Clasification of Erectile Dysfunction

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CLASSIFICATION OF ERECTILE DYSFUNCTION ED may be classified as psychogenic, organic (neurogenic, hormonal, arterial, cavernosal and drug-induced), and mixed. Mixed ED is the most common encountered having both a psychogenic and organic component (Table 1). Table 1. Classification and Common Causes of Erectile Dysfunction  Dysfunction  

Category of Erectile dysfunction

Neurogenic

Psychogenic

Hormonal

Common disorders

Pathophysiology

Stroke or Alzheimer’s disease Spinal cord injury Radical Interrupted neuronal pelvic surgeries Diabetic neuropathy transmission Failure to initiate nerve impulse Pelvic injury

Depression Psychological stress Performance anxiety Relationship problems

Impaired nitric oxide (NO) release Overinhibition of NO release Loss of libido

Hypogonadism Hyperprolactinemia

Loss of libido Inadequate NO release

Vasculogenic Impaired venoHypertension Atherosclerosis Diabetes mellitus Trauma/ (arterial and occlusion Inadequate Bicycling accident Peyronie’s disease cavernosal) arterial inflow

Druginduced

Central suppression Decreased Antihypertensives Antiandrogen Antidepressants Alcohol libido Alcoholic abuse Cigarette smoking neuropathy Vascular insufficiency

Systemic diseases

Multifactorial Neuronal Old age Diabetes mellitus Chronic renal failure Coronary and vascular heart disease dysfunction

Sexual function progressively declines as men age. The latent period between sexual stimulation and erection increases, erections ere ctions are less turgid, ejaculation is less forceful,

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ejaculatory volume decreases, and the refractory period between erections lengthens (8). There is also a decrease in penile sensitivity to tactile stimulation, a decrease in serum testosterone concentration, and an increase in cavernous muscle tone (9-11). Erectile dysfunction is noted in patients with neurologic disorders such as Parkinson's and Alzheimer's diseases, stroke, and cerebral trauma. This is caused by a decrease in libido or inability to initiate the erectile process. Spinal cord injury patients have varying degrees of erectile dysfunction largely dependent on the location and extent of the lesion. Sensory input from the genitalia is essential to achieve and maintain reflexogenic r eflexogenic erection, and this input becomes more important as the effect of psychological stimuli abates with age. About 50 percent of men with chronic diabetes mellitus are reported to have erectile dysfunction. In addition to the disease's d isease's effect on small vessels, it may also affect the cavernous nerve terminals and endothelial cells, resulting in deficiency of neurotransmitters (7). Additionally, in diabetics, corporal smooth muscle relaxation r elaxation in response to neuronal- and endothelial-derived nitric oxide (NO) is impaired and may be due to the accumulation of glycosylation products . Chronic renal failure has frequently been associated with diminished erectile function, impaired libido, and infertility. The mechanism is probably multifactorial: low serum testosterone concentrations, diabetes mellitus, vascular insufficiency, multiple medications, autonomic and somatic neuropathy (16), and psychological stress. Men with angina, myocardial infarction, or heart failure may have erectile dysfunction from anxiety, depression, or concomitant penile arterial insufficiency. Psychogenic ED can be caused by performance anxiety, strained relationship, lack of sexual arousability, and overt psychiatric disorders such as depression and schizophrenia. Several studies have confirmed the strong relationship between depression and sexual dysfunction (17, 18). Androgen deficiency results in a decrease in nocturnal erections and decreases libido. However, erection in response to visual sexual stimulation is preserved in men with hypogonadism, suggesting that androgen is not essential for erection (19) as a result of multiple pathways . The inhibitory action of prolactin on central dop dopaminergic aminergic activity and therefore on gonadotropin-releasing hormone secretion, means that hyperprolactinemia of any cause results in reproductive and sexual dysfunction as a result of secondary hypogonadotropic hypogonadism. Many common medical conditions may induce erectile dysfunction. Common risk factors associated with generalized gen eralized penile arterial insufficiency include hypertension, hyperlipidemia, cigarette smoking, diabetes mellitus, and pelvic irradiation (22, 23). Focal stenosis of the common penile artery most often occurs in men who have sustained blunt pelvic or perineal trauma (e.g., biking accidents) (22) . Patients with hypertension may develop erectile dysfunction from the associated arterial stenotic lesions associated with elevated blood pressure (24). Veno-occlusive dysfunction (VOD) may result from the formation of large venous channels draining the corpora cavernosa. Veno-occlusive Veno- occlusive dysfunction can cause erectile dysfunction (25). Venous leak impotence may be the result of degenerative changes that may affect the penis including Peyronie's disease, old age, and diabetes mellitus. A patient may develop VOD from traumatic injury to the tunica albuginea such as a penile fracture. Venous leak can be seen in anxious men with excessive adrenergic tone causing structural alterations of the cavernous smooth muscle and endothelium and insufficient trabecular smooth muscle relaxation (10). Finally, VOD can be seen in patients with acquired shunts that result from the operative correction of priapism. Many drugs have been reported to cause erectile dysfunction. Central neurotransmitter pathways, including serotonergic, noradrenergic, and dopaminergic pathways involved in sexual function, may be disturbed by antipsychotics, antidepressants and centrally acting antihypertensive drugs. Although any antihypertensive agent could theoretically cause ED by decreasing the availability of blood to the corporal arteries (i.e. a pressure-head phenomenon), differences are noted between b etween various classes of medications, with less ED associated with angiotensin

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converting enzyme inhibitors and selective beta-adrenergic blocking drugs. Non-selective beta -adrenergic blocking drugs may cause erectile dysfunction by potentiating a-1 adrenergic activity in the penis. Thiazide diuretics have been reported to cause erectile dysfunction by an unknown mechanism. Spironolactone, acting as an anti-androgen, can cause a decrease in libido and gynecomastia as well as causing erectile dysfunction. Cimetidine, a histamine-H2 receptor antagonist, has been reported to decrease libido and cause erectile failure; it acts as an anti-androgen and can cause hyperprolactinemia(30). Other drugs known to cause erectile dysfunction are estrogens and drugs with anti-androgenic action such as ketoconazole and cyproterone acetate. Social drugs including cigarettes and alcohol also affect erectile ffunction. unction. Cigarette smoking may induce vasoconstriction and penile venous leakage because of its contractile effect on the cavernous smooth muscle mu scle (31); more importantly, chronic use may accelerate atherosclerotic changes in penile microvaculature. Alcohol in small amounts may improve erections and increases libido because of its vasodilatory effect and the suppression of anxiety; however, large amounts can cause central sedation, decreased libido and transient erectile dysfunction. Chronic alcoholism may cause hypogonadism and polyneuropathy, which may affect penile nerve function (32). Prev  Prev  Chapter 8. MEDICAL AND SURGICAL THERAPY OF ERECTILE DYSFUNCTION

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