral linings are all derived from the endoderm and could share immune profiles.
One last piece of information that’s critical to note: the most recent research is finding that in the clinical setting, self-reported pain levels at the vulvar vestibule are closely connected with the release of an immune system messenger known as cytokine. That means when research study participants reported increased pain, the presence of cytokines in the examined vulvar tissue also increased.
What does all of this really mean? It means that we know that chronic genital, sexual, and pelvic pain is real in a clinical and biological sense. We of course recommend treatment modalities that work from the top-down to address the mind-body connection and help turn the central nervous system pain ‘volume dial’ down. But we also want to highlight the science behind the pain and the need for bottom-up approaches in line with current research and the desperate need for earlier diagnosis and appropriate treatment modalities and medications to counter these inflammatory and painful processes.
Stephanie Yeager: Passionate about spreading the word of hope and healing for those like her, influencing a paradigm shift in the medical community toward greater understanding of chronic pelvic pain disorders, and prevention initiatives that may protect young women before onset can occur.