What is erectile dysfunction?

Causes and Symptoms

When a human male is sexually aroused, the brain sends a signal through the nervous system to the penis. The signal tells the blood vessels in the penis to relax so that the vessels get larger and fill with blood. Two spongy, cylinder-shaped chambers called the corpora cavernosa run the length of the penis. It is these chambers filled with blood vessels and blood sinuses that become engorged with blood. The same nerve signals that tell the vessels entering the penis to fill with blood also slow down the rate of blood leaving the penis, such that the penis fills with blood and becomes erect. In most males with erectile dysfunction (ED), the blood flow or nerve signals to the penis are reduced or damaged such that one cannot achieve an erection suitable for sexual intercourse.

Erectile dysfunction is more common with advancing age. The prevalence of any degree (mild to complete) of erectile dysfunction in men forty years of age and older is about 40 percent. Age is strongly associated with erectile dysfunction, but men with heart
disease, hypertension, diabetes, and depression are more likely to experience erectile dysfunction than are men of the same age without these health problems. Men who have surgery of the prostate gland, located near the base of the penis, might have damage to the nerves that go to the penis and might experience erectile dysfunction that is either temporary or permanent.

Erectile dysfunction seems to be associated with cardiovascular diseases, leading to speculation that vascular causes for erectile dysfunction might be due to a process similar to atherosclerosis that occurs in the penile blood vessels and keeps them from being able to relax and enlarge. Sometimes drugs taken for other disorders can cause erectile dysfunction. They include drugs taken for depression (amitriptyline, doxepin), psychosis (phenothiazines, haloperidol, benzisoxazole), and high blood pressure (beta blockers, thiazide diuretics, methyldopa, clonidine).

Although complete erectile dysfunction, defined as no hardening of the penis with sexual stimulation, may be easily recognized as erectile dysfunction, the subtler symptoms of milder erectile dysfunction are not always identified as such by men. Additionally, despite the publicity and advertisements for ED medications, some men are still reluctant to discuss erection problems with their health care provider or are concerned that treatments for ED are unsafe.

Treatment and Therapy

Lifestyle changes such as weight loss, which can improve high blood pressure and type 2 diabetes, can also improve erectile dysfunction. Oral therapy with phosphodiesterase type 5 inhibitors (Viagra, Cialis, or Levitra) are the treatment options usually tried first in men with erectile dysfunction. These drugs act by stimulating the blood vessels in the penis to relax. Phosphodiesterase inhibitors have a good safety record, but some men experience visual or other side effects after taking these drugs. Men who take nitrates for chest pain should not take phosphodiesterase inhibitors, because the combination of nitrates and phosphodiesterase inhibitors can cause the blood pressure to drop below normal and cause blackouts.

Other treatments include mechanical vacuum devices, intracavernous injection therapy, intraurethral suppositories, penile implants, and surgery. Mechanical vacuum devices create a vacuum around the penis, which draws blood into the penis to cause an erection. The penis is placed in a plastic cylinder and then a pump pulls the air out of the cylinder. Once an erection is achieved, an elastic band is placed at the base of the penis to maintain the erection after the cylinder is removed. With intracavernous injection therapy, drugs are injected directly into the penis to cause an erection. Intraurethral suppositories are prostaglandin-containing pellets that are inserted into the urethra. Occasional side effects include pain in the penis and sometimes in the testicles, mild urethral bleeding, and dizziness. After inserting the pellet, the man must remain standing to increase blood flow to the penis. It can take about fifteen minutes to achieve an erection. This method can also have consequences for a man’s female sex partner by causing vaginal itching and possibly uterine contractions. The latter reason is why men should not use this method when having intercourse with a pregnant woman unless a condom or other type of barrier device is also used.

Penile implants are inflatable inserts surgically implanted on either side of the penis. The implants are attached to a pump placed in the scrotum and a reservoir fitted just below the groin muscles. The implants are inflated with saline solution from the reservoir to make the penis erect. There is some risk of mechanical failure with these kinds of devices.

Vascular reconstructive surgery for erectile dysfunction is rarely performed and is considered experimental. The surgery involves taking a vein from the leg and attaching it so that it allows blood to bypass areas of vascular blockage in the penis. Venous ligation is performed to keep the veins going out of the penis from leaking so that enough blood stays in the penis to keep it erect.

Studies carried out at the Rambam Medical Center in Israel indicated that extracorporeal shockwave therapy, a procedure used to treat kidney stones, may be able to replace prescription medication to treat ED in some cases. The shockwave procedure increases blood flow and enables new blood vessels to be created, enhancing a man's chances of producing an erection.

Perspective and Prospects

Before the approval of Viagra, the subject of erectile dysfunction or impotence was rarely discussed. To market the drug, Pfizer, the company that produces Viagra, launched an advertising campaign that included several celebrities who acknowledged that they had ED. This advertising campaign brought the subject of erectile dysfunction into the public domain, and soon erectile dysfunction was no longer a forbidden topic of conversation. Viagra was originally developed as a medicine intended to treat the heart disease
angina pectoris. Viagra was not effective as a treatment for that condition, but one of the side effects reported during clinical trials in angina was that of erections.

Phosphodiesterase inhibitors have also become drugs of abuse, because these drugs can also enhance erections in persons who do not have erectile dysfunction. Some men take a phosphodiesterase inhibitor after taking illicit recreational drugs that can cause erection problems to counteract the effect on their sexual performance.

Bibliography

Kirby, Michael. Erectile Dysfunction and Vascular Disease. Malden, Mass.: Blackwell, 2003.

Kirby, Roger S. An Atlas of Erectile Dysfunction. 2d ed. New York: Parthenon, 2003.

Kirby, Roger S., Culley C. Carson, and Irwin Goldstein. Erectile Dysfunction: A Clinical Guide. Oxford, England: Isis Medical Media, 1999.

Lalong-Muh J., T. Colm, and M. Steggall. "Erectile Dysfunction Following Retropubic Prostatectomy." British Journal of Nursing 22, no. 4 (February/March, 2013): S4, S7–9.

Resnick M. J., et al. "Long-Term Functional Outcomes After Treatment for Localized Prostate Cancer." New England Journal of Medicine 368, no. 5 (January, 2013):436–445.

Schwarz, Ernst R. Erectile Dysfunction. New York: Oxford University Press, 2013.

Vardi, Yoram, et al. "Can Low-Intensity Extracorporeal Shockwave Therapy Improve Erectile Function? A Six-Month Follow-Up Pilot Study in Patients with Organic Erectile Dysfunction." European Urology 58, no. 2 (August, 2010): 243–248.