What Causes Sexual Impotence ?


We may classify the causes of impotence, or erectile dysfunction, into two major groups:

Psychological Causes

There are many reasons for a purely psychological, or non-organic cause for impotence. It may start abruptly, usually after a major psychological trauma. Or, it may install itself gradually as a result of depression, anxiety and chronic stress. In addition, in many mental disorders, sexual libido and potency may be affected.

On the other hand, there is a very common situation, which affects at least once all adult men, particularly those involved in casual sexual relationships, which is called "performance anxiety", or fear of failure. Many societies expect from men an aggressive sexual role, and consider that the failure to perform is shameful. Thus, a man's self-esteem may be hurt by occasional impotence and this may lead to anxiety and inhibition of sexual reflexes.

Occasional failure to perform is also found in many other situations. They may be, for instance, a simple lack of rapport with the sexual partner, marital discord (such as after a fight) the presence of disturbing elements in the environment, such as noise or light, a temporary decrease in sexual libido, due to fatigue or worries, or the fear of being caught in an illicit relationship.

One important question made by physicians to determine the cause of impotence, is whether the patient often awakes with an erection. "Morning" erections are physiological, and are related to blood supply mechanisms during sleep, and not the sexual arousal. The presence of these erections usually mean that no organic disorder is the main cause. Using a ring of postage stamps glued around the flaccid penis during the night is also a simple device to ascertain whether erections occur in the sleep (a broken ring in the morning is the proof).

However, psychological factors are also present when the cause of impotence is a purely organic one. The inability to achieve erection in these cases increase anxiety and the fear of not performing.

Physical Causes

There are many physical causes for temporary or chronic impotence, which can range from the easily avoidable or curable, to very severe causes, which cannot be cured without radical, invasive measures, such as surgeries.

The following causes are well known and studied:


Peripheral Vascular Disease

This is by far the most common cause of erectile dysfunction, because is correlated with many systemic diseases which affect the blood vessels of the genital region, directly or indirectly. Chronic diseases such as diabetes mellitus, high cholesterol, high blood pressure, renal failure, heart disease, and others, are very common and lead to the destruction of the contractile walls of the veins or provoke hardening, narrowing or blockages of the arteries leading to the penis. As it is explained in the section "Erection Process in Man", in the current issue of Brain & Mind, erection of the penis takes place when blood, carried by the supply arteries of the penis, engorge erectile bodies made of spongeous tissue. Any failure in this filling mechanism, such as the narrowing of arteries by atherosclerotic plaques, may lead to an erectile insufficiency. Erection is maintained by a physiological closure of the outflow of the blood accumulated in the penis, via the venous vessels. Any failure in this mechanism (relaxation of the vascular system of the penis) result in less rigid erections or the inability to maintain them long enough to complete coitus.

Vascular insufficiency is perhaps the cause which correlates the best with age, explaining a lot of the increase in erectile dysfunction. Generally, impotence caused by vascular factors appear slowly over the months or years, first causing a decrease in the firmness of erections,and then becoming more intense.

The diagnostic approach to vascular disease is to investigate with an special ultrasound apparatus, called Doppler cavernosonogram, which is able to make a color picture of the bloodflow in the penis.

Medications and Drugs

More than 200 prescription and non-prescription medicines are known to affect erectile function in man. In fact, there are so many, and for so many conditions, that this should be one the leading causes of organic impotence. Some of these drugs promote impotence by acting on the central nervous system. Other affect the intensity of blood supply to the penis, or promote relaxation of the blood vessels. Among them are:

In addition, the abuse of substances, such as alcohol, tobacco, marijuana (cannabis), cocaine and others is a major cause of impotence, nowadays. It is ironic that many of these substances of abuse are considered aphrodysiacs, when taken in small amounts. In fact, a glass of wine during a romantic encounter, may "loose" inhibitions a little bit and decrease the "performance anxiety" or other psychological inhibiting factors we explained above. A mild anxiolytic may cause the same effect. Some smokers are calmed down by slowly enjoying a cigarette or a pipe. For some persons, the powerful rush of well being which accompanies the intake of cocaine, metamphetamines and other drugs, may act as a sexual excitant. However, chronic abuse and high dosages have the opposite effect. More than 80 % or chronic alcoholics suffer from chronic impotence. Scientific studies have shown that heavy smokers have important damage to their genital blood supply.

Neurological Damage

Nervous diseases or damage to the nerves which control the erection process are among the most common causes of impotence.

The tremendous increase in prostate cancer in the last decades is one of the major culprits. Prostate surgery damages the nerves in more than 80 % of the cases. Part of these patients recover sexual function, completely or partially, after a year or so, but the majority remains impotent for life. Radiation therapy of prostate cancer, although less damaging, has a effect on sexual potency too. Other pelvic surgeries may have a detrimental effect of erection.

Another significant cause of impotence is trauma to the groin. This is more common than we suppose, particularly in some sports. Recently, a group of researchers unveiled the fact that biking may be a major cause of impotence, because strong blows of the perineum (the triangle between the anus and the base of the scrotum) against the front bar are very damaging. It remains to be proved whether the constant, low intensity trauma caused by forcing the perineum against the seat could also be held responsible for erectile dysfunction.

Sone nervous diseases affect strongly the ability to achieve erection, because they act on the brain structures which are responsible for the central control of sexual drive and performance (see the article in this issue). These are: Parkinson's disease and other diseases of the motor system, stroke, multiple sclerosis, neurosyphilis, hypothalamo-hypophysiary disease, some tumors of the brain and of the pituitary gland, and epilepsy. Injuries to the spinal cord or nerves leading or coming from the genital area, of course, are also very common, such as in vertebral disc compression, and in traumatic injuries, such as in paraplegy or tetrapley, or in regional paralysis.

Structural Damage to the Penis

These are less common diseases, but, nonetheless they should be sought by the examining physician as a probable cause. Fibrosis of the penis tissues, caused by scarring or organic diseases, Peyronie's disease (which lead to an abnormal curving of the penis), the painful retraction of the penis' foreskin, genital herpes, cysts and tumors, are among the causes.


Hormonal Disorders

About 5 to 10 % of the male population suffers from some kind of hormonal disorder. The most common, which also correlates well with age, is a constant decrease in the levels of testosterone, the main sexual hormone of man. It is now well known why this decrease occurs, but it probably has something to do with a decrease in the capacity of the testicular cells to synthesize the hormone. This phenomenon has lead some specialists to pronounce that there is a kind of "menopause" for man, not so drastic as for women, which has been named "andropause". Although this is controversial, the undisputable fact remains that many metabolic precursors of testosterone (substances used by the body in the synthesis process), such as the DHEA (dihydroxiepiandrosterone), decrease significantly with age.

The decrease in testosterone has been associated with a decrease in sexual libido and performance, because the brain circuits and the penis tissues are dependent on this hormone's levels (however, a significant percentage of men with low testosterone levels maintain unaltered sexual performance). When low levels of testosterone affect the primary and secondary sexual characteristics in man (for instance, when the growth of beard is slowed down considerably, or there is loss of pelvic and breast hair, or there is an atrophy of the testes and penis, and an enlargement of the breasts, called gynecomastia), we say that there is a condition named hypogonadism (from gonads, or sexual glands). There are two types of hypogonadism:

The most common form of secondary hypogonadism is called hypogonadotrophic hypogonadism, because there is a demonstrable decrease in the levels of FSH (follicle-stimulating hormone), also called gonadotrophic hormone, which is a substance produced by the pituitary gland, located in the base of the brain,. Primary hypogonadism, in contrast, has normal or even increased levels of FSH.

Another condition which leads often to impotence is called hyperprolactinemia. This is an abnormal increase in the levels of a hormone produced also by the pituitary, called prolactin. In women, prolactine is responsible for stimulating the mammary glands to produce milk. Men usually have low levels of prolactine, but some conditions may increase it, such as a kind of benign brain tumor called prolactinoma.

In the diagnostic workup for organic impotence, the physicians usually order laboratory tests to evaluate the levels of testosterone, FSH and prolactine. Simultaneously low levels of testosterone and FSH mean a diagnosis of hypogonadotrophic hypogonadism. Hyperprolactinemia many times is associated with this condition.

From: Sexual Disorders. 1. Sexual Impotence

By: Renato M.E. Sabbatini, PhD and Silvia Helena Cardoso, PhD

In: Brain & Mind Magazine, August-November 1997