Health Topics: Erectile Dysfunction

Impotence, which is more commonly now called erectile dysfunction (ED), is a very common problem with significant medial and psychosocial implications. It is estimated that almost 1 in 2 men between 40 and 70 years of age suffer from some degree of ED. This extrapolates to some 30 million men in the U.S. alone and 100 million men worldwide who have this problem. When complete ED is looked at--that is, the absolute inability to achieve penetration--5% of men at 40 years of age and 25% of men at 75 years of age suffer this degree of ED.

Men with ED often suffer from a loss of self-esteem and self-confidence, and it may have a huge detrimental impact upon their relationships, both physical and emotional. What is not well appreciated is the link between ED and other medical conditions. ED may be the first sign of other significant medical conditions such as diabetes, lumbar disc disease, multiple sclerosis, abdominal aortic aneurysm and potentially coronary artery disease (heart attack).

How do erections occur?

Erection is a hydraulic event. Simply stated, it involves the inflow of blood into the erectile body (corpus cavernosum) followed by entrapment of this blood. Paired cylinders that run on the dorsum of the penis (the corpora cavernosa) contain the pressurized blood and form the rigid structure of the erect penis. Each cylinder is composed of a tough outer lining (tunica albuginea) which surrounds a centrally located spongy network of muscle (corporal sinusoids). Blood flows into these cylinders and causes rigidity when it is trapped and high pressure develops. After ejaculation/orgasm the blood drains out of the cylinders through veins present between the erectile tissue and the tunica.

The key event in the development of an erection is relaxation of the smooth muscle inside the erectile cylinder. This event is primarily mediated by the chemical (neurotransmitter) nitric oxide (NO). Blood flows in to fill the relaxing muscle, the muscle mass expands and pressure increases typically reaching 200 (mm of mercury). Loss of rigidity is dependent upon the contraction of the muscle in the erectile bodies. As this muscle contracts, the size of the spaces shrink, allowing the drainage veins to open, which results in loss of rigidity. This process is under adrenaline control.

What causes ED?

Atherosclerotic disease (hardening of the arteries) is the cause of approximately 40% of ED in men older than 50 years. The effect of cigarette smoking on the prevalence of ED has been evaluated in a survey of 4,462 male military veterans. After adjusting for age, race, marital status, vascular disease, psychiatric disease, hormonal factors and substance abuse, the risk of ED in a smoker is approximately 1.5 that of a non-smoker. Results of the Massachusetts Male Aging Study showed that the incidence of ED in men with treated heart disease was 21% for those who did not smoke versus 56% for smokers with treated heart disease. This indicates that cigarette smoking may cause ED through its serious threats on cardiovascular health rather than its immediate pharmacological effects.

In patients with diabetes mellitus, irrespective of type, the prevalence of ED is approximately 50% (range 20-75%), the incidence depending on the patient's age, duration of diabetes and severity of the disease. Chronic disease states associated with a high prevalence of ED include chronic renal (kidney) failure, hepatic (liver) failure, multiple sclerosis, Alzheimer's disease, sleep apnea and chronic obstructive pulmonary disease (like emphysema). Endocrine disorders such as low testosterone levels, hyper-prolactinaemia, hypothyroidism and hyperthyroidism may also result in ED, but are the cause in only a small proportion of cases in the overall population. Pelvic trauma, pelvic surgery (radical prostatectomy, radical cystectomy or abdominoperineal resection), and radiation therapy to the pelvic area are associated with ED. This can result from nervous and/or vascular injury. Direct trauma to the perineum (bicycle straddle injury) can cause vascular inflow problems to the penis and may lead to ED that may be amenable to arterial revascularization. Many medications and drugs, including certain blood pressure medications, cold medications, hormones, antidepressants, tranquilizers, alcohol, tobacco, and other so-called recreational drugs, are associated with ED.

ED is commonly classified as psychological or organic (physical). Psychological erectile dysfunction, which is most prevalent in younger men (up to 70% of ED in men under 35 years of age) accounts for approximately 10% of ED in men older than 50 years of age. Psychogenic erection usually stems from anxiety and inappropriate release of adrenaline at the time of attempted intercourse. It is characterized by a sudden onset, intermittent problems and normal night-time and morning erections. It is the predominant type of dysfunction in younger males.

There is, however, a significant number of younger men with physically-based ED. Organic ED can result from abnormalities in blood flow, nerves, hormones or structural components of the penis. Vascular alterations involve diminished inflow or failure to halt outflow (venous leak). Nerve dysfunction can be secondary to disease of the peripheral nerves (diabetes), pharmacologic effects of drugs on the central nervous system (CNS), or surgical injury to nerves (radical prostatectomy, abdominoperineal resection or radiation therapy). Scarring of the smooth muscle itself (associated with diabetes mellitus, radiation and disuse) is under investigation as a potential factor of ED.

How is the patient with ED evaluated?

A careful patient interview and physical examination is important prior to commencing any form of ED therapy. Disease states, medications, trauma and prior surgeries should be noted.

• Is there a history of any urologic problems? The patient's development as a young man should be documented.

• Was the onset of ED gradual or sudden?

• Does the patient understand the important terms?

• Does the patient have orgasmic dysfunction or premature ejaculation, versus ED?

• Does he have nocturnal and morning erections?

• Can he masturbate successfully?

• Has he had painful or curved erections?

• Is the patient in a stable relationship?

We commonly ask the patient to quantify his best erection in the last month (l00% rigid, 60% barely adequate for penetration, 40% engorged but too soft for penetration or 20% barely engorged).

A standardized questionnaire that is filled out by the patient prior to his appointment helps to gather this large amount of information. Patients with purely psychological ED should be identified and considered for counseling. Again, this diagnosis is made by the presence of normal nighttime and morning erections and normal masturbatory function. The absence of identifiable risk factors, however, does not exclude organic disease.

Precise definition of the cause of ED is possible with numerous vascular studies. These tests can identify patients with severe venous leak (who would be expected to fail drug therapy) or those with arterial blockages that can be bypassed. In the simplified approach to ED, this testing is reserved for young patients without risk factors, patients who fail to respond to therapy or patients with complicated histories or problems.

The most commonly used blood flow study is penile ultrasound. Another form of vascular test, known as DICC, is reserved for certain less common situations, especially in younger men and men with penile curvature. Other forms of vascular testing such as penile-brachial index (PBI) and plethysmography are now generally considered old-fashioned, are less accurate and have, therefore, fallen out of use.

Other forms of testing can be used to evaluate the psychological aspects of ED. The most commonly used one is called nocturnal penile tumescence testing (NPT). Done in the privacy of a patient's own bedroom, it is a small computer box with rings attached to it that are placed around the penis. The device is used to measure nighttime erections (number, hardness and duration). Further tests can be used to assess the neurological nature of a man's ED. In summary, the majority of men require little or no investigation. Certain groups of men with ED benefit from the aforementioned testing and therefore each patient is assessed individually and the decision regarding testing is made on a case-by-case basis.

Is it safe for a man with ED to resume sex?

The safety of continuing or resuming sexual activity is sometimes questioned in the older male, specifically those with heart disease. In the past, sex was often considered an event that could trigger a heart attack (known medically as a myocardial infarction or MI). Older patients and their physicians are often reluctant to discuss resumed or continued sexual activity because of its "dangers."

A recent study looked at 1,774 patients (Muller) who had suffered a heart attack and were looked at carefully. The risk of suffering a heart attack in the 2 hours following sexual activity compared to other times of the day was 2.5 times for healthy individuals, 2.1 times for those with a history of prior chest pain and 2.9 times for those with prior heart attack, the study found. Regular exercise was shown to have some protective effect.

The hourly risk of suffering an MI in general is 1 in a million for a 50-year-old non-smoking, non-diabetic male (information derived from the Framingham Heart Study). Given one episode of sex per week, it has been concluded that the annual risk of MI would be expected to increase from 1% to only 1.0l%.

In another recent study (Drory), 88 patients with known coronary artery disease underwent exercise stress tests as well as home cardiac (Holter) monitoring during sex. One third of the men had decreased coronary artery blood flow during sexual activity. All of those patients who experienced coronary blood flow reduction during sex had previously had an abnormal cardiac stress test. No patient who had a prior normal stress test developed a decrease in coronary blood flow during sex.

In summary, sexual activity carries a low risk for patients with a normal cardiac stress test. Not all patients with ED require stress testing, however. Indeed, asking a patient if he can briskly climb two flights of stairs is a reasonable substitute for most men. All patients seen in our clinic are asked this question. If they answer yes, they are deemed to have enough exercise reserve to be able to pursue exertional activity such as sexual relations.

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