Female sexual function and dysfunction: Assessment and treatment

Introduction

Sexual health is an important component of a woman’s well-being. Evidence suggests that healthy sexual functioning is a fundamental component of a woman’s sense of self and quality of life. Diminished sexual function has been found to correlate with advancing age, menopause, and economic and health problems ( ; ). Sexual dysfunction is associated with poorer mental health and reduced vitality and social function, as well as relationship problems and undiagnosed medical conditions ( ). Sexual problems are highly prevalent in women in the United States: about 40% have sexual concerns, and nearly 12% report sexual distress ( ). Sexual functioning is best approached from a biopsychosocial perspective. There are different types of sexual dysfunction, and treatment typically is individualized and tailored to the diagnosis and to the psychological, physical, and medical etiological factors.

The World Health Organization (WHO) stipulated that the maintenance of sexual health is the physician’s responsibility ( ). In 2001, the US Surgeon General, in his Call to Action to promote sexual health as one of the goals of Healthy People 2010, described the role of health care professionals and the need for better education and preparation ( ). For these concerns to be addressed, health care professionals must understand what constitutes functional sexuality. Unfortunately, there is a culturally-driven difficulty in determining normal sexual functioning ( ). Moreover, sexual medicine is not given a high priority in medical education, which leaves many providers uncomfortable. This discomfort, ultimately, is an obstacle to competency. Additionally, many patients are unaware of, or have misconceptions about, sexual dysfunction and treatment and are hesitant to discuss these problems with their providers. This also contributes to the underdiagnosis and undertreatment of female sexual dysfunction. However, patients prefer for their health care providers to initiate conversations about their sexual health ( ).

This chapter will offer the provider a working knowledge of the evolving theoretical models to describe a healthy sexual response, as well as an understanding of the neurobiology of sexual function. Additionally, a framework for assessment, diagnosis, and management of sexual dysfunction in women will be outlined and will include surgical and medical conditions that can contribute to the development of sexual dysfunction.

Models of female sexual response

Several models have been put forth to demonstrate the female sexual response. The female sexual response was first described by as a linear model of discrete events in which excitement always precedes arousal and then is followed by orgasm and resolution ( Fig. 10.1 ). This model then was modified by and independently to a triphasic model that emphasized desire (and neurobiology) as a critical stage of the sexual response, in contrast to physiologic genital arousal.

In the late 1990s, Basson added her intimacy-based, nonlinear model to help explain the multifactorial character of the female sexual response. This model includes the interplay of emotional intimacy, sexual stimuli, psychological factors, and relationship satisfaction. This model also introduces the concept of receptive (or responsive) desire, the idea that arousal often precedes desire, and that women often begin a sexual encounter from a position of sexual neutrality ( ). It encompasses the impact of biologic and nonbiologic factors on a woman’s sexual response like motivation, interpersonal issues, cultural and religious beliefs, partner health, relationship quality, past sexual abuse, and distractions. These theoretical models of sexual response may reflect the variation that women experience in sexuality. This was demonstrated by The Nurses’ Sexuality Study, in which nurses were asked to endorse the model that best fit their response ( ). Approximately 33% endorsed the Masters and Johnson model, 33% endorsed Kaplan’s models, and 33% endorsed Basson’s model. Of note, the women who had sexual concerns were more likely to endorse Basson’s model of sexual response.

Sexual function is best considered through the lens of a biopsychosocial model ( Fig. 10.2 ). This is an integrative, evolving model that reflects fluctuations in a woman’s physical health, mental health, neurochemical balance, sociocultural factors, and interpersonal issues. It highlights that sexual function is multifactorial, and that a multidisciplinary treatment approach to sexual dysfunction is often indicated. Biological (e.g., use of medications, physical health, neurobiological factors, and endocrine functioning), psychological (e.g., depression, sexual performance anxiety, and body image), interpersonal (e.g., relationship functioning, communication skills, and history of sexual abuse), and sociocultural (e.g., religious beliefs about sex and reproduction, and gender norms) all may affect sexual function and should be assessed ( ; ).

Physiology

Female sexual response is partly determined by neurobiological factors, including hormonal and neurochemical influences in the brain and signaling between the central nervous system (CNS) and erogenous zones (e.g., genitalia). Sexual response is thought to be influenced by excitatory and inhibitory pathways in the brain, involving the hypothalamus and limbic system affecting both excitatory and inhibitory mechanisms, and the cortex and midbrain affecting inhibitory mechanisms. Excitatory factors include dopamine and melanocortins (believed to influence attention to sexual stimuli and desire), as well as norepinephrine and oxytocin (believed to influence sexual arousal). Inhibitory factors include serotonin (thought to control satiety), opioids (believed to manage sexual rewards), and endocannabinoids (thought to promote sedation) ( ; ). Research, largely based on animal models, indicates that the balance or summation of inhibitory and excitatory signals determines an individual’s sexual response. This has been referenced as the “sexual tipping point” ( ). It is believed that hypoactive sexual desire disorder (HSDD) may result from hypofunctional excitatory factors, hyperfunctional inhibitory factors, or both. Imaging research showed that women with HSDD had higher activation in the medial frontal gyrus and right inferior gyrus (areas involved in attentional control of stimuli and response inhibition) than those without sexual dysfunction, providing support for hyperfunctional inhibition in women with HSDD ( ).

Furthermore, it is believed that the reward circuitry of the brain, involving the hypothalamus and basal ganglia that influence goal-directed and stimulus-directed behaviors, is a major determinant of sexual response. The prefrontal cortex exerts cognitive influence on sexual response by evaluating the reward value of a stimulus to encourage or discourage a behavior. Multiple other neurobiologic factors determine sexual response, such as attentional processes.

Sexual arousal is a normal physiologic response occurring in anticipation of, and during, sexual activity. Genital arousal occurs because of increased activity in the central and peripheral nervous system in response to physical (genital and nongenital) and nonphysical stimuli. The physiologic pathway of arousal in women is an intricate neurobiologic process that is not fully understood. The female sexual anatomy includes the mons pubis; the vulva, including the labia majora, labia minora, interlabial space, and clitoris; and the inner genitalia, including the vestibule, periurethral glans and vagina, uterus, fallopian tubes, and ovaries ( ). The cycle of arousal is initiated by genital vasocongestion driven by increased sympathetic nervous system activity. The vulva swell, exposing the introitus; the vagina lengthens and dilates; the outer third of the vagina tightens; the clitoris increases in length and diameter; and the uterus rises above the levator plate. Stimulation of the pelvic nerves induces smooth muscle relaxation and decreases the resistance within the arteries, leading to increased blood flow to the clitoris. This blood flow results from active neurogenic dilation of the sinusoidal blood spaces, which causes the corpora cavernosa of the clitoris to become engorged, and the clitoris becomes progressively more prominent. It has been noted that the vulvar structures become engorged, but they do not become erect, because the thinner tunica in women does not trap venous blood, and it therefore pools with persistent inflow and outflow ( ). In addition, vaginal lubrication occurs as a result of increased pressure in the capillaries of the genital vasculature and transudation of fluid through the subepithelium of the vaginal walls. Secretions are a combination of androgen-dependent glands of the vulva releasing mucin and aquaporin channels in the vaginal mucosa releasing a transudate of blood serum. Extragenital changes associated with arousal include nipple erection, skin flushing, and increases in heart rate, blood pressure, and respiration rate ( ).

It is likely that nitric oxide (NO), vasoactive intestinal peptide (VIP), and acetylcholine (ACh) play significant roles in sexual arousal ( ). Most of what we understand about their roles in female sexual excitement and response comes from studies of penile erection and sexual biology in animal models. Sexual stimulation releases NO from the vascular endothelium, which stimulates the release of guanylate cyclase, which in turn converts guanosine triphosphate into cyclic guanosine monophosphate ( ). This stimulates smooth muscle relaxation in the penile arteries and corpora cavernosum, causing blood flow to the penis. VIP and ACh also have been shown to relax smooth muscle and increase blood flow in the penis in animal models.

Before orgasm, physical changes occur, including tumescence, color change in the labia minora, lubrication, and relaxation of smooth muscles in the vaginal wall. Orgasm occurs with the release of contraction-producing agents (e.g., serotonin and oxytocin), leading to rhythmic contractions of the levator plate, uterus, and vagina, and multiple orgasms may occur if stimulation continues. The pelvic muscles repetitively contract in varying degrees of intensity and duration across women; for some women, contractions are not perceived. There is no current consensus regarding the brain regions activated during orgasm. Following orgasm, heart rate, respiration, and blood pressure immediately decrease, and detumescence, decongestion, and discontinuation and reabsorption of excess lubrication occurs ( ). The time required for resolution to take place varies among women.

Female sexual disorders

The International Society for the Study of Women’s Sexual Health (ISSWSH) has published a process of care (POC) document outlining recommendations for the identification and management of sexual problems in women and describing nomenclature for female sexual dysfunction, including dysfunction in the domains of sexual desire, arousal, orgasm, and sexual pain ( ). The sexual dysfunction subtypes characterized in the POC include HSDD, female sexual arousal disorders (FSADs), persistent genital arousal disorder, female orgasmic illness syndrome, and genitopelvic pain penetration dysfunction. The POC nomenclature departs from the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5; ), which combines desire and arousal problems into one condition (female sexual interest/arousal disorder). ISSWSH retained the separation of desire and arousal disorders in part because of research supporting the distinction between HSDD and FSAD ( ; ). In addition, whereas desire and arousal dysfunction can be comorbid, treatment of sexual dysfunction is often targeted toward the primary sexual problem. The ISSWSH POC nomenclature also differs from the DSM-5 definition of genitopelvic pain/penetration disorder (a classification combining vaginismus and dyspareunia) by including, in their classification of genitopelvic pain penetration dysfunction, difficulties associated with genital contact beyond intercourse, and hypertonicity or overactivity of the pelvic floor muscles with or without genital contact. The ISSWSH and International Consultation for Sexual Medicine nomenclature and definitions are presented in Box 10.1 .

Sexual dysfunction is characterized by persistent difficulties in a domain of sexual function (desire, arousal, or orgasm) or by sexual pain that is persistent (i.e., at least 3 months’ duration and occurring with ≥75% of sexual experiences) and accompanied by personal or interpersonal distress (e.g., bother, concern, unhappiness). The dysfunction must not be better accounted for by another psychiatric disorder or due exclusively to the direct physiologic effects of a substance or gynecologic or general medical condition ( Table 10.1 ). Each disorder is further subtyped into lifelong versus acquired and generalized versus situational. Sexual problems may co-occur ( ), and the best approach for clinical practice is to identify the most problematic or primary issue and focus initial treatment there.