Description

• Vulvar discomfort, often described as burning. Occurs in the absence of relevant visible findings, relevant lab abnormalities, or a clinically identifiable neurologic disorder
• Classification is based on whether pain is generalized or localized and whether it is provoked (by physical contact), spontaneous, or mixed:
  • Generalized: Involvement of majority of the vulva; usually persistent or spontaneous pain
  • Localized: Severe pain of certain vulvar areas, such as the vestibule (formerly known as vestibulodynia), usually provoked with touch or attempted vaginal entry; thought to be the leading cause of painful intercourse among premenopausal women:
    • Primary: Introital dyspareunia from first episode of intercourse or first insertion of tampon or vaginal speculum
    • Secondary: Introital dyspareunia developing after a period of painless intercourse, tampon use, or speculum exams

Epidemiology

• Most women diagnosed between the ages of 20 and 80.
• Patients are psychologically comparable to asymptomatic controls and have similar marital satisfaction.

• Recent retrospective study estimates annual rate of new onset vulvodynia to be 1.8% (1).
• Evidence indicates lifetime cumulative incidence approaches 15%, suggesting nearly 14 million US women will experience persistent vulvar discomfort at some point in their lives (2).

• Reports between 3.1% and 15%; nonclinic-based studies approximate a prevalence of 7% with validation by exam.
• Studies show Hispanics 80% are more likely to present with vulvar pain compared with Caucasians and African Americans (3).

Risk Factors

• Vulvovaginal infections, specifically candidiasis. Unclear if infection, treatment, or underlying hypersensitivity is the cause (4)
• Hormonal factors: Controversial evidence proposes increased risk with use of OCPs; early age at first use of OCPs and longer duration of use have been associated with increased risk.
• Pelvic floor dysfunction: Increased instability of pelvic floor muscles may perpetuate vulvar tissue inflammation, leading to vascular changes and histamine release.
• Comorbid interstitial cystitis and painful bladder syndrome; potentially related to common embryological origin of structures
• Abuse: Increased risk of vulvodynia if childhood physical or sexual abuse by a primary family member; causal relationship remains unclear (2)
• Depression and anxiety (4)
• Other neuropathic disorders, including regional pain syndrome

Genetics
Proposed genetic deficiency impairing one's ability to stop the inflammatory response triggered by infection or chemicals; homozygosity of the 2 alleles of the IL1 receptor antagonist occurs in 25–50% of vestibulodynia patients, compared witho fewer than 10% in controls (5).

General Prevention

• Wear 100% cotton underwear in the daytime and no underwear to sleep.
• Avoid douching and other vulvar irritants such as perfumes, dyes, detergents.
• Avoid abrasive activities and tight, synthetic clothing.
• Avoid panty liners.
• Clean the vulva with water only and pat area dry after bathing.
• Avoid use of hairdryers in the vulvar area.

Pathophysiology

• Vulvodynia is likely to be neuropathically mediated:
  • Allodynia and hyperalgesia are thought to result from neurogenic inflammation leading to sensitization of primary afferents by inflammatory peptides, prostaglandins, and cytokines. Impulses transmitted to CNS, where reinforcing signals sustain pain loop.
  • In recent investigations of vulvar biopsy specimens, increased neuronal proliferation and branching in vulvar tissue are evident when compared with tissue of asymptomatic women (5).
• Pelvic floor pathology also should be considered: In one study, the vulvodynia group showed an increase in pelvic floor hypertonicity at the superficial muscle layer, less vaginal muscle strength with contraction, and decreased relaxation of pelvic floor muscles after contraction (2).

Etiology

No cause of vulvodynia has been established. It is most likely a neuropathic pain caused by:

• Recurrent vulvovaginal candidiasis or other infections
• Chemical exposure (trichloroacetic acid) or physical trauma
• Reduced estrogen receptor expression/changes in estrogen concentration
• CNS etiology, similar to other regional pain syndromes

Commonly Associated Conditions

Higher incidence of chronic pain syndromes associated with vulvodynia, including: Chronic cystitis, irritable bowel syndrome (IBS), fibromyalgia, migraines, depression, endometriosis, low back pain