New Developments in the Pathophysiology of Genital Pain: Role of Central Sensitization

Pelvic floor muscle activation amplitude at rest, during voluntary contraction, and during Valsalva maneuver-a comparison between those with and without provoked vestibulodynia

BACKGROUND

The neuromuscular contribution to increased tone of the pelvic floor muscles (PFMs) observed among those with provoked vestibulodynia (PVD) is unclear.

AIM

To determine if PFM activity differs between those with provoked PVD and pain free controls, and if the extent of PFM activation at rest or during activities is associated with pain sensitivity at the vulvar vestibule, psychological, and/or psychosexual outcomes.

METHODS

This observational case-control study included forty-two volunteers with PVD and 43 controls with no history of vulvar pain. Participants completed a series of questionnaires to evaluate pain, pain catastrophizing, depression, anxiety and stress, and sexual function, then underwent a single laboratory-based assessment to determine their pressure pain threshold at the vulvar vestibule and electromyographic (EMG) signal amplitudes recorded from three PFMs (pubovisceralis, bulbocavernosus, and external anal sphincter).

OUTCOMES

EMG signal amplitude recorded at rest, during maximum voluntary contraction (MVC), and during maximal effort Valsalva maneuver, pressure pain threshold at the vulvar vestibule, and patient-reported psychological (stress, anxiety, pain catastrophizing, central sensitization) and psychosexual (sexual function) outcomes.

RESULTS

Participants with PVD had higher activation compared to controls in all PFMs studied when at rest and during Valsalva maneuver. There were no group differences in EMG amplitude recorded from the pubovisceralis during MVC (Cohen's d = 0.11), but greater activation was recorded from the bulbocavernosus (d = 0.67) and the external anal sphincter(d = 0.54) among those with PVD. When EMG amplitudes at rest and on Valsalva were normalized to activation during MVC, group differences were no longer evident, except at the pubovisceralis, where tonic EMG amplitude was higher among those with PVD (d = 0.42). While those with PVD had lower vulvar pressure pain thresholds than controls, there were no associations between PFM EMG amplitude and vulvar pain sensitivity nor psychological or psychosexual problems.

CLINICAL IMPLICATIONS

Women with PVD demonstrate evidence of PFM overactivity, yet the extent of EMG activation is not associated with vulvar pressure pain sensitivity nor psychological/psychosexual outcomes. Interventions aimed at reducing excitatory neural drive to these muscles may be important for successful intervention.

STRENGTHS AND LIMITATIONS

This study includes a robust analysis of PFM EMG. The analysis of multiple outcomes may have increased the risk statistical error, however the results of hypothesis testing were consistent across the three PFMs studied. The findings are generalizable to those with PVD without vaginismus.

CONCLUSIONS

Those with PVD demonstrate higher PFM activity in the bulbocavernosus, pubovisceralis, and external anal sphincter muscles at rest, during voluntary contraction (bulbocavernosus and external anal sphincter) and during Valsalva maneuver; yet greater activation amplitude during these tasks is not associated with greater vulvar pressure pain sensitivity nor psychological or psychosexual function.

The role of interoceptive sensibility on central sensitization to pain in vulvodynia

BACKGROUND

Interoception may be linked to central sensitization in chronic pain.

AIM

We aimed to provide evidence about the role of interoceptive sensibility on central sensitization in vulvodynia.

METHODS

In this cross-sectional study, a sample of females who received a diagnosis of vulvodynia filled out validated questionnaires relative to the individual level of interoceptive sensibility and the symptoms of central sensitization.

OUTCOMES

Interoceptive sensibility and symptoms of central sensitization were measured with the Multidimensional Assessment of Interoceptive Awareness and the Central Sensitization Inventory, respectively.

RESULTS

A lower level of trust and a higher level of emotional awareness predicted a higher number of central sensitization symptoms in our sample.

CLINICAL IMPLICATIONS

Our evidence may increase the researchers' and physicians' attention toward the involvement of the central nervous system in pain phenomenology in vulvodynia.

STRENGTHS AND LIMITATIONS

No ad-hoc control sample was collected. No behavioral assessments about interoception were performed.

CONCLUSION

As registered in other chronic pain conditions, interoceptive sensibility may play a crucial role in the expressions of symptoms of central sensitization in vulvodynia.

Investigating the link between severity of dyspareunia and female sexual distress among a group of women with endometriosis: the mediating role of body functionality appreciation

BACKGROUND

While existing studies have predominantly focused on negative body image and its potential link to female sexual distress in women with endometriosis, no studies have investigated how positive body image (ie, body functionality appreciation) mediates the association between dyspareunia severity and sexual distress in this population.

AIM

This study aimed to investigate the mediating role of body functionality appreciation in the relationship between severity of dyspareunia and sexual distress in women living with endometriosis.

METHODS

A total of 232 women with endometriosis (M = 35 years) took part in the study. Participants completed an anonymous questionnaire evaluating dyspareunia severity, functionality appreciation, female sexual distress, sociodemographic factors, and endometriosis-related clinical information. All participants were administered the following questionnaires: numerical rating scale, body functionality appreciation, female sexual distress scale.

OUTCOMES

Using a mediation model, the study analyzed both the direct and indirect effects of dyspareunia severity on sexual distress, with functionality appreciation as a mediator.

RESULTS

The findings suggest that the severity of dyspareunia significantly contributes to sexual distress both directly and indirectly, by diminishing the appreciation for body functionality.

CLINICAL IMPLICATIONS

Clinicians should not only focus on the severity of dyspareunia when evaluating sexual distress in women; instead, they should also acknowledge the protective role of positive body image. Integrated treatments that promote body functionality appreciation could enhance treatment outcomes.

STRENGTHS AND LIMITATIONS

The study is the first to examine the mediating role of body functionality appreciation in the relationship between dyspareunia severity and sexual distress in a sample of women with endometriosis; however, the assessment was cross-sectional and did not encompass other factors that may influence the connection between dyspareunia severity and sexual distress.

CONCLUSION

These findings, in addition to advancing theoretical understanding of the role of positive body image in women with dyspareunia, may be valuable in guiding the design of interventions aimed at reducing sexual distress in women with high levels of dyspareunia severity.

Pelvic floor muscle activation in response to pressure stimuli applied to the vulvar vestibule: an observational study comparing women with and without provoked vestibulodynia

BACKGROUND

The nature of pelvic floor muscle (PFM) involvement in provoked vestibulodynia (PVD) is poorly understood.

AIM

We aimed to determine if PFM electromyographic (EMG) activity in anticipation of or response to pressure applied to the posterior vaginal fourchette differs between those with and without PVD, and if the magnitude of PFM response is associated with pressure pain sensitivity, psychological or psychosexual function.

METHODS

This was an observational case-control study. Forty-two volunteers with PVD and 43 controls with no vulvar pain participated. Five on-line questionnaires were completed, then participants underwent a laboratory-based evaluation of vulvar pain sensitivity. EMG activation of the PFMs, hip adductor, and upper trapezius muscles was measured before, during, and after pressure stimuli (low, moderate) were applied, in random order, to the posterior vaginal fourchette and the posterior thigh (control site).

OUTCOMES

EMG amplitude of the pubovisceralis (PV), bulbocavernosus (BC), and external anal sphincter (EAS) muscles. Secondary outcomes were EMG activation of the hip adductor brevis and upper trapezius muscles, questionnaire scores reflecting psychological/psychosexual outcomes, pressure pain threshold (PPT) at the vulvar vestibule, pain reported on a tampon test, and heart rate/heart rate variability.

RESULTS

Compared to controls, EMG activation of the PV and EAS, but not the BC, was higher in anticipation of the pressure applied to the vaginal fourchette, was higher in all PFMs while the pressure was applied, and remained higher than baseline after the pressure was removed among those with PVD. EMG response amplitudes were modulated by the intensity of the pressure applied, with the largest responses reaching over 40% MVC in the EAS among those with PVD. PFM EMG amplitudes were associated with greater pain sensitivity and lower sexual function, but not with pain catastrophizing, central sensitization, depression, anxiety, or stress.

CLINICAL IMPLICATIONS

While some anticipatory activation was observed, EMG responses were primarily observed during and after the application of the pressure. Among those with PVD, digital assessment of PFM tone might reflect PFM responses to pain at the vulvar vestibule, and interventions to reduce local pain sensitivity may be an important first step to successful improvements in vaginal function.

STRENGTHS AND LIMITATIONS

This study includes a robust analysis of EMG activation. However, the cross-sectional design precludes the determination of causal relationships.

CONCLUSIONS

Those with PVD demonstrate higher PFM responses and a higher prevalence of anticipatory activation in the PV and EAS muscles than controls in response to pressure applied at the vulvar vestibule.

Central sensitization symptoms in vulvodynia: exploring the role of temperament, personality traits, childhood adverse events, defense mechanisms, and mental pain on quality of life

BACKGROUND

Vulvodynia is a chronic pain syndrome characterized by persistent vulvar pain, occurring without clinically identifiable disorders. Central sensitization (CS) is suggested to play a role in the pathophysiology of vulvodynia, as for other nociplastic pain conditions.

AIM

This study delves into the complex interplay between psychosocial factors and CS burden in women with vulvodynia, aiming to identify potential predictors (temperament, personality traits, childhood adverse events, defense mechanisms, and mental pain) and understand their impact on quality of life (QoL).

METHODS

A cohort-based cross-sectional web survey of 357 women with vulvodynia.

OUTCOMES

Outcomes included 8 self-report measures to assess the Central Sensitization Inventory (CSI) and psychological variables, including sensory processing sensitivity, traumatic experiences, personality traits, defense mechanisms, and mental pain.

RESULTS

Hierarchical multiple regression analyses were conducted in study 1, revealing that the following predicted higher CSI scores in women with vulvodynia: higher emotional overexcitability, decreased low sensory threshold, increased bodily threat experiences, elevated psychoticism, greater use of immature and neurotic defense mechanisms, and heightened mental pain. The final regression model identified the following as the strongest predictors of CS: low sensory threshold (β = 0.316), bodily threat experiences (β = 0.145), neurotic defenses (β = 0.210), and mental pain (β = 0.269). In study 2, the model presented interactions among these psychological factors in predicting CSI values explaining 48.9% of the variance in CS, 30.3% in psychological QoL, and 57.1% in physical QoL.

CLINICAL TRANSLATION

This model opens discussion for tailored psychological interventions aimed to improve overall QoL in women with vulvodynia.

STRENGTHS AND LIMITATIONS

Strengths of the study include innovative insights into the interplay between psychological variables and the construct of CS and quality of life. As a limitation, the research was conducted as a cross-sectional study with self-reported measures.

CONCLUSION

The study calls for comprehensive assessments that consider physical and mental aspects, paving the way for holistic health care approaches in the management of vulvodynia.

Inflammation as a Potential Mechanism Contributing to Sexual Functioning Following Initiation of Gender-Affirming Hormone Therapy

Purpose of Review

Many transgender and gender non-conforming (TGNC) people seek gender-affirming hormone therapy (GAHT). While GAHT is generally safe and increases well-being, it is essential to accurately understand potential unintended effects and risk factors to better inform and manage treatment. This narrative review covers recent literature documenting changes in sexual function following the initiation of GAHT and explores inflammation as a potential mediator of these changes.

Recent Findings

Generally, the initiation of GAHT is correlated with increased sexual desire in transgender men and decreased sexual desire in transgender women, with time-limited effects that return to levels approaching baseline after about a year; there are also changes in inflammation markers that parallel this timeline. Findings on other aspects of sexual function (e.g., orgasm, pain, and sexual quality of life) are more limited. As there is evidence from cisgender populations that inflammation acts as a mechanism by which hormones influence sexual function, we propose applying this model to TGNC people taking GAHT.

Summary

Sexual function may change in TGNC patients receiving GAHT, and those changes may be influenced by inflammation. However, these changes often return to baseline as TGNC patients' bodies adjust to a new hormonal equilibrium.

If I stop, then what am I supposed to do? The experiences of sexual intimacy of women who live with provoked vestibulodynia

We explored the experiences of sexual intimacy in women living with provoked vestibulodynia (PVD), a chronic pain condition where pain at the vaginal opening is triggered by touch. We conducted in-depth interviews with nine women who had suffered from PVD. Our findings reveal that their ability to trust and accept themselves is essential to how they cope when pain disrupts their freedom to have sexual intercourse. The tendency to endure painful intercourse and not tell the partner is driven by fear of rejection and conflict. Those who are able to overcome their fear, experience deeper intimacy and more sexual pleasure.

#ItsNotInYourHead: A Social Media Campaign to Disseminate Information on Provoked Vestibulodynia

Provoked Vestibulodynia (PVD) is a type of localized vulvodynia (or pain in the vulva). The estimated prevalence of this condition is about 12% of the general population and approximately 20% of women under the age of 19. Many women who live with PVD suffer in silence for years before receiving a diagnosis. Whereas cognitive behavioral therapy (CBT) was already known to be effective for managing symptoms of PVD, there has recently been a published head-to-head comparison of CBT versus mindfulness-based therapy for the primary outcome of pain intensity with penetration. The trial revealed that both treatments were effective and led to statistically and clinically meaningful improvements in sexual function, quality of life, and reduced genital pain, with improvements retained at both 6- and 12-month follow-ups. We then undertook an end-of-grant knowledge translation (KT) campaign focused on the use of social media to disseminate an infographic video depicting the findings. Social media was strategically chosen as the primary mode of dissemination for the video as it has broad reach of audience, the public can access information on social media for free, and it presented an opportunity to provide social support to the population of women with PVD who are characterized as suffering in silence by starting a sensitive and empowering dialogue on a public platform. In this paper, we summarize the social media reach of our campaign, describe how and why we partnered with social media influencers, and share lessons learned that might steer future KT efforts in this field.

Pelvic floor muscle tenderness on digital palpation among women: convergent validity with central sensitization

BACKGROUND

Tenderness on palpation of the pelvic floor muscles (PFMs) is a clinical assessment tool used alongside other tests to identify PFM involvement in pelvic complaints including pelvic pain. Although reliability of PFM tenderness has been determined, validity has yet to be established.

OBJECTIVES

To assess convergent validity of PFM tenderness on digital palpation with the presence of central pain mechanism, as determined by a score of greater than 40 on the Central Sensitization Inventory (CSI). A secondary objective was to assess the agreement between PFM tenderness and self-reported symptoms of PFM sensitivity.

METHODS

Participants completed a battery of self-report questions, the CSI, and various physical assessments (blinded assessors). Convergent validity was assessed between tenderness on palpation and the CSI. Kappa statistics were used to determine agreement between tenderness on palpation and self-reported perineal pain, urinary urgency, dyspareunia, and dysmenorrhea.

RESULTS

Ninety-nine female participants with hip or back pain and at least one self-reported symptom of pelvic floor dysfunction were included in the study (mean age 40.56±12.72 years). Convergent validity was found between PFM tenderness on palpation and scores greater than 40 on the CSI (X₁²=4.2,p=0.04). There was poor agreement between tenderness on palpation with dyspareunia (agreement 62.83%, Kappa=0.27), dysmenorrhea (agreement 55.75%, Kappa=0.14), or perineal pain (agreement 53.04%, Kappa=0.10).

CONCLUSIONS

PFM tenderness on digital palpation confirmed convergent validity with CSI scores, suggesting central pain mechanisms. Clinicians may need to consider the role of central pain mechanisms in their clinical decision making when treating PFM dysfunction.

Physical Pain as Pleasure: A Theoretical Perspective

Physical pain represents a common feature of Bondage and Discipline/Dominance and Submission/Sadism and Machochism (BDSM) activity. This article explores the literature accounting for how painful stimuli may be experienced as pleasurable among practitioners of BDSM, and contrasting this with how it is experienced as painful among non-BDSM individuals. We reviewed the available literature on pain and on BDSM, and used the findings to postulate a theory accounting for how painful stimuli are experienced as pleasurable. Our theory was then checked with BDSM practitioners. The emotional, physiological, and psychological elements of pain interact to facilitate the experience of pain as pleasure in BDSM. A multitude of interconnected factors was theorized to alter the experience of BDSM pain, including: neural networks, neurotransmitters, endogenous opioids and endocannabinoids, visual stimuli, environmental context, emotional state, volition and control, interpersonal connection, sexual arousal, and memories. The experience of pain in this context can bring about altered states of consciousness that may be similar to what occurs during mindfulness meditation. Through understanding the mechanisms by which pain may be experienced as pleasure, the role of pain in BDSM is demystified and, it is hoped, destigmatized.

Interactions between inflammation and female sexual desire and arousal function

PURPOSE OF REVIEW

To describe the current state of research on interactions between inflammation and female sexual function.

RECENT FINDINGS

Inflammation may interfere with female sexual desire and arousal via direct (neural) and indirect (endocrine, vascular, social/behavioral) pathways. There are significant sex differences in the effect of inflammation on sexual function, arising from different evolutionary selection pressures on regulation of reproduction. A variety of inflammation-related conditions are associated with risk of female sexual dysfunction, including cardiovascular disease, metabolic syndrome, and chronic pain.

SUMMARY

Clinical implications include the need for routine assessment for sexual dysfunction in patients with inflammation-related conditions, the potential for anti-inflammatory diets to improve sexual desire and arousal function, and consideration of chronic inflammation as moderator of sexual effects of hormonal treatments. Although the evidence points to a role for inflammation in the development and maintenance of female sexual dysfunction, the precise nature of these associations remains unclear.

A Descriptive and Longitudinal Analysis of Pain During Intercourse in Pregnancy

INTRODUCTION

Pain during vaginal intercourse in pregnancy has largely been ignored despite physiological and psychological components of pregnancy that may be associated with its onset and persistence.

AIM

The current study aimed to determine the prevalence and the characteristics of clinically significant pain during intercourse in the second (18-24 weeks) and third (32-36 weeks) trimesters of pregnancy.

METHODS

Pregnant women (N = 501) recruited from a local women's hospital completed an online survey in the second and third trimesters of their pregnancy regarding the presence, intensity, and characteristics of pain during intercourse. Women with clinically significant pain (ie, pain greater than or equal to 4 of 10 on a numerical rating scale) were grouped according to whether the pain was resolved, persistent, or new onset across the 2 pregnancy time points. Following guidelines outlined by the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT), we conducted a descriptive analysis assessing the intensity and characteristics (eg, quality, onset, degree of improvement over time, and treatment strategies utilized) of clinically significant pain during intercourse.

MAIN OUTCOME MEASURE

The main outcome measures in this study were the prevalence, intensity, and characteristics of clinically significant pain during intercourse.

RESULTS

Overall, 21% of pregnant women (106/501) reported clinically significant pain during intercourse. We found that 22% (N = 16/106) of women who had this pain at 20 weeks reported that it had resolved at 34 weeks, 33% (40/106) reported persistent pain at both time points, and 46% (50/106) reported new onset of pain during intercourse at 34 weeks. The majority of women across all pain groups reported that the pain began during pregnancy and remained at the same intensity. Most women reported not using any pain management strategies to cope with their pain.

CLINICAL IMPLICATIONS

One in 5 women experienced clinically significant pain during intercourse in pregnancy, with the majority of women not seeking treatment.

STRENGTHS & LIMITATIONS

This study is the first to comprehensively assess and describe the prevalence and characteristics of clinically significant pain during intercourse across 2 time points in pregnancy using IMMPACT guidelines. Small sample sizes in our pain groups may limit the generalizability of pain characteristics.

CONCLUSION

Findings suggest that many pregnant women in this study experienced significant pain during intercourse in pregnancy. Understanding the characteristics of this pain may improve its identification by health care providers and inform better prevention and treatment recommendations. Rossi MA, Mooney KM, Binik YM, et al. A Descriptive and Longitudinal Analysis of Pain During Intercourse in Pregnancy. J Sex Med 2019;16:1966-1977.

Self-Reported Neuropathic Pain Characteristics of Women With Provoked Vulvar Pain: A Preliminary Investigation

BACKGROUND

Provoked vestibulodynia (PVD) is a common chronic genital pain condition affecting approximately 12% of premenopausal women. Although parallels have been drawn between PVD and neuropathic pain (NP), no studies have examined self-reported NP characteristics in PVD.

AIM

To explore pain symptoms that resemble NP reported by those with PVD and compare responses with those with an established NP condition.

METHODS

Women with provoked vulvar pain (PVP; n = 65) completed online questionnaires designed to assess characteristics of NP. Responses were compared with those of women with postherpetic neuralgia (PHN; n = 30).

OUTCOMES

In addition to a range of descriptive questions, participants completed the McGill Pain Questionnaire, the Self-Complete Leeds Assessment of Neuropathic Signs and Symptoms (S-LANSS), the Neuropathic Pain Symptom Inventory (NPSI), and the Pain Quality Assessment Scale (PQAS).

RESULTS

PVP exhibits some neuropathic characteristics, typically evoked pain (as opposed to the more constant pain of PHN) indicative of allodynia and hyperalgesia. Specifically, women with PVP scored, on average, higher than the NP cutoff on the S-LANSS, and there were no significant differences between women with PVP and those with PHN on some NPSI subscales. However, women with PHN reported more NP symptoms on the PQAS, S-LANSS, and other NPSI subscales.

CLINICAL IMPLICATIONS

Validated NP questionnaires could be of particular use for health care professionals who need a more efficient way to assess symptoms of patients with PVP and should be included in future studies investigating the mechanisms and treatment of this pain.

STRENGTHS AND LIMITATIONS

This study takes a unique approach to the examination of PVP by using multiple validated NP measures to compare pain characteristics with those of a group of participants with PHN, an established NP condition. However, it is limited by self-reported data not confirmed with clinical examination, small size of the PHN group, and the severity of the pain experienced in the PVP group.

CONCLUSION

Women with PVP report some symptoms suggestive of NP characteristics, and future research should use NP measures in addition to physical examinations to further investigate the mechanisms that maintain this pain condition. Dargie E, Gilron I, Pukall CF. Self-Reported Neuropathic Pain Characteristics of Women With Provoked Vulvar Pain: A Preliminary Investigation. J Sex Med 2017;14:577-591.