Impotence
From Encyclopedia of Sex and Sexuality
In recent years our understanding of how men’s erections develop has improved tremendously and has helped physicians to understand how the process can fail. We now recognize that most cases of impotence are a result of physical problems, and the condition is no longer a taboo topic. There are many reasonable options of treatment, allowing people to regain a more satisfying sex life.
An erection develops in the following way. Normal levels of the male sex hormone testosterone create the libido, or sex drive, that encourages sexual stimulation. Stimulation, whether by touch, vision, or thought, causes the blood vessels leading to the erectile chambers of the penis (corpus cavernosum) to dilate, thus increasing the flow of blood to the penis. This increased blood flow causes the erectile chambers to fill with blood. Subsequently, there is a natural and normal release of chemical substances that causes the muscle tissue within the penis to relax. This increases the space in the erectile chambers that can fill with blood. When the penis is not erect, blood flows in and out of it quite freely. However, during an erection the increased blood flow causes the erectile chambers to swell. The normal swelling or expansion of these chambers prevents the usual flow of blood out of the penis, creating a sustained erection. When sexual stimulation stops, the blood flow to the penis decreases, the muscles in the penis contract, and blood flows out of the erectile chambers through the “holes or veins” (called subtunical venules) leading out of these chambers and that were compressed by the increased blood flow.
Any abnormality in this process can cause problems with erections. There can be vascular problems, such as decreased blood flow into the penis, abnormal relaxation of the muscles within the penis, and/or increased blood flow out of the penis. Conditions that increase the likelihood of such problems are similar to the factors affecting circulation to other parts of the body: high blood pressure, heart disease, smoking, high cholesterol, diabetes, trauma (to the penis or pelvis), and radiation injury.
Injuries of the nerves leading to the penis can also cause problems with erections. Conditions such as spinal cord injury, multiple sclerosis, diabetes, severe alcoholism, or surgery in the penile or pelvic area (such as radical prostate, bladder, rectal, or colon surgery) can cause nerve-related impotence. Male hormones are responsible for creating the normal male libido, or sex drive. The absence or low levels of these hormones can be caused by medications or by high levels of other circulating hormones, such as prolactin from a tumor of the pituitary gland. Certain medical conditions can lower hormone levels, too. If an erection problem is the result of a hormone imbalance, it is usually associated with a decreased sex drive and can be treated with replacement hormones.
[edit] Treatments for Impotence
Urologists are well-trained in the diagnosis and treatment of impotence. At present, the two most successful treatments for impotence are injection therapy and the implantation of a penile prosthesis. However, these treatments are reserved for patients whose cause of impotence cannot be reversed by, for example, treating high blood pressure or a hormone imbalance.
A major breakthrough in the treatment of erection problems occurred in the 1970s with the development of a functionally reliable penile prosthesis. The idea of using a substitute for the erectile chambers was first described in 1936, when cartilage was used for this purpose. Penile prostheses are now made of inert materials.
Penile prostheses or implants are either hydraulic or non-hydraulic. Non-hydraulic prostheses were developed first and are rigid or semi-rigid rods that are surgically placed within the erectile chambers. These are easy to insert, have few mechanical failures, a low complication rate, and a high degree of patient satisfaction. However, although the implanted penis can be positioned downward when sex is not occurring, it stays rigid at all times, and this can be embarrassing.
Hydraulic penile prostheses were developed to produce a more natural appearing penis in both the flaccid and erect states. This implant has three parts: cylinders placed inside the erectile chambers; a pump placed in the scrotum; and the reservoir placed behind the abdominal muscles. When the penis is in the flaccid (non-erect) state, fluid sits in the reservoir and the cylinders are empty, giving the penis a relatively normal appearance. When an erection is desired, fluid is transferred from the reservoir into the cylinders. The patient can do this manually by activating the pump mechanism that has been surgically implanted in the scrotum. Patient satisfaction is highest with this type of implant but the mechanical failure rate is higher.
The penile prosthesis is a very effective form of treating otherwise intractable impotence. Advantages include its relative simplicity, a minimal loss of spontaneity, and overall reliability. However, placement of a penile implant does involve surgery which usually requires a hospital stay. If infection occurs, the device is almost always removed as part of the treatment of the infection. Despite overall satisfaction, penile length and girth with a prosthesis are not always as good as with prior erections. Pre-operative counseling leads to more realistic expectations. Unlike silicon breast implants, no problems have been reported to date with penile implants.
The development of penile self-injection therapy has been the major breakthrough in the treatment of impotence in the 1980s. This involves the injection of medications with a small needle directly through the skin at the base of the penis and into the erectile chambers. The medications relax the muscles within the penis. This treatment works best in patients with injury to the nerves of the penis, but it is also effective in other situations. The medications have been used in the United States for many years, although they are not approved by the government for such use. Nevertheless, self-injection has become a very common and successful treatment of impotence in this country and overseas.
A relatively painless injection results in an erection after about ten to fifteen minutes and lasts from thirty minutes to one hour. Of all the treatment options, this provides the most natural erection. Patients learn the technique of self-injection at a urologist’s office, where the correct dose of the medicine is determined. Short-term side effects are relatively few but include rare liver problems, scarring at the injection site, and potentially the most serious: priapistic erections, sustained, painful erections that can only be relieved by medication. Though extremely rare, priapistic erections must be treated promptly.
Another treatment option for patients with erection problems is the vacuum constriction device. To obtain an erection with this device, a hand-held pump is placed over the end of the penis and air is sucked out, creating a vacuum and causing blood to flow into the penis. The vacuum device is removed, but a constriction ring is left in place, impeding the outflow of blood and maintaining the erection. During intercourse, the rubber ring is kept in place. This treatment is noninvasive and does not require surgery, but some find the device difficult to use because of decreased spontaneity, mild bruising, difficulty with ejaculation, and a lower quality erection. These problems have precluded its more widespread use.
Reconstructive bypass blood vessel surgery has also been used to treat impotence, but it is successful only in specific cases. Overall, the diagnosis and treatment of erection problems have improved significantly during the last ten to fifteen years. Almost all erection problems can be successfully treated in some fashion.
[edit] Male Sleep Disorders Centers and the Evaluation of Impotence
Sleep disorders centers play a new and innovative role in evaluating patients for medical, neurologic, and psychiatric causes of sexual dysfunction. These centers and their laboratories can provide valuable information to help determine if a patient’s sexual response problem is “organic” or “psychological.” In this context, “organic” means due to a medical disorder such as diabetes or high blood pressure; “psychological” indicates a cause such as depression or a personality disorder.
A male patient coming to a sleep center with a complaint of impotence (medically, an erectile dysfunction) first undergoes a medical and neurologic evaluation for any physical disease. If no obvious cause of the erectile dysfunction is found, the center will try to determine if the problem is organic or psychological. One way to answer this question is to determine if there are any circumstances under which erection is possible. The key to the center’s work is a phenomenon called “nocturnal penile tumescence” (NPT). Sleep occurs in several stages, and the last, called REM (Rapid Eye Movement) sleep, is the stage during which most dreams occur. During this stage, normal men and boys have penile erections. These erections occur reliably during REM sleep, whether the man is dreaming or not and whether the dream is sexual or otherwise in content.
When NPT was first discovered, it was thought it would be a perfect way to evaluate impotence. If a man could have an erection while he slept, researchers theorized, he was physically capable of erections and any problem was psychological. If he did not have erections when he slept, then the problem was physical or organic. Unfortunately, things are not so simple. Medical, psychiatric, and technical problems may prevent erections in a man with a primarily psychiatric problem and allow erections to occur in one with a primarily physical one. However, if the manifestations of NPT are interpreted by a qualified physician or therapist in the context of an appropriate evaluation, NPT can still be valuable in determining the cause of impotence.
There are several means of evaluating NPT. The simplest is to ask the patient if he ever wakes up with an erection. Since we frequently wake up from REM sleep, most men, at least occasionally, will wake with an erection. It is important for the physician to ask this specific question because many men do not associate these erections with sex and may not recall waking up with them.
One of the oldest methods is the stamp test. In this simple test, the patient goes to sleep with a ring of postage stamps around the penis. In theory, if the ring of stamps is broken in the morning, then NPT has occurred, but this test is fraught with problems. The stamps used will vary in the strength of attachment, glue, perforation, and size, and all these factors will affect the size of the erection needed to snap them. Furthermore, movement by the patient at night can break the ring in a man who did not experience NPT or cause it to slide off intact in a man who did experience NPT.
One way to avoid these problems is a device called the snap gauge. This consists of three plastic layers and Velcro connectors that attach around the penis. The bands are designed to break at 10, 15, and 20 ounces of pressure. Thus an attempt to quantitatively measure the pressure of the erection is made. If all the bands are broken during the night, it is likely that a full, firm erection has occurred. If no bands are broken, the capacity for erection is impaired. However, this method still has major limitations. Unless the patient’s sleep is professionally monitored, there is no way to know if the crucial stage of REM sleep occurred during the night.
While there is no “gold standard” for measuring NPT, the best is probably sleep laboratory evaluation. This provides a fairly uniform and objective environment for the study. The disadvantage is that the environment is unfamiliar to the patient and the studies can be expensive. The exact procedures of each sleep laboratory vary, but almost all incorporate the following features: the patient sleeps in the laboratory with monitoring devices called electrodes pasted to the head and legs to measure brain wave and sleep stage activity; elastic belts are placed around the chest to monitor breathing; and strain gauges are fitted around the penis at the base and under the glans (the dome) of the penis to monitor its circumference. The entire procedure is carefully explained to the patient before the study begins. The patient then sleeps in the laboratory for one or more nights and various characteristics of the erections that might occur, such as size and duration, are measured.
An alternative means of measuring rigidity is with a device called the rigiscan. This instrument places loops around the penis that automatically tighten at fixed intervals of time and monitor characteristics of the erections similar to those described above. The rigiscan can be irritating and uncomfortable to wear but it has the advantage of adaptability for home use. The patient is instructed in the use of the device and places it on the penis at home at bedtime. This is an inexpensive and convenient way of doing the test, but great caution must be taken in interpreting the results, because it relies on the technical skills of the patient and because there is no means of determining whether sleep, especially REM sleep, was adequate.
A device called the plethysmograph, which can monitor blood flow, and a technique called ultrasound doppler scanning, which measures blood velocity in the blood vessels, have also been used to measure penile erectile function. More research and clinical experience is needed to determine the role of these methods.
The evaluation of sexual function in women has lagged behind that in men. This is partly due to social and cultural factors, but it is also due to the mechanical difficulties of studying physiological sexual responses in women. Nevertheless, it is known that vaginal and clitoral blood flow and temperature changes do occur as part of a sexual response. Several devices have been developed to measure these variables. One of the more promising instruments is the “light reflectance vaginal photoplethysmograph.” This device measures vaginal pulse amplitude and contraction pressure. One type is constructed of clear plastic with a head and base separated by a steel rod, which forms a central space enclosed by a flexible, clear, rubber membrane. Although the device can be placed in the vagina by the woman herself, the wires and attachments must be placed by an experienced technician. This device should be able to measure the sexual response of women in the same way that the NPT procedure does in men. However, much more experience is needed in this area and clinical sleep laboratories do not generally offer such testing at this time.
Sleep disorders centers can serve as a valuable adjunct in the evaluation of sexual dysfunction in both men and women. Some of the equipment can also be adapted for home use, but the tests must still be supervised and interpreted by qualified professionals.
