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Impotence (Erectile Dysfunction)

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of erectile dysfunction.

Physical Causes

A number of conditions share a common problem with erectile dysfunction--which is impaired ability of blood vessels to open and allow normal blood flow. Such conditions include diabetes, hypertension, coronary artery disease, kidney failure, peripheral artery disease, and stroke. Increasingly, researchers are studying the role of nitric oxide, which plays a major role in keeping blood vessels open, in all of these disorders.

Some of these diseases, notably the following are highly associated with erectile dysfunction and have other factors involved in its development:

  • Diabetes. Diabetes, for example, 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. Blocked arteries and nerve damage are both common complications of diabetes; when the blood vessels or nerves of the penis are involved, erectile dysfunction can result. In June 2004, researchers reported on the first study looking at men with type 2 diabetes and symptomless heart disease. Their report in Circulation: Journal of the American Heart Association suggests that erectile dysfunction (ED) in men with type 2 diabetes may signal silent coronary artery disease (CAD). The study found that those who had silent CAD and type 2 diabetes were nine times more likely to have ED than diabetic men who did not have silent heart disease.
  • High Blood Pressure (Hypertension). Erectile dysfunction is a very common problem in men with high blood pressure. More than 40 percent of men with erectile dysfunction have hypertension. The disease process is the major contributor to impotence, but many of the drugs used to treat hypertension also cause it. Newer anti-hypertensive agents, including angiotensin-converting enzyme (ACE) inhibitors and angiotensin-receptor blockers (ARBs) are less likely to cause erectile dysfunction. In fact, ARBs may be particularly effective in restoring erectile function in men with high blood pressure who suffer from impotence.

Other Common Medical Conditions That Contribute to Erectile Dysfunction

Parkinsons Disease. As a risk factor for impotence, Parkinsons disease (PD) is an under-appreciated problem. It is estimated that about one-third of men with PD experience impotence. The physical cause of PD-related impotence is most likely an impaired nervous system. Depression and lowered self-esteem also contribute to erectile dysfunction in these patients.

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.)

Other Common Medical Conditions. Other medical conditions that have been associated with erectile dysfunction in some cases include allergies, thyroid problems, lung disease, and epilepsy.

Prostate Cancer and Its Treatments

Advanced prostate cancer can damage nerves needed for erectile function. Prostate surgery and surgical and radiation treatments for prostate cancer can also cause impotence. A number of treatments for sexual dysfunction are available that may help some men.

Prostate Cancer Surgery (Radical Prostatectomy). The first nationally representative study to evaluate long-term outcomes after radical prostatectomy concluded that impotence occurs far more frequently than previously reported. Those who have so-called nerve-sparing surgeries have better results than those whose surgeries affect the nerves around the prostate. Some evidence also suggests that sexual function rates might improve if the nerve-sparing prostate surgeries also spare the ducts that carry semen.

Some studies suggest that impotence after prostate surgery may in part be due to injury to the smooth muscles in the blood vessels. Early treatments to maintain penile blood flow, particularly alprostadil injections, may helpful in restoring erectile function. In one study, men administered injections every other night for six months. They then started taking sildenafil (Viagra) three months after surgery. At six months, 82% of these men achieved penetration compared to only 52% of men who took Viagra only. The vacuum pump may serve a similar purpose as the injections.

Radiation. Although it is generally believed that radiation poses a lower risk for impotence than does surgery, studies have reported similar rates after three years. Experts suggest radiation injures the blood vessels and so lead to erectile dysfunction over time. Some studies report a lower risk for impotence from brachytherapy, a radiation technique that involves the implantation of radioactive seeds compared to external-beam radiation. Still, there have been very few studies that have lasted more than two years. One five-year study reported a high long-term rate of impotence (53%) with brachytherapy, which is close to that of standard externally administered radiation. Early use of alprostadil injections and Viagra may help these men as well as those who had surgery.

Drug Treatments. Prostate cancer medical treatments commonly employ androgen-suppressive treatments, which cause erectile dysfunction.

Surgical Treatments that Affect Intestinal Tracts

Surgery for Colon and Rectal Cancers. Surgical and radiation treatments for colorectal cancers can cause impotence in some patients. In general, colostomy does not usually affect sexual function. However, wide rectal surgery can cause short term or long-term sexual dysfunction. Total mesorectal excision (TME) may pose fewer risks than standard surgery. Sildenafil (Viagra) may help many men who experience this after surgery.

Surgical Treatment of Inflammatory Bowel Disease. Rectal excision for inflammatory bowel disease (IBD) can cause impotence, but rates are low (2% to 4%). Sildenafil (Viagra) is very effective in restoring potency after IBD surgery.

Operations for Fistulas. Surgery to repair anal fistulas can affect the muscles that control the rectum (external anal sphincter muscles), sometimes causing impotence. (Repair of these muscles may restore erectile function.)

Treatments for Benign Prostatic Hyperplasia (BPH)

Surgery and drug treatments for benign prostatic hyperplasia (BPH) can also increase the risk for impotence, although to a much lesser degree than surgery for prostate cancer.

  • Between 4% and 10% of patients who have transurethral resection of the prostate (TURP) and open prostatectomy for BPH report impotence afterward. The risk is very low, however, in men who were functioning normally before surgery.
  • Finasteride (Proscar) has been associated with impotence in between 6% and 19% of patients. Anti-androgen agents used to treat BPH can also cause erectile dysfunction.

Medications

About a quarter of all cases of impotence can be attributed to medications. Many drugs pose a risk for erectile dysfunction. Some authorities go so far as to say that nearly every drug, prescription or nonprescription, can be a cause of temporary erectile dysfunction.

Among the drugs that are common causes of impotence are the following:

  • Drugs used in chemotherapy.
  • Many drugs taken for high blood pressure, particularly diuretics and beta-blockers.
  • Most drugs used for psychological disorders, including anti-anxiety drugs, anti-psychotic drugs, and antidepressants, especially selective serotonin reuptake inhibitors (SSRIs). Newer antidepressants pose fewer problems.
  • Anti-androgens, including drugs known as gonadotropin-releasing hormone agonists. They are used in prostate cancer and also for treating BPH.

Drugs that sometimes cause impotence include:

  • Older anti-ulcer medications (cimetidine).
  • Anticholinergic drugs (including some antihistamines).
  • Antinausea agents, particularly metoclopramide (Reglan).
  • Antifungal drugs (especially ketoconazole).

Physical Trauma, Stress, or Injury

Injury to the Spine. Spinal cord injury and pelvic trauma, such as a pelvic fracture, can cause nerve damage that results in impotence. Other conditions that can injure the spine and effect impotence include spinal cord tumors, spina bifida, and a history of polio.

Bicycling. Studies have indicated that frequent bicycling may pose a risk for erectile dysfunction by reducing blood flow to the penis. The greatest risk is in cyclers who sit upright while cycling. In addition, a report in the August 2004 Journal of Urology found that long distance cyclers may reduce their risk by riding a road bike instead of a mountain bike and by choosing saddles without a cutout.

Note: Vasectomy does not cause erectile dysfunction. When impotence occurs after this procedure, it is often in men whose female partners were unable to accept the operation.

Hormonal Abnormalities

Hypogonadism (Testicular Failure). Hypogonadism in men is a deficiency in male hormones, usually due to an abnormality in the testicles, which secrete these hormones. It affects four to five million men in the United States. In addition to impotence, hypogonadism causes reductions in energy, sex drive, lean body mass, and bone density. Hypogonadism can be caused by a number of different conditions. Among them are the following:

  • Disorders in the pituitary or hypothalamus glands.
  • Malnutrition.
  • Genetic factors.
  • Myotonic dystrophy.
  • Orchitis (inflammation of the testicles).
  • Physical injury.
  • Mumps.
  • Radiation treatments.
  • Exercise-induced hypogonadism. Only a few cases of exercise-induced hypogonadism have been identified in men. Some researchers believe, however, that certain athletes may be at risk, including those who began endurance training before full sexual maturity, have very low body weight, and have a history of stress fractures.

Low Testosterone Levels. Only about 5% of men who see a physician about erectile dysfunction have low levels of testosterone, the primary male hormone. In general, lower testosterone levels appear to reduce sexual interest, not cause impotence. A 1999 study, however, suggests that testosterone levels are not an accurate reflection of sexual drive.

Other Hormonal Abnormalities. Other hormonal abnormalities that can lead to erectile dysfunction include:

  • High levels of the female hormone estrogen (which may occur in men with liver disease).
  • Abnormalities of the pituitary gland that cause high levels of the hormone prolactin are particularly likely to cause impotence.
  • Other, uncommon hormonal causes of impotence include an underactive or overactive thyroid or adrenal gland abnormalities.

Varicoceles

A varicocele is an enlarged (varicose) vein in the cord that connects to the testicle. Varicoceles are found in 15% to 20% of all men and in 25% to 40% of infertile men. When varicoceles occur in both testicles, they may contribute to hormone imbalances that cause erectile dysfunction.

Other Problems in Sexual Function

Premature Ejaculation

Premature ejaculation is the most common male sexual dysfunction and occurs in as many as 40% of men. It is defined as the inability to delay ejaculation to the point where both partners are satisfied. This can vary widely depending on the preferences of the partners. Younger men tend to have this problem more than older men. Anxiety is a major factor at any age. In general, the longer the duration between ejaculations, the faster they are. Various techniques are available to help delay orgasm. The standard medications used for this condition are the selective serotonin reuptake inhibitors (SSRIs), which include Prozac and Paxil. Some studies suggest that sildenafil (Viagra) in combination with an SSRI may be helpful.

Peyronies Disease

Peyronies disease is an accumulation of scar tissue within the penis shaft, which causes it to curve. The curvature can make erection and intercourse difficult and painful. This condition may be associated with an injury to the penis, but no clear information exists on its origin. Some men may not even be aware that they have it, and there is some evidence that it may be more common than currently believed. In one study, 6.7% of men with an average age of 62 had signs of curvature, but only 2.2% were aware of any difficulties. The disease often goes into a type of spontaneous remission, and some individuals who had previously experienced erectile dysfunction are able to resume sexual activity. Scarring may still cause erection problems, however, even in these cases.

Treatment for Peyronies Disease. If Peyronies disease is treated early, ultrasound, heat application, and anti-inflammatory drugs may help reduce scar formation. Some experts believe that the extracorporeal shock wave therapy (ESWT) is the safest and most effective first-line therapy. ESWT uses sound waves to break up scar tissue. It has been used with some success.

Studies are also suggesting that the calcium channel blocker verapamil may be very beneficial. It can be administered using injection, as a gel patch, or through a process called electromotive drug administration (EMDA), also referred to as iontophoresis. EMDA delivers the agent through an electrical transport of charged molecules. Some studies are reporting good success with EMDA delivery of verapamil along with the steroid dexamethasone.

In severe cases of scarring, the only treatment is surgery to straighten the penis and reduce the curve. Penile implants may also be beneficial.

Priapism

Priapism is a sustained, painful, and unwanted erection that persists 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.

Treatment of Priapism. If priapism occurs, applying ice for 10-minute periods to the inner thigh may help reduce blood flow. Erections that last four hours or longer require emergency care.

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