Quality-of-life issues in healthcare have come to be of paramount importance for a population that increasingly expects healthcare not only to treat major illnesses but also to optimize normal levels of physical and psychosocial functioning and overall well-being. Healthcare providers have also increasingly appreciated the impact that adverse effects of treatment can have on quality of life, as well as on compliance with and the effectiveness of treatment.

Many functional impairments and adverse treatment effects take the form of clinical complaints that patients and caregivers typically report to their healthcare providers without prompting. Other adverse effects are not so obviously clinical or treatment-related, and patients may not be inclined or may even be reluctant to bring them up when talking with the provider. Impairment of sexual function is a problem of this kind.

Sexual dysfunction appears to be common and frequently underrecognized in certain patient populations. For example, it has been estimated that 25% to 63% of women and 10% to 52% of men with epilepsy have some form of sexual dysfunction, yet in clinical reviews of sexual disorders, epilepsy is not listed as one of the medical conditions commonly associated with impaired sexual function.

Sexual desire, arousal, and orgasm are mediated by complex—and as yet not fully understood—interactions of the somatic and autonomic nervous systems, operating at cerebral, spinal, and peripheral levels. Furthermore, neural activity within these systems is modulated by the presence of steroid and peptide hormones, which affect male and female response differentially. At the central level, dopaminergic and serotonergic systems appear to play a significant role in various components of sexual response, although adrenergic, cholinergic, nitergic, γ-aminobutyric acidergic, and other neuropeptide transmitter systems may contribute as well. At the peripheral level, adrenergic, cholinergic, and nitergic activation mechanisms control vascular changes that underlie vaginal lubrication and penile erection. In addition, these systems respond to descending brain and spinal influences that generate orgasmic response. Disruption of endocrine, neural, or vascular response—caused by aging, disease, surgery, or medication—has the potential to lead to sexual inadequacy. At the same time, psychological and relationship factors play an important role in healthy sexual response and may enhance or impair sexual functioning.

Most people with epilepsy maintain normal reproductive and sexual lives. However, a significant minority of women with epilepsy (20% to 30%) have some degree of sexual dysfunction, including problems with libido, arousal, and orgasm. Men with epilepsy are at risk for decreased sexual functioning, including sexual interest and sexual performance, at least in part because of increased sex hormone-binding globulin levels and lower bioactive testosterone levels, particularly in association with the use of enzyme-inducing antiepileptic drugs, such as phenytoin and carbamazepine. A decrease in bioactive testosterone levels probably has a significant effect on the sexuality of women with epilepsy as well. Antiepileptic drugs may also affect sexual function in women through alterations of serotonergic neurotransmission. Epilepsy itself appears to have the potential to affect sexual function. The amygdala is emerging as a brain structure with significant involvement in sexuality in patients with epilepsy, as shown by alterations in sexual functioning after temporal lobectomy. Preliminary evidence suggests that people with temporal lobe epilepsy have reduced genital blood flow in response to erotic stimulation; the etiology of this phenomenon is not well understood, but disruption of the limbic and frontal cortex by epileptic activity may be implicated. Psychosocial factors, including sexual anxiety and stigma associated with epilepsy, can also affect the sexual life of patients with epilepsy.

Little is known about the prevalence, typology, and natural course of non—drug-induced sexual dysfunction in patients with depression. Loss of libido has been reported in various studies to affect from 25% to 75% of patients with unipolar depression, and its prevalence appears to be correlated with the severity of depression. Disorders of arousal also appear to be relatively common in both men and women with major depression, of whom ~25% may experience problems with erection or lubrication. The scant available data regarding orgasmic difficulties in patients with depression who have not yet taken antidepressant medication suggest that they are more common than in the general population. The potential causes of sexual dysfunction in patients with depression are complex and little investigated, and future research must distinguish and explore the various biological, psychological, and psychosocial factors that are likely to be involved.

Psychotropic drugs are often associated with sexual dysfunction. The frequency of antidepressant-associated sexual dysfunction is greatly underestimated in clinical trials that rely on patient self-report of these adverse events. Direct inquiry reveals that delayed orgasm/ejaculation occurs in ≥50% and anorgasmia in at least one third of patients given selective serotonin reuptake inhibitors. Antidepressant-induced sexual dysfunction can be successfully managed. A different antidepressant without significant sexual effects, such as bupropion or mirtazapine, can often be substituted. Other strategies involve drug holidays or adjunctive therapy with drugs such as sildenafil. Dopamine antagonist antipsychotic drugs are most commonly associated with decreased libido. The newer atypical antipsychotics, with less effect on dopamine, are less commonly associated with sexual dysfunction. Sexual dysfunction is commonly reported with seizure disorders, and many anticonvulsant drugs affect levels of sex hormones. Because sexual dysfunction can be related to many factors, care must be taken to establish the patient's baseline sexual functioning before the initiation of psychotropic drug therapy and to rule out other etiologies before drugs are implicated as causative.

Sexual dysfunction is a frequently encountered comorbid condition in patients with many medical and psychiatric conditions, such as epilepsy and depression. Most depressed patients experience some type of sexual dysfunction, decreased sexual desire being the most common. The association of sexual dysfunction with epilepsy is less clear. Changes in sex hormone levels are common in patients with epilepsy and may be attributable to the disease or to antiepileptic drugs (AEDs). Sexual dysfunction associated with depression or epilepsy is generally treated according to standard guidelines for the management of sexual disorders, since data from special populations are not available. The most common forms of female sexual dysfunction are lack of sexual desire and difficulty achieving orgasm. There are no approved pharmacotherapies for female hypoactive sexual desire disorder or female orgasmic disorder. Female sexual arousal disorder is treated with estrogen replacement therapy when indicated or vaginal lubricants. The most common male sexual dysfunction disorders are premature ejaculation and erectile dysfunction.  Phosphodiesterase type-5 inhibitor drugs are now the first-line treatment for erectile dysfunction, and selective serotonin reuptake inhibitors and topical anesthetic creams are nonapproved but effective treatments for premature ejaculation. Testosterone and aromatase inhibitors have been used investigationally to treat sexual dysfunction in men taking AEDs. Patient education and follow-up appointments are essential to ensure optimal outcomes of pharmacologic treatments for sexual dysfunction.

Sexual dysfunction is common among patients with epilepsy, but many clinicians do not include inquiries about this aspect of the patient's health in their routine evaluations. This article presents approaches for taking a sexual history and for discussing sexual problems. The utility of standardized sexual dysfunction questionnaires is reviewed and the important elements of appropriate and effective counseling are highlighted.