Women's Sexual Function and Dysfunction. Irwin Goldstein MD

Sexual pain disorders: pathophysi ologic factors

Caroline F Pukall, Marie-Andrée Lahaie, Yitzchak M Binik

Introduction

The sexual pain disorders included in the Diagnostic and Statistical Manual of Mental Disorders (DSM)1 - dyspareunia and vaginismus - have long been classified as sexual dysfunctions (see Chapter 9.1 of this volume), despite recent research indicating that sexuality is just one aspect affected in these conditions and that other factors should be given equal importance.The purpose of this chapter is to give an overview of etiologic factors involved in the development and maintenance of these conditions (see Chapters 12.1-12.6).

Dyspareunia

Classification

The fourth edition of the DSM (DSM-IV-TR)1 has continued the tradition started in the third edition (DSM-III-R)3 of including dyspareunia as a sexual pain disorder, defining it as a “recurrent and persistent genital pain associated with sexual intercourse”. This definition, based on interference with sexual intercourse, is understandable, given that this is what brings many women to clinical attention. However, this focus has drawn attention away from the major clinical symptom of pain. One major reason for the classification of dyspareunia as a sexual dysfunction is the lack of a known physical basis for the pain; however, the presence of physical findings is not an important criterion for defining a pain syndrome. For example, 85% of patients with back pain present without identifiable pathology,yet they still receive the diagnosis of back pain.

The DSM-IV-TR1 reinforces the outdated view that pain is either physical or psychologic. For example, it mentions post menopausal dyspareunia but classifies it as a sexual dysfunction due to a general medical (i.e., physical) condition, despite the fact that there is very little systematic research evidence to support a strong link between physical factors and dyspareunia in this age group.5 Deep dyspareunia, the most common symptom associated with pelvic pathology and chronic pelvic pain6, is similarly classified. While the distinction between dyspareunia due to psychologic versus physical factors seems intuitively useful from a classification standpoint, it does not reflect the reality of the pain experience. Therefore, we have adopted a pain perspective of dyspareunia,7 which views pain as a multidimensional experience, including both physical and psychologic factors. Adopting this approach necessitates that pain is the major focus of assessment and treatment; psychosocial, psychologic, and sexual factors are also ascribed great importance since they play a crucial role in the disability resulting from the pain, and in pain perception and control.

Consistent with this approach, the International Society for the Study of Vulvovaginal Disease proposed a new classification of vulvodynia based on pain location: generalized and localized. Each of these is subdivided into provoked, unprovoked, or mixed pain presentations; both sexual and nonsexual situations can elicit pain. This classification, based on pain characteristics, is in line with viewing dyspareunia as a vulvar pain problem.8 However, as this classification is new and has not yet been adopted in research, we will standardize our use of the terminology in this chapter as follows: “dyspareunia” denotes any form of recurrent or chronic genital pain that interferes with, but may not be limited to, sexual activity in women of any age. Dyspareunic pain can be experienced in a number of different genital locations and can be characterized by different pain qualities and patterns. “Vulvar vestibulitis syndrome” refers to pain experienced in the vulvar vestibule upon contact,9 and the term “vulvodynia” denotes generalized and chronic vulvar pain that occurs in the absence of external stimulation. This part of the chapter will focus on vulvar vestibulitis syndrome and vulvodynia.

Etiologic factors

Vulvar vestibulitis syndrome

Vulvar vestibulitis syndrome is the most common form of dyspareunia in premenopausal women,1 affecting an estimated 12% in the general population.11 Women with vulvar vestibulitis typically experience a severe burning pain at the entrance of the vagina in response to contact during both sexual and nonsexual activities.10,12 Friedrich9 proposed the following diagnostic criteria for vulvar vestibulitis syndrome: (1) severe pain upon vestibular touch or attempted vaginal entry; (2) tenderness to pressure localized within the vulvar vestibule; and (3) physical findings limited to vestibular erythema of various degrees. While the last criterion has not proven to be a reliable diagnostic indicator of vulvar vestibulitis,12 its diagnosis of vulvar vestibulitis syndrome is relatively easy to make via the cotton-swab test, which consists of the application of a cotton swab to various areas of the vulvar vestibule.

Yeast infections

Numerous etiologic theories exist regarding what initiates the increase in sensitivity of the vulvar vestibule in sufferers.13 One of the most consistently reported findings associated with the onset of vulvar vestibulitis is a history of repeated yeast infec- tions.14 However, it is not clear whether the culprit is the yeast itself, the treatments undertaken, which can sensitize the vestibular tissue, or an underlying sensitivity already present in the tissue.15 Since not all women with vulvar vestibulitis syndrome report a history of repeated yeast infections, many researchers have recently begun to examine the properties of vestibular tissue in controlled studies.

Physical findings in the vulva

While early, uncontrolled studies concluded that inflammation played a role in vulvar vestibulitis, recently published controlled studies suggest that inflammatory infiltrates are common in the vestibule.16,17 Other investigations suggest that altered tissue properties play a role in the development and/or maintenance of the pain in vulvar vestibulitis syndrome. Evidence for this includes heightened innervation of intraepithelial nerve fibers,18,19 increase in vanilloid receptor 1 expression (i.e., a receptor present in pain fibers),20 increase in blood flow,21 presence of calcitonin gene-related peptide (a peptide found in pain nerves),22 lowered tactile and pain thresholds,23 and nociceptor sensitization.24 These properties would lead to a heightened sensitivity in response to vestibular pressure, consistent with the clinical picture of provoked pain in women with vulvar vestibulitis.

In addition to abnormalities present in the vestibule, controlled studies have found that women with vulvar vestibulitis syndrome exhibit an increase in pelvic floor muscle tension,25,26 possibly representing a protective reaction against, or a conditioned response to, vulvar pain. While there has been much advancement in terms of pain-related findings at the local (i.e., genital) level, other research indicates that there may be more generalized abnormalities in women with vulvar vestibulitis.

Genetic factors and generalized sensitivity

Gerber et al.27 conducted a series of studies examining genetic factors in women with vulvar vestibulitis syndrome. They demonstrated that affected women were more frequently homozygous at allele 2 of the interleukin-1 receptor antagonist gene and at allele 2 of the interleukin-1 beta gene than nonaffected women. Each of these alleles has been associated with a severe and prolonged proinflammatory immune response.28 Consistent with this finding, they demonstrated that the immune systems of women with vulvar vestibulitis syndrome are not effective in terminating the inflammatory process. Based on these findings, they proposed that, in some women with vulvar vestibulitis syndrome, there is a genetic susceptibility to development of a chronic localized inflammation in the vestibule after an initial inflammatory response has been triggered (as after yeast infections). The prolonged and intensified inflammation could then trigger other events that may result in increased pain sensitivity due to chronic inflammation in both genital and nongenital areas of the body. Although this is just beginning to be examined, controlled studies support the implication of higher sensitivity in nongenital body areas in women with vulvar vestibulitis: they are more sensitive to nongenital touch, pain, pressure, and heat pain23,29 and report more somatic pain-related complaints23,30 than nonaffected women.

Hormonal factors

Hormonal factors are also associated with vulvar vestibulitis syndrome in controlled studies. Bazin et al.31 and Bouchard et al.32 found that women who used oral contraceptives, especially those who started at a young age, had an increased risk of developing vulvar vestibulitis syndrome later in life. Early menarche and dysmenorrhea were also associated with increased risk.11,31 In addition, one recently published controlled study found that women with vulvar vestibulitis have significantly decreased estrogen receptor-alpha expression.33 These findings suggest that hormonal factors may play a role in vulvar vestibulitis syndrome, but the question of how hormones are involved remains to be elucidated (see Chapter 12.4).

Psychosocial factors

Elevated levels of psychologic distress, anxiety, depression, shyness, harm avoidance, hypervigilance to pain stimuli, pain catastrophization, and somatization, as well as low sexual self- esteem,23,29,30,34-36 have been found in women with vulvar vestibulitis syndrome. Not surprisingly, women with vulvar vestibulitis report lower frequencies of intercourse; lower levels of sexual desire, arousal, and pleasure; and less orgasmic success than nonaffected women.10,37,38 Despite the significant effects on sexuality, the examination of relationship factors has been limited. In addition, while uncontrolled reports imply that sexual abuse is common in women with vulvar vestibulitis syndrome,13,39 controlled studies of sexual abuse10,37,40 show no difference between affected and nonaffected women.

Vulvodynia

Vulvodynia is a noncyclic, chronic vulvar discomfort extending to the urethral and rectal areas, characterized by the patient’s complaint of burning, stinging, irritation, or rawness.41 Light touch of the vulvar area often exacerbates the ongoing pain; however, dyspareunia is not always reported. Vulvodynia affects 6-7% of women in the general population, with a higher prevalence in women over the age of 30.11 The diagnosis of vulvo- dynia is a diagnosis of exclusion; hence, a careful physical examination to rule out all potential causes (e.g., dermatologic conditions, yeast infections) must precede the diagnosis.42 The onset of vulvodynia is sometimes linked to episodes of local treatments, such as vulvar cream application, laser surgery for genital wart or malignancy removal, or vulvar injury.

Vulvodynia as a neuropathic pain syndrome

McKay42 proposed that the pain of vulvodynia results from altered cutaneous perception, as in neuropathic pain syndromes. This perspective has gained support; vulvodynia patients report symptom reduction when they are treated with medications typically prescribed for neuropathic pain (e.g., amitriptyline).43 Neuropathic pain states originate with an injury to the nervous system itself; this leads to the transmission of pain signals even when acute injury is no longer present. Neuropathic pain in the vulva can result from damage to sensory nerves during surgery, or damage to the pudendal nerve due to sports trauma (e.g., horseback riding), childbirth, or vaginal surgery.44 Another potential cause of vulvodynia is the condition of referred pain (i.e., when injury in one area causes pain in a different body area); any injury or orthopedic condition affecting muscles (e.g., pubococcygeus) or joints (e.g., sacroiliac) can refer pain to the perineal, vaginal, and rectal areas. In addition, injuries to the spinal cord (e.g., ruptured disk) and other conditions (e.g., varicella zoster) may manifest as vulvodynia.44

Pelvic floor muscle abnormalities and psychosocial factors Women with vulvodynia exhibit abnormalities in pelvic floor contractile amplitudes of tonic, phasic, and endurance contractions as compared with nonaffected women.45 Rehabilitation of the pelvic floor muscles via surface electromyography has been found successful in reducing pain and increasing sexual interest (see Chapter 4.4), pleasure, and activity.46 Vulvodynia is not associated with depression47,48 or with higher than normal instances of sexual abuse.40,49 It is unfortunate that so little research has been conducted in the physical, psychosocial, and sexual realms of vulvodynia; more research is needed.

Discussion

It is likely that multiple etiologies for vulvar vestibulitis syndrome and vulvodynia exist, and that these vary from woman to woman. Spending much time trying to determine what initially “caused” the pain will not be particularly helpful since a vicious cycle of pain has already been put into motion, involving physical, muscular, psychologic, sexual, behavioral, and relationship factors. What is important is managing the pain and its consequences; many areas of these women’s lives must be addressed simultaneously in order to achieve therapeutic success. We believe the same to be true for vaginismus.

Vaginismus

Classification

Vaginismus made its first appearance in the DSM-III-R3 and has been present in all versions of the DSM since then, including the most recent.1 Vaginismus is defined as a “recurrent or persistent involuntary spasm of the musculature of the outer third of the vagina that interferes with intercourse” (p. 558). However, several problems exist with this definition. Perhaps the most damaging evidence against it is that the occurrence of vaginal muscle spasms is neither exclusive nor specific to vaginismus.26 Nevertheless, the criterion of the vaginal muscle spasm remains the hallmark of the definition of vaginismus; this can be seen in other classification systems.50

In addition, although vaginismus is classified as a sexual pain disorder in the DSM, the experience of pain is not required for its diagnosis, and no information is provided on the location, intensity, duration, or quality of the pain experienced by vaginismic women. Related to this point is the confusion about whether the pain should be considered a consequence of the vaginal muscle spasm or whether the spasm is a reaction to the pain experience.51 Another important limitation is that vaginismus is reported to interfere solely with sexual intercourse, despite indications that spasms can occur when vaginal insertion is attempted with tampons and during gynecologic examinations. These difficulties with the current definition of vaginismus have led us to propose a reappraisal, with the major focus on the phobic, muscular, and pain aspects of vaginismus.

Etiologic factors

Vaginismus

There are no epidemiologic studies investigating the prevalence of vaginismus; however, in clinical settings, the rates range from 12% to 17%.52,53 Moreover, there are no standardized assessment protocols for vaginismus. It is not uncommon for vaginismus to be diagnosed based on a single report of difficulties with pene- tration54 and without a gynecologic examination.55 The diagnosis is typically made by health professionals who have little experience in the assessment and treatment of muscle problems; physical therapists are rarely consulted.

Vaginal muscle spasm

It has long been suggested that lack of control over the pelvic floor muscles can contribute to vaginismus. According to Barnes et al.,56 women with vaginismus have difficulty in evaluating vaginal muscle tone and differentiating between a relaxed state and a spasm. Since the early 1940s, acquiring greater control over pelvic floor muscles has been an important component in the treatment of vaginismus. While two well- controlled studies comparing women with and without vaginismus on voluntary control of the pelvic floor muscles found no differences between the groups in terms of baseline measures57 or in response to physically or sexually threatening film segments58 via a vaginal surface electromyography device, Reissing et al.26 demonstrated - by pelvic floor physical therapy techniques - that women with vaginismus display higher vaginal/pelvic muscle tone and lower muscle strength than both women with vulvar vestibulitis syndrome and a control group. In addition, they found that the presence of vaginal muscle spasm did not differentiate among the groups, indicating that this criterion should not be used as the defining characteristic for women with vaginismus. While the muscle component plays a role in vaginismus, further research is needed to clarify whether it is a cause, a symptom, or a consequence of vaginismus.

Dyspareunia

While dyspareunia has frequently been found to play a role in the development of vaginismus,37,59 the relationship between dyspareunia and vaginismus remains unclear, with some researchers arguing that chronic dyspareunia results in vaginismus and others reporting that the spasms cause pain.60 It has been proposed that chronic dyspareunia as a result of physical disorders, such as hymeneal and congenital abnormalities, is likely to result in vaginismus,51 leading some researchers to propose that vaginismus and dyspareunia are difficult, if not impossible, to differentiate.61,62 In support of this, Reissing et al.26 found no differences in the reported quality and intensity of the pain experienced during attempted vaginal penetration between women with vaginismus and vulvar vestibulitis syndrome. Although pain seems to be an important component of vaginismus, further investigation is needed to clarify its role in the development and/or maintenance of this condition.

Psychosocial factors, such as a penetration fear/phobia, negative sexual attitudes, lack of sexual knowledge, sexual abuse, and relationship factors, have also been implicated in the etiology of vaginismus (see Chapters 3.1-3.3 and 11.1-11.5).

Penetration phobia

Numerous reports in the literature suggest that vaginismus results from fear of pain, of vaginal penetration, or of sexual intimacy. As early as 1909, Walthard63 suggested that vaginismus is a phobic reaction to an excessive fear of pain. This idea was reiterated by Kaplan,64 who perceived vaginismus as a reflexive or phobic reaction to the anticipation of pain, resulting in the avoidance of intercourse. In concordance with these claims, a survey study found fear of pain to be the primary reason reported by women with vaginismus for their abstinence.65 Although fear of pain has been reported by some to be an etiologic factor associated with vaginismus, others suggest that fear of pain should be perceived as a symptom rather than a cause of vaginismus.66

It has also been suggested that vaginismus be considered a sexual phobia;67 however, women with vaginismus avoid not only sexual situations involving penetration but also vaginal penetrative situations such as tampon insertion and gynecologic examinations. Moreover, some women with vaginismus engage in and enjoy sexual activities that do not involve penetration; this would not be the case if vaginismus were a purely “sexual” phobia. On the other hand, the strong behavioral reactions to penetration observed in women with vaginismus may be related specifically to a vaginal penetration phobia, regardless of the situation (i.e., sexual or nonsexual). In support of this, women with vaginismus behave in ways consistent with those of a phobic who is exposed to the feared stimulus. Reissing et al.26 found women with vaginismus to be characterized by intense emotional and behavioral reactions to attempted vaginal penetration, active avoidance of intercourse, and chronic hypertonicity of the pelvic floor muscles. Some authors have proposed a reconceptualization of vaginismus as a specific phobia of vaginal penetration.26 The phobic element in vaginismus should be further investigated.

Negative sexual attitudes and lack of sexual knowledge/education Vaginismus has been associated with a lack of sexual education and knowledge.68 One study showed that vaginismic women believed that “being brought up to believe that sex was wrong” played a major role in the development of their condition. Consistent with this finding, Basson69 found that the majority of women with vaginismus in her study held negative views about sexuality. Furthermore, Leiblum59 reported that it is not uncommon for women with vaginismus to have received negative messages about men and sexual pleasure, resulting in negative attitudes toward sex and penile penetration. Masters and Johnson70 found that a large proportion of vaginismic women reported a strict religious upbringing involving strong taboos regarding sexuality. However, two well-controlled studies demonstrated no differences in the level of sexual knowledge and education between a group of vaginismic women and controls.37,71 However, Reissing et al.37 found that although women with vaginismus do not hold more negative sexual selfviews than women with vulvar vestibulitis syndrome and control women, they have less positive sexual self-schemas. With this in mind, the role of negative sexual attitudes and lack of sexual knowledge in the development of vaginismus still remains to be determined.

Sexual abuse

The belief about the relationship between sexual abuse and the development of vaginismus has had a long history;55,59 yet, in general, well-controlled empirical studies have found no evidence of a higher prevalence of sexual abuse in women with vaginismus.61,72 While Reissing et al.37 reported that women with vaginismus were twice as likely to report a history of negative sexual experiences in childhood than a control group, they were not more likely to report a history of childhood or adulthood physical abuse, or a history of negative sexual experiences in adulthood, than women with vulvar vestibulitis syndrome and a control group. According to current studies, sexual abuse does not seem to be an important etiologic factor in the development of vaginismus (see Chapter 3.4).

Couple and relationship factors

While vaginismus has frequently been stated to result from marital problems and poor communication,55,73 only a few empirical studies have investigated the role of couple factors in the etiology of vaginismus. They report no differences between women with vaginismus and control women on marital adjust- ment,37,74 leading investigators to examine patterns related to behaviors, personality, and sexuality in male partners of vaginismic women. For instance, it has been reported that partners of vaginismic women are more likely to suffer from sexual problems, such as premature ejaculation and erectile dysfunc- tion,70,75,76 and from lack of self-confidence, passivity, dependency, and fear of failure73,77 than partners of nonaffected women. Given the significance of the effects of vaginismus on relationship and couple factors, more research in this area is needed (see Chapter 3.1).

Discussion

It is difficult to examine the various etiologic factors involved in the development and maintenance of vaginismus when we do not have a clear understanding of what this disorder entails. Is it a sexual dysfunction? A phobia? A pain disorder? Or a combination of these? There is significant need for empirical studies to investigate the different aspects of vaginismus. In particular, exploring the similarities and differences between women with vulvar vestibulitis syndrome and women with vaginismus could prove fruitful, as many authors suggest they are part of the same disorder. Given that women with vaginismus and those with dyspareunia both suffer from pain and hypertonic pelvic floor muscles, the difference between these two disorders might be one of degree rather than kind,51,78 with vaginismic women exhibiting more fear of pain and/or penetration than dyspare- unic women.

Future directions

It is interesting to note that much research concerning vulvar vestibulitis syndrome has focused on physical factors, such as innervation and genetics, with relatively little research examining relationship or psychosocial factors despite their importance in the development and maintenance of this condition. With vaginismus, it appears to be the opposite case, and with respect to vulvodynia, not much research has been done in either realm. It is clear that all subtypes of dyspareunia and vaginismus need to be examined from a multidisciplinary perspective; therefore, we suggest a reappraisal of the “sexual pain disorders”. We suggest that dyspareunia and its subtypes be seen as pain disorders, focusing on psychologic, relational, cognitive, sexual, and behavioral aspects involved in pain perception and control, and that the investigation of vaginismus focus on the pain, muscular, and phobic components.

We will continue to adopt a multidisciplinary perspective to examine dyspareunia and vaginismus in order to support the reclassification of these conditions. For example, current studies in our laboratory are investigating baseline superficial blood flow in the vestibule and how this changes over time after the application of a painful stimulus, the effects of sexual arousal on pain perception, hypnosis as a treatment in women with vulvar vestibulitis syndrome, and genital pain in postmenopausal women. In terms of examining the phobic aspect in women with vaginismus, we plan to investigate the pain aspect by psychophysical methods, the muscular component by pelvic floor physical therapy, and the phobic aspect through psychophysiologic, behavioral, and self-report measures. These studies will provide valuable information regarding the interplay of different factors in both conditions, as well as similarities between the two.

Acknowledgments

We thank Samir Khalifé, the gynecologist on our research team, for the countless gynecologic examinations he has performed over the years and for his endless insight and enthusiasm. We extend much gratitude to Rhonda Amsel, the statistical expert on our research team, for her patience, wit, and ability to help us with any statistical issue, no matter how obscure. We extend a heartfelt thank-you to Katherine Muldoon, our full-time research assistant, who helped us in countless ways over the last year, and the members of our McGill laboratory: Nicole Flory, Alina Kao, Tuuli Kukkonen, and Kimberley Payne. The research performed in our laboratory could not have been done without the help of the following granting agencies: the Canadian Institutes of Health Research (CIHR), Health Canada, and Pfizer Canada, Inc. Caroline F. Pukall was supported by the Fonds pour la formation de Chercheurs et l’Aide à la Recherche (FCAR), the Lloyd Carr-Harris McGill Majors Fellowship, and the McGill University Health Center PostDoctoral Fellowship; Marie-Andrée Lahaie was supported by the Fonds pour la formation de Chercheurs et l’Aide à la Recherche (FCAR) and the McGill University Health Center Doctoral Fellowship.

References

1. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, 4th edn, text revision. Washington, DC: 2000.

2. Binik YM. Should dyspareunia be classified as a sexual dysfunction in DSM-V? A painful classification decision. Arch Sex Behav 2005; 34: 11-21.

3. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, 3rd edn, (rev.) Washington, DC: 1987.

4. Deyo RA. Early diagnostic evaluation of low back pain. J Gen Intern Med 1986; 1: 328-38.

5. Laan E, van Lunsen RHW. Hormones and sexuality in postmenopausal women: a psychophysiological study. J Psychosomat Obstet Gynecol 1997; 18: 126-33.

6. Bachmann GA, Phillips NA. Sexual dysfunction. In Steege JF, Metzger DA, Levy BS, eds. Chronic Pelvic Pain: An Integrated Approach. London: W.B. Saunders, 1988: 77-90.

7. Binik YM, Reissing ED, Pukall CF et al. The female sexual pain disorders: genital pain or sexual dysfunction? Arch Sex Behav 2002; 31: 425-9.

8. Foster DC. Chronic vulval pain. In AB MacLean, RW Stones, S Thornton, eds. Pain in Obstetrics and Gynecology. London: RCOG Press, 2001: 198-208.

9. Friedrich EG Jr. Vulvar vestibulitis syndrome. J Reprod Med 1987; 32: 110-14.

10. Meana M, Binik YM, Khalifé S et al. Biopsychosocial profile of women with dyspareunia. ObstetOyneegl 1997; 90: 583-9.

11. Harlow BL, Wise LA, Stewart, EG. Prevalence and predictors of chronic lower genital tract discomfort. Am J Obstet Gynecol 2001; 185: 545-50.

12. Bergeron S, Binik YM, Khalifé S et al. Reliability and validity of the diagnosis of vulvar vestibulitis syndrome. Obstet Gynecol 2001; 98: 45-51.

13. Bergeron S, Binik Y, Khalifé S et al. Vulvar vestibulitis syndrome: a critical review. СжІРш 1997; 13: 27-42.

14. Mann MS, Kaufman RH, Brown D et al. Vulvar vestibulitis: significant clinical variables and treatment outcome. Obstet Gynecol 1992; 79: 122-5.

15. Goetsch MF. Vulvar vestibulitis: prevalence and historic features in a general gynecologic practice population. Am J Obstet Gynecol 1991; 164: 1609-16.

16. Chadha S, Gianotten WL, Drogendijk AC et al. Histopathologic features of vulvar vestibulitis. Int J Gynecol Pathol 1998; 17: 7-11.

17. Bohm-Starke N, Falconer C, Rylander E et al. The expression of cyclooxygenase 2 and inducible nitric oxide synthase indicates no active inflammation in vulvar vestibulitis. Acta Obstet Gynecol Scand 2001; 80: 638-44.

18. Bohm-Starke N, Hilliges M, Falconer C et al. Increased intraepithelial innervation in women with vulvar vestibulitis syndrome. Gynecol Obstet Invest 1998; 46: 256-60.

19. Westrom LV, Willén R. Vestibular nerve fiber proliferation in vulvar vestibulitis syndrome. Obstet Gynecol 1998; 91: 572-6.

20. Tympanidis P, Casula MA, Yiangou Y et al. Increased vanilloid receptor VR1 innervation in vulvodynia. EurJ^ain 2004; 8: 129-33.

21. Bohm-Starke N, Hilliges M, Blomgren BO et al. Increased blood flow and erythema in the posterior vestibular mucosa in vulvar vestibulitis. ObstetOyneçol 2001; 98: 1067-74.

22. Bohm-Starke N, Hilliges M, Falconer C et al. Neurochemical characterization of the vestibular nerves in women with vulvar vestibulitis syndrome. Gynecol Obstet Invest 1999; 48: 270-5.

23. Pukall CF, Binik YM, Khalifé S et al. Vestibular tactile and pain thresholds in women with vulvar vestibulitis syndrome. Pain 2002; 96: 163-75.

24. Bohm-Starke N, Hilliges M, Brodda-Jansen G et al. Psychophysical evidence of nociceptor sensitization in vulvar vestibulitis syndrome. Pain 2001; 94: 177-83.

25. Glazer HI, Rodke G, Swencionis C et al. Treatment of vulvar vestibulitis syndrome with electromyographic biofeedback of pelvic floor musculature. J Reprod Med 1995; 40: 283-90.

26. Reissing ED, Binik YM, Khalifé S et al. Vaginal spasm, pain, and 33: 5-17.

27. Gerber S, Bongiovanni AM, Ledger WJ et al. Interleukin-1B gene polymorphism in women with vulvar vestibulitis syndrome. Eur J_ObstetGyneeolR£pro!l£iol 2003; 107: 74-7.

28. Witkin SS, Gerber S, Ledger WJ. Influence of interleukin-1 receptor antagonist gene polymorphism on disease. Clin Infect Dis 2002; 34: 204-9.

29. Granot M, Friedman M, Yarnitsky D et al. Enhancement of the perception of systemic pain in women with vulvar vestibulitis. Br J Obstet Gynecol 2002; 109: 863-6.

30. Danielsson I, Eisemann M, Sjoberg I et al. Vulvar vestibulitis: a multi-factorial condition. Br J Obstet Gynecol 2001;108:456-61.

31. Bazin S, Bouchard C, Brisson J et al. Vulvar vestibulitis syndrome: an exploratory case-control study. Obstet Gynecol 1994; 83: 47-50.

32. Bouchard C, Brisson J, Fortier M et al. Use of oral contraceptives and vulvar vestibulitis: a case-control study. Am J Epidemiol 2002; 156: 254-61.

33. Eva LJ, MacLean AB, Reid W et al. Estrogen receptor expression in vulvar vestibulitis syndrome. AmJOhMetGjnecol 2003; 189: 458-61.

34. Payne KA, Binik YM, Amsel R et al. When sex hurts, anxiety and fear orient attention towards pain. Eu^LPain 2005; 9: 427-36.

35. van Lankveld JJ, Weijenborg, PT, Ter Kuile MM. Psychologic profiles of and sexual function in women with vulvar vestibulitis and their partners. ObstetGyn££oL 1996; 88: 65-70.

36. Gates EA, Galask RP. Psychological and sexual functioning in women with vulvar vestibulitis. J Psychosom Obstet Gynecol 2001; 22: 221-8.

37. Reissing ED, Binik YM, Khalifé S et al. Etiological correlates of vaginismus: sexual and physical abuse, sexual knowledge, sexual self-schema, and relationship adjustment. J Sex Marital Ther 2003; 29: 47-59.

38. Reed BD, Advincula AP, Fonde KR et al. Sexual activities and attitudes of women with vulvar dysesthesia. Obstet Gynecol 2003; 102: 325-31.

39. Jantos M, White G. The vestibulitis syndrome: medical and psychosexual assessment of a cohort of patients. J Reprod Med 1997; 42: 145-52.

40. Dalton VK, Haefner HK, Reed BD et al. Victimization in patients with vulvar dysesthesia/vestibulodynia: is there an increased prevalence? J Reprod Med 2002; 47: 829-34.

41. McKay M. Vulvodynia versus pruritus vulvae. Clin Obstet Gynecol 1985; 28: 123-33.

42. McKay M. Vulvodynia. In JF Steege, DA Metzger, BS Levy, eds. Chronic Pelvic Pain: An Integrated Approach. London: W.B. Saunders, 1988: 188-96.

43. McKay M. Dysesthetic (“essential”) vulvodynia: treatment with amitriptyline. J Reprod Med 1993; 38: 9-13.

44. Stewart EG. Vulvodynia: diagnosing and managing generalized dysesthesia. OBG Manag 2001; 13: 48-57.

45. Glazer HI, Jantos M, Hartmann EH et al. Electromyographic comparisons of the pelvic floor in women with dysesthetic vulvodynia and asymptomatic women. J Reprod Med 1998; 43: 959-62.

46. Glazer HI. Dysesthetic vulvodynia: long term follow-up after treatment with surface electromyography-assisted pelvic floor muscle rehabilitation. J Reprod Med 2000; 45: 798-802.

47. Bodden-Heinrich R, Küppers V, Beckmann MW et al. Psychosomatic aspects of vulvodynia: comparison with the chronic pelvic pain syndrome. J Reprod Med 1999; 44: 411-16.

48. Aikens JE, Reed BD, Gorenflo DW et al. Depressive symptoms among women with vulvar dysesthesia. Am J Obstet Gynecol 2003; 189: 462-6.

49. Edwards L, Mason M, Phillips M et al. Childhood sexual and physical abuse: incidence in patients with vulvodynia. J Reprod Med 1997; 42: 135-9.

50. American College of Obstetricians and Gynecologists, ACOG technical bulletin: sexual dysfunction. Int Gynecol Obstet 1995; 51: 265-77.

51. Reissing ED, Binik YM, Khalifé S. Does vaginismus exist? A critical review of the literature. J Nerv Ment Dis 1999; 187: 261-74.

52. Spector I, Carey M. Incidence and prevalence of the sexual dysfunctions: a critical review of the empirical literature. Arch Sex Behav 1990; 19: 389-96.

53. Hirst JF, Baggaley MR, Watson JP. A four year survey of an inner city psychosexual problems clinic. Sex Marital Ther 1996; 11: 19-36.

54. Harrison CM. Le vaginisme. Contraception Sex Fertil 1996; 24: 223-8.

55. Biswas A, Ratnam SS. Vaginismus and outcome of treatment. Ann Acad Med 1995; 24: 755-8.

56. Barnes J, Bowman EP, Cullen J. Biofeedback as an adjunct to psychotherapy in the treatment of vaginismus. Biofeedback Self Regul 1984; 9: 281-9.

57. van der Velde J, Everaerd W. Voluntary control over pelvic floor muscles in women with and without vaginismic reactions. Int UrogyneçolJlPelyi£Floor.Dy.£ynï 1999; 10: 230-6.

58. van der Velde J, Laan E, Everaerd W. Vaginismus, a component of a general defensive reaction: an investigation of pelvic floor muscle activity during exposure to emotion inducing film excerpts in women with and without vaginismus. Int Urogynecol J Pelvic FloorDyfnct 2001; 12: 328-31.

59. Leiblum SR. Vaginismus: a most perplexing problem. In SR Leiblum, RC Rosen eds. Principles and Practice of Sex Therapy, 3rd edn. New York: Guilford, 2000: pp 181-202.

60. Abramov L, Wolman I, Higgins MP. Vaginismus: an important factor in the evaluation and management of vulvar vestibulitis syndrome. Gynecol Obstet Invest 1994; 38: 194-7.

61. van Lankveld JJDM, Brewaeys AMA, Ter Kuile MM et al. Difficulties in the differential diagnosis of vaginismus, dyspareunia and mixed sexual pain disorder. J Psychosom Obstet Gynecol 1995; 16: 201-9.

62. Kaneko K. Penetration disorder: dyspareunia exists on the extension of vaginismus. J Sex Marital Ther 2001; 27: 153-5.

63. Walthard M. Die psychogene Atiologie und die Psychotherapie des Vaginismus. Munch Med Wochenschr 1909; 56: 1997-2000.

64. Kaplan HS. The New Sex Therapy. New York: Brunner/Mazel, 1974.

65. Ward E, Ogden J. Experiencing vaginismus - sufferers’ beliefs about causes and effects. J Sex Marital Ther 1994; 9: 33-45.

66. Dawkins S, Taylor R. Non-consummation of marriage: a survey of seventy cases. Lancet 1961; 280: 1029-33.

67. Rachman SJ. Fear and Courage. New York: WH Freeman, 1978.

68. Ellison C. Psychosomatic factors in the unconsummated marriage. J Psychosom Res 1968; 12: 61-5.

69. Basson R. Lifelong vaginismus: a clinical study of 60 consecutive cases. J Soc Gynecol Obstet Can 1996; 3: 551-61.

70. Masters WH, Johnson VE. Human Sexual Inadequacy. Boston: Little & Brown, 1970.

71. Duddle M. Etiological factors in the unconsummated marriage. J sychosomMei 1977; 21: 157-60.

72. Hawton K, Catalan J. Sex therapy for vaginismus: characteristics of couples and treatment outcome. Sex Marital Ther 1990;5:39-48.

73. van de Wiel HBM, Jaspers JPM, Weijmar Schultz WCM et al. Treatment of vaginismus: a review of concepts and treatment modalities. J Psychosom Obstet Gynecol 1990; 11: 1-18.

74. Rust J, Golombok S, Collier J. Marital problems and sexual dysfunction: how are they related? Br J Psychiatry 1988; 152: 629-31.

75. Lamont JA. Vaginismus. Am J Obstet Gynecol 1978; 131: 632-6.

76. Steege JF. Dyspareunia and vaginismus. Clin Obstet Gynecol 1984; 27: 750-9.

77. Freidman LJ. Virgin Wives: A Study of Unconsummated Marriages. London, Tavistock Publications, 1962.

78. de Kruiff ME, ter Kuile MM, Weijenborg PThM et al. Vaginismus and dyspareunia: is there difference in clinical presentation? J Psychosom Obstet Gynecol 2000; 21: 149-55.