A functional nervous system is necessary for women’s genital tissue responsiveness and important for a woman’s overall sexual health. The standard sexual medicine physical examination of the woman with sexual health concerns emphasizes the integrity of the nervous system (somatic sensory and motor; and autonomic parasympathetic and sympathetic) as assessed by genital neurologic examination. The neurological examination should be part of the biologic-focused evaluation of all women with sexual health problems. Abnormal ?ndings on initial physical examination may prompt further neurological testing, such as referral to a neurologist or neurosurgeon/spine specialist to obtain more detailed evaluations such as genital-cerebral evoked response testing (electrophysiological evaluations) and magnetic resonance imaging of the central nervous system. It is important to rule out signi?cant neurologic disease as the basis for a woman’s sexual health concerns, or to con?rm a neurologic cause for the sexual health problem, particularly in women with known neurologic disease, such as diabetes or multiple sclerosis. Neurologic impairment has been implicated in the cause of hypoactive sexual desire disorder, reduced sexual arousal, decreased vaginal lubrication, orgasmic dysfunction, and sexual pain in women with diabetes.
Currently the sexual medicine physical examination focuses on the integrity of the somatic sensory and motor examination because conclusions concerning the integrity of the autonomic nervous system cannot be reached from genitourinary physical examination ?ndings. Standardized neurological evaluations exist for all parts of the body including the women’s genitalia, incorporating a sensory exam, motor exam, and genital re?exes. Somatic innervation (sensory and motor) of the woman’s genitalia is mediated via branches of the pudendal nerve. The pudendal nerve, derived from the second through fourth segments of the sacral spinal cord, provides critical sensation to all the erogenous areas in a woman’s genitalia and critical motor function to the pelvic ?oor muscles, including the urinary and anal sphincters. The three branches of the pudendal nerve include the right and left dorsal nerve of the clitoris (sensory to the clitoris shaft and glans), the right and left perineal nerve (sensory to both labia and the perineum), and the right and left inferior rectal nerve (sensory to the perianal skin).
Neurologic assessment of the autonomic innervation of the genital organs, mediated via branches of the thoracolumbar (sympathetic), and sacral (parasympathetic) out?ow tracts may be objectively assessed indirectly by measuring changes in genital blood flow as implied by changes in peak systolic and end-diastolic velocity measurements during duplex Doppler ultrasound of the clitoral arteries pre-and post-sexual stimulation. In general, however, the autonomic nervous system contributions to the woman’s genital organs have not yet been well characterized.
Neurologic testing is typically performed in a quiet room at a controlled temperature of 21–23°C. The innervation of women’s genitals is bilateral and somatic innervation does not cross the midline. Thus somatic testing should be performed on both the right and left sides, except for the clitoris shaft and glans where it is difficult to accurately assess right and left sides separately.
The sensory genital neurologic exam in a woman with sexual health problems elicits information concerning sensory pudendal nerve integrity. Testing is performed on the mons and periclitoral area (dorsal nerve branches of the pudendal nerve), labia majora and labia minora (perineal nerve branches of the pudendal nerve), and perianal areas (inferior rectal nerve branches of the pudendal nerve). Subjective assessment of peripheral neuropathy is based on the woman’s response to pinprick (21 gauge, one inch sterile needle) and light touch (cotton ball) sensation. Objective assessment of peripheral neuropathy is based on quantitative sensory testing examination using vibratory (biothesiometry), and hot and cold thermal sensory thresholds. Quantitative sensory testing involves the administration of quantified stimuli, vibration or hot or cold temperature in controlled manner, so that the subject defines the minimum sensory threshold by indicating the onset of the perceived sensation. Quantitative sensory testing is a repeatable and valid descriptor of a woman’s sensory state that has been used to assess sensory function for other neuropathies. There are age-corrected normograms for thresholds of vibratory, hot, and cold thermal sensations for the clitoris and for the vagina.
A-beta fibers are the largest nerve fibers, mediating touch, mild pressure, sensation of joint position and vibration. Biothesiometry measures the integrity of the A-beta fibers. A-delta fibers are smaller nerve fibers mediating cold sensation and the first components of pain sensation. Cold thermal testing measures the integrity of the A-delta fibers. C fibers are the smallest and slowest of the nerve fibers, mediating heat sensation and is the main component of pain sensation, subserving most of autonomic peripheral functions. Hot thermal testing measures the integrity of the C fibers. For quantitative sensory testing, the control or non-genital reference site is typically the right pulp index finger but other sites may be chosen. The test sites for the dorsal nerve branches of the pudendal nerve are the midline glans and shaft of the clitoris. The test sites for the perineal nerve branches of the pudendal nerve are the right and left labia minora. The test sites for the inferior rectal nerve branches of the pudendal nerve are the right and left perianal skin regions.
The motor genital neurologic exam in a woman with sexual health problems elicits information concerning motor pudendal nerve integrity related to strength of pelvic motor contraction and ability to sustain the pelvic floor contraction. A perineometry device can be utilized to objectively record the strength of pelvic motor contraction directly in cm/H20 and the ability to sustain the pelvic floor contraction in seconds.
The sacral reflex genital neurologic exam in a woman with sexual health problems exam provides information concerning the integrity of the afferent and efferent arms of the bulbocavernosus re?ex (the afferent arm is the sensory dorsal nerve of the clitoris, and the efferent arm is the motor perineal nerve) and the anal wink reflex (the afferent and efferent arms both arise from the inferior rectal nerve). All arms of these reflexes are branches of the pudendal nerve. An intact sacral re?ex indicates that both sensory and motor arms of the re?ex are intact. For the bulbocavernosus re?ex, the index ?nger of one hand is placed in the vagina along posterolateral aspect of either the right or left vaginal wall. Beneath the introitus at this level lies the bulbocavernosus muscle at the crus of the clitoris. A short-lived squeeze of the glans clitoris with the opposite hand will elicit contraction of the bulbocavernosus muscle. The examination is repeated with the examining ?ngers facing the opposite vaginal wall. The anal wink re?ex is performed by using the wooden shaft end of the cotton tipped applicator to touch the perianal skin near the anus at the right and left sides. A brief contraction of the anal sphincter will be noted.
At the present time, the safest and most effective means of assessing for neurologic causes of sexual health problems involves a detailed neurologic examination as part of the sexual medicine physical examination.
San Diego Sexual Medicine is conveniently located on the spacious campus of Alvarado Hospital, a private, physician-owned hospital just ten miles from downtown San Diego, and is easily access by car or public transportation.