IMPOTENCE
Posted by admin on August 24th, 2010Etiology 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, ?-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.
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