Sexual function relies on a complex network of peripheral and central pathways involving the participation of autonomic and somatic nerves and the integration of numerous spinal and supraspinal sites in the central nervous system, with the hypothalamic and limbic regions playing a pivotal role.
Neurological diseases have long been recognized as causing sexual dysfunction through an altered processing of sexual stimuli to preclude arousal, to decrease or increase desire, or to curtail genital engorgement.
Various studies have shown a significant decrease in sexual satisfaction after cerebrovascular accident. In men affected by stroke, a decline in libido and poor or tailed erection and ejaculation are frequently observed. Indeed, the reported prevalence of post-stroke diminished libido varies from 17% to 42%. Korpelainen et al. showed a significant decline in libido, sexual arousal and satisfaction with sexual life in both male and female stroke patients, but the frequency of patients who ceased having sexual intercourse was lower (28% at 2 months and 14% at 6 months) than in the previous studies. The same authors demonstrated that sexual dysfunction was strictly related to the presence of sensory hemisyndrome, in agreement with Sjogren et al, who found that changes in the frequency of intercourse were related to the degree of cutaneous sensibility impairments and levels of independence in activities of daily living, but not with the degree of motor impairment. Tactile stimulations are extremely important in sexual arousal and orgasm during foreplay and intercourse. Therefore, it is obvious that sensory hemisyndrome may be related to problems with erection, ejaculation and orgasm resulting in impaired libido and quality of life.
Interestingly, a significant decline in coital frequency, sexual satisfaction, libido, sexual arousal and orgasm has been demonstrated among stable stroke patients with mild or no disability.
Some male patients experience temporary sexual problems, usually regaining erectile function after around seven weeks following the stroke, whereas others do not seem to recover sexual intercourse, and/or show a worsening in time.
The cause of sexual dysfunction is often multifactorial with a complex interplay between psychological and organic factors. In fact, sexual problems seem to be related to various factors, like the general attitude toward sexuality, an incipient depression with anxiety after the cerebrovascular accident or prior medical conditions such as hypertension, diabetes mellitus, or the use of specific drugs.
Some authors have postulated a relationship between the location of the lesion and sexual change, since sexual disorders appear to be more frequent when the right hemisphere is involved. Coslett et al. reported in a study of unilateral stroke patients that those with a stroke lesion in the right cerebral hemisphere experienced a significant decrease in sexual desire and in the frequency of intercourse. Indeed, libido and ability to achieve erection may require activation of specific limbic and cortical structures, and the right hemisphere seems to be dominant for attention/activation functions and in processing emotions. Moreover, the right hemisphere dominance for male sexual activity may be related to the specific control of hypothalamus-pituitary axis, as suggested by the observation of altered sexual behaviors in patients with right temporal lobe epilepsy.
Nevertheless, to date, a few studies have attempted to determine the correlations between the sexual function of stroke patients and the locations of their lesions. Jun et al have shown that patients with multiple brain lesions had a significant decrease of erectile function compared with those with one lesion. In particular, a decrement of sexual desire was associated with a stroke lesion on the left basal ganglia; patients with lesions in the right cerebellum experienced significant ejaculatory disorders; and patients with lesion in the right pons were associated with a decrease in the International Index of Erectile Function-5 score. Jeon et al demonstrated that patients with cerebrovascular accident lesions of the thalamus showed more erectile dysfunction than the patients with cerebrovascular accident lesions of any other areas. This would point out the possible role of thalamus in human penile erection supporting those data from preclinical studies that suggested how thalamic caudal and lateral intralaminar nuclei are involving in processing the sexual outflow from the spinothalamic pathway towards the preoptic area, amygdala, temporal lobe, and the frontal cortex.
On the contrary, few authors did not find a significant correlation between decline of sexual intercourse after stroke and injured hemisphere, whereas few findings reported a greater incidence of sexual disorders after left-hemisphere. However, it should be taken into account that depression often accompanies left rather than right hemisphere damage and depression may certainly lead to sexual impairment.
Interestingly, behavioral alterations after stroke may play a role in the aetiology of sexual changes. Hypersexuality has been related to temporal lobe lesions, history of poststroke seizures and antidepressant activity. A case of hypersexuality following bilateral thalamic infarction has been recently described, showing how frontal-subcortical circuits may have a pivotal role in the pathogenesis of this sexual disorder. Indeed, it seems that lacunar strokes that affect the frontolimbic connections have special propensity to cause hypersexuality: profoundly disinhibited sexuality and hemiballism has been reported after the infarction of the subthalamic nucleus.
Jawad et al reported on a case of altered sexual orientation (homosexual to heterosexual) following an infarct in the left middle cerebral artery region; thus, the authors recommended addressing this issue, in addition to other possible behavioral changes, while assessing patients after a brain injury. Stroke that affects the right-medial frontal cortex and the anterior portion of the corpus callosum is one of the possible vascular causes of the so-called alien hand syndrome, which can cause the perception that one hand belongs to someone else, and can induce purposeful involuntary movements, even self-masturbatory movements on the genitalia.
Emotional incontinence, characterized by excessive and/or inappropriate laughing/crying, has been occasionally reported after unilateral stroke. Chi-Kwon and Kim have investigated, for the first time, both post-stroke Emotional incontinence and sexual activity changes in the subacute as well as the chronic stage of stroke; according to the authors, the presence of Emotional incontinence is a factor related to decreased poststroke sexual activity suggesting a possible alteration of an identical neurotransmitter system. Moreover, a stroke may impair the ability to correctly interpret other’s emotions, to express the emotions of love and joy, and to notice, interpret and express the subtle emotional cues essential to romance and love.
Physical impairment could have an important role in the etiology of long-term sexual problems. In common with severe brain trauma, the effects of a devastating stroke may influence body positioning and movement and challenge the ability to embrace and stimulate the partner during sexual intercourse. Obvious drawbacks are drooling, bladder and bowel incontinence, and other potentially unattractive behaviors. Indeed, facial dropping, speech and memory problems, hemiparesis, difficulty eating, and incontinence all may contribute to feeling less attractive with a consequent loss of desire and important reduction in sexual intercourse. Right-middle cerebral artery strokes have the potential to produce not only hemianesthesia but also perceptual neglect (i.e. the inability to interpret the left side of the environment), both of which might interfere with erotic sensations.
The role of previous medical conditions in the pathogenesis of post-stroke sexual dysfunction is still under debate. Because stroke tends to occur with increasing age, changes in sexual response with aging have to be taken into account when dealing with survivors of stroke. Indeed, in men it takes longer and more direct stimulation to achieve an erection; erections are not as hard and do not last long; orgasm may be not reached with every sexual encounter.
Risk factors for having a stroke, beyond older age, include diabetes mellitus, hypertension, dyslipidemia and hyperhomocysteinemia, heart disease, peripheral vascular disease, and chronic lung disease. Although it is unlikely that people with stroke have all of these premorbid conditions, they are likely to have at least one. The atherosclerosis, that causes hypertension, heart disease, and stroke, may also reduce genital circulation and cause erectile dysfunction (ED). However, the longer one has the disease and the more severe the symptoms are, and the more likely the sexual problems are. Beside the direct impact of the disease on the sexual function, many drugs used in these diseases, such as antihypertensives, particularly beta blockers, may lead to sexual problems.
Bener et al. have demonstrated that the most important co-morbid factors for erectile dysfunction in stroke patients were diabetes, hypertension, and hypercholesterolemia, and the risk factors were smoking and obesity.
Mood disorders, such as depression, anxiety, and post-traumatic stress syndrome, are often observed after a stroke, and therefore post-stroke depression commonly results in sexual dysfunction and conversely. Changes in mood seem to be related to dependence to activities in daily living and to the severity of neurological deficits. It is not a coincidence that people with more severe physical impairments experience emotional disorders and decreased sexual intercourse more frequently than people with mild impairment. Indeed, Kimura et al reported that patients with sexual dysfunction after stroke had more frequent and severe depressive disorder or more impaired activities in daily living compared with patients without sexual dysfunction. Depression and fear of a recurrent stroke are examples of psychological factors influencing sexual function and, in particular, sexual desire, but low self esteem, partner refusal, loss of work, etc are other important issues to take into account. The dual-control model of male sexual responsiveness, developed to explain psychogenic erectile dysfunction, assumes that individuals vary in their propensity for inhibition and excitation and that these propensities can be regarded as personality traits specifically related to sexuality.
Duits et al, for the first time, attempted to identify the relevance of sexual responsiveness to sexual function in male stroke patients using the Sexual Inhibition/Sexual Excitation Scale (SIS/SES). This questionnaire includes 45 items exploring the propensity for sexual excitation, the propensity for sexual inhibition because of the threat of performance failure (SIS1) – this fear is more intrinsic and related to inhibitory tone with a good response to pharmacological therapy-, and the propensity for sexual inhibition because of the threat of performance consequences (SIS2) – this fear is related to the perception of an external threat in a specific situation, such as the risk of catching a sexually transmitted disease or, in the case of stroke patients, the fear of a recurrent stroke. The authors found significant and negative relationships between SIS1 and both orgasmic and sexual desire whereas SIS2, anxiety and depression were not related to any of sexual variables; sexual excitation was instead significantly but positively associated to sexual desire.
There is general agreement that a lack of nocturnal penile erections indicates an organic etiology for impotence. In Korpelainen et al.’s series, 45% of the male patients showed penile erections, 55% showed impaired post-stroke penile erections, and none of the patients had a complete absence of nocturnal erections. Interestingly, 28% of the patients at 2 months and 14% at 6 months reported they had stopped having sexual intercourse, although their nocturnal erections still exist. Therefore, the authors supposed that both psychological and organic factors (i.e lesions of the autonomic and limbic nervous systems) may determine the form and quality of the sexual life of stroke patients.
The role of psychological factors is further confirmed by the observation that sexual disorders are reported not only by the patients, but also by their partners. The illness is often experienced as a critical event in life and the impact of stroke on the psychological health of caregivers is relevant. A higher level of emotional disorders among care-givers, especially in stroke patients’ spouses, as compared with control, has been demonstrated. Nevertheless, little information is available about the consequences of stroke on sexual behavior and attitudes of the stroke patients’ spouses, although they are very important in terms of stroke survivors’ well-being. Previous studies suggest that spouses experience negative changes in the quality of their sexual life similar to those of stroke patients, but there is a lack of detailed information regarding the changes in their sexual life. Korpelainen et al revealed a significant decline in libido, coital frequency, sexual arousal, and satisfaction with sexual disorders significantly associated with various psychological factors, such as general attitude towards sexuality, fear of stroke recurrences and ability to discuss sexuality.
In addition to comorbidity, neurological and psychological factors, central nervous system driven alterations of the control of the autonomic system may also contribute to sexual impairments in stroke patients. Indeed, poststroke sympathetic hyper-function and/or parasympathetic hypofunction can determine abnormalities in heart response, pressure regulation, sudomotor and vasomotor regulatory systems. In this context, bladder and bowel dysfunction and impotence may be related to autonomic failure following stroke. Experimental and human studies suggest that the insular cortex, especially the right insula, is the most important cortical area controlling both sympathetically and parasympathetically mediated cardiovascular regulation thanks to its connection with other autonomic regulatory areas located in the subcortical limbic and forebrain regions. Penile erection and ejaculation requires interplay of smooth and skeletal fibers, glandular and endothelial cells, controlled by the autonomic nervous system. As a result of this, autonomic pathways might constitute privileged targets for pharmacological treatment of poststroke sexual dysfunctions. Indeed, drugs focusing on the imbalance between sympathetic and parasympathetic systems may have important implications not just to reduce the risk of adverse cardiovascular events in the acute phase but also to improve the quality of life in stroke survivors.
Aphasia and Sexuality. As we have previously underlined, changes in sexuality have attracted during the past decades the interest of researchers, but studies rarely included aphasic subjects because of the extreme difficulty to interview them. A pilot study by Lemieux et al. showed a reduced frequency of sexual intercourse and an increasing in other sexual activities in their aphasic patients. Interestingly, patients reported it was harder to verbally initiate and talk about desire of sex, while their spouses evidenced that the aphasic partner was no longer able to express their feelings or engage in sexually intimate conversation. Thus, it is authors’ opinion that aphasia affects sexuality differently than for other stroke patients and that their couples need discussing sexuality with their physicians.
Sexuality of stroke survivors is commonly affected by motor, sensory and autonomic dysfunction, but for people with aphasia sexual dysfunction is often more related to their communication disorder, since adequate communication skills are essential for forming and maintaining social and sexual relationships. Aphasia also represents a formidable barrier to talking about sexuality with health care professionals, especially when he is mute on this issue. Neglect of sexuality by health care workers denies access to assessment, counselling and treatment services, particularly in this scenario, wherein aphasic people lack the words to initiate these discussions themselves.
Stroke during sexual intercourse. The association between the various risk factors and stroke are well established, but very little is known about factors that may precipitate acute stroke. Negative emotions, anger, sudden changes in body posture in response to a startling event, and all Valsalva-provoking activities in the presence of a patent foramen ovale, i.e lifting a heavy weight, straining a stool, laughing, coughing, and trumpet or horn playing, appear to be independent triggers for ischemic stroke. Sexual intercourse has been described in few cases as an unusual trigger of stroke. Becker et al reported 4 patients who had stroke during sexual intercourse; all had echocardiographic evidence of a patent foramen ovale and no obvious explanation for their strokes, making paradoxical embolism plausible. If patent foramen ovale predispose to stroke, then it is assumed that venous clots may pass in the arterial circulation at the level of the atria. Since deep venous thrombosis has been rarely documented in patients with patent foramen ovale and cryptogenic stroke, emerging evidence suggests that trombophilias are more prevalent in these individuals. During Valsalva maneuver, there is an increase in intrathoracic, central venous and right atrial pressure; if the right pressure exceeds the left one, a right-to-left shunt may occur through the patent foramen ovale. The physiologic changes during coital activity, i.e heart rate and blood pressure increasing, are likely similar to those seen during Valsalva maneuver and thus could predispose individuals to paradoxical embolization.
The occurrence of acute stroke immediately after intercourse has been also attributable to vasospasm, cerebral hemorrhage or subarachnoid hemorrhage. Nonetheless, the only epidemiologic study which examined the relation between frequency of sexual intercourse and risk of ischemic stroke failed to demonstrate this correlation reassuring for the public who might reasonably believe that sexual activities can cause strokes.