Erectile dysfunction, sometimes called "impotence," is the repeated inability to get or keep an erection firm enough for sexual intercourse. The word "impotence" may also be used to describe other problems that interfere with sexual intercourse and reproduction, such as lack of sexual desire and problems with ejaculation or orgasm. Using the term erectile dysfunction makes it clear that those other problems are not involved.

Erectile dysfunction, or ED, can be a total inability to achieve erection, an inconsistent ability to do so, or a tendency to sustain only brief erections. These variations make defining ED and estimating its incidence difficult. Estimates range from 15 million to 30 million, depending on the definition used. According to the National Ambulatory Medical Care Survey (NAMCS), for every 1,000 men in the United States, 7.7 physician office visits were made for ED in 1985. By 1999, that rate had nearly tripled to 22.3. The increase happened gradually, presumably as treatments such as vacuum devices and injectable drugs became more widely available and discussing erectile function became accepted. Perhaps the most publicized advance was the introduction of the oral drug sildenafil citrate (Viagra) in March 1998. NAMCS data on new drugs show an estimated 2.6 million mentions of Viagra at physician office visits in 1999, and one-third of those mentions occurred during visits for a diagnosis other than ED.

In older men, ED usually has a physical cause, such as disease, injury, or side effects of drugs. Any disorder that causes injury to the nerves or impairs blood flow in the penis has the potential to cause ED. Incidence increases with age: About 5 percent of 40-year-old men and between 15 and 25 percent of 65-year-old men experience ED. But it is not an inevitable part of aging.

ED is treatable at any age, and awareness of this fact has been growing. More men have been seeking help and returning to normal sexual activity because of improved, successful treatments for ED. Urologists, who specialize in problems of the urinary tract, have traditionally treated ED; however, urologists accounted for only 25 percent of Viagra mentions in 1999.

How does an erection occur?

The penis contains two chambers called the corpora cavernosa, which run the length of the organ (see figure 1). A spongy tissue fills the chambers. The corpora cavernosa are surrounded by a membrane, called the tunica albuginea. The spongy tissue contains smooth muscles, fibrous tissues, spaces, veins, and arteries. The urethra, which is the channel for urine and ejaculate, runs along the underside of the corpora cavernosa and is surrounded by the corpus spongiosum.

Erection begins with sensory or mental stimulation, or both. Impulses from the brain and local nerves cause the muscles of the corpora cavernosa to relax, allowing blood to flow in and fill the spaces. The blood creates pressure in the corpora cavernosa, making the penis expand. The tunica albuginea helps trap the blood in the corpora cavernosa, thereby sustaining erection. When muscles in the penis contract to stop the inflow of blood and open outflow channels, erection is reversed.

Figure 1. Arteries (top) and veins (bottom) penetrate the long, filled cavities running the length of the penis—the corpora cavernosa and the corpus spongiosum. Erection occurs when relaxed muscles allow the corpora cavernosa to fill with excess blood fed by the arteries, while drainage of blood through the veins is blocked.

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What causes erectile dysfunction (ED)?

Since an erection requires a precise sequence of events, ED can occur when any of the events is disrupted. The sequence includes nerve impulses in the brain, spinal column, and area around the penis, and response in muscles, fibrous tissues, veins, and arteries in and near the corpora cavernosa.

Damage to nerves, arteries, smooth muscles, and fibrous tissues, often as a result of disease, is the most common cause of ED. Diseases—such as diabetes, kidney disease, chronic alcoholism, multiple sclerosis, atherosclerosis, vascular disease, and neurologic disease—account for about 70 percent of ED cases. Between 35 and 50 percent of men with diabetes experience ED.

Lifestyle choices that contribute to heart disease and vascular problems also raise the risk of erectile dysfunction. Smoking, being overweight, and avoiding exercise are possible causes of ED.

Also, surgery (especially radical prostate and bladder surgery for cancer) can injure nerves and arteries near the penis, causing ED. Injury to the penis, spinal cord, prostate, bladder, and pelvis can lead to ED by harming nerves, smooth muscles, arteries, and fibrous tissues of the corpora cavernosa.

In addition, many common medicines—blood pressure drugs, antihistamines, antidepressants, tranquilizers, appetite suppressants, and cimetidine (an ulcer drug)—can produce ED as a side effect.

Experts believe that psychological factors such as stress, anxiety, guilt, depression, low self-esteem, and fear of sexual failure cause 10 to 20 percent of ED cases. Men with a physical cause for ED frequently experience the same sort of psychological reactions (stress, anxiety, guilt, depression). Other possible causes are smoking, which affects blood flow in veins and arteries, and hormonal abnormalities, such as not enough testosterone.

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How is ED diagnosed?

Patient History

Medical and sexual histories help define the degree and nature of ED. A medical history can disclose diseases that lead to ED, while a simple recounting of sexual activity might distinguish among problems with sexual desire, erection, ejaculation, or orgasm.

Using certain prescription or illegal drugs can suggest a chemical cause, since drug effects account for 25 percent of ED cases. Cutting back on or substituting certain medications can often alleviate the problem.

Physical Examination

A physical examination can give clues to systemic problems. For example, if the penis is not sensitive to touching, a problem in the nervous system may be the cause. Abnormal secondary sex characteristics, such as hair pattern or breast enlargement, can point to hormonal problems, which would mean that the endocrine system is involved. The examiner might discover a circulatory problem by observing decreased pulses in the wrist or ankles. And unusual characteristics of the penis itself could suggest the source of the problem—for example, a penis that bends or curves when erect could be the result of Peyronie's disease.

Laboratory Tests

Several laboratory tests can help diagnose ED. Tests for systemic diseases include blood counts, urinalysis, lipid profile, and measurements of creatinine and liver enzymes. Measuring the amount of free testosterone in the blood can yield information about problems with the endocrine system and is indicated especially in patients with decreased sexual desire.

Other Tests

Monitoring erections that occur during sleep (nocturnal penile tumescence) can help rule out certain psychological causes of ED. Healthy men have involuntary erections during sleep. If nocturnal erections do not occur, then ED is likely to have a physical rather than psychological cause. Tests of nocturnal erections are not completely reliable, however. Scientists have not standardized such tests and have not determined when they should be applied for best results.

Psychosocial Examination

A psychosocial examination, using an interview and a questionnaire, reveals psychological factors. A man's sexual partner may also be interviewed to determine expectations and perceptions during sexual intercourse.

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How is ED treated?

Most physicians suggest that treatments proceed from least to most invasive. For some men, making a few healthy lifestyle changes may solve the problem. Quitting smoking, losing excess weight, and increasing physical activity may help some men regain sexual function.

Cutting back on any drugs with harmful side effects is considered next. For example, drugs for high blood pressure work in different ways. If you think a particular drug is causing problems with erection, tell your doctor and ask whether you can try a different class of blood pressure medicine.

Psychotherapy and behavior modifications in selected patients are considered next if indicated, followed by oral or locally injected drugs, vacuum devices, and surgically implanted devices. In rare cases, surgery involving veins or arteries may be considered.

Psychotherapy

Experts often treat psychologically based ED using techniques that decrease the anxiety associated with intercourse. The patient's partner can help with the techniques, which include gradual development of intimacy and stimulation. Such techniques also can help relieve anxiety when ED from physical causes is being treated.

Drug Therapy

Drugs for treating ED can be taken orally, injected directly into the penis, or inserted into the urethra at the tip of the penis. In March 1998, the Food and Drug Administration (FDA) approved Viagra, the first pill to treat ED. Since that time, vardenafil hydrochloride (Levitra) and tadalafil (Cialis) have also been approved. Additional oral medicines are being tested for safety and effectiveness.

Viagra, Levitra, and Cialis all belong to a class of drugs called phosphodiesterase (PDE) inhibitors. Taken an hour before sexual activity, these drugs work by enhancing the effects of nitric oxide, a chemical that relaxes smooth muscles in the penis during sexual stimulation and allows increased blood flow.

While oral medicines improve the response to sexual stimulation, they do not trigger an automatic erection as injections do. The recommended dose for Viagra is 50 mg, and the physician may adjust this dose to 100 mg or 25 mg, depending on the patient. The recommended dose for either Levitra or Cialis is 10 mg, and the physician may adjust this dose to 20 mg if 10 mg is insufficient. A lower dose of 5 mg is available for patients who take other medicines or have conditions that may decrease the body's ability to use the drug. Levitra is also available in a 2.5 mg dose.

None of these PDE inhibitors should be used more than once a day. Men who take nitrate-based drugs such as nitroglycerin for heart problems should not use either drug because the combination can cause a sudden drop in blood pressure. Also, tell your doctor if you take any drugs called alpha-blockers, which are used to treat prostate enlargement or high blood pressure. Your doctor may need to adjust your ED prescription. Taking a PDE inhibitor and an alpha-blocker at the same time (within 4 hours) can cause a sudden drop in blood pressure.

Oral testosterone can reduce ED in some men with low levels of natural testosterone, but it is often ineffective and may cause liver damage. Patients also have claimed that other oral drugs—including yohimbine hydrochloride, dopamine and serotonin agonists, and trazodone—are effective, but the results of scientific studies to substantiate these claims have been inconsistent. Improvements observed following use of these drugs may be examples of the placebo effect, that is, a change that results simply from the patient's believing that an improvement will occur.

Many men achieve stronger erections by injecting drugs into the penis, causing it to become engorged with blood. Drugs such as papaverine hydrochloride, phentolamine, and alprostadil (marketed as Caverject) widen blood vessels. These drugs may create unwanted side effects, however, including persistent erection (known as priapism) and scarring. Nitroglycerin, a muscle relaxant, can sometimes enhance erection when rubbed on the penis.

A system for inserting a pellet of alprostadil into the urethra is marketed as Muse. The system uses a prefilled applicator to deliver the pellet about an inch deep into the urethra. An erection will begin within 8 to 10 minutes and may last 30 to 60 minutes. The most common side effects are aching in the penis, testicles, and area between the penis and rectum; warmth or burning sensation in the urethra; redness from increased blood flow to the penis; and minor urethral bleeding or spotting.

Research on drugs for treating ED is expanding rapidly. Patients should ask their doctor about the latest advances.

Vacuum Devices

Mechanical vacuum devices cause erection by creating a partial vacuum, which draws blood into the penis, engorging and expanding it. The devices have three components: a plastic cylinder, into which the penis is placed; a pump, which draws air out of the cylinder; and an elastic band, which is placed around the base of the penis to maintain the erection after the cylinder is removed and during intercourse by preventing blood from flowing back into the body (see figure 2).

Figure 2. A vacuum-constrictor device causes an erection by creating a partial vacuum around the penis, which draws blood into the corpora cavernosa. Pictured here are the necessary components: (a) a plastic cylinder, which covers the penis; (b) a pump, which draws air out of the cylinder; and (c) an elastic ring, which, when fitted over the base of the penis, traps the blood and sustains the erection after the cylinder is removed.

One variation of the vacuum device involves a semirigid rubber sheath that is placed on the penis and remains there after erection is attained and during intercourse.

Surgery

Surgery usually has one of three goals:

• to implant a device that can cause the penis to become erect
• to reconstruct arteries to increase flow of blood to the penis
• to block off veins that allow blood to leak from the penile tissues

Implanted devices, known as prostheses, can restore erection in many men with ED. Possible problems with implants include mechanical breakdown and infection, although mechanical problems have diminished in recent years because of technological advances.

Malleable implants usually consist of paired rods, which are inserted surgically into the corpora cavernosa. The user manually adjusts the position of the penis and, therefore, the rods. Adjustment does not affect the width or length of the penis.

Inflatable implants consist of paired cylinders, which are surgically inserted inside the penis and can be expanded using pressurized fluid (see figure 3). Tubes connect the cylinders to a fluid reservoir and a pump, which are also surgically implanted. The patient inflates the cylinders by pressing on the small pump, located under the skin in the scrotum. Inflatable implants can expand the length and width of the penis somewhat. They also leave the penis in a more natural state when not inflated.

Figure 3. With an inflatable implant, erection is produced by squeezing a small pump (a) implanted in a scrotum. The pump causes fluid to flow from a reservoir (b) residing in the lower pelvis to two cylinders (c) residing in the penis. The cylinders expand to create the erection.

Surgery to repair arteries can reduce ED caused by obstructions that block the flow of blood. The best candidates for such surgery are young men with discrete blockage of an artery because of an injury to the crotch or fracture of the pelvis. The procedure is almost never successful in older men with widespread blockage.

Surgery to veins that allow blood to leave the penis usually involves an opposite procedure—intentional blockage. Blocking off veins (ligation) can reduce the leakage of blood that diminishes the rigidity of the penis during erection. However, experts have raised questions about the long-term effectiveness of this procedure, and it is rarely done.

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Hope through Research

Advances in suppositories, injectable medications, implants, and vacuum devices have expanded the options for men seeking treatment for ED. These advances have also helped increase the number of men seeking treatment. Gene therapy for ED is now being tested in several centers and may offer a long-lasting therapeutic approach for ED.

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) sponsors programs aimed at understanding the causes of erectile dysfunction and finding treatments to reverse its effects. NIDDK's Division of Kidney, Urologic, and Hematologic Diseases supported the researchers who developed Viagra and continue to support basic research into the mechanisms of erection and the diseases that impair normal function at the cellular and molecular levels, including diabetes and high blood pressure.

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Points to Remember

• Erectile dysfunction (ED) is the repeated inability to get or keep an erection firm enough for sexual intercourse.
• ED affects 15 to 30 million American men.
• ED usually has a physical cause.
• ED is treatable at all ages.
• Treatments include psychotherapy, drug therapy, vacuum devices, and surgery.

Erectile dysfunction

Erectile dysfunction (ED, "male impotence ") is a sexual dysfunction characterized by the inability to develop or maintain an erection of the penis sufficient for satisfactory sexual performance^{[1][dead link]}

An erection occurs as a hydraulic effect due to blood entering and being retained in sponge-like bodies within the penis. The process is most often initiated as a result of sexual arousal, when signals are transmitted from the brain to nerves in the penis. Erectile dysfunction is indicated when an erection is difficult to produce. There are various circulatory causes, including alteration of the voltage gated potassium channel as in the case of arsenic poisoning from drinking water.^[2] The most important organic causes are cardiovascular disease and diabetes, neurological problems (for example, trauma from prostatectomy surgery), hormonalinsufficiencies (hypogonadism) and drug side effects. It is important to realize that erectile dysfunction can signal underlying risk for cardiovascular disease. ^{[citation needed]}

Psychological impotence is where erection or penetration fails due to thoughts or feelings (psychological reasons) rather than physical impossibility; this is somewhat less frequent but often can be helped. Notably in psychological impotence, there is a strong response to placebo treatment. Erection, tied closely as it is about ideas of physical well being, can have severe psychological consequences. There is a strong culture of silence and inability to discuss the matter. ^{[citation needed]} In reality, it has been estimated that around 1 in 10 men will experience recurring impotence problems at some point in their lives.^{[3][not in citation given]}

Besides treating the underlying causes such as potassium deficiency or arsenic contamination of drinking water, the first line treatment of erectile dysfunction consists of a trial of PDE5 inhibitor drugs (the first of which was sildenafil or Viagra). In some cases, treatment can involve prostaglandin tablets in the urethra, intracavernous injections with a fine needle into the penis that cause swelling, a penile prosthesis, a penis pump or vascular reconstructive surgery.^[4]

The Latin term impotentia coeundi describes simple inability to insert the penis into the vagina. It is now mostly replaced by more precise terms.^[vague] The study of erectile dysfunction within medicine is covered by andrology, a sub-field within urology.

Signs and symptoms

Erectile dysfunction is characterized by the regular or repeated inability to obtain or maintain an erection. There are several ways that erectile dysfunction is analyzed:

• Obtaining full erections at some times, such as when asleep (when the mind and psychological issues, if any, are less present), tends to suggest the physical structures are functionally working.

• Obtaining erections which are neither rigid nor full (lazy erection), or are lost more rapidly than would be expected (often before or during penetration), can be a sign of a failure of the mechanism which keeps blood held in the penis, and may signify an underlying clinical condition, often cardiovascular in origin. ^{[citation needed]}

• Other factors leading to erectile dysfunction are diabetes mellitus (causing neuropathy) or hypogonadism (decreased testosterone levels due to disease affecting the testicles or the pituitary gland). ^{[citation needed]}

Erection problems are very common. The Sexual Dysfunction Association estimates that 1 in 10 men in the UK have recurring problems with their erections at some point in their life.^{[3][not in citation given]}

[edit]Causes

• Drugs (anti-depressants (SSRIs) and nicotine are most common. A study entitled “Drug-induced male sexual dysfunction” concluded that of the 12 most commonly prescribed medications on the market today, 8 of those medications list impotence as a side effect of the drug.^{[citation needed][dated info]} Other drugs such as alcohol, cocaine, and heroin negatively impact male sexual libido.)^{[citation needed]}
• Neurogenic Disorders (spinal cord and brain injuries, nerve disorders such as Parkinson's disease, Alzheimer's disease, multiple sclerosis, and stroke.^[5])
• Hormonal Disorders (pituitary gland tumor; low or abnormally high levels of the hormone testosterone).^{[citation needed]}

• Arterial Disorders (peripheral vascular disease, hypertension; reduced blood flow to the penis).^{[citation needed]}
• Venous leak^{[citation needed]}
• Cavernosal Disorders (Peyronie's disease.^[6])
• Psychological causes: performance anxiety, stress, mental disorders (clinical depression, schizophrenia, substance abuse, panic disorder, generalized anxiety disorder, personality disorders or traits.^[7]), psychological problems, negative feelings.^{[8][not in citation given]}
• Surgery (radiation therapy, surgery of the colon, prostate, bladder, or rectum may damage the nerves and blood vessels involved in erection. Prostate and bladder cancer surgery often require removing tissue and nerves surrounding a tumor, which increases the risk for impotence.^[9])
• Aging. It is four times higher in men in their 60s than in men in their 40s.^[10]
• Kidney failure
• Lifestyle: alcohol and drugs, obesity, cigarette smoking (Incidence of impotence is approximately 85 percent higher in male smokers compared to non-smokers^{[11][not in citation given]}., Smoking is a key cause of erectile dysfunction.^[12][13] Smoking causes impotence because it promotes arterial narrowing.^[14] See also Tobacco and health. )
• Other disorders.^{[specify][citation needed]}

A few causes of impotence may be iatrogenic (medically caused). Various antihypertensives (medications intended to control high blood pressure) and some drugs that modify central nervous system response may inhibit erection by denying blood supply or by altering nerve activity.^{[citation needed]}

Surgical intervention for a number of different conditions may remove anatomical structures necessary to erection, damage nerves, or impair blood supply. Complete removal of the prostate gland or external beam radiotherapy of the gland are common causes of impotence; both are treatments for prostate cancer. Some studies have shown that male circumcision may result in an increased risk of impotence,^{[15][non-primary source needed][16][non-primary source needed]} while others have found no such effect,^{[17][non-primary source needed][18][non-primary source needed][19][non-primary source needed]} and another found the opposite.^{[20][non-primary source needed]}

Excessive alcohol use has long been recognised as one cause of impotence, leading to the euphemism "brewer's droop," or "whiskeydick;"^{[citation needed]} Shakespeare made light of this phenomenon in Macbeth.

A study in 2002 found that ED can also be associated with bicycling. The number of hours on a bike and/or the pressure on the penis from the saddle of an upright bicycle is directly related to erectile dysfunction.^{[21][non-primary source needed]}

[edit]Pathophysiology

Penile erection is managed by two different mechanisms. The first one is the reflex erection, which is achieved by directly touching the penile shaft. The second is the psychogenic erection, which is achieved by erotic or emotional stimuli. The former uses the peripheral nerves and the lower parts of the spinal cord, whereas the latter uses the limbic system of the brain. In both conditions, an intact neural system is required for a successful and complete erection. Stimulation of penile shaft by the nervous system leads to the secretion of nitric oxide (NO), which causes the relaxation of smooth muscles of corpora cavernosa (the main erectile tissue of penis), and subsequently penile erection. Additionally, adequate levels of testosterone (produced by the testes) and an intact pituitary gland are required for the development of a healthy erectile system. As can be understood from the mechanisms of a normal erection, impotence may develop due to hormonal deficiency, disorders of the neural system, lack of adequate penile blood supply or psychological problems. Restriction of blood flow can arise from impaired endothelial function due to the usual causes associated with coronary artery disease, but can also be caused by prolonged exposure to bright light.

[edit]Diagnosis

There are no formal tests to diagnose erectile dysfunction. Some blood tests are generally done to exclude underlying disease, such ashypogonadism and prolactinoma. Diabetes is considered a disorder, but is also a risk. Impotence is also related to generally poor physical health, poor dietary habits, obesity, and most specifically cardiovascular disease such as coronary artery disease and peripheral vascular disease.

A useful and simple way to distinguish between physiological and psychological impotence is to determine whether the patient ever has an erection. If never, the problem is likely to be physiological; if sometimes (however rarely), it could be physiological or psychological. The current diagnostic and statistical manual of mental diseases (DSM-IV) has included a listing for impotence.

Duplex ultrasound

Duplex ultrasound is used to evaluate blood flow, venous leak, signs of atherosclerosis, and scarring or calcification of erectile tissue. Injecting prostaglandin, a hormone-like stimulator produced in the body, induces erection. Ultrasound is then used to see vascular dilation and measure penile blood pressure. Measurements are compared to those taken when the penis is flaccid.^{[citation needed]}

Penile nerves function

Tests such as the bulbocavernosus reflex test are used to determine if there is sufficient nerve sensation in the penis. The physician squeezes the glans (head) of the penis, which immediately causes the anus to contract if nerve function is normal. A physician measures the latency between squeeze and contraction by observing the anal sphincter or by feeling it with a gloved finger inserted past the anus. Specific nerve tests are used in patients with suspected nerve damage as a result of diabetes or nerve disease. ^{[citation needed]}

Nocturnal penile tumescence (NPT)

It is normal for a man to have five to six erections during sleep, especially during rapid eye movement (REM). Their absence may indicate a problem with nerve function or blood supply in the penis. There are two methods for measuring changes in penile rigidity and circumference during nocturnal erection: snap gauge and strain gauge. A significant proportion of men who have no sexual dysfunction nonetheless do not have regular nocturnal erections. Thus presence of NPT tends to signify physically functional systems, but absence of NPT may be ambiguous and not rule out either cause.^{[citation needed]}

Penile biothesiometry

This test uses electromagnetic vibration to evaluate sensitivity and nerve function in the glans and shaft of the penis. A decreased perception of vibration may indicate nerve damage in the pelvic area, which can lead to impotence.^{[citation needed]}

Penile Angiogram

Invasive test - allows visualization of the circulation in the penis and is used during the repair of a priapism.^{[citation needed]}

Dynamic Infusion Cavernosometry

(Abbreviated DICC) technique in which fluid is pumped into the penis at a known rate and pressure. It gives a measurement of the vascular pressure in the corpus cavernosum during an erection. To do this test, a vasodilator like prostaglandin E-1 is injected to measure the rate of infusion required to get a rigid erection and to help find how severe the venous leak is.^{[citation needed]}

Corpus Cavernosometry

Cavernosography measurement of the vascular pressure in the corpus cavernosum. Saline is infused under pressure into the corpus cavernosum with a butterfly needle, and the flow rate needed to maintain an erection indicates the degree of venous leakage. The leaking veins responsible may be visualised by infusing a mixture of saline and x ray contrast medium and performing a cavernosogram.^[22]

Digital Subtraction Angiography

In DSA, the images are acquired digitally. The computer creates a mask from lower-contrast x-rays of the same area and digitally isolates the blood vessels (this is done manually through darkroom masking with traditional angiography).^{[citation needed]}

Magnetic resonance angiography (MRA)

This is similar to magnetic resonance imaging. Magnetic resonance angiography uses magnetic fields and radio waves to provide detailed images of the blood vessels. Doctors may inject a "contrast agent" into the patient's bloodstream that causes vascular tissues to stand out against other tissues. The contrast agent provides for enhanced information regarding blood supply and vascular anomalies. Aside from the IV used to introduce the contrast material into the bloodstream, magnetic resonance angiography is noninvasive and painless.^{[citation needed]}

[edit]Treatment

Treatment depends on the cause. Testosterone supplements may be used for cases due to hormonal deficiency. However, the cause is more usually lack of adequate penile blood supply as a result of damage to inner walls of blood vessels. This damage is more frequent in older men, and often associated with disease, in particular diabetes.

Treatments (with the exception of testosterone supplementation, where effective) work on a temporary basis: they enable an erection to be attained and maintained long enough for intercourse, but do not permanently improve the underlying condition.

ED can in many cases be treated by drugs taken orally, injected, or as penile suppositories. These drugs increase the efficacy of nitric oxide, which dilates the blood vessels of corpora cavernosa. When oral drugs or suppositories fail, injections into the erectile tissue of the penile shaft are extremely effective but occasionally cause priapism.^{[citation needed]}

Exercise, particularly aerobic exercise is an effective cheap treatment for erectile dysfunction.^{[23][non-primary source needed]}

When pharmacological methods fail, a purpose-designed external vacuum pump can be used to attain erection, with a separate compression ring fitted to the penis to maintain it. These pumps should be distinguished from other penis pumps (supplied without compression rings) which, rather than being used for temporary treatment of impotence, are claimed to increase penis length if used frequently, or vibrate as an aid to masturbation. More drastically, inflatable or rigid penile implants may be fitted surgically. Implants are irreversible and costly.^{[citation needed]}

All these mechanical methods are based on simple principles of hydraulics and mechanics and are quite reliable, but have their disadvantages. In a few cases there is a vascular problem which can be treated surgically.^{[citation needed]}

Counselling is often a consideration, both where a psychological cause is suspected or must be ruled out, or to assist in management of any distress.^{[citation needed]}

[edit]Medications

The cyclic nucleotide phosphodiesterases constitute a group of enzymes that catalyse the hydrolysis of the cyclic nucleotides cyclic AMP and cyclic GMP. They exist in different molecular forms and are unevenly distributed throughout the body.

One of the forms of phosphodiesterase is termed PDE5. The prescription PDE5 inhibitors sildenafil (Viagra), vardenafil (Levitra) and tadalafil(Cialis) are prescription drugs which are taken orally. They work by blocking the action of PDE5, which causes cGMP to degrade. CGMP specific phosphodiesterase type 5 causes the smooth muscle of the arteries in the penis to relax, allowing the corpus cavernosum to fill with blood.^{[citation needed]}

These medications work when there is sexual stimulation. Depending on the treatment, it will need to be taken 20 minutes to 1 hour before sex and the period of time over which it works can vary between 3 hours and up to 36 hours.^{[citation needed]}

Alprostadil

Alprostadil can be injected into the penis or inserted using a special applicator - usually just before sexual intercourse.^{[citation needed]}

Alprostadil has also become available in some countries as a topical cream (under the brand name Befar),^[24] and preliminary studies have shown a clinical efficacy of up to 83%.^{[25][non-primary source needed]}

Androskat

Androskat is a mixture of papaverine and phentolamine injected into the penis before sexual intercourse. It does not require refrigeration.^{[citation needed]}

[edit]Surgery

Main article: Penile prosthesis

Often, as a last resort if other treatments have failed, the most common procedure is prosthetic implants which involves the insertion of artificial rods into the penis.^{[26][unreliable source?]}

[edit]Devices

Vacuum Therapy

Main article: penis pump

These work by placing the penis in a vacuum cylinder device.^{[27][not in citation given]} The device helps draw blood into the penis by applying negative pressure. A tension ring is applied at the base of the penis to help maintain the erection.^{[27][not in citation given]} This type of device is sometimes referred to as penis pump and may be used just prior to sexual intercourse. Several types of FDA approved vacuum therapy devices are available with a doctor's prescription.

[edit]Alternative medicine

Numerous alternative therapies are used to improve sexual function. Some include: niacin, zinc, ginseng root, ginkgo. None of these however have been recognized as effective by the FDA.^{[28][clarification needed]} While zinc deficiency may be a cause of lower testosterone levels inhemodialysis patients, which may benefit from zinc supplementation,^{[29][dead link][non-primary source needed]} such supplements have no effect on the testosterone levels of healthy males who consume a zinc-sufficient diet.^{[30][dead link][non-primary source needed]}

[edit]Research

A new research was conducted at the Ramban Medical Center in Haifa, Israel by Dr. Yoram Vardi, head of the Neuro-Urology Department and its results were presented to the European Society of Sexual Medicine in Lyon, France in November, 2009.

The study involved 20 middle – aged volunteers who had suffered erectile dysfunction for more than three years. The participants were administered a shockwave therapy in two 20-minute sessions each week, during a three week treatment. Patients rested for three weeks and then received the treatment for three weeks more.^[31]

The treatment involved the use of a mild form of lithotripsy, which is a technique that uses sound waves that can smash up kidney stones. Several studies showed in recent years that this therapy triggers the release of Vascular Endothelial Growth Factor (VEGF), in charge of sending out a signal for new blood vessels to start growing.^[32] In the case of erectile dysfunction, this therapy appears to stimulate the growth of new blood cells in the genital region. This treatment uses a device that looks like a computer mouse to beam the wave sounds through the skin

Vardi reported that 15 of the 20 men had consistent results and that all men noted a return of erectile functioning by the seventh week. These men were followed up for six months and 13 of them showed long lasting effective effects and the other two men had to take additional treatments. Furthermore, they did not report pain or side effects. However, Vardi reported that the treatment would not work on men withmuscle or nerve problems and stressed that this therapy is intended for those men whose erectile problem arises from reduced blood flow.^[31]Erectile Dysfunction treatments depend on the underlying cause that triggers them which may be psychogenic or physiological, therefore, these causes must previously identified in order to use the appropriate treatment.

The study is still experimental and according to Dr. Andrew McCullough, director of Male Sexual Health, Fertility and Microsurgery in the Department of Urology at NYU Langone Medical Center, more study is necessary before this treatment could be available in the United States.^[33]

[edit]History

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The earliest attempts at treating erectile dysfunction date back to Muslim physicians and pharmacists in the Islamic Golden Age. They were the first to prescribe medication for the treatment of this problem, and they developed several methods of therapy for this issue, including a single-drug therapy method where a drug was prescribed and a "combination method of either a drug or food." Most of these drugs were oral medication, though a few patients were also treated through topical and transurethral means. Erectile dysfunctions were being treated withtested drugs in the Islamic world since the 9th century until the 16th century by a number of Muslim physicians and pharmacists, includingMuhammad ibn Zakarīya Rāzi, Thabit bin Qurra, Ibn Al-Jazzar, Avicenna (The Canon of Medicine), Averroes, Ibn al-Baitar, and Ibn al-Nafis(The Comprehensive Book on Medicine).^{[34][broken citation]}

Dr. John R. Brinkley initiated a boom in male impotence cures in the US in the 1920s and 1930s. His radio programs recommended expensive goat gland implants and "mercurochrome" injections as the path to restored male virility, including operations by surgeon Serge Voronoff. After the Kansas State Medical Board revoked his medical license and the Federal Radio Commission refused to renew his radio license (both in 1930), Brinkley moved his operations just over the Texas border to Mexico where he opened a medical clinic and broadcast advertisements into the US from a border blaster radio station.^{[citation needed]}

Surgeons began providing patients with inflatable penile implants in the 1970s.^{[citation needed]}

Modern drug therapy for ED made a significant advance in 1983, when British physiologist Giles Brindley, Ph.D. dropped his trousers and demonstrated to a shocked American Urological Association audience his phentolamine-induced erection. The drug Brindley injected into his penis was a non-specific vasodilator, an alpha-blocking agent, and the mechanism of action was clearly corporal smooth muscle relaxation. The effect that Brindley discovered established the fundamentals for the later development of specific, safe, orally-effective drug therapies.^{[35][non-primary source needed][36][non-primary source needed]}

Male Sexual Dysfunction Male sexual dysfunction is a problem with 1 of the 4 main components of male sexual function (libido, erection, ejaculation, orgasm) that interferes with interest in or ability to engage in sexual intercourse. Many drugs and numerous physical and psychologic disorders affect sexual function. Libido: Libido is the conscious component of sexual function. Decreased libido manifests as a lack of sexual interest or a decrease in the frequency and intensity of sexual thoughts, either spontaneous or in response to erotic stimuli. Libido is sensitive to testosterone levels as well as to general nutrition, health, and drugs. Conditions particularly likely to decrease libido include hypogonadism (see Male Reproductive Endocrinology: Male Hypogonadism), uremia, and depression. Drugs that sometimes decrease libido include weak androgen receptor antagonists, such as spironolactone  or cimetidine  , and virtually all drugs that are active in the CNS, such as SSRIs, tricyclic antidepressants, and antipsychotics. Loss of libido due to SSRIs or tricyclic antidepressants sometimes is reversible with the addition of bupropion  ortrazodone  . Erection: Erection occurs as the result of a complex neuropsychologic process. Higher cortical input and a sacrally mediated parasympathetic reflex arc combine to stimulate erection. Nerve output travels through the pudendal nerves, which traverse the posterolateral aspect of the prostate. Terminating in the penis, these nonadrenergic/noncholinergic nerves activate nitric oxide synthase, producing nitric oxide, which relaxes smooth muscle lining the sinusoidal spaces that connect the arterioles and venules within the corpus cavernosa. The blood flow within the sinusoids increases markedly, distending them and compressing the venules, causing veno-occlusion. The increased inflow and veno-occlusion together produce penile rigidity. Many factors affect the ability to have an erection (see Male Reproductive Endocrinology: Erectile Dysfunction). Ejaculation and orgasm: Ejaculation is controlled by the sympathetic nervous system.α-Adrenergic stimulation produces contractions of the epididymis, vas deferens, prostate, and muscles of the pelvic floor. In addition, the neck of the bladder closes, preventing retrograde ejaculation of semen into the bladder. SSRIs may delay or inhibit ejaculation. Orgasm is the highly pleasurable sensation that occurs in the brain generally simultaneously with ejaculation. Anorgasmia may be a physical phenomenon due to decreased penile sensation (eg, from neuropathy) or a neuropsychologic phenomenon due to psychiatric disorders or psychoactive drugs. Ejaculatory insufficiency is reduced or absent semen volume that may result from retrograde ejaculation (prostatic fluid flowing backward into the bladder) or interruption of sympathetic stimulation. Retrograde ejaculation is common in men with diabetes and can also be caused by surgery on the neck of the bladder or transurethral resection of the prostate. Sympathetic interruption, either from surgery or with drugs (eg, guanethidine,phentolamine  , phenoxybenzamine  , thioridazine  ), diminishes ejaculatory volume. Premature ejaculation is ejaculation occurring sooner than desired by the man or his partner. It is usually caused by sexual inexperience, anxiety, and other psychologic factors instead of disease. It can be treated successfully with sex therapy and SSRIs. ERECTILE DYSFUNCTION (Impotence) Erectile dysfunction is the inability to attain or sustain an erection satisfactory for sexual intercourse. Most erectile dysfunction is related to vascular, neurologic, psychologic, and hormonal disorders; drug use can also be a cause. Evaluation typically includes screening for underlying diseases and measuring testosterone levels. Treatment options include oral phosphodiesterase inhibitors or apomorphine, intraurethral or intracavernosal prostaglandins, mechanical pump devices, and surgical implants. The term impotence has been replaced by the term erectile dysfunction (ED). In the US, at least 10 to 20 million men > 18 are affected. The prevalence of partial or complete ED is about 50% in men 40 to 70 and increases with aging. However, many men can be successfully treated. Etiology Primary ED (ie, the man has never been able to attain or sustain erections) is rare and is almost always due to psychologic factors (guilt, fear of intimacy, depression, severe anxiety) or clinically obvious anatomic abnormalities. Most often, ED is secondary (ie, a man who previously could attain and sustain erections no longer can). Over 80% of secondary ED cases have an organic etiology. However, in many men with organic disease, ED leads to secondary psychologic difficulties that compound the problem. Psychologic factors must be considered in every case. Psychologic causes may relate to performance anxiety, stress, or a mood disorder (particularly depression). ED may be situational, involving a particular place, time, or partner. The major organic causes of ED are vascular and neurologic disorders, often stemming from atherosclerosis and diabetes. Complications of surgery, usually prostate surgery, are another common cause. Other causes include hormonal disorders, drugs, and structural disorders of the penis (eg, Peyronie's disease). The most common vascular cause is atherosclerosis of penile arteries, often secondary to diabetes. Atherosclerosis and aging decrease the capacity for dilation of arterial blood vessels and smooth muscle relaxation, limiting the amount of blood that can enter the penis. Inadequate impedance of venous outflow (venous leaks) may cause ED or, more commonly, failure to maintain tumescence as long as desired. Venous leaks make it difficult for blood to remain in the penis during erection, so erections occur but cannot be sustained. Priapism, particularly as in sickle cell disease, may damage penile vasculature and lead to ED. Stroke, partial complex seizures, multiple sclerosis, peripheral and autonomic neuropathies, and spinal cord injuries are among the neurologic causes. Diabetic neuropathy and surgical injury are particularly common causes. Any endocrinopathy associated with testosterone deficiency (hypogonadism) may decrease libido and cause ED. However, erectile function only rarely improves with normalization of serum testosterone levels. Numerous drug causes are possible (see Table 2: Male Reproductive Endocrinology: Commonly Used Drugs That Can Cause Erectile Dysfunction). Alcohol can cause temporary ED. Table 2 Commonly Used Drugs That Can Cause Erectile Dysfunction Class Drugs Antihypertensives Clonidine  , thiazides, probably loop diuretics,spironolactone  , β-blockers CNS drugs Monoamine oxidase inhibitors, SSRIs, tricyclics, anxiolytics, alcohol, opioids, cocaine Other Anticholinergics, estrogens  , cimetidine  , anticancer drugs, amphetamines, anti androgens, GnRH analogs Of men who have undergone transurethral resection of the prostate, up to 40% can experience problems with erections for reasons that are not clear. ED is more common after more extensive prostatic resection (eg, radical prostatectomy). Prolonged perineal pressure (as occurs during bicycle riding) can cause temporary ED. Diagnosis Clinical evaluation Screening for depression Testosterone level Evaluation should include history of drug and alcohol use, smoking, diabetes, hypertension, and atherosclerosis; and symptoms of vascular, hormonal, neurologic, and psychologic disorders. It is vital to screen for depression, which may not always be apparent. The Beck Depression Scale or, in older men, the Yesavage Geriatric Depression Scale is easy to administer and may be useful. Satisfaction with sexual relationships should also be explored. Partner sexual dysfunction (eg, atrophic vaginitis, depression) must be considered and evaluated. Examination is focused on the genitals and extragenital signs of hormonal, neurologic, and vascular disorders. Genitals are examined for anomalies, signs of hypogonadism, and fibrous bands or plaques (Peyronie's disease). Poor rectal tone, perineal sensation, or abnormal anal wink or bulbocavernosus reflexes may indicate neurologic dysfunction. Diminished peripheral pulses suggest vascular dysfunction. A psychologic cause should be suspected in young healthy men with abrupt onset of ED, particularly if onset is associated with a specific emotional event or if the dysfunction occurs only in certain settings. A history of ED with spontaneous improvement also suggests psychologic origin (psychogenic ED). Men with psychogenic ED usually have normal nocturnal erections and erections upon awakening, whereas men with organic ED often do not. Laboratory assessment should include measurement of testosterone level; if the level is low or low-normal, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) should be measured (see Male Reproductive Endocrinology: Diagnosis of primary and secondary hypogonadism). Evaluation for occult diabetes, dyslipidemias, hyperprolactinemia, thyroid disease, and Cushing's syndrome should be done based on clinical suspicion. A penile pressure–brachial pressure index (systolic BP in the penis divided by systolic BP in the arm) < 0.6 indicates impaired blood flow to the penis, but this test is seldom done in general clinical practice. Additional invasive or provocative penile tests include duplex ultrasonography before and after injection of a vasoactive drug and cavernosography or cavernosometry; these tests can be considered in some patients, such as those with post-traumatic erectile dysfunction or before penile reconstructive surgery (eg, for Peyronie's disease). Treatment Treatment of cause Usually an oral phosphodiesterase inhibitor Sometimes a mechanical device or an intracavernosal or intraurethral prostaglandin Underlying organic disorders require appropriate treatment. Drugs that are temporally related to onset of ED should be stopped or switched. Depression may require treatment. For all patients, reassurance and education (including of the patient's partner whenever possible) are important. For further therapy, noninvasive methods (mechanical devices and drugs) are tried first. All drugs and devices should be tried ≥ 5 times before being considered ineffective. Mechanical devices: Men who can develop but not sustain an erection may use a constriction ring. As soon as erection occurs, a metal or elastic ring or a leather band with snaps (sold by prescription in pharmacies or OTC in sex paraphernalia stores as a “cock ring”) is placed around the base of the penis, preventing venous outflow. If the man cannot develop an erection, a vacuum device can draw blood into the penis, after which the band or ring is placed at the base of the penis to retain the erection. Bruising of the penis, coldness of the tip of the penis, and lack of spontaneity are some drawbacks to this modality. A constriction ring and vacuum devices might also be useful adjuncts for patients who do not respond satisfactorily to drug therapy. Drugs: The primary drugs for ED are oral phosphodiesterase inhibitors, oral apomorphine (not available in the US), and intracavernosal or intraurethral prostaglandins. Almost all patients prefer oral drug therapy to other methods for treating ED. Oral phosphodiesterase inhibitors selectively inhibit cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5), the predominant phosphodiesterase isoform in the penis. These drugs include sildenafil  , vardenafil  , and tadalafil  . By increasing cGMP, these drugs enhance the nitric oxide release essential for normal erection. Although vardenafil  and tadalafil  are more selective for the penile vasculature than sildenafil  , adverse effects of these drugs are similar. Although no clinical trials directly compare the drugs, all 3 appear to be equally effective (60 to 75%). Sildenafil  dose is 50 mg, although most men respond best to 100 mg. Tadalafil  has a significantly longer half-life (24 to 48 h) than sildenafil  and vardenafil  (about 4 to 6 h), which might lead to more convenient dosing. The usual dosage for tadalafil  and vardenafil  is 5 to 20 mg. All PED5 inhibitors are generally taken at least 1 h before sexual intercourse. Dosing frequency should not be ≤ 24 h for sildenafil  and vardenafil  and not ≤ 48 h fortadalafil  . All PDE5 inhibitors cause direct coronary vasodilation and potentiate the hypotensive effects of other nitrates, including those used to treat cardiovascular disease as well as recreational amyl nitrate (“poppers”). Thus, all nitrates are contraindicated for 24 h after the administration of any PDE5 inhibitor. Other adverse effects of PDE5 inhibitors include flushing, visual abnormalities, and headache. Sildenafil  and vardenafil  may cause abnormal color perception. Tadalafil  use has been linked with myalgias. Some users of PDE5 inhibitors have rarely developed anterior ischemic optic neuropathy, but whether there is a causal relationship is unclear. Vardenafil  should be administered cautiously and at lower initial dosages to those receiving α-blockers, such as prazosin  ,doxazosin  , and tamsulosin  , because of the risk of prolonged hypotension. One study showed that sildenafil  may be safely administered with doxazosin  . Apomorphine increases erectile neurogenic signals by CNS mechanisms. It appears to be only moderately effective and can cause nausea, somnolence, and hypotension. Alprostadil (the prostaglandin PGE1), given via intraurethral insertion or intracavernosal injection, can produce erections with a mean duration of about 60 min. It causes priapism (see Penile and Scrotal Disorders: Phimosis and Paraphimosis) in ≤ 1% and penile pain in about 10%. The intracavernosal dose is adjusted by the physician to minimize priapism; the patient can then self-inject at home. Priapism is less common with intraurethral therapy, but intraurethral therapy is much less effective (50 to 60 %) than intracavernosal injection, the most effective pharmacotherapy for erectile dysfunction (80 to 90%). Combination therapy with a PDE5 inhibitor and alprostadil  may be useful for some patients who fail to respond to oral PDE5 inhibitors alone. Surgery: For patients who do not respond to drug therapy, invasive treatment options include implantation of a penile prosthesis. Prostheses can be rigid plastic rods or hydraulically operated devices. Both involve the risks of general anesthesia, infection, and prosthetic malfunction.