Impotence
posted in Sexuality, Male Hypogonadism and Impotence |Etiology and Pathogenesis
Impotence increases progressively in frequency with age. About 25% of 65-yr-old men and 50% of 80-yr-old men are impotent. Impotence can be caused by vascular, neurologic, and endocrine disorders and by structural abnormalities of the penis. Drugs also cause impotence in the elderly.
Vascular disorders that can affect sexual function include atherosclerosis and venous leakage. Any occlusion of the arterial supply to the corpora cavernosa—such as from atherosclerosis, a clot (as in Leriche’s syndrome), or vascular surgery (eg, aoitoiliac bypass surgery)—that results in inadequate arterial pressure to the penis can lead to impotence. Venous leakage, in which inadequate compression of the venous drainage of the corpora cavernosa results in excessive venous outflow, occurs in 75% of impotent men with normal neurologic and hormonal function.
Neurologic causes of impotence include trauma, diabetes, multiple sclerosis, and toxins. Trauma to the nerves of the penis can occur from lumbar disk disease and from surgical procedures such as rectal surgery and prostatectomy. Diabetic neuropathy is a particularly common cause of impotence in the elderly. Alcoholism can produce a similar peripheral neuropathy.
Endocrine causes of impotence are relatively rare in the elcierly. However, testicular failure as a result of childhood exposure to mumps, Klinefelter”s syndrome, radiation and chemotherapy, pituitary and adrenal tumors, and other conditions (see TABLE 69-1) can cause extremely low testosterone levels and impotence.
Structural abnormalities of the penis are not common causes of impotence in the elderly. Peyronie’s disease, which is more common in younger men, is characterized by fibrous accumulation in the tunica albuginea, which leads to a deformed erection. Although not technically impotence, the deformed erection may not allow penetration.
Drugs cause an estimated 25% of cases of erectile dysfunction (see TABLE 69-2). Among the most common offenders are some antihypertensives (most notably reserpine, β-blockers, guanethidine, and methyldopa), alcohol, cimetidine, antipsychotics, antidepressants, lithium, sedative-hypnotics, and hormones.
Psychologic causes are less common than organic causes and account for a smaller proportion of impotence cases in the elderly than in younger men. The misperception that prostate surgery will result in impotence may actually cause psychogenic impotence, which may be prevented by thorough explanations both before and after the surgery. Depression can lead to impotence in the elderly, as in younger men, and older men can also experience performance anxiety, especially when having sexual intercourse with a new partner.
Diagnosis
Elderly men today are more likely than past generations to seek help for impotence, and physicians should make them feel comfortable discussing the problem. A comfortable environment can be eslablished by
explaining that impotence is a common problem and by reassuring the patient that treatment is often effective. In private, the patient should be asked if he would like to discuss the matter alone or have his sexual partner present.
History: Before beginning the physical examination, the physician should be relatively certain whether the problem is erectile dysfunction or some other sexual dysfunction. History begins by establishing whether libido is intact and if nocturnal or morning erections occur. A history of changes in secondary sex characteristics or of vascular, pelvic, rectal, or prostate surgery may give clues to the cause. Depression, anxiety, and stress must also be sought, and the physician should learn about changes in sexual partners or problems with relationships. A review of all medication use, including alcohol and over-the-counter and illicit drugs, is essential.
Physical examination: The physical examination is usually less revealing than the history, but it helps detect signs of severe hypogonadism, such as small, soft testes, loss of pubic hair, and gynecomastia.
The bulbocavernous reflex helps establish the normalcy of the peripheral nerves innervating the pelvis. Measuring penile arterial pressure is not generally useful, although measuring pressures in the legs may help establish whether the patient has peripheral arterial disease.
Laboratory evaluation: Laboratory tests generally include obtaining a tree (or total) testosterone level. Other tests for the common diseases that can lead to impotence should be ordered, such as CBC count fasting blood sugar, and thyroid-stimulating hormone (TSH) level. A nocturnal penile tumescence measurement is useful if the occurrence of spontaneous erections cannot be ascertained. The simplest and least expensive test uses a ring of postage stamps placed around the penis at night: if the perforations are broken in the morning, an erection has occurred. More sensitive and reliable measurements can be made at home using a portable computerized unit.
While several tests are available to assess the penile vascular system, duplex ultrasonography with intracorporeal injections of vasoactive agents is generally the best. A papaverine-phentolamine combination is injected into the corpus cavernosum. Because the drugs are arterial vasodilators, an erection should occur; if erection occurs, such injections could possibly be used therapeutically (see below). Failure to produce an erection indicates venous leakage.
Treatment
Erectile dysfunction can usually be treated successfully, often without surgery. Determining the cause of impotence helps in choosing the initial treatment.
Men whose impotence is the result of psychosocial problems may benefit from psychologic counseling. Even those with primary erectile dysfunction may need psychologic counseling, and it often helps to have the patient’s partner involved. Referral to experts in treating sexual disorders may be helpful when explanations and reassurance are inadequate.
Several drugs may ameliorate impotence, although none is remarkably effective. Yohimbine, an (^-adrenergic blocker taken orally at 5 4 mg tid, appears to help a small proportion of men, especially those with vascular causes. Testosterone replacement therapy benefits only those whose impotence is due to hypogonadism (see above).
Binding and vacuum tumescence devices are often useful for obtaining and maintaining erections, but men who are taking anticoagulants or who have low platelet levels or bleeding disorders should not use these devices. Binding devices, which slow venous outflow at the base of the penis, used alone often help those with mild impotence The devices are made of metal, rubber, or leather with snaps and can be purchased from medical supply houses or pharmacies (see FlG. 69-1)
However, they can also be purchased less expensively at stores selling sexual paraphernalia, where they are known as “cock rings.” The vacuum devices improve on the binder device by increasing arterial engorgement through vacuum assistance (see FIG, 69-2). A plastic cylinder vacuum device is fitted over the unerect penis, and a gentle vacuum is produced by sucking out air with a syringe, pump, or one’s mouth (via tubing). Once an erection occurs, a wide rubber binding band is applied at the base of the penis and the vacuum device is removed. The band retards venous return and helps sustain the erection for up to 30 niin. Binding devices can produce local discomfort and occasional difficulty with ejaculation, especially if too tight, anil vacuum devices can produce petechiae if used excessively. Long-term safety and effectiveness are being evaluated.
Self-injection of vasoactive compounds (intracavernous pharmacotherapy) directly into the corpus cavernosum before sexual activity can help produce an erection (see FIG. 69-3). Self-injection therapy is usually effective when vascular disease is mild to moderate but not when it is severe. Furthermore, self-injection is not acceptable to all patients. A papaverine-phentolamine combination is often used, although the drugs do not have FDA approval. Alprostadil (prostaglandin Ei) is another drug that is used for intracavernous pharmacotherapy. The three agents may be given together, but no advantage of combined therapy over monotherapy has been established. The optimum combination of drugs to maximize effect while minimizing side effects is still being studied.
After injection, the patient should immediately initiate foreplay. He can expect to experience an erection after 5 to 10 min, and under ideal conditions, the erection will last up to 60 min. Problems include priapism, hematomas due to subcutaneous instead of intracavernosal injection, and pain. An injection of dilute epinephrine (20 μg/20 mL saline) or phenylephrine (500 μg/mL saline) usually reverses the priapism.
Permanent penile prostheses or implants may benefit patients with impotence that does not respond to other treatments, especially chronic organic impotence caused by diabetes. A prosthesis produces an erection but cannot correct neurologic deficits that preclude normal sensation. Devices that produce a permanent erection include the Small Carrion semirigid rod prosthesis with a silicone sponge interior and the Flexi-rodII, a hinged modification of the Small Carrion device 1 hat allows the penis to be bent downward more easily when not being used for sexual activity. An inflatable (AMS 700 CX) prosthesis is also available. Contraindications to surgical implants include untreated depression, psychosis, severe personality disorder, and other severe psychiatric problems.
Penile revascularization surgery is still largely experimental. Surgery should be reserved for those with localized, identifiable lesions and performed only by highly skilled surgeons. Ligation of venous drainage is sometimes beneficial for those with impotence caused by venous leakage.
