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Erectile Dysfunction

Overview

Erectile dysfunction, also called sexual dysfunction or impotence, is one of the most common health problems affecting men and is more common with increasing age. It is estimated that chronic ED affects about 5% of men in their 40s and 15-25% of men by the age of 65. And about 50% of men between the ages of 40 and 70 suffer from transient ED and inadequate erection.

Erectile dysfunction is the inability to get or keep an erection suitable for sexual intercourse. ED can be a total inability to achieve erection, an inconsistent ability to do so, or a tendency to sustain only brief erections. This is not an illness of its own, but rather a result of another medical problem.

Causes & Risk factors

Although some men may think that sexual dysfunction is "all in their head", actually there are various physical and psychological factors that can provoke it.

The development of successful erection is a complex event and requires a healthy brain; healthy endocrine, vascular and circulatory systems; functional nerves, arteries, and veins; and certain hormones. Therefore, ED can be caused a by a fail in any one of these systems.

There are many underlying physical and psychological causes of erectile dysfunction. Most men with physical causes usually have an associated psychological component. Various diseases may affect erectile function by altering the nervous, vascular, or hormonal systems or by influencing the patient's psychologic mood and behavior. Reduced blood flow to the penis and nerve damage are the most common physical causes.

Physical conditions

Problems with the nervous system can affect the transmission of signals from the brain to the blood vessels in the penis. This occurs in conditions including multiple sclerosis, spinal cord injury and Parkinson's disease. The nerves involved in sexual arousal can also be damaged in surgery to the pelvic area, such as removal of the prostate. In a small number of cases, problems with hormone levels, can also affect erection.

  • Vascular diseases, those that affect the blood vessels, account for nearly half of all cases of erectile dysfunction in men older than 50 years.
    • Atherosclerosis - fatty deposits on the walls of the arteries lead to narrowing of blood vessels and can prevent adequate blood supply to the penis.
    • Veno-occlusive disease (venous leak) - problems with keeping the blood within the penis during an erection.
    • Peripheral vascular disease - a circulation disorder that affects blood vessels that supply the blood to the areas of the body away from the heart, such as the legs, feet and genitals.
    • High blood pressure over time damages the lining of the arteries and accelerates the development of atherosclerosis.
    • Heart disease (coronary artery disease) is often caused by atherosclerosis. Men with erectile dysfunction are 80% more likely to develop heart disease3.
    • Blood vessel trauma.
    • High cholesterol levels contribute to atherosclerosis, raising the risk of sexual dysfunction.
  • Systemic diseases:
    • About 60% of men with diabetes mellitus experience erectile dysfunction. Chronic high levels of blood sugar associated with diabetes often damage small blood vessels and nerves throughout the body, which can impair nerve impulses and blood flow necessary for erection.
    • Scleroderma - a rare autoimmune disease in which the skin and connective tissues tighten and harden. About one third of men with scleroderma experience ED.
    • Kidney disease can affect hormones, circulation, and energy level.
    • Liver cirrhosis
    • Hemochromatosis (too much iron in the blood) in this condition the excess iron gradually builds up and causes the damage to the organs.
    • Dyslipidemia, a disorder of lipoprotein metabolism.
    • Obesity is a significant risk factor for many cardiovascular conditions.
  • Neurologic diseases. Problems with the nervous system can affect the transmission of signals from the brain to the blood vessels in the penis. Diseases that affect the nervous system and are commonly associated with erectile dysfunction include:
    • Multiple sclerosis
    • Spinal cord and brain injuries (paraplegia, stroke)
    • Parkinson's disease
    • Alzheimer's disease
    • Epilepsy
    • Guillain-Barre syndrome
  • Respiratory disease associated with erectile dysfunction include:
    • Chronic obstructive pulmonary disease
    • Sleep apnea
  • Conditions of the penis:
    • Peyronie's disease (a rare inflammatory condition that causes scarring of erectile tissue)
    • Epispadias
    • Priapism
    • Infections, including sexually transmitted diseases may also lead to erectile problems.

Traumatic Causes

Trauma or injury to the penis, spinal cord, prostate, bladder, and pelvis can lead to erectile dysfunction by harming nerves, smooth muscles, arteries, and fibrous tissues of the corpora cavernosa. Injuries to the penis may also result in scar tissue formation as well as penis curvature during an erection. Bicycle riding for long periods has also been implicated as a cause of erectile dysfunction.

Some types of prostate or bladder surgery. Surgery of the colon, prostate, bladder, or rectum may damage the nerves and blood vessels involved in erection.

Medications

A great variety of medication are known to cause or contribute to erectile dysfunction:

  • antihypertensives (especially beta-blockers)
  • digoxin
  • antihistamines
  • antidepressants
  • tranquilizers
  • antipsychotics
  • anticonvulsants
  • appetite suppressants
  • cimetidine

Psychological conditions

The brain is the most sensitive "sex organ" and greatly influences the ability to get and maintain erections. Anxiety and guilt are the most common psychological causes of erectile dysfunction. Depression, worry, stress, low self-esteem, and fear of sexual failure all contribute to loss of libido and impotence. One episode of failure, regardless of cause, may propagate further psychological distress leading to further erectile failure.

Psychological factors in impotence are often secondary to physical causes, and they magnify their significance. Experts believe that psychological factors cause 10 to 20% of ED cases.

Substance abuse

Chronic use of alcohol, tobacco, marijuana and substance abuse often causes erectile dysfunction and decreased sexual drive.

  • Alcoholism. Drinking too much alcohol commonly affects the ability to get and maintain an erection. It interferes with the production of the male hormone testosterone, which can reduce libido.
  • Smoking. Prolonged tobacco use (smoking) is considered an important risk factor for erectile dysfunction because it is associated with poor blood circulation and its impact on cavernosal function. Now medical experts believe that ED may be a symptom of silent vascular disease in exsmokers2.

Hormone Disorders account for fewer than 5% of cases of erectile dysfunction. Hormonal abnormalities such as hyperthyroidism (overactive thyroid gland), hypothyroidism (underactive thyroid gland), hypogonadism (leads to lower testosterone levels), increased prolactin (a hormone produced by the anterior pituitary gland), steroid abuse by body-builders may cause impotence. Rarely is low testosterone alone responsible for poor erections. Testosterone stimulates desire, but is believed to have little effect on erections.

Age

All studies demonstrate a strong association with age, even when data are adjusted for the confounding effects of other risk factors. Erection problems tend to become more common with age, but they can affect men at any age and at any time in their lives. Physical causes are more common in older men, while psychological causes are more common in younger men.

Treatment options

In around 95% of the cases, a suitable treatment can be found. Erectile dysfunction is treatable at any age, and awareness of this fact has been growing. More men have been seeking help and returning to normal sexual activity because of improved, successful treatments.

PDE-5 inhibitors

There are three phosphodiesterase (PDE) inhibitors approved for the treatment of erectile dysfunction: sildenafil (Viagra), vardenafil (Levitra), and tadalafil (Cialis). They vary in dosage, duration of effectiveness and possible side effects, but are generally well tolerated.

These agents block the enzyme phosphodiesterase-5 (PDE-5) which helps to maintain levels of cyclic guanosine monophosphate (GMP), a chemical produced in the penis during sexual arousal. Balanced levels of GMP causes the smooth muscles of the penis to relax and increases blood flow. This allows a natural sequence to occur - an erection in response to sexual stimulation. These medications don't automatically produce an erection. Instead they allow an erection to occur after physical and psychological stimulation.

PDE-5 inhibitors, unless contraindicated, should be offered as a first-line therapy for erectile dysfunction. They are a good choice for men at any age and in any ethnic group who are in good health and who do not have conditions that preclude taking them (such as the use of nitrates or alpha-blockers). The success rates of all three vary between 70% and 90%.

References

  • 1. Erectile Dysfunction. National kidney and urologic diseases information clearinghouse.
  • 2. Shiri R, Häkkinen J, Koskimäki J, Tammela TL, Auvinen A, Hakama M. Smoking causes erectile dysfunction through vascular disease. Urology. 2006 Dec;68(6):1318-22. PubMed
  • 3. Araujo AB, Hall SA, Ganz P, Chiu GR, Rosen RC, Kupelian V, Travison TG, McKinlay JB. Does erectile dysfunction contribute to cardiovascular disease risk prediction beyond the Framingham risk score? J Am Coll Cardiol. 2010 Jan 26;55(4):350-6.

Last updated: March 2012