Immune activation enhances epithelial nerve growth in provoked vestibulodynia

Immunohistochemical staining with CD117 and PGP9.5 of excised vestibular tissue from patients with neuroproliferative vestibulodynia

BACKGROUND

Neuroproliferative vestibulodynia (NPV), a provoked genital pain characterized by severe allodynia and hyperalgesia, is confirmed in excised vestibular tissue by immunohistochemical staining (>8 CD117-positive immunostained cells/100× microscopic field) rather than by hematoxylin and eosin staining.

AIM

In this study we sought to assess immunostaining of tissue samples obtained during vestibulectomy surgery and to correlate results with patient outcomes.

METHODS

Patients (n = 65) meeting criteria for NPV who underwent vestibulectomy during the period from June 2019 through December 2022 formed the study cohort. We performed assessment of pathology of vestibular tissues by use of immunohistochemical staining, including quantitation of mast cells by CD117 (mast cell marker) and nerve fibers by protein gene product (PGP) 9.5 (neuronal marker). We analyzed 725 photomicrographs of immunostained tissue sections (100× and 200×) by manual counting and computer-assisted histometry and correlated these data to clinical assessments.

OUTCOMES

Outcomes included density of CD117 and PGP9.5 immunostaining in the 1:00-11:00 o'clock and 12:00 o'clock vestibular regions, and patient-reported outcomes assessing sexual function, pain, distress, and symptom improvement.

RESULTS

All 65 NPV patients (median age 26 years), 45 with lifelong and 20 with acquired NPV, had severe pain documented by PROs and vulvoscopy and had >8 CD117-immunopositive cells/100× microscopic field. Median cell count values were similar in the 1:00-11:00 o'clock and 12:00 vestibular regions (28.5 and 29.5/100× field, respectively). Likewise, the marker) and nerve fibers by protein gene product (PGP) 9.5 (neuronal marker). We analyzed 725 photomicrographs of immunostained tissue sections (100× and 200×) by manual counting and computer-assisted histometry and correlated these data to clinical assessments.

OUTCOMES

Outcomes included density of CD117 and PGP9.5 immunostaining in the 1:00-11:00 o'clock and 12:00 o'clock vestibular regions, and patient-reported outcomes assessing sexual function, pain, distress, and symptom improvement.

RESULTS

All 65 NPV patients (median age 26 years), 45 with lifelong and 20 with acquired NPV, had severe pain documented by PROs and vulvoscopy and had >8 CD117-immunopositive cells/100× microscopic field. Median cell count values were similar in the 1:00-11:00 o'clock and 12:00 vestibular regions (28.5 and 29.5/100× field, respectively). Likewise, the median area of CD117 immunostaining was similar in both regions (0.69% and 0.73%). The median area of PGP9.5 immunostaining was 0.47% and 0.31% in these same regions. Pain scores determined with cotton-tipped swab testing were nominally higher in lifelong vs acquired NPV patients, reaching statistical significance in the 1:00-11:00 o'clock region (P < .001). The median score for the McGill Pain Questionnaire affective subscale dimension was also significantly higher in lifelong vs acquired NPV patients (P = .011). No correlations were observed between hematoxylin and eosin results and density of mast cells or neuronal markers. Of note, 63% of the patient cohort reported having additional conditions associated with aberrant mast cell activity.

CLINICAL IMPLICATIONS

The pathology of NPV is primarily localized to the vestibular epithelial basement membrane and subepithelial stroma with no visible vulvoscopic findings, making clinical diagnosis challenging.

STRENGTHS AND LIMITATIONS

Strengths of this study include the large number of tissues examined with what is to our knowledge the first-ever assessment of the 12:00 vestibule. Major limitations are specimens from a single timepoint within the disease state and lack of control tissues.

CONCLUSIONS

Performing immunohistochemical staining of excised vestibular tissue with CD117 and PGP9.5 led to histometric confirmation of NPV, indications that NPV is a field disease involving all vestibular regions, validation for patients whose pain had been ignored and who had experienced negative psychosocial impact, and appreciation that such staining can advance knowledge.

Inflammation, lipid dysregulation, and transient receptor potential cation channel subfamily V member 4 signaling perpetuate chronic vulvar pain

ABSTRACT

Localized provoked vulvodynia is characterized by chronic vulvar pain that disrupts every aspect of the patient's life. Pain is localized to the vulvar vestibule, a specialized ring of tissue immediately surrounding the vaginal opening involved in immune defense. In this article, we show inflammation is the critical first step necessary for the generation of pain signals in the vulva. Inflammatory stimuli alone or combined with the transient receptor potential cation channel subfamily V member 4 (TRPV4) agonist 4α-phorbol 12,13-didecanoate stimulate calcium flux into vulvar fibroblast cells. Activity is blocked by the TRPV4 antagonist HC067047, denoting specificity to TRPV4. Using lipidomics, we found pro-resolving lipids in the vulvar vestibule were dysregulated, characterized by a reduction in pro-resolving mediators and heightened production of inflammatory mediators. We demonstrate specialized pro-resolving mediators represent a potential new therapy for vulvar pain, acting on 2 key parts of the disease mechanism by limiting inflammation and acutely inhibiting TRPV4 signaling.

Exploring venlafaxine effects on chronic vulvar pain: Changes in mood and pain regulation networks

The etiology of idiopathic pain conditions, such as Provoked vulvodynia (PV), is multifactorial. The efficiency of venlafaxine, serotonin-noradrenaline reuptake inhibitor (SNRIs) in modulating vulvar pain led to the hypothesis that PV might involve central mechanisms. Here, we investigate whether vulvar pain is associated with gene-expression changes in mood, stress and pain systems, including amygdala (Amg), medial prefrontal cortex (mPFC), and periaqueductal gray matter (PAG). Additionally, we examined the analgesic and anxiolytic effects of venlafaxine. We found that the development of chronic vulvar pain in an animal model of PV is associated by overexpression of genes related to neuronal-activity and neuroinflammation in the Amg, mPFC, and PAG. Additionally, changes in the expression of GABA and serotonin synthesis, and reuptake were noted in the Amg and mPFC. Unsurprisingly, anxiety-like behavior and emotional-disorder were observed in rats with chronic vulvar pain. Nevertheless, treatment with venlafaxine (37.5 mg/kg) for one month significantly improves the vulvar hypersensitivity, as well as reduces the anxiety level. More critically, the long-term gene expression adaptation in serotonin receptor and synthesis, GABA synthesis, neuroplasticity, and neuroinflammation in the Amg, mPFC, and PAG, were modulated by venlafaxine in rats with vulvar pain. Our findings suggest that vulvar hypersensitivity induced by inflammation might associated with gene expression changes in brain areas that are involved in mood, stress and pain regulation. These changes probably play a role in central sensitization, and anxiety. Strikingly, enhancing the activity of serotonin and noradrenaline via venlafaxine treatment in rats with vulvar pain induces analgesic and anxiolytic effects.

Neuroproliferative dyspareunia in endometriosis and vestibulodynia

INTRODUCTION

Endometriosis is a common cause of deep dyspareunia, while provoked vestibulodynia is a common cause of superficial dyspareunia. The etiology of dyspareunia in both conditions is multifactorial and may include the role of local nerve growth (neurogenesis or neuroproliferation) that sensitizes pelvic structures and leads to pain with contact.

OBJECTIVES

To review the evidence for neuroproliferative dyspareunia in endometriosis and provoked vestibulodynia.

METHODS

Narrative review.

RESULTS

The pelvic peritoneum and vulvar vestibule receive somatic and autonomic innervation. Various markers have been utilized for nerve subtypes, including pan-neuronal markers and those specific for sensory and autonomic nerve fibers. The nerve growth factor family includes neurotrophic factors, such as nerve growth factor and brain-derived neurotrophic factor, and their receptors. Studies of endometriosis and provoked vestibulodynia have demonstrated the presence of nerve fibers around endometriosis epithelium/stroma in the pelvic peritoneum and within the vulvar vestibule. The number of nerve fibers is higher in these pain conditions as compared with control tissue. Nerve growth factor expression by endometriosis stroma and by immune cells in the vulvar vestibule may be involved in local neuroproliferation. Local inflammation is implicated in this neuroproliferation, with potential roles of interleukin 1β and mast cells in both conditions. Several studies have shown a correlation between nerve fibers around endometriosis and dyspareunia severity, but studies are lacking in provoked vestibulodynia. There are several possible clinical ramifications of neuroproliferative dyspareunia in endometriosis and provoked vestibulodynia, in terms of history, examination, biopsy, and surgical and medical treatment.

CONCLUSIONS

A neuroproliferative subtype of dyspareunia may be implicated in endometriosis and provoked vestibulodynia. Additional research is needed to validate this concept and to integrate it into clinical studies. Neuroproliferative pathways could serve as novel therapeutic targets for the treatment of dyspareunia in endometriosis and provoked vestibulodynia.

The Association Between Immune-Related Conditions Across the Life-Course and Provoked Vulvodynia

Vulvodynia, impacts up to 8% of women by age 40, and is hypothesized to manifest through an altered immune-inflammatory response. To test this hypothesis, we identified all women born in Sweden between 1973 and 1996 diagnosed with localized provoked vulvodynia (N76.3) and/or vaginismus (N94.2 or F52.5) between 2001 and 2018. We matched each case to two women from the same birth year with no vulvar pain ICD codes. As a proxy for immune dysfunction, we used Swedish Registry data to capture 1) immunodeficiencies, 2) single organ and multiorgan autoimmune conditions, 3) allergy and atopies, and 4) malignancies involving immune cells across the life course. Women with vulvodynia, vaginismus or both were more likely to experience immune deficiencies (OR 1.8, 95% CI, 1.2-2.8), single organ (OR 1.4, 95% CI, 1.2-1.6) and/or multi-organ (OR 1.6, 95% CI, 1.3-1.9) immune disorders, and allergy/atopy conditions (OR 1.7, 95% CI, 1.6-1.8) compared to controls. We observed greater risk with increasing numbers of unique immune related conditions (1 code: OR = 1.6, 95% CI, 1.5-1.7; 2 codes: OR = 2.4, 95% CI, 2.1-2.9; 3 or more codes: OR = 2.9, 1.6-5.4). These findings suggest that women with vulvodynia may have a more compromised immune system either at birth or at points across the life course than women with no vulvar pain history. PERSPECTIVE: Women with vulvodynia are substantially more likely to experience a spectrum of immune related conditions across the life course. These findings lend support to the hypothesis that chronic inflammation initiates the hyperinnervation that causes the debilitating pain in women with vulvodynia.

Inflammation, lipids, and pain in vulvar disease

Localized provoked vulvodynia (LPV) affects ∼14 million people in the US (9% of women), destroying lives and relationships. LPV is characterized by chronic pain (>3 months) upon touch to the vulvar vestibule, which surrounds the vaginal opening. Many patients go months or years without a diagnosis. Once diagnosed, the treatments available only manage the symptoms of disease and do not correct the underlying problem. We have focused on elucidating the underlying mechanisms of chronic vulvar pain to speed diagnosis and improve intervention and management. We determined the inflammatory response to microorganisms, even members of the resident microflora, sets off a chain of events that culminates in chronic pain. This agrees with findings from several other groups, which show inflammation is altered in the painful vestibule. The vestibule of patients is acutely sensitive to inflammatory stimuli to the point of being deleterious. Rather than protect against vaginal infection, it causes heightened inflammation that does not resolve, which coincides with alterations in lipid metabolism that favor production of proinflammatory lipids and not pro-resolving lipids. Lipid dysbiosis in turn triggers pain signaling through the transient receptor potential vanilloid subtype 4 receptor (TRPV4). Treatment with specialized pro-resolving mediators (SPMs) that foster resolution reduces inflammation in fibroblasts and mice and vulvar sensitivity in mice. SPMs, specifically maresin 1, act on more than one part of the vulvodynia mechanism by limiting inflammation and acutely inhibiting TRPV4 signaling. Therefore, SPMs or other agents that target inflammation and/or TRPV4 signaling could prove effective as new vulvodynia therapies.

Innervation of the human vulvar vestibule: A comprehensive review

Pain of the vulvar vestibule, including provoked vestibulodynia, is prevalent among women, yet challenging to treat due to its multifactorial etiology. Recent evidence indicates a neuroproliferative subtype in which hypersensitivity of the vulvar vestibule is due, in part, to hyperinnervation. Detailed knowledge regarding the innervation of the vulvar vestibule is crucial to understanding and treating pain conditions impacting this region. The purpose of this review is to consolidate the current evidence regarding the innervation of the human vulvar vestibule and discuss the implications of this innervation for pathological conditions affecting this tissue. A comprehensive review of the literature was conducted using keywords including vulvar vestibule, innervation, and vestibulodynia to identify articles concerning the innervation of the vulvar vestibule. Fifteen studies published between 1998 and 2017 were reviewed. Evidence from immunohistochemical investigations support that the vulvar vestibule has nociceptive, mechanosensory, sympathetic, and parasympathetic innervation. In pathological samples, hyperinnervation supports the neuroproliferative etiology of provoked vestibulodynia. Additionally, there is some evidence supporting the role of the pudendal nerve in vulvar vestibule innervation, although no cadaveric studies have been reported to date. Progress has been made in our understanding of the innervation of the vulvar vestibule, though further research into the origin of sensory and autonomic innervation of this region is needed. Advancing the knowledge of vulvar vestibule innervation is crucial towards improving our understanding of the function of this tissue, in addition to informing the etiology and management of pain syndromes impacting this region.

Characterization of Early Inflammatory Events Leading to Provoked Vulvodynia Development in Rats

Background

Provoked vulvodynia (PV) is the main cause of vulvar pain and dyspareunia. The etiology of PV has not yet been elucidated. However, PV is associated with a history of recurrent inflammation, and its often accompanied by increases in the numbers of mast cells (MCs) and sensory hyperinnervation in the vulva. Therefore, this study aimed to examine the role of MCs and the early inflammatory events in the development of chronic vulvar pain in a rat model of PV.

Methods

Mechanical and thermal vulvar sensitivity was measured for 5 months following zymosan vulvar challenges. Vulvar changes in glutamate and nerve growth factor (NGF) were analyzed using ELISA. Immunofluorescence (IF) staining of the vulvar section after 20, 81, and 160 days of the zymosan challenge were performed to test MCs accumulation, hyperinnervation, and expression of pain channels (transient receptor potential vanilloid/ankyrin-1-TRPV1 & TRPA1) in vulvar neurons. Changes in the development of vulvar pain were evaluated following the administration of the MCs stabilizer ketotifen fumarate (KF) during zymosan vulvar challenges.

Results

Zymosan-challenged rats developed significant mechanical and thermal vulvar sensitivity that persisted for over 160 days after the zymosan challenge. During inflammation, increased local concentrations of NGF and glutamate and a robust increase in MCs degranulation were observed in zymosan-challenged rats. In addition, zymosan-challenged rats displayed sensory hyperinnervation and an increase in the expression of TRPV1 and TRPA1. Treatment with KF attenuated the upregulated level of NGF during inflammation, modulated the neuronal modifications, reduced MCs accumulation, and enhanced mechanical hypersensitivity after repeated inflammation challenges.

Conclusion

The present findings suggest that vulvar hypersensitivity is mediated by MCs accumulation, nerve growth, and neuromodulation of TRPV1 and TRPA1. Hence, KF treatment during the critical period of inflammation contributes to preventing chronic vulvar pain development.

A Pilot Proteomic Study of Vestibular Fluid From Patients With Vulvodynia

OBJECTIVE

Many women are affected by vulvodynia, but medical therapies to date have proven ineffective. We performed a pilot study using gel-based proteomics to develop a map of proteins present in vaginal/vestibular secretions and identify proteins that could be considered for future evaluation as potential therapeutic targets.

MATERIALS AND METHODS

We collected vestibular fluid from 4 controls and 4 patients with vulvodynia by placing a cotton swab in the vestibule and extracting the absorbed proteins. The proteins underwent 2-dimensional difference gel electrophoresis and mass spectrometry to develop a protein map. Immunohistochemistry was used to validate proteomic findings.

RESULTS

A map was constructed of 32 of the more abundant proteins in vestibular fluid and their levels compared in control subjects and vulvodynia patients. Among these were annexin A1, interleukin 1 receptor antagonist, protein S100 A9, and a number of antiproteases and proteases. Many of these proteins differed by at least 50% between groups, but only annexin A1, one of the protease inhibitors, and immunoglobulin G κ chain were significantly different. The results with annexin A1 were validated by similar findings with immunohistochemistry.

CONCLUSIONS

The findings of this pilot study demonstrate a set of vestibule mucosa proteins that differ significantly-either increasing or decreasing-in vulvodynia patients compared with controls, and several others that exhibited greater than 1.5-fold change but did not reach statistical significance. This study constitutes a proof-of-principle that an open, unbiased proteomic approach can identify molecular participants in vulvodynia, some of which had not been identified to date by hypothesis-driven studies.

Specialized Pro-resolving Mediators Reduce Pro-nociceptive Inflammatory Mediator Production in Models of Localized Provoked Vulvodynia

Localized provoked vulvodynia (LPV) is the most common cause of chronic dyspareunia in premenopausal women, characterized by pain with light touch to the vulvar vestibule surrounding the vaginal opening. The devastating impact of LPV includes sexual dysfunction, infertility, depression, and even suicide. Yet, its etiology is unclear. No effective medical therapy exists; surgical removal of the painful vestibule is the last resort. In LPV, the vestibule expresses a unique inflammatory profile with elevated levels of pro-nociceptive proinflammatory mediators prostaglandin E2 (PGE2) and interleukin-6 (IL-6), which are linked to lower mechanical sensitivity thresholds. Specialized pro-resolving mediators (SPMs), lipids produced endogenously within the body, hold promise as an LPV treatment by resolving inflammation without impairing host defense. Ten of 13 commercially available SPMs reduced IL-6 and PGE2 production by vulvar fibroblasts, administered either before or after inflammatory stimulation. Using a murine vulvar pain model, coupling proinflammatory mediator quantification with mechanical sensitivity threshold determination, topical treatment with the SPM, maresin 1, decreased sensitivity and suppressed PGE2 levels. Docosahexaenoic acid, a precursor of maresin 1, was also effective in reducing PGE2 in vulvar fibroblasts and rapidly restored mouse sensitivity thresholds. Overall, SPMs and their precursors may be a safe and efficacious for LPV. Perspective: Vulvodynia, like many pain conditions, is difficult to treat because disease origins are incompletely understood. Here, we applied our knowledge of more recently discovered vulvodynia disease mechanisms to screen novel therapeutics. We identified several specialized pro-resolving mediators as likely potent and safe for treating LPV with potential for broader application.

Localized Provoked Vulvodynia-An Ignored Vulvar Pain Syndrome

Localized provoked vulvodynia (LPV) causes dyspareunia among reproductive aged women. We review the pathogenesis of LPV and suggest that LPV is an inflammatory pain syndrome of the vestibular mucosa triggered by microbial antigens in a susceptible host. Tissue inflammation and hyperinnervation are characteristic findings which explain symptoms and clinical signs. Education of health care providers of LPV is important since this condition is common, often unrecognized, and patients often become frustrated users of health care. Research is needed on the antigen triggers of the syndrome. Randomized clinical trials are needed to evaluate treatment modalities.

Vestibular Anatomic Localization of Pain Sensitivity in Women with Insertional Dyspareunia: A Different Approach to Address the Variability of Painful Intercourse

The pathophysiology underlying painful intercourse is challenging due to variability in manifestations of vulvar pain hypersensitivity. This study aimed to address whether the anatomic location of vestibular-provoked pain is associated with specific, possible causes for insertional dyspareunia. Women (n = 113) were assessed for “anterior” and “posterior” provoked vestibular pain based on vestibular tenderness location evoked by a Q-tip test. Pain evoked during vaginal intercourse, pain evoked by deep muscle palpation, and the severity of pelvic floor muscles hypertonicity were assessed. The role of potential confounders (vestibular atrophy, umbilical pain hypersensitivity, hyper-tonus of pelvic floor muscles and presence of a constricting hymenal-ring) was analyzed to define whether distinctive subgroups exist. Q-tip stimulation provoked posterior vestibular tenderness in all participants (6.20 ± 1.9). However, 41 patients also demonstrated anterior vestibular pain hypersensitivity (5.24 ± 1.5). This group (circumferential vestibular tenderness), presented with either vestibular atrophy associated with hormonal contraception use (n = 21), or augmented tactile umbilical-hypersensitivity (n = 20). The posterior-only vestibular tenderness group included either women with a constricting hymenal-ring (n = 37) or with pelvic floor hypertonicity (n = 35). Interestingly, pain evoked during intercourse did not differ between groups. Linear regression analyses revealed augmented coital pain experience, umbilical-hypersensitivity and vestibular atrophy predicted enhanced pain hypersensitivity evoked at the anterior, but not at the posterior vestibule (R = 0.497, p < 0.001). Distinguishing tactile hypersensitivity in anterior and posterior vestibule and recognition of additional nociceptive markers can lead to clinical subgrouping.

Emerging Evidence of Macrophage Contribution to Hyperinnervation and Nociceptor Sensitization in Vulvodynia

Vulvodynia is an idiopathic chronic pain disorder and a leading cause of dyspareunia, or pain associated with sexual intercourse, for women. The key pathophysiological features of vulvodynia are vaginal hyperinnervation and nociceptor sensitization. These features have been described consistently by research groups over the past 30 years, but currently there is no first-line recommended treatment that targets this pathophysiology. Instead, psychological interventions, pelvic floor physiotherapy and surgery to remove painful tissue are recommended, as these are the few interventions that have shown some benefit in clinical trials. Recurrence of vulvodynia is frequent, even after vestibulectomy and questions regarding etiology remain. Vestibular biopsies from women with vulvodynia contain increased abundance of immune cells including macrophages as well as increased numbers of nerve fibers. Macrophages have multiple roles in the induction and resolution of inflammation and their function can be broadly described as pro-inflammatory or anti-inflammatory depending on their polarization state. This state is not fixed and can alter rapidly in response to the microenvironment. Essentially, M1, or classically activated macrophages, produce pro-inflammatory cytokines and promote nociceptor sensitization and mechanical allodynia, whereas M2, or alternatively activated macrophages produce anti-inflammatory cytokines and promote functions such as wound healing. Signaling between macrophages and neurons has been shown to promote axonal sprouting and nociceptor sensitization. This mini review considers emerging evidence that macrophages may play a role in nociceptor sensitization and hyperinnervation relevant to vulvodynia and considers the implications for development of new therapeutic strategies.

Vulvovestibular Syndrome and Vaginal Microbiome: A Simple Evaluation

Background

The vulvovestibular syndrome (VVS) is a chronic, inflammatory, multifactorial, chronic inflammation of the female urogenital access.

Methods

The aim of this anecdotal, observational, retrospective, case-control study was to comparatively evaluate the most common bacterial strains (Lactobacillus spp., Klebsiella spp., Gardnerella spp., and Streptococcus spp.) and fungi (Candida spp., Pennicillum spp., and Aspergillus spp.) in vulvodinic women, and in women without gynecological symptoms (control group).

Results

We found that vulvodinic patients had statistically lower Lactobacilli and higher total Fungi concentration.

Conclusions

Our preliminary study is useful to further clarify the etiopathology of vulvodynia and suggest new therapeutic strategies for approaching the VVS.

Differentiating overlapping symptoms of vulvodynia and pudendal neuralgia

Context

Vulvodynia is defined as a chronic vulvar pain non-associated with infectious, inflammatory, neoplastic or hormonal disorders.

Objectives

To present a case demonstrating the difficulty in assessing concomitant disease in vulvodynia.

Methods

A 26-year-old woman, presented with persistent vulvodynia. She received oral and topical medications and behavioural interventions to lessen sexual pain and restore sexuality. As sexual pain decreased, the patient reported symptoms previously not mentioned: continuous, intense periclitoral pain and numbness at the perineum when sitting for a long time. These new symptoms suggest the involvement of the peripheral neural system. The physical evaluation confirmed right-side pelvic distortion, and pathological increase in lumbar lordosis, which caused neuralgia radiating to the external genitalia and perineum, and overlapping with sexual pain. After diagnosing pudendal neuralgia according to the Nantes criteria, physical treatment and relaxation exercises to de-contract the spine were added to the vulvodynia regimen.

Results

During treatment, vulvodynia was sometimes present but never unbearable, allowing satisfactory sex. With physical therapy, the symptoms of pudendal neuralgia decreased.

Conclusion

Differentiating the presence of two conditions with overlapping symptoms is difficult because the vestibular pain had shadowed pudendal neuralgia symptoms at initial assessment. Syndromes of chronic pain tend to associate with each other and one syndrome may shadow symptoms of the concomitant condition affecting adjacent anatomical areas. Only the accurate identification of all the syndromes involved allows adopting the correct treatment.

Recent advances in understanding provoked vestibulodynia

Vulvodynia refers to pain in the vulva of at least 3 months’ duration in the absence of a recognized underlying cause. Provoked, localized vestibulodynia is the term used to describe superficial pain confined to the vulvar vestibule, provoked by touch. This review will focus on provoked vestibulodynia with regard to its suggested causative factors and will discuss the role of inflammation, vulvovaginal infections, mucosal nerve fiber proliferation, hormonal associations, central pain mechanisms, pelvic floor muscle dysfunction, and genetic factors.

Clinical observations, epidemiological studies, and data from basic research emphasize the heterogeneity of vulvar pain syndromes. There is a critical need to perform prospective, longitudinal studies that will allow better diagnostic criteria and subgrouping of patients that would lead to improvements in our understanding of provoked vestibulodynia and its treatment.