International Journal of Impotence Research (2000) 12, Suppl 4, S152±S157 ß 2000 Macmillan Publishers Ltd All rights reserved 0955-9930/00 $15.00 www.nature.com/ijir Female sexual arousal disorder: new insights I Goldstein1* 1Department of Urology, Boston University School of Medicine, MA, USA Epidemiologic investigations of women with female sexual dysfunction (FSD) from well-designed, random-sample, community-based populations are limited. Based on available information, FSD is common and estimated to occur in 22 ± 43% of women. There are limited data on age-related and para-aging risk factors, which are critical to understand when planning treatment and prevention efforts. Based on correlates of FSD, associated risk factors include age, education, history of sexual abuse or sexually transmitted disease, overall state general happiness and physical health. This brief overview attempts to review what is known about the female sexual anatomy, describes factors that may affect female sexual responsiveness, and identi®es several areas where additional research is needed to promote understanding of this complex physiological and psychosocial phenomenon. International Journal of Impotence Research (2000) 12, Suppl 4, S152±S157. Keywords: female sexual function and dysfunction; female sexual arousal disorder Introduction sensory input primarily genital. Orgasm consists of multiple sensory afferent information from trigger points such as clitoris, labia, vagina, periurethral The female sexual response has been characterized glans, etc, which pass centrally to supraspinal as consisting of desire, arousal and orgasm structures probably involving the thalamic septum. phases.1±3 Desire involves the existence of sexual Following suf®cient sensory stimulation, central fantasies, thoughts, and=or receptivity to sexual neurotransmitter discharge during orgasm results activity. Desire is the mental state created by in repeated 1 sec motor contractions of the pelvic external and internal stimuli that induces a need ¯oor (3 ± 8=orgasm) followed in 2 ± 4 sec by repeated or want to partake in sexual activity. Desire may be uterine and vaginal smooth muscle contraction. said to consist of: (1) biologic roots, which are in Pleasurable sensory information is also carried to part based on hormones such as androgen and the cortical pleasure sites. Orgasm involves a central estrogen; (2) motivational roots, which are in part thalamic sensory depolarizing wave resulting in based on intimacy, pleasure and relationship issues; synchronous motor activity following suf®cient and (3) cognitive issues such as risk and wish. sexual stimulation and arousal.3 Arousal involves the ability to attain, or maintain A speci®c and thorough description of the sexual adequate sexual excitement and may be experienced problems a woman experiences is achieved through as subjective excitement or genital lubrication and nosology. Female sexual dysfunction consists of or swelling or other somatic responses. Arousal is disorders of desire, arousal, orgasm and sexual pain. the state with speci®c feelings and physiologic Speci®cally for this review, the focus will be upon changes usually associated with sexual activity the condition of female sexual arousal disorder. involving the genitals. Arousal may be said to Sexual arousal disorder is de®ned as the persistent consist of: (1) central mechanisms including activa- or recurring inability to attain, or maintain adequate tion of thoughts, dreams and fantasies; (2) non- sexual excitement causing personal distress. It may genital peripheral mechanisms such as salivation, be experienced as a lack of subjective excitement sweating, cutaneous vasodilation and nipple erec- or a lack of genital (lubrication=swelling) or other tion; and (3) genital mechanisms such as clitoral, somatic responses.2 Disorders of female sexual labial and vaginal engorgement. Orgasm involves arousal include, but are not limited to, lack of or the altered state of consciousness associated with diminished vaginal lubrication, decreased clitoral and labial sensation, decreased clitoral and labial engorgement or lack of vaginal smooth muscle *Correspondence: I Goldstein, Doctor's Of®ce Building, 720 relaxation. These conditions may occur secondary Harrison Avenue, Suite P606, Boston, MA 02118-2334, USA. to psychological factors. However, there is often a E-mail: [email protected] medical or physiologic basis such as diminished Female arousal disorders I Goldstein S153 vaginal=clitoral blood ¯ow, altered hormonal milieu, including aging, hypertension, cigarette smoking, prior pelvic trauma, pelvic surgery such as hyster- hypercholesterolemia, are also associated with ectomy, vaginal injury from childbirth, or use of female sexual dysfunction. medications such as selective serotonin re-uptake inhibitors. Female sexual dysfunction is a multi-causal and Anatomy and physiology multi-dimensional medical problem that adversely effects physical health and emotional well being. The focus of this paper is to update new insights There are multiple anatomical structures which into the epidemiology, physiology, pathophysio- comprise the internal and external female genital logy, diagnosis and treatment of the speci®c dis- tract such as the clitoris, labia minora and vestibular order of female sexual arousal. (corpus spongiosum) erectile tissue, peri-urethral glans, urethra, G-spot, Halban's fascia, anterior fornix erogenous zone, pubococcygeus muscle and Epidemiology cervix. There are also multiple non-genital periph- eral anatomic structures involved in female sexual responses such as salivary and sweat glands, Epidemiologic investigations of women with female cutaneous blood vessels and nipples.8±12 sexual dysfunction from well-designed, random- In response to neurogenic stimulation, clitoral sample, community-based populations are limited. and vaginal smooth muscle tone relax allowing for Based on available information, female sexual increased blood ¯ow, vaginal and clitoral engorge- dysfunction is common and estimated to occur in ment and increases vasocongestion. Thus, the state 22 ± 43% of women.4±7 There are limited data on of smooth muscle tone determines the changes in age-related and para-aging risk factors, both critical the hemodynamic and genital arousal.13 to plan treatments and prevention efforts. Based on Sexual stimulation results in physiologic arousal correlates of female sexual dysfunction, associated or sensory afferent activation of these structures risk factors include age, education, history of sexual ultimately leading to an orgasmic response. In abuse or sexually transmitted disease, overall state particular, the clitoris consists of two corpora of general happiness and physical health. Epide- cavernosa lined by the tunica albuginea. The miologic information from the large, well-designed internal erectile tissue includes endothelial-lined National Health and Social Life Survey revealed that lacunar spaces, trabecular smooth muscle and in 1622 US women between the ages of 18 and 59 y, trabecular connective tissue (collagen and elastin). trouble lubricating and sex not pleasurable was Efferent autonomic innervation occurs via the noted in 18.8% and 21.2%, respectively, of the cavernosal nerve. In the basal state, corporal smooth subjects. Overall, 43% of female subjects had muscle is under contractile tone. Following sexual complaints of sexual dysfunction. Women over the stimulation, neurogenic- and endothelial-mediated age of 60 were not included in this study, and no release of nitric oxide (NO) plays an important role adjustment or association was made for menopausal in clitoral cavernosal artery and helicine arteriolar status or medical risk factors.4,5 smooth muscle relaxation leading to clitoral engor- Rosen et al, in a non-population based study of gement. With sexual stimulation, increased blood 329 women aged 18 ± 73 y from a wellness out- ¯ow to the clitoral cavernosal arteries results in patient gynecology center, reported that lack of increased clitoral intracavernosal pressure and sexual pleasure and lack of lubrication was noted tumescence and protrusion of the glans. Studies in 16.3% and 13.65%, respectively, of the subjects. show that the clitoris achieves tumescence, but not Based on the 1997 US Department of Commerce rigidity or effective corporal veno-occlusion during Bureau of the Census, 26 million women are post- sexual arousal. Duplex ultrasounds of the clitoris menopausal. According to Rosen, 66% of post- reveal that during sexual simulation the clitoris menopausal women have intercourse, 45% and increases in length and diameter and blood ¯ow 20% have two and 10 intercourse occasions per almost doubles. In the clitoris, NO has been month, respectively. Thus, 17 million post-meno- identi®ed in human tissue and is hypothesized to pausal women are engaging in 600 million inter- be the primary mediator of clitoral and labial course occasions per year in the USA. Also engorgement. Organ bath analysis of rabbit clitoral according to Rosen, 57% experience lack of lubrica- cavernosal smooth muscle strips demonstrates tion; 13% in 37.5% and 44% in greater than 75% enhanced relaxation in response to sodium nitro- of intercourse occasions, respectively. Thus, 9.7 prusside and L-arginine (both NO donors) which million women experience lack of lubrication in supports the above hypothesis. Recently, phospho- 229 million intercourse occasions per year.7 diesterase Type V (PDE V), the enzyme responsible Ongoing epidemiologic studies in