Erectile dysfunction, sometimes called “impotence,” is the repeated inability to get or keep an erection firm enough for sexual intercourse. The word “impotence” may also be used to describe other problems that interfere with sexual intercourse and reproduction, such as lack of sexual desire and problems with ejaculation or orgasm. Using the term erectile dysfunction makes it clear that those other problems are not involved.

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. These variations make defining ED and estimating its incidence difficult. Estimates range from 15 million to 30 million, depending on the definition used. According to the National Ambulatory Medical Care Survey (NAMCS), for every 1,000 men in the United States, 7.7 physician office visits were made for ED in 1985. By 1999, that rate had nearly tripled to 22.3. The increase happened gradually, presumably as treatments such as vacuum devices and injectable drugs became more widely available and discussing erectile function became accepted. Perhaps the most publicized advance was the introduction of the oral drug sildenafil citrate (Viagra) in March 1998. NAMCS data on new drugs show an estimated 2.6 million mentions of Viagra at physician office visits in 1999, and one-third of those mentions occurred during visits for a diagnosis other than ED.

In older men, 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. Incidence increases with age: About 5 percent of 40-year-old men and between 15 and 25 percent of 65-year-old men experience ED. But it is not an inevitable part of aging.

ED is treatable at any age, and awareness of this fact has been growing. More men have been seeking help and returning to normal sexual activity because of improved, successful treatments for ED. Urologists, who specialize in problems of the urinary tract, have traditionally treated ED; however, urologists accounted for only 25 percent of Viagra mentions in 1999.
How does an erection occur? The penis contains two chambers called the corpora cavernosa, which run the length of the organ (see figure 1). 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.

Erectile Dysfunction in Prostate cancer

Regardless of whether the nerves were spared during surgery or whether the most precise dose planning was used during radiation therapy, nearly all men will experience some erectile dysfunction for the first few months after treatment. The reason for this is simple: the nerves and blood vessels that control the physical aspect of an erection are incredibly delicate, and any trauma to the area will result in changes to the natural order.

However, within one year after treatment, nearly all men with intact nerves will see a substantial improvement. By this point, about 50% of men who undergo nerve-sparing prostatectomy will have returned to their pre-treatment function; after two years, about 75% will have returned to pre-treatment function.

For those who underwent radiation therapy, the numbers are better, but tend not to improve too much over time. About 25% of men who undergo brachytherapy will experience erectile dysfunction vs nearly 50% men who have standard external beam radiation; after two years, few men will see much of an improvement.

Men who undergo procedures that are not designed to minimize side effects and/or those whose treatments are administered by physicians who are not proficient in the procedures will fare worse. In addition, men with other diseases or disorders that impair their ability to maintain an erection, such as diabetes or vascular problems, will have a more difficult time returning to pre-treatment function.
Management of Erectile Dysfunction

When a man is sexually aroused, the erectile nerves running alongside the penis stimulate the muscles to relax, allowing blood to rush in. At the same time, tiny valves at the base of the penis lock shut, preventing the blood from flowing back out and therefore causing the penis to stay rigid.

The oral medications for erectile dysfunction, sildenafil (Viagra), tadalafil (Cialis), and vardenafil (Levitra), relax the muscles in the penis, allowing blood to rapidly flow in. On average, the drugs take about an hour to begin working; the erection helping effects of sildenafil and vardenafil last for about 8 hours and tadalafil about 36 hours. About 75% of men who undergo nerve-sparing prostatectomy or more precise forms of radiation therapy have reported successfully achieving erections after using these drugs. However, these drugs are not for everyone. Many men with angina or other heart problems take medications that contain nitrates to help the blood flow better to the heart. All three agents used for erectile dysfunction can affect the way that the nitrates work—and cause blood pressure to drop to dangerously low levels. They can also interfere with alpha-blockers, drugs that are commonly used in men with the noncancerous growth of the prostate known as BPH, and that are often used in men following certain types of radiotherapy, particularly brachytherapy.

In addition to the oral medications, there are a number of alternative treatments that might be helpful to men with erectile dysfunction. MUSE is a medicated pellet about half the size of a grain of rice that is inserted into the urethra through the opening at the tip of the penis using a disposable plastic applicator. Like the oral medications, it, too, stimulates blood flow into the penis; an erection typically occurs within 10 minutes after insertion of the pellet, and can last for 30 to 60 minutes. About 40% of men have reported successfully achieving erections after using this drug, but the results are often inconsistent.

Caverject uses the same drug that is in the MUSE pellets, but delivers it via an injection directly into the penis. It takes about 10 minutes to work and lasts for about 30 minutes. Although nearly 90% of men using Caverject reported erections about six months after therapy, most men are not willing to inject themselves regularly, so the treatment is not often used for long periods of time.
Mechanical Devices

For those unwilling or unable to use any form of medication to help improve erectile function, there are still a number of choices. The vacuum constriction device, or vacuum pump, creates an erection mechanically, by forcing blood into the penis using a vacuum seal. Because the blood starts to flow back out once the vacuum seal is broken, a rubber ring is rolled onto the base of the penis, constricting it sufficiently so that the blood does not escape. About 80% of men find this device successful, but it, too, has a high drop-out rate.
Note that the constriction ring at the base of the penis is effectively cutting off fresh circulation. Because of this effect, it is crucial that the ring be removed immediately after intercourse, or the tissue can be damaged due to lack of flowing oxygen. (See When to Seek Help for more information.)

Surgical Options

The final option for treating erectile dysfunction is the surgically inserted penile implant. With the three-piece implant, a narrow flexible plastic tube is inserted along the length of the penis, a small balloon-like structure filled with fluid is attached to the abdominal wall, and a release button is inserted between the testicles. The penis remains flaccid until an erection is desired, at which point the release button is pressed and fluid from the balloon rushes into the plastic tube. As the tube straightens from being filled with the fluid, it pulls the penis up with it, creating an erection. Assuming the mechanics are working correctly, it is, by definition, 100% effective, and about 70% of men remain satisfied with their implants even after 10 years.

Note that the surgical procedure is done under general anesthesia, so this option is not available to men who are not considered good candidates for surgery because of other issues.

How prostate cancer treatment affects erections

Some prostate cancer treatments may affect the nerves or arteries responsible for erections; others may affect libido, or sex drive.

Radical prostatectomy

The bundles of nerves sitting on either side of the prostate send messages to the penis to initiate erections. Even if the nerve bundles are not removed during radical prostatectomy, they may still sustain damage and are very slow to heal. However, even if the bundles are not injured during surgery, some men will be experience erectile dysfunction afterward; the reasons are unclear.

Another common reason for difficulty with erections is that the veins in the penis may have suffered trauma during surgery and are unable to keep blood trapped inside the penis.

Erection problems can also result from injury to the blood vessels in the penis, although this is extremely rare in radical prostatectomy.

Likelihood of erectile dysfunction following surgery
The effect of surgery on the ability to achieve an erection is related to a man’s age and whether nerve-sparing surgery was performed.

The likelihood and duration of erectile dysfunction following radical prostatectomy depend on the following factors:

The extent of the cancer. Men whose cancers are small and confined to the prostate have a greater potential of regaining erectile function than men with more extensive tumors.

The quality of erections prior to surgery. Men with good erections are far more likely to recover potency after surgery or radiation therapy than those with erection difficulties prior to treatment.

Age. Men in their 40s have the best potential of potency returning after nerve-sparing radical prostatectomy. Men in their 70s and older have significantly diminished potential to regain potency, even if they have nerve-sparing surgery.

The skill of the surgeon. The American Cancer Society reports that after standard (not nerve-sparing) radical prostatectomy, between 65 percent and 90 percent of men will experience erectile dysfunction, depending on their age. A recent study reports that in the hands of a surgeons experienced in nerve-sparing radical prostatectomy, over 80 percent of men were potent (able to have unassisted intercourse with or without the use of Viagra) 18 months after surgery.¹ However, other studies report a much lower percentage of patients achieving potency following nerve-sparing surgery.

Duration of erectile dysfunction following surgery

It is important to remember that surgery is a traumatic procedure and your body will take time to recover, as will the ability to have an erection. Most men experience an improvement in their erections over time.

During the first three to 12 months after radical prostatectomy, most men will not be able to get a spontaneous erection and will need to use medications or other treatments if they wish to have an erection.

After surgery, men experience dry orgasms in which there is no ejaculation. The reason is that the two structures responsible for most of the fluid in semen – the prostate and the seminal vesicles – have been removed. The vas deferens, the tube which transports sperm from the testicles, has been shut off. This lack of fluid emission has no connection to and does not interfere with, a man’s ability to feel sexual desire and arousal, or achieve orgasm.

Radiation therapy

Unlike radical prostatectomy, radiation therapy may cause problems slowly and over time. The main cause of erectile dysfunction following radiation is damage to the blood vessels supplying the nerves responsible for erections. External beam radiation therapy appears to cause more problems with potency than brachytherapy.


When the prostate gland is frozen during cryosurgery, the nerve bundles controlling erections can often be permanently damaged.

Hormone therapy

The male sex hormone testosterone is responsible for sex drive, or libido, as well the ability to achieve an erection. When hormone therapy stops testosterone production, most men lose interest in sexual activity.

Treating erectile dysfunction

Viagra is an oral prescription medication that has revolutionized the treatment of erectile dysfunction. It works by relaxing smooth muscles in the arteries of the penis, allowing more blood flow to produce an erection. Viagra does not improve sex drive; it only improves erections. It may cause mild side effects, including headaches, flushing and indigestion.

Candidates for Viagra: Studies have shown that men with erectile dysfunction after prostatectomy respond well to Viagra if the nerve bundles on both sides of the prostate have been spared. However, Viagra is not effective when one or both nerve bundles have been damaged.

Penile injections

Medication that relaxes the smooth muscle of the penis and increases blood flow is injected with a tiny needle into the side of the penis. It usually takes about 5 minutes from time of injection for erection to occur; the erection lasts from 30 minutes to 2 hours. A doctor can generally teach a man or his partner to administer the injections in one or two office visits. Patients will have to return for follow-up visits, particularly at the beginning of treatment, to ensure they are receiving proper dosage of the medication.

Advantages: The injections produce completely normal erections and are easy to prepare and administer. This treatment option does not involve surgery, is only minimally painful and can be used any time. Although self-injection therapy can cost up to $25 per injection, it is much less expensive than surgery.

Disadvantages: Reports of satisfaction with this technique range between 50 percent and 70 percent. Some men report that the injections cause urethral pain and burning. Injections should be limited to once or twice a week to minimize risks of scars or penile damage. The most serious complication of penile injections is priapism, a painful condition where the erection persists and does not go away.

Vacuum constriction or vacuum erection device

A large plastic tube attached to a pump. Placed over a lubricated penis, the pump is activated, causing a vacuum in the tube. The vacuum allows blood to flow into the penis, producing an erection. A rubber ring is then placed around the base of the penis, trapping the blood and maintaining the erection. The ring must be removed after no more than 30 minutes to allow the blood in the penis to circulate and prevent penile swelling.Men who are able to achieve but not maintain erections may use the ring only.

Advantages: The device works for almost everyone, regardless of nerve damage. It can be used as often as desired, as long as the ring is removed every 30 minutes.

Disadvantages: The vacuum device costs hundreds of dollars and is available only by prescription. If the ring is too tight, it may cause pain or diminished sensation in the penis. The erection begins above the ring, so the base of the penis may swivel with erection. The device takes effort to use and the ring must be removed after no more than 30 minutes. It may be harmful to men who use blood thinners or have blood clotting problems.

Penile implant

A prosthetic device surgically implanted inside the penis.

Advantages: High rates of satisfaction have been reported and implants can restore sexual function to normal levels.

Disadvantages: Surgery carries the risk of complications including bleeding, scarring, or problems with anesthesia. Post-surgical pain is common. There is a small chance of infection that could require removal of the implant. Some men notice numbness at the head of the penis. The head of the penis remains soft during the erection, which may bother some men.