Table of Contents
Physiology of Female Sexual Response
The human sexual response, as proposed by Masters and Johnson, consists of four stages:
However, this model lacks the concept of desire, which was added in Kaplan’s Triphasic model:
Basson (2001) recognized that the female sexual response was non-linear and was more complex with additional factors such as intimacy.
Considering this complexity, the female sexual response, in addition to the genital organs and internal pelvic structures (labia, vagina, ovaries, etc.) also involves the central nervous system and the spine.
The hippocampus, hypothalamus, limbic system, and medial preoptic area are particularly implicated. Indeed, a number of neurotransmitters partake in the female sexual response, such as:
- Nitric oxide
- Vasoactive intestinal peptide
When the clitoris is stimulated signals are transmitted to the spinal cord via the pudendal nerve. When the vagina is stimulated signals are transmitted via the pelvic nerve as well as the pudendal and hypogastric nerves. The primary mediator of the female sexual response is the spinal cord reflex system, which is under the inhibitory control of the brainstem, especially the nucleus paragigantocellularis, which lies in the ventral medulla.
This nucleus has direct projections to the pelvic efferent neurons and interneurons in the lumbosacral spinal cord. Although in men, activation of the sympathetic nervous system inhibits the sexual response, in women its activation facilitates the sexual response.
Theoretically, vaginal blood flow can be an indicator of a woman’s sexual arousal. However, in practice the association between the two is weak. This means that women are less sensitive to the genital blood flow changes than men or that they value external stimuli (more than men do) in their assessment of sexual arousal.
Besides the clitoris and vagina, erotic stimulation for women following arousal can originate from many non-genital sites such as breasts, nipples, periurethral glands, etc. The regulation of the female sexual response is also under the control of estrogens and androgens, although the role of testosterone in this regard is not well established. However, decreased desire and arousal are shown to occur because of a reduction in the estradiol levels.
Definitions of Female Sexual Dysfunction
The American Foundation for Urological Diseases (AFUD) categorizes female sexual disorders into the following groups:
|Sexual Desire Disorders||Hypoactive Sexual Desire Disorder||Deficiency or absence of sexual fantasies and desire for sexual activity|
|Sexual Aversion Disorder||Aversion to and active avoidance of genital sexual contact with a sexual partner|
|Sexual Arousal Disorder||Female Sexual Arousal Disorder||Persistent or recurrent inability to attain, or to maintain until completion of the sexual activity, an adequate lubrication-swelling response of sexual excitement|
|Orgasmic Disorders||Female Orgasmic Disorder||Persistent or recurrent delay in, or absence or, orgasm following a normal sexual excitement phase|
|Sexual Pain Disorders||Dyspareunia||Genital pain that associated with sexual intercourse|
|Vaginismus||Recurrent or persistent involuntary contraction of the perineal muscles surrounding the outer third of the vagina when vaginal penetration with penis, finger, tampon, or speculum is attempted|
Changes in DSM-5
There have been considerable revisions in the DSM-5 with respect to sexual disorders in an attempt to remove multiple ambiguous labels by grouping similar disorders and eliminating the vague. DSM-5 took the non-linear, complex female sexual response into consideration and combined hypoactive sexual desire disorder and female sexual arousal disorder into one disorder—the female sexual interest/arousal disorder.
DSM- 5 also grouped sexual pain syndromes into one under the term genito-pelvic pain/penetration disorder, because of their highly comorbid and overlapping nature that often made them difficult to distinguish.
Finally, the diagnosis of sexual aversion disorder has been removed because it was rarely used and there was hardly any research done related to the disease in order to present considerable evidence of the disorder. The orgasmic disorder remains as it is.
Epidemiology of Female Sexual Dysfunction
Female sexual interest/arousal disorder is observed in 8–9 % among women below the age of 44, and it increases with age. Orgasmic disorder can occur in 10–42 % of women. There is considerable variation in terms of age, culture, etc.
Etiology of Female Sexual Dysfunction
Female sexual function can be affected by numerous factors, direct or indirect. All of the following conditions can influence a woman’s sexual response or motivation:
- Physical illness
- Medications or other forms of therapy
- Psychological illnesses, including everyday stresses and conflicts
Physical illnesses that have been implicated in the etiology of female sexual disorders include:
- Cardiovascular diseases
- Diabetes mellitus
- Autoimmune disorders
- Neurologic impairment
- Urologic or gynecologic abnormalities
Estrogen deficiency (which may cause vaginal dryness) menopause or premature ovarian failure may lead to various sexual complaints in women. Other conditions that can lead to sexual dysfunction directly or indirectly include amenorrhea, bulimia, and postpartum state.
A woman on medications or chemo- or radiotherapy can also experience sexual disorders. The most common drugs implicated in this are the following:
- Psychiatric medications (antipsychotics, antidepressants, mood stabilizers, etc.)
- Most cardiovascular drugs (beta-blockers, digoxin, calcium channel blockers, etc.)
- Histamine receptor blockers
- Oral contraceptives
- Others: anticonvulsants, antiandrogens, and gonadotropin-releasing hormone agonists
As evidenced by Basson’s non-linear model of the female sexual response, emotional states are an integral part of a healthy sexual response in women. Consequently, the following can have an adverse effect on a woman’s sexual function:
- Stress and interpersonal conflicts (marital infidelity)
- Depressive tendencies
- Substance use (or abuse)
- Past history of abuse (sexual or physical)
- Partner’s health
- Cultural issues
- Privacy issues
- General well-being in the relationship
- Partner’s technical skills
- Lack of knowledge or misconceptions about sexual anatomy and orgasms
Diagnosis of Female Sexual Dysfunction
The diagnostic criteria laid down in the American Psychiatric Association (2013). Diagnostic and statistical manual of mental disorders (DSM 5) are listed below. Note that in all disorders, the minimum symptom duration is 6 months. The symptoms should cause significant clinical distress to the individual, and they should not be explained by any medical or nonsexual mental condition or substance use. All these disorders can be classified, based on the age of onset, as lifelong or acquired.
Female Orgasmic Disorder
The patient shows the following:
- Delay or absence of orgasms
- Decreased intensity of orgasms
Female Sexual Interest/Arousal Disorder
The patient should show at least three of the following:
- Decreased interests or thoughts of sexual activity
- Decreased response to sexual intimacy from partner
- Decreased sexual pleasure during intercourse
- Lack of sexual arousal
- Decreased genital/non-genital sensation during sexual intercourse or activity
Genito-Pelvic Pain/Penetration Disorder
Persistent or recurrent difficulties with one (or more) of the following:
- Pain during penetration
- Fear or anxiety about sex or pain during sex
- Constriction of the vagina during sex
- Routine hematological parameters to rule out anemia
- Levels of various hormones—a thyroid-stimulating hormone, prolactin, adrenal precursors such as dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS), and estrone, estradiol, progesterone, and testosterone panel
- Lipid panel
- Liver function tests
Ultrasonography of the pelvis (especially transvaginal ultrasonography) can be helpful in ruling out any underlying structural abnormality.
- Biothesiometry; assessment of neurological pelvic status
- Perineometry; assessment of pelvic floor musculature
- Vaginal photoplethysmography; assessment of genital blood flow
- Vulvoscopy; assessment of the vulvar and surrounding structures
- Nonsexual mental disorders (e.g. major depressive disorder)
- Substance (ab)use or medication-induced sexual dysfunction
- Other medical conditions (e.g. condition with hormonal imbalance such as diabetes mellitus or thyroid dysfunction or any injury)
- Interpersonal factors (e.g. violence, stress, problems in a relationship)
- Other sexual dysfunctions: neither a different diagnosis or, more commonly, another condition (e.g. genital pain) coexisting with the one in consideration (e.g. lack of arousal)
- Inadequate or absent sexual stimuli (e.g. poor, perceived, technical skills by the partner)
Treatment of Female Sexual Dysfunction
Psychotherapy, which involves
- Couple therapy
- Cognitive-behavioral therapy
- Sex therapy (i.e. behaviorally oriented sex therapy, which may be combined with cognitive-behavioral therapy) with or without the partner
- Other psychotherapeutic strategies
Depending on the problem and the approach, the therapy may include a demonstration of vaginal dilatation. Individual cognitive-behavioral therapy aims to resolve underlying individual problems, such as anxiety, which is commonly believed to affect sexual functioning.
Physical therapy, which can be
- Pelvic floor physiotherapy
- Dilator therapy
- Kegel exercises, the effectiveness of which can range from very useful (e.g., in vaginismus) to useful only as adjuncts (e.g., in orgasmic disorders)
- New FDA-approved vacuum device, Eros Clitoral Therapy Device, which facilitates blood flow to the clitoris, causing its engorgement, which facilitates continued sexual arousal and orgasm
Pharmacotherapy, which, so far, only includes one drug for female sexual disorders (in terms of desire, arousal, and orgasm) that has been approved by the FDA. It is called flibanserin (as 100 mg bedtime dose), and it has been approved for ‘acquired, generalized hypoactive sexual desire disorder in premenopausal women’.
Flibanserin is a 5-HT 1A receptor agonist and 5-HT 2A receptor antagonist. It boosts sexual drive. It has several side effects, the most notable being severe hypotension and syncope if consumed along with alcohol.
The FDA has approved conjugated estrogens and ospemifene for dyspareunia, which can indirectly play a role in hypoactive sexual desire disorder. Tibolone and phosphodiesterase inhibitors such as sildenafil may be used, but are not approved by the FDA.