Vulvodynia is a chronic pain disorder localized to the region at the opening of the vagina, the vulvar and vestibule regions. Vulvodynia is not a single condition, rather a constellation of different conditions with various clinical presentations. Various studies have shown that vulvodynia affects approximately 15% to 20% of adult women. It is the most common cause of sexual pain in premenopausal women.
The vestibule surrounds the opening of the vagina and is approximately 1/2 inches wide starting at the hymenal remnant of the vaginal opining and extending to approximately half way along the inner surface of the labia minora. The inner and outer surface of the labia minora are separated by Hart’s line. At Hart’s line, the outermost surface of skin, called the stratum corneum, stops. As a result, the vestibule has a whitish color, while the vulva is brown or black and has thickness of regular skin. The vestibule contains mucous-secreting vestibular glands that release lubrication during sexual arousal.
Patients with provoked vulvodynia (PVD) may experience severe burning, cutting, or searing, raw-like pain at the opening to the vagina upon some sort of provocation such as cotton swab testing or upon initial vaginal penetration. The term generalized vulvodynia (GVD) is used if the pain exists all the time and is not related to provocation.
Vulvodynia may be the result of inflammatory and infectious disease processes, neurologic conditions, genetic factors, stress factors, and hormone factors.
When specifically addressing provoked vestibulodyna (PVD), the most common causes are hormonal changes, tight (hypertonic) pelvic floor muscles, and an increased number of nerve endings in the mucosa of the vestibule.
In some women, the provoked vestibulodynia may be caused by a hormonal- mediated vestibulodynia where there is an absence of these hormone receptors. A common risk factor is use of hormonal contraception, the birth control pill, the patch or the ring. In such cases, the preferred treatment is to discuss with the healthcare provider stopping the hormonal contraception and to consider other options. In addition, hormonal treatment is started with either local estradiol to the vestibule and systemic testosterone, or local estradiol and testosterone.
Other etiologies include a proliferation or growth of pain nerves, called “c-afferent nociceptors” in the skin layer of the vestibule. This high density of nerve endings, called neuronal hyperplasia, may explain the fact that women with provoked vestibulodynia experience severe pain from a stimuli that does not normally cause pain.
For women with primary or lifetime PVD, it is felt by some experts that the high density of pain nerves in the vestibule has occurred as the result of a congenital accumulation of nerve fibers. For women with secondary or acquired PVD, researchers have shown the high density of pain nerves in the vestibule has occurred as the result of healing cells called mast cells excessively releasing a protein called nerve growth factor. The mast cells may be responding to a healing stimulus from an allergy on the skin of the vestibule from medications used for yeast infections, or from trauma to the vestibule from bicycle riding or spinning, or from local treatments from diseases such as herpes or HPV. Once the nerves have proliferated, they are not known to disappear.
There are multiple other causes including dermatologic conditions such as lichen sclerosis, and lichen planus, infectious reasons such as chronic infection from fungi/yeast, tissue injury reasons from a fissure that forms related to poorly healing episiotomy repairs.
On physical examination of the pelvic floor, women have increased spasm and increased tone of the levator ani muscle in response to vulvar pain. Studies have shown vestibular tissues to have more redness (erythema).
One of the most distressing aspects of vulvodynia or vestibulodynia is that afflicted women frequently experience pain for many months, often years, before being diagnosed.