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Erectile Dysfunction
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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. The wide scope of the definition of ED make estimating its incidence difficult, but it is thought to affect 15 to 30 million men worldwide.
Other Names
- ED
- Impotence
Types
Erectile dysfunction can be physiologic or psychogenic. Physiologic means that the disorder is due to an anatomic problem that prevents blood from flowing into or remaining inside of the penis. Psychogenic means that the condition is related to a condition such as anxiety regarding sexual performance that prevents one from being able to obtain or maintain a sufficient erection.
Signs and Symptoms
The definition of erectile dysfunction is "the inability to achieve or maintain an erection sufficient for satisfactory sexual performance."[1] Men with erectile dysfunction may also experience alterations of sexual desire (libido), problems with ejaculation, difficulty with orgasms, and genital pain.
Anatomy and Physiology
The penis contains two chambers called the corpora cavernosa, which run the length of the organ. 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.
Causes
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% of ED cases. ED reportedly occurs in 25% of young diabetic men and 75% of older men with diabetes.
Lifestyle choices that contribute to heart disease and vascular problems also raise the risk of erectile dysfunction. Smoking,being overweight, and not exercising 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, including 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%-20% 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 low levels of testosterone.
Diagnosis
Exams and tests
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% 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 may mean that the endocrine system is involved. The examiner might discover a circulatory problem by observing decreased pulses in the wrist or ankles. An 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 tests, 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 men 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.
Treatment
The American Urological Association's Erectile Dysfunction Guideline Update Panel concluded that informed patient decision making should be the standard by which decisions on treatment of erectile dysfunction are made.[1] 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 a particular drug is causing problems with erection, it may help to inform the doctor and ask whether a different class of blood pressure medicine can be prescribed.
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.
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.
Medications
Drugs for treating ED can be taken by mouth, 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 sildenafil (Viagra), the first pill to treat ED. Since that time, vardenafil (Levitra) and tadalafil (Cialis) have also been approved. Additional medications are being tested for safety and effectiveness.
Medications taken by mouth
Sildenafil, vardenafil, and tadalafil 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 medications taken by mouth improve the response to sexual stimulation, they do not trigger an automatic erection as injections do. The recommended dose for sildenafil is 50 mg, and the physician may adjust this dose anywhere from 25 mg to 100 mg, depending on the patient. The recommended dose for either vardenafil or tadalafil is 10 mg. 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. Vardenafil 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, drugs called alpha-blockers, which are used to treat prostate enlargement or high blood pressure, can interact with PDE inhibitors. Taking a PDE inhibitor and an alpha-blocker within 4 hours of each other can cause a sudden drop in blood pressure.
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 noted that other drugs, including yohimbine, dopamine, 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.
Injections
Many men achieve stronger erections by injecting drugs into the penis, causing it to become engorged with blood. Drugs such as papaverine, 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.
Insertions
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.
Therapies
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.
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.
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 penile prostheses, can restore erection in many men with ED. Possible problems with implants include mechanical breakdown and infection.
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. 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 expand the length and width of the penis. They also leave the penis in a more natural state when not inflated.
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.
Holistic and alternative treatments
Many herbal therapies are used for treating erectile dysfunction around the world.[2] Studies of Korean red ginseng have shown effectiveness in treating erectile dysfunction.[3][4]
A holistic approach to the management of erectile dysfunction means making lifestyle changes to allow the body to reach optimal health. In a review of these measures, researchers found that some changes, such as losing weight, could reverse symptoms of erectile dysfunction, while other changes, such as stopping smoking, worked to prevent ED from developing, but did not necessarily improve symptoms if smoking was stopped after the diagnosis had been made.[5]
Prevention
A study of the health behaviors of over 22,000 men in the United States showed that those who were obese and smoked had a higher chance of developing erectile dysfunction and that those who engaged in regular physical activity had a lower chance of the disorder.[6]
Chances of Developing Erectile Dysfunction
Risk factors
There are several risk factors for developing erectile dysfunction. These include smoking, trauma to the pelvis or penis, neurologic disease, endocrine (hormonal) disease, obesity, pelvic radiation therapy, Peyronie's disease, and recreational and prescription drug use.[1]
Related Problems
Comorbidity
Some disorders that are commonly seen in association with erectile dysfunction follow:
Because heart disease and erectile dysfunction are commonly associated, the Princeton Consensus Panel has developed special guidelines for patients with heart disease. Patients are categorized as high-risk if they have ongoing chest pain (angina), uncontrolled high blood pressure, congestive heart failure, a heart attack within the last 2 weeks, certain abnormal heart rhythms, and some forms of cardiac or valvular disease. The Panel recommends that these patients do not receive treatment for sexual dysfunction until the cardiac condition has been treated.[7]
Related disorders
- Peyronie's disease
- Premature ejaculation
- Psychosexual relationship problems
Clinical Trials
For a list of U.S. government-sponsored clinical trials on erectile dysfunction, go here.
Research
Gene therapy for ED is now being tested in several centers and may offer a long-lasting therapeutic approach for ED.[8]
Controversy
Researchers purchased 7 herbal products marketed for erectile dysfunction on the Internet and at health food stores. They analyzed the ingredients and found that 2 of them contained prescription-strength doses of two medications for erection, sildenafil (Viagra) and tadalafil (Cialis).[9]
Expected Outcome
With the variety of treatments available for erectile dysfunction today, most men can achieve a satisfactory outcome. The AUA estimates that PDE5 inhibitors such as sildenafil (Viagra) are effective for 80% of men, penile injection therapy for 85%, penile insertion therapy (through the urethra) for 40%, vacuum device for 75%, and implanted penile prosthesis for 90%.
History
In the 1970s, urologists F. Bradley Scott, Michael Small, and Hernan Carrion developed the first versions of [inflatable penile prostheses]. In 1983, British physiologist Gile Brindley literally showed that injections of medication could cause erections, by demonstrating on himself and exposing his erect penis at the annual meeting of the American Urological Association.[10]
Epidemiology
A population-based study in 3 cities in China found that 28% of all men and 40% of all men over age 40 have erectile dysfunction.[11] A United States study showed that 22% of all men have ED.[12]
References
- ↑ 1.0 1.1 1.2 American Urological Association. Clinical Guidelines: Management of Erectile Dysfunction.
- ↑ Kamatenesi-Mugisha M, Oryem-Origa H. Traditional herbal remedies used in the management of sexual impotence and erectile dysfunction in western Uganda. Afr Health Sci. 2005 Mar;5(1):40-9. Abstract | Full Text
- ↑ Hong B, Ji YH, Hong JH, Nam KY, Ahn TY. A double-blind crossover study evaluating the efficacy of korean red ginseng in patients with erectile dysfunction: a preliminary report. J Urol. 2002 Nov;168(5):2070-3. Abstract
- ↑ de Andrade E, de Mesquita AA, Claro Jde A, de Andrade PM, Ortiz V, Paranhos M, Srougi M. Study of the efficacy of Korean Red Ginseng in the treatment of erectile dysfunction. Asian J Androl. 2007 Mar;9(2):241-4. Epub 2006 Jul 11. Abstract
- ↑ Horasanli K, Boylu U, Kendirci M, Miroglu C. Do lifestyle changes work for improving erectile dysfunction? Asian J Androl. 2008 Jan;10(1):28-35. Abstract | PDF
- ↑ Bacon CG, Mittleman MA, Kawachi I, Giovannucci E, Glasser DB, Rimm EB. A prospective study of risk factors for erectile dysfunction. J Urol. 2006 Jul;176(1):217-21. Abstract
- ↑ Jackson G, Rosen RC, Kloner RA, Kostis JB. The second Princeton consensus on sexual dysfunction and cardiac risk: new guidelines for sexual medicine. J Sex Med. 2006 Jan;3(1):28-36; discussion 36. Abstract
- ↑ Strong TD, Gebska MA, Burnett AL, Champion HC, Bivalacqua TJ. Endothelium-specific gene and stem cell-based therapy for erectile dysfunction. Asian J Androl. 2008 Jan;10(1):14-22. Abstract | PDF
- ↑ Fleshner N, Harvey M, Adomat H, et al. Evidence for contamination of herbal erectile dysfunction products with phosphodiesterase type 5 inhibitors. J Urol. 2005 Aug;174(2):636-41; discussion 641; quiz 801. Abstract
- ↑ William P. Didusch Center for Urologic History. Milestones in Urology: Sexual Dysfunction.
- ↑ Bai Q, Xu QQ, Jiang H, Zhang WL, Wang XH, Zhu JC. Prevalence and risk factors of erectile dysfunction in three cities of China: a community-based study. Asian J Androl. 2004 Dec;6(4):343-8. Abstract
- ↑ Laumann EO, West S, Glasser D, Carson C, Rosen R, Kang JH. Prevalence and correlates of erectile dysfunction by race and ethnicity among men aged 40 or older in the United States: from the male attitudes regarding sexual health survey. J Sex Med. 2007 Jan;4(1):57-65. Epub 2006 Nov 1. Abstract
External Links
American Urological Association
American Association of Sex Educators, Counselors, and Therapists
National Kidney and Urologic Diseases Information Clearinghouse
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