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Impotence (Erectile Dysfunction)

  • Definition

    Erectile dysfunction (ED), also called impotence, is characterized by a man's inability to have an erection hard enough to have sex or to keep an erection long enough to finish having sex.


    ED affects over 15 million men in the U.S. The normal physiology of erection involves a complex series of events. The penis contains two cylinders of sponge-like tissue that run along it’s shaft, parallel to the urethra. When sexual excitation occurs, blood flow to this tissue normally increases. As the tissue fills with the extra blood, it stiffens to create an erection. An erection is maintained by continued increased blood flow to this area. Once ejaculation occurs, or after sexual excitation stops, the blood flow decreases, and the sponge-like tissue empties and softens to the non-erect state.

    Proper erectile function depends on physical and psychological arousal, which then must be communicated to the body’s nervous system. The nervous system responds to arousal by releasing chemicals, such as nitric oxide, into the penile blood to cause the blood vessels that carry blood to the penis to enlarge, increasing blood flow to the sponge-like cylinders, and forming an erection. Any interruption along this pathway may result in erectile dysfunction.

    Risks and Factors

    Erectile dysfunction can be caused by psychological or physical factors. Psychological factors are the cause approximately 10% of the time. This is commonly due to anxiety, stress, depression, excess fatigue or dissatisfaction with the relationship with the partner.

    Physical causes can include any disorder that prevents the nervous system or vascular system from responding appropriately to arousal. That includes injuries to spinal cord, or damage to the nerves in the genital area from diabetes, multiple sclerosis or surgery. Vascular problems can be caused by medications, diabetes, high blood pressure, and atherosclerosis (hardening of the arteries). Hormonal problems, kidney disease, liver disease, excessive alcohol ingestion, and infections can also cause ED.


    Symptoms of erectile dysfunction are the inability to have an erection or inability to sustain an erection long enough to finish having sex. An occasional difficulty may be considered normal, however, frequent episodes or prolonged problems lasting more than a couple of weeks may require further evaluation by a physician.


    The diagnosis of erectile dysfunction is established through a detailed visit with your doctor that is designed to evaluate for all of the causes listed above. This can usually be accomplished through a series of questions and a detailed physical examination. Further tests may be necessary to look for some of the physical or medical causes of ED. Blood tests to measure blood sugar, kidney and liver function and hormone levels may be ordered. More specialized tests include an ultrasound of the genital area to view it’s blood vessel anatomy and measure the blood flow characteristics of the area. This may involve scanning before and after an injection of a drug that creates an erection. Less commonly, more invasive tests may be used if vascular problems are suspected. Cavernosometry is a test that measures the pressure in the penile blood vessels and the sponge-like penile tissue. It assesses if blood flow to the area is adequate for forming an erection. Cavernosography involves the injection of radiographic dye into the penile blood system to see if there is an abnormal leakage of blood out of the sponge-like tissue that is preventing the proper accumulation of blood necessary to create an erection.


    Treatment of erectile dysfunction is tailored to each individual and depends upon the cause. Psychological causes may be treated with therapy or medication, and proper treatment can result in improved sexual function. A six to twelve week course of sex therapy has been useful in such cases as well.

    Various medications can be used to improve penile blood flow and allow for an erection. A relatively new class of drugs, called PDE5 inhibitors, create increased blood flow by enhancing the levels of nitric oxide in the blood vessels in the penis. The first drug of this new class, Viagra, has received widespread attention and use. More recently, a new drug in this class, Levitra, was approved which functions using the same mechanism. Both drugs require sexual arousal in order to work. Viagra should be taken on an empty stomach 30 to 60 minutes prior to the desired time of effect. Levitra can be taken, with or without an empty stomach, 30 to 60 minutes prior to sex. About 60 to 70% of men who take the drugs experience longer and more rigid erections. Side effects for both drugs include headaches, flushing, indigestion, dizziness, and stuffy or runny nose. Both drugs may rarely cause blue-tinged vision and diarrhea. Neither drug should be used by patients taking nitrates, such as nitroglycerine, or in patients with recent heart attack or stroke. Neither drug should be taken more than once every 24 hours.

    For patients that do not respond to PDE5 inhibitors, medications can be injected directly into the penis. Such drugs include alprostadil, papaverine and phentolamine.

    Devices such as vacuum devices or penile implants may also be recommended by your doctor depending upon the specific cause of ED or your medical condition.


    What is the cause of my erectile dysfunction?

    Do I need to have any tests performed to determine or confirm my diagnosis?

    How serious is it?

    What type of treatment will you be recommending?

    Will you be prescribing any medication?

    Can any of my current medications interact with this new medication?

    What are the side effects?

    How successful is this treatment?

    Should a specialist be consulted?