Erectile dysfunction (ED) is the inability to get or keep an erection firm enough for sexual intercourse. ED can be a total inability to achieve an erection, an inconsistent ability to do so, or a tendency to sustain only brief erections.
ED is sometimes called impotence, but that word is being used less often so that it will not be confused with other, nonmedical meanings of the term.
The National Institutes of Health estimates that ED affects as many as 30 million men in the United States. Incidence increases with age: About 4 percent of men in their 50s and nearly 17 percent of men in their 60s experience a total inability to achieve an erection. The incidence jumps to 47 percent for men older than 75. But ED is not an inevitable part of aging. ED is treatable at any age.
Causes of ED
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.
Because 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, high blood pressure, nerve disease or nerve damage, multiple sclerosis, atherosclerosis, and heart disease-account for the majority of ED cases. Patients should be thoroughly evaluated for these conditions before they begin any form of treatment for ED.
Lifestyle choices that contribute to heart disease and vascular problems also raise the risk of ED. Smoking, drinking alcohol excessively, being overweight, and not exercising are possible causes of ED.
Surgery-especially radical prostate and bladder surgery for cancer-can also 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 the fibrous tissues of the corpora cavernosa.
In addition, ED can be a side effect of many common medicines such as blood pressure drugs, antihistamines, antidepressants, tranquilizers, appetite suppressants, and cimetidine, an ulcer drug.
Psychological factors such as stress, anxiety, guilt, depression, low self-esteem, and fear of sexual failure can also cause ED. Even when ED has a physical cause, psychological factors may make the condition worse.
Hormonal abnormalities, such as low levels of testosterone, are a less frequent cause of ED.
Diagnosis of ED
A person's medical and sexual histories help define the degree and nature of ED. The medical history can disclose diseases that lead to ED, and a simple recounting of sexual activity might identify problems with sexual desire, erection, ejaculation, or orgasm.
Use of certain prescription or illegal drugs can suggest a chemical cause because drug effects are a frequent cause of ED.
A physical examination can give clues to systemic problems. For example, if the penis is not sensitive to physical touch, a problem in the nervous system may be the cause. Abnormal secondary sex characteristics, such as unusual hair pattern or breast enlargement, can point to hormonal problems, which would mean the endocrine system is involved. The doctor 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.
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 available testosterone in the blood can yield information about problems with the endocrine system and may explain why a patient has decreased sexual desire.
Penile Doppler ultrasound is a diagnostic test used in the evaluation of erectile dysfunction by using ultrasound to measure blood flow to the penis. A penile injection will be performed to provide the penis with a medicine that causes increased blood inflow by vasodilating the penile arteries. The test will assess the inflow and outflow of blood in the penile tissue.
A psychosocial examination, using an interview and a questionnaire, can reveal psychological factors. A man's sexual partner may also be interviewed to determine expectations and perceptions during sexual intercourse.
Treatment of ED
Most doctors suggest that treatments proceed from least to most invasive. Making a few healthy lifestyle changes may solve the problem. Quitting smoking, reducing alcohol consumption, losing excess weight, and increasing physical activity may help some men regain sexual function.
Cutting back on or replacing medicines that could be causing ED is considered next. For example, if a patient thinks a particular blood pressure medicine is causing problems with erection, he should tell his doctor and ask whether he 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.
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 during treatment for ED from physical causes.
Drugs for treating ED can be taken orally, injected directly into the penis, or inserted into the urethra at the tip of the penis.
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.
The recommended dose for Viagra is 50 milligrams (mg), and the doctor 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 doctor may adjust this dose to 20 mg if 10 mg is insufficient. Lower doses of 5 mg and 2.5 mg are available for patients who take other medicines or have conditions that may decrease the body's ability to use the drug. The 5 mg and 2.5 mg doses of Cialis are FDA-approved for daily use.
None of these PDE inhibitors should be used more than once a day. Men who take nitrate-based drugs such as nitroglycerin pills for heart problems should not use any of the three drugs because the combination can cause a sudden drop in blood pressure. Also, men should tell their doctor if they take any drugs called alpha-blockers, which are used to treat prostate enlargement or high blood pressure. The doctor may need to adjust the ED prescription. Taking a PDE inhibitor and an alpha-blocker within 4 hours of each other can cause a sudden drop in blood pressure. A small number of men have experienced vision or hearing loss after taking a PDE inhibitor. Men who experience vision or hearing loss should seek prompt medical attention.
While oral medicines improve the response to sexual stimulation, they do not trigger an automatic erection as injections do. Many men achieve stronger erections by injecting drugs into the penis, These drugs may create unwanted side effects, however, including scarring of the penis and persistent erection, known as priapism.
Research on drugs for treating ED is expanding rapidly. Patients should ask their doctor about the latest advances.
Mechanical vacuum devices cause an erection by creating a partial vacuum, which draws blood into the corpora cavernosa, engorging and expanding the penis.
Couples may find that using a vacuum device requires some practice or adjustment. An erection achieved with a vacuum device may not feel like an erection achieved naturally. The penis may feel cold or numb and have a purple color. Bruising on the shaft of the penis may occur, but the bruises are usually painless and disappear in a few days. Ejaculation may be weakened because the elastic ring blocks some of the semen from traveling through the urethra, but the pleasure of orgasm is usually not affected.
Surgery usually has one of three goals:
- to implant a device that can cause the penis to become erect
- to reconstruct arteries to increase blood flow 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.
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. The pump causes fluid to flow from a reservoir residing in the lower pelvis to two cylinders residing in the penis. Inflatable implants can expand the length and width of the penis to some degree. They also leave the penis in a more natural state than malleable implants do when not inflated.
Once a man has either a malleable or inflatable implant, he must use the device to have an erection. Possible problems with implants include mechanical breakdown and infection, although mechanical problems have decreased in recent years because of technological advances.
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 groin or fracture of the pelvis. The procedure is usually unsuccessful 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, called ligation, can reduce the leakage of blood that diminishes the rigidity of the penis during an erection. However, experts have raised questions about the long-term effectiveness of this procedure, and it is rarely done.