Impotence, also called erectile dysfunction, is estimated to affect between 10 and 30 million men in the United States. Previously thought to be mainly a psychological problem or caused by the aging process, physicians now believe that more than 80 percent of cases stem from physical causes, including disease, injury (especially spinal cord injury), substance abuse, or the side effects of prescription medications. And while incidence increases with aging, it is not an inevitable result. Because the term impotence has developed a negative connotation, it is now rarely used in technical literature.

Among the most common causes are diseases that affect blood flow, such as heart disease, arteriosclerosis, and high blood pressure. Other common causes are diabetes, kidney disease, chronic alcoholism, liver failure, elevated cholesterol level, hormonal abnormalities, and neurological disorders, such as multiple sclerosis or spinal cord damage. Smoking also restricts blood flow. Drugs, such as cocaine, marijuana, anti-depressants, narcotics, blood pressure medications, antifungals, and beta-blockers may also cause impotence.

Psychological factors-such as stress, anxiety, guilt, depression, or low self-esteem-are estimated to cause between 10 and 20 percent of cases.

Signs and Symptoms

Inability in males to achieve or sustain an erection for sexual intercourse more than 25 percent of the time or a tendency to sustain only brief erections

Conventional Medical Treatment

Since achieving and sustaining an volves the man's mental state-as erection in-well as the nerves, muscles, and circulatory system-physicians often take a team approach to treatment. Your doctor generally begins by taking a medical and sexual history and giving you a complete physical examination. Typical tests ordered include a blood count, urinalysis, lipid profile, measurements of creatinine and liver enzymes, and a blood testosterone analysis. Since healthy men have involuntary erections during sleep, you may also be asked to monitor your erections during the night, to help evaluate the possibility of psychological problems.

Though today about 95 percent of cases of erectile dysfunction are treatable, only 5 to 10 percent of men seek treatment. Among the most successful and least invasive treatments is the prescription medicine sildenafil, sold as Viagra originally used to treat high blood pressure disorders. Viagra works by inhibiting a particular enzyme in the body, therefore allowing blood to flow into the penis. It is not recommended for men with certain types of heart disease, but is effective for about 65 to 70 percent of men, including those with physical and psychological problems.

Before Viagra became available, other medications recommended included testosterone and yohimbine hydrochloride, but both are controversial. Testosterone is effective in only a small percentage of men with hormonal imbalances. Yohimbine, which is derived from tree bark and has been used for centuries as an aphrodisiac, has not been proven effective in clinical trials.

Several mechanical devices also have been used with varying degrees of success. One of these, a vacuum constriction device, pulls blood into the penis by means of a vacuum created when the penis is inserted into a plastic tube and air is then pumped out of the tube. The result mimics an erection, which can be maintained for about a half an hour by placing an elastic band around the penis.

With penile injection therapy, medication is injected into the side of the penis to create an erection. The drawbacks, however, include the pain of the injection and the possibility of a prolonged erection of two hours or more. In the treatment known as intraurethral therapy, a soft pellet of medication, about the size of a grain of rice, is inserted into the urethra with an applicator. The medication is absorbed directly into the erection chambers of the penis, resulting in an erection in between 30 to 80 percent of men that can last 30 minutes to an hour.

In some cases, especially in young men with vascular injuries, physicians may recommend surgery. Surgery may be used to implant a prosthesis to cause the penis to be erect, reconstruct arteries to increase blood flow to the penis, or repair veins that may allow a too-rapid exit of blood from the penis. Two types of implants are used: one consists of two semi-rigid but malleable rods; the other is an inflatable implant that can be expanded with a pressurized saline fluid. Men and their partners using prosthesis report a 93 percent satisfaction rate.