Erectile Dysfunction. Impotence

Erectile Dysfunction / Impotence

What Is Impotence?

The Penis and Erectile Function

The penis is composed of three different regions: a pair of parallel spongy columns called the corpus cavernosum and the central corpus spongiosum, which contains the urethra (the tube that carries urine from the body). All three regions are made up of erectile tissue. Erectile tissue is rich in tiny pool-shaped blood vessels called cavernous sinuses, which are surrounded by smooth muscles and supported by elastic fibrous tissue composed of a protein called collagen. In the flaccid, or unerect, normal penis, the small arteries leading to the cavernous sinuses contract, reducing the inflow of blood. The smooth muscles regulating the many tiny blood vessels within the penis also contract. When a man becomes aroused, his central nervous system stimulates the release of a number of chemicals, including acetylcholine and nitric oxide, that relax the smooth muscles in the penis, allowing blood to flow into the tiny pool-like sinuses and flood the penis. The spongy chambers almost double in diameter due to the increase in blood flow. The veins surrounding the corpus cavernosum and corpus spongiosum are squeezed almost completely shut by the pressure of the erectile tissue; they are unable to drain blood out of the penis, causing it to become rigid.

Oxygen-rich blood is critical for erectile health. Oxygen itself affects two substances that are important in achieving erection: it suppresses transforming growth factor beta 1 (TGF-B1) and enhances prostaglandin E1. The smooth muscles produce TGF-B1, which is a component of the immune system, and one of its roles is to produce collagen. Collagen contributes not only to structural tissue in the body but is also the material that comprises scar tissue. Prostaglandin E1 is produced during erection by the muscle cells in the penis; it activates an enzyme that results in calcium release by the smooth muscle cells, which, in turn, relaxes them and allows blood flow. Prostaglandin E1 also suppresses collagen production. Oxygen levels vary widely from reduced levels in the flaccid state to very high in the erect state. During sleep, for instance, oxygen levels are high and a man can normally have three to five erections per night, each one lasting from 20 to 40 minutes.

Normal levels of hormones, especially testosterone, are essential for erectile function, though it is not clear what their role is in potency.

Impotence (Erectile Dysfunction)

Impotence or erectile dysfunction is the inability to achieve or maintain an erection sufficiently rigid for intercourse, ejaculation, or both. It does not affect sexual drive or the ability to have an orgasm. Rarely does erectile dysfunction signify a chronic problem. When a consistent pattern of sexual dysfunction extends over a prolonged period of time, however, a physical or serious emotional disorder may be indicated. Impotence is not new in the medical texts or in human experience. It is not easily or openly discussed, however. Our cultural expectations of male sexuality have forced many men to refrain from seeking help for a disorder that can, in most cases, benefit from medical treatment. Perhaps a good first step is to think of the problem as erectile dysfunction instead of impotence, a term which comes from the Latin meaning “loss of power.” Certainly this physical event, usually temporary and normal, should not be described exclusively with a word falsely suggesting a sweeping diminution in a man’s overall capabilities.

Two disorders that are frequently discussed in association with impotence are Peyronie’s disease and priapism. Peyronie’s disease is an accumulation of scar tissue within the penis shaft. This inflammation may be associated with an injury to the penis, but no clear information exists on its origin. The scar tissue within the shaft often causes the penis to curve and can make erection and intercourse difficult and painful. The disease often goes into a type of spontaneous remission, and some individuals are able to resume sexual activity, although there may be scarring, which results in problems with erection.

Priapism is a sustained, painful, and unwanted erection that occurs despite a lack of sexual stimulation. Generally, priapism results when the smooth muscle tissue remains relaxed so that a constant flow of blood into the vessels of the penis occurs with no leakage back out. The development of priapism has been associated with urinary stones, certain medications, neurologic disorders, and, more recently, with self-injection therapy used for impotence.

Who Becomes Impotent?

It is safe to say that every man experiences erectile dysfunction from time to time. Medically speaking, impotence is defined as the inability to sustain an erection sufficient for intercourse on at least 25% of attempts. Using this definition, experts have estimated that between 10 and 20 million American men between ages 40 and 70 experience erectile dysfunction. Some surveys report that 30% of all men experience at least temporary erectile dysfunction at some time.

Older Men. Aging is most often associated with impotence. About 5% of men at 40 report complete erectile dysfunction; by age 65, 15% to 25% of men are troubled by this problem, and over age 75, about 55% of men report being chronically impotent. Nevertheless, impotence is not inevitable with age. A recent survey of men over 60 years old reported that 61% of them were sexually active, and nearly half derived as much if not more emotional benefit from their sex lives as they did in their 40s.

Men with Serious Medical Conditions. Severe erectile dysfunction in elderly men often has more to do with disease than age itself. Atherosclerosis, heart disease, and hypertension are some conditions that can afflict the older male and cause sexual dysfunction (see What Causes Impotence?, below).

Other Risk Factors. One survey indicated that men who had experienced sexual abuse as children were more likely to have erectile dysfunction as adults. Losing a job or having lower income also increase the risk. One study found that depression is a strong risk factor for impotence, which in turn can also exacerbate the emotional disorder.

What Causes Impotence?

Over the past decades the medical perspective on the causes of impotence has shifted. Common wisdom used to attribute almost all cases of impotence to psychological factors. Now, investigators estimate that between 70% and 80% of impotence cases are caused by medical problems: most often atherosclerosis (hardening of the arteries); complications of diabetes; prostatectomy (surgical removal of the prostate); and medications. Many experts believe that negative emotional states occurring with the condition are more likely to be a reaction to the experience of impotence than its causes. Psychological problems are more apt to be the causes of erectile dysfunction in younger men, however, while physical problems are usually the cause in older men. So many physical and psychological situations can bring about erectile dysfunction, in fact, that a man should consider brief periods of impotence to be as normal as having a cold. (Even a cold can, in fact, cause temporary impotence.) Oxygen deprivation is the most common cause of impotence and can occur from numerous conditions that deprive the penis of blood. Nerve damage in the penis or the pelvic area and deficient levels of important hormones can also be responsible for erectile dysfunction.

Deprivation of Oxygen-Rich Blood Supply

Erectile dysfunction most commonly occurs when the penis is deprived of oxygen-rich blood. There is some evidence that when oxygen levels to the penis are low, TGF-B1 production increases and prostaglandin E1 production decreases. TGF-B1 produces collagen, which forms hard, structural tissue, including scar tissue; prostaglandin E1 suppresses collagen production and relaxes the smooth muscles that allow blood flow resulting in an erection. When TGF-B1 levels increase and prostaglandin E1 levels decrease, smooth muscles waste away and collagen is overproduced, causing scarring, loss of elasticity, and reduced blood flow to the penis. A number of conditions can deprive the penis of oxygen-rich blood.

Ischemia. The primary cause of oxygen deprivation is ischemia — the blockage of blood vessels. The same conditions, such as unhealthy cholesterol levels, that cause blockage in the blood vessels leading to heart problems may also contribute to erectile dysfunction. When cholesterol and other factors are imbalanced, a fatty substance called plaque forms on artery walls. As the plaque builds up, the arterial walls slowly constrict, reducing blood flow; this process, known as atherosclerosis, is the major contributor to the development of coronary heart disease. It may also play a role in the development of erectile dysfunction.

Lack of Frequent Erections. Infrequent erections deprive the penis of oxygen-rich blood. Without daily erections, collagen production increases and eventually may form a tough tissue that interferes with blood flow. The spontaneous erections men experience while sleeping or during the day may be a natural protection against this process.

Bicycling. Studies have indicated that regular bicycling may pose a risk for erectile dysfunction by reducing blood flow to the penis.

Specific Medical Conditions Contributing to Erectile Dysfunction

Diabetes. Diabetes may contribute to as many as 40% of impotence cases. Between one third and one half of all diabetic men report some form of sexual difficulty. Diabetics often develop atherosclerosis and nerve damage; when the blood vessels or nerves of the penis are involved, erectile dysfunction can result. (It should be noted that women with diabetes also suffer from sexual dysfunction due to damaged circulation and can also be helped by some of the drugs given to men for impotence.)

High Blood Pressure. In one study, 17% of men with high blood pressure experienced erectile dysfunction even before being treated. Many of the drugs used to treat hypertension may cause impotence as a side effect, although it is reversible when the drugs are stopped. One study, in fact, suggested that impotence in men with hypertension actually usually occurs if they also have coronary artery disease, and that it is this dangerous combination — not the drugs — that causes erectile dysfunction in such men. More recent drugs, such as ACE inhibitors, in any case, appear to be less likely to cause erectile dysfunction.

Multiple Sclerosis. Multiple sclerosis (MS), which affects the central nervous system, also precipitates sexual dysfunction in as many as 78% of male patients. (Corticosteroids, which are common treatments for MS may improve sexual function.)


In one survey, about half of all men believed that impotence is an inevitable consequence of aging. As a man ages, blood flow through the penis slows down, causing an increased refractory period (the amount of time it takes for the penis to become erect again after an orgasm). Age also seems to affect the time it takes for ejaculation to occur. It is important to note that these changes are generally thought to be a normal and inevitable part of the aging process, but are not an inevitable cause of impotence.

Male Hormones

Levels of testosterone, the primary male hormone, decline gradually after ages 40 to 50; by 70 they have declined by about 30%. (These levels would still be considered within the normal range, although low, in a younger man.) In any case, only about 5% of men who see a physician about erectile dysfunction actually have low levels of testosterone. Reduced testosterone levels appear to be associated with lower sexual interest — not impotence. One study identified aging-related reductions in two specific male hormones: dehydroepiandrosterone sulfate (DHEAS) and bioavailable testosterone (BT). One study found that men with higher levels of DHEA had a lower risk for impotence. DHEAS is converted into testosterone, although it is not a major source of testosterone; BT is a free form of testosterone that circulates in the blood stream without being bound chemically to any other molecules. The age-related lower levels of these male hormones are not as severe as the estrogen drop in women after menopause, but they may contribute to declines in muscle strength and sexual drive. Lower levels of BT appear to play the major role in causing these changes.

Hypogonadism and Other Hormonal Abnormalities

Hypogonadism is testicular failure, which can be due to hormonal insufficiencies, genetic factors, physical injury, radiation, genetic conditions (such as Klinefelter’s syndrome), or diseases such as mumps, myotonic dystrophy, or orchitis (inflammation of the testicles). Hormone insufficiencies leading to hypogonadism are usually caused by disorders in the pituitary or hypothalamus glands. In rare cases of adult-onset hypogonadism, depression or malnutrition may reduce hormone levels. Severely reduced hormone levels from excessive exercise occur in women and may rarely occur in men. Only a few cases of exercise-induced hypogonadism have been identified, but some researchers believe certain athletes may be at risk, such as those who began endurance training before they were fully sexually matured, those with very low body weight or fat content, and men with a history of stress fracture. In one case, treatment with hormones known as LH and FSH restored testicular size and sexual function. Hormonal abnormalities from other conditions can affect erectile function. High levels of the female hormone estrogen account for the impotence experienced by men with liver disease. Abnormalities of the pituitary gland (particularly those producing high levels of a hormone called prolactin), thyroid gland, and adrenal glands are less common causes of impotence.

Prostate Cancer and Treatments for Prostate Disease

Advanced prostate cancer can damage nerves needed for erectile function. Prostate surgery and surgical and radiation treatments for prostate and colorectal cancers can also cause impotence. Although improved techniques are reducing this risk, up to 90% of men who undergo total removal of the prostate and about 75% of those who have had radiation treatment for prostate cancer experience erectile dysfunction afterward. Surgery and drug treatments, for benign prostatic hyperplasia (BPH) can also increase the risk for impotence, although to a much lesser degree. Between 4% and 10% of patients who have transurethral resection of the prostate (TURP) and open prostatectomy for BPH are at risk for impotence, although it should be noted that studies indicate that the risk for impotence is low in men who were functioning normally before surgery. Vasectomy does not cause erectile dysfunction; if impotence occurs after this sterilization procedure, it is often in men whose female partners were unable to accept the operation.


About a quarter of all cases of impotence can be attributed to medications. Many drugs pose a risk for erectile dysfunction. Fortunately the condition is always resolved when the medication is changed. Among the drugs that can cause impotence are many of those taken for high blood pressure (particularly diuretics and beta blockers), anti-ulcer medications, drugs used in chemotherapy, and most drugs that are used for psychological disorders, including antidepressants, anti-anxiety, and antipsychotic drugs. Other drugs that sometimes cause impotence include the antifungal drug ketoconazole, antihistamines, anticholinergic drugs, and drugs that block male hormones. Some authorities go so far as to say that nearly every drug – prescription or nonprescription – can be a cause of temporary erectile dysfunction.

Physical Injuries

Spinal cord injury and pelvic trauma, such as a fracture, can cause nerve damage that frequently results in impotence.

Smoking and Alcohol Use

Heavy smoking is frequently cited as a contributory factor in the development of impotence, mainly because it accentuates the actions of other disorders of the blood vessels, including high blood pressure and atherosclerosis. Alcohol has also been implicated in causing impotence. In small doses, alcohol releases inhibitions, but in doses larger than one drink, it can depress the central nervous system and impair sexual function.

Psychological Factors

In virtually every case of impotence there appear to be emotional issues that may seriously affect both an individual’s self-esteem and relationships and may even cause or perpetuate erectile dysfunction. Many men tend to fault themselves for their impotence even if it is clearly caused by physical problems over which they have little control.

Anxiety is among the most frequently cited contributors to psychological impotence. For many reasons, cultural as well as situational, anxiety over sexual performance may provoke an intense fear of failure and self-doubt on the part of the individual. Often called performance anxiety, these feelings can sometimes set off a cycle of chronic anxiety-induced impotence. When anxiety is experienced, the brain releases chemicals known as neurotransmitters that constrict the smooth muscles of the penis and its arteries. This constriction decreases the blood flow into and increases the blood flow out of the penis, resulting in impotence. Simple stress may promote the release of brain chemicals that negatively affect potency in a similar way.

Depression is another disorder that is strongly associated with erectile dysfunction. In one study, 82% of men who reported moderate to severe erectile dysfunction also had symptoms of depression. It is not clear which condition causes the other. Depressed people may have difficulty functioning sexually because of inhibited sexual desire and inattention to the sexual partner.

Problems in relationships often have a direct impact on sexual functioning. Partners of men with erectile dysfunction may feel rejected and resentful, particularly if the affected man does not confide his own anxieties or depression. Both partners commonly experience guilt for what they each perceive as a personal failure. Tension and anger frequently arise between people who are unable to discuss sexual or emotional issues with each other. It can be very difficult for the man to perform sexually when both partners harbor negative feelings.

What Are the Symptoms of Impotence?

The characteristic symptom of impotence is a change in the quality of the erection, either in rigidity, in the ability to sustain the erection, or both. One indicator of physical impotence, as opposed to psychological, is the inability to experience or maintain an erection upon waking up in the morning. Psychological impotence tends to be abrupt and related to a recent situation; physical impotence occurs gradually but continuously over a period of time. Also, with psychological impotence, a man may be able to have an erection in some circumstances, but not in others. Impotence persisting over a three-month period and not due to an apparent stressful event, drugs, alcohol, or medical conditions signals the need for medical attention by a urologist specializing in impotence (as one in three urologists do).

How Serious Is Impotence?

Impotence is not life threatening, of course. It can be symptomatic, however, of other serious problems, such as atherosclerosis, diabetes, and hypertension. Impotence can also be indicative of an injury, age-related changes in tissue, or the possible long-term effects of risky behaviors such as smoking, heavy drinking, or an unhealthy diet.

Psychological factors related to impotence can be significant. Erectile dysfunction can have a devastating effect on a relationship and can cause extreme depression, which may become chronic if the erectile dysfunction is not treated.

Erectile Dysfunction. Impotence
Erectile Dysfunction. Impotence
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