Impotence (Erectile Dysfunction)
DescriptionAn in-depth report on the causes, diagnosis, treatment, and prevention of erectile dysfunction.
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:
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.
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 that sometimes cause impotence include:
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.
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:
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:
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.