The role of the endothelium in erectile function became clearer with the observation that the phosphodiesterase type 5 (PDE5) inhibitor, sildenafil, enhanced erectile function. Erection occurs with the release of nitric oxide (NO) from the vascular endothelial cells.17 The reduction in endothelial cell production of NO results in the negative impact on the smooth muscles in the corporal bodies and results in less relaxation of the smooth muscle cells with decrease in blood supply and resulting ED. A similar phenomenon is well known to impact the coronary arterial system resulting in CVD.

Measurement of the penile vibration perception threshold provides an inexpensive, reproducible, and painless screening test with acceptable sensitivity for detecting neuropathy. Abnormalities at the level of the sacral cord can be documented by sacral latency testing, while upper motor neuron impotence can be demonstrated with genital-cerebral evoked response testing. These latter procedures are not indicated in unselected patients with impotence.
Penile erection is managed by two mechanisms: the reflex erection, which is achieved by directly touching the penile shaft, and the psychogenic erection, which is achieved by erotic or emotional stimuli. The former uses the peripheral nerves and the lower parts of the spinal cord, whereas the latter uses the limbic system of the brain. In both cases, an intact neural system is required for a successful and complete erection. Stimulation of the penile shaft by the nervous system leads to the secretion of nitric oxide (NO), which causes the relaxation of smooth muscles of corpora cavernosa (the main erectile tissue of penis), and subsequently penile erection. Additionally, adequate levels of testosterone (produced by the testes) and an intact pituitary gland are required for the development of a healthy erectile system. As can be understood from the mechanisms of a normal erection, impotence may develop due to hormonal deficiency, disorders of the neural system, lack of adequate penile blood supply or psychological problems.[17] Spinal cord injury causes sexual dysfunction including ED. Restriction of blood flow can arise from impaired endothelial function due to the usual causes associated with coronary artery disease, but can also be caused by prolonged exposure to bright light.
There are also alternative treatments, such as using a penis pump or a penile injection. Penis pumps work by creating a vacuum and thereby causing more blood to flow to your penis. Penile injections need to be used shortly before intercourse. They contain a medication which widens your blood vessels. A doctor’s prescription is needed for the injections.
The Latin term impotentia coeundi describes simple inability to insert the penis into the vagina; it is now mostly replaced by more precise terms, such as erectile dysfunction (ED). The study of erectile dysfunction within medicine is covered by andrology, a sub-field within urology. Research indicates that erectile dysfunction is common, and it is suggested that approximately 40% of males with erectile dysfunction or impotence, at least occasionally.[35] The condition is also on occasion called phallic impotence.[36] Its antonym or opposite condition is priapism.[37][38]
An approach to the diagnosis and management of the impotent patient is presented in Figure 187.1. Apparent and likely causes of impotence should be considered first and, if possible, eliminated before the work-up continues. For instance, observing the patient for a few weeks off offending medication may be all that is necessary to establish the cause of impotence. When no obvious or remediable cause is present, the next step is based on the clinical impression of the likelihood of organic versus psychologic impotence. If the latter is considered more likely, it is perfectly reasonable to refer the patient directly for sexual therapy, with the option of reconsidering the diagnosis if, after appropriate therapy, there is no improvement. While an occasional patient with organic impotence will be misrouted, many more with psychogenic impotence will be spared an unnecessary and costly evaluation for organic causes. When organic impotence is likely, a serum testosterone level is the initial screening test for hypogonadism and should be obtained prior to urologic referral. Patients with low testosterone levels require further endocrine evaluations as depicted in Figure 187.1.

An alprostadil cream that patients apply into the tip of the penis (the urethral meatus, the opening that urine passes through) is currently available in the UK and Europe. It is currently under review by the U.S. Food and Drug Administration (FDA). After application of the cream, an erection occurs within five to 30 minutes, and the erection lasts one to two hours in men who respond to the cream. Doctors recommend that one use the cream for a maximum frequency of two to three times per week and no more frequent than once every 24 hours. It has essentially the same contraindications and side effects as the other formulations of alprostadil. The cream may cause vaginal burning in roughly 4% of partners. Men should not use alprostadil cream for sexual intercourse with women of childbearing potential unless a condom is used. Researchers have performed controlled trial studies to evaluate the safety and effectiveness of this drug. Overall, 52% of men reported improvement in their erections compared to 20% of men receiving placebo. A later analysis demonstrated that 36% of men using the alprostadil cream had a clinically relevant improvement in vaginal penetration ability and 31% clinically relevant improvement in ability to have successful intercourse to ejaculation.
If surgical intervention is an acceptable option, the work-up then proceeds with a noctural penile tumescense (NPT) test, the single most valuable study to establish the diagnosis of organic impotence. The NPT test exploits the fact that males from birth to old age normally have erections during rapid eye movement (REM) sleep. Psychogenic impotence is associated with normal erections during sleep. In organic impotence there should be no evidence of erection or, if erections are present, they should be limited and poorly sustained.
Vardenafil and tadalafil belong to the same group of chemical compounds as sildenafil, namely phos-phodiesterase type 5 (PDE-5) inhibitors. Some men cannot benefit from sildenafil or the two newer PDE-5 inhibitors because they have low levels of nitric oxide. British investigators reported in late 2002 that three different types of compounds are being studied as possible medications for men with low levels of nitric oxide. They are Rho-kinase inhibitors, soluble guanylate cyclase activators, and nitric oxide-releasing PDE-5 inhibitors.
You should talk to your doctor about possible treatments. You may want to talk to other patients who have had the treatment planned for you. You also may want to seek a second doctor's opinion about surgery before making your decision. You may find it difficult to talk to your doctor about impotence. You will want to find a doctor who treats this condition and will help you feel comfortable talking about the problem and choosing the best treatment. You can also get more information by contacting your local National Kidney Foundation affiliate.

Erection dissatisfaction can actually enhance lovemaking. The dark cloud of erection changes has a silver lining. Young couples often have problems because young men become aroused faster than young women. Young men are often all finished before young women have even started to get aroused. Post-50 erection changes slow men’s arousal process so their erotic pace more closely matches women’s. A slower pace allows plenty time for kissing, cuddling, and whole-body massage, all essential to most women’s enjoyment of sex. Seen in this light, for many older couples, erection dissatisfaction can be a gift.
It is common for a healthy older man to still want sex and be able to have sex within appropriate limitations. Understanding what is normal in older age is important to avoid frustration and concern. Older men and their partners often value being able to continue sexual activity and there is no age where the man is ‘too old’ to think about getting help with his erection or other sexual problems.
Sildenafil (Viagra) was the first oral phosphodiesterase type 5 (PDE5) inhibitor approved by the FDA in the United States for the treatment of erectile dysfunction (it is not approved for women). Sildenafil inhibits PDE5, which is an enzyme that destroys cGMP. By inhibiting the destruction of cGMP by PDE5, sildenafil allows cGMP to accumulate. The cGMP in turn prolongs relaxation of the smooth muscle of the corpora cavernosa. Relaxation of the corpora cavernosa smooth muscle allows blood to flow into the penis resulting in increased engorgement of the penis. In short, sildenafil increases blood flow into the penis and decreases blood flow out of the penis.
All studies demonstrate a strong association with age, even when data are adjusted for the confounding effects of other risk factors. The independent association with aging suggests that vascular changes in the arteries and sinusoids of the corpora cavernosa, similar to those found elsewhere in the body, are contributing factors. Other risk factors associated with aging include depression, sleep apnea, and low HDL levels.

In many cases, diagnosing erectile dysfunction requires little more than a physical exam and a review of your symptoms. If your doctor suspects that an underlying health problem may be at play, however, he may request additional testing. Once you’ve determined the cause for your ED, you and your doctor can decide on a form of treatment – here are some of the options:


If you just got off solo, you might have to wait before you can hop into bed with your partner, says Dr. Brahmbhatt. It might have something to do with a spike in the hormone prolactin after you orgasm, according to a study published in the International Journal of Impotence Research. This hormone has been linked to difficulties maintaining an erection or even ejaculating.
Acetylcholine released by the parasympathetic nerves is thought to act primarily on endothelial cells to release a second nonadrenergic-noncholinergic carrier of the signal that relaxes the trabecular smooth muscle. Nitric oxide released by the endothelial cells, and possibly also of neural origin, is currently thought to be the leading of several candidates as this nonadrenergic-noncholinergic transmitter; but this has not yet been conclusively demonstrated to the exclusion of other potentially important substances (e.g., vasoactive intestinal polypeptide). The relaxing effect of nitric oxide on the trabecular smooth muscle may be mediated through its stimulation of guanylate cyclase and the production of cyclic guanosine monophosphate (cGMP), which would then function as a second messenger in this system.
Long-term predictions based on an aging population and an increase in risk factors (eg, hypertension, diabetes, vascular disease, pelvic and prostate surgery, benign prostatic hyperplasia, and lower urinary tract symptoms) suggest a large increase in the number of men with ED. In addition, the prevalence of ED is underestimated because physicians frequently do not question their patients about this disorder.
There are many alternative impotence treatments available but many of them are neither licensed nor legitimate, Beware of sellers offering “herbal” impotence treatments - these remedies do not work and are often sold illegally. You should also be wary of online sellers who offer Viagra and other prescription drugs without asking you for a prescription. Illegal pharmacies often sell counterfeit or fake medication and buying from them could put your health at risk.

The main medical causes of erectile dysfunction are based around poor blood flow (due to furring of the arteries thanks to raised cholesterol or high blood pressure), poor nerve supply caused by diabetes-related nerve damage, or low testosterone as a result of obesity, old age or failing gonads. We doctors get just as concerned with men who have variable erections as well as those that can't get an erection at all. Failing to get an erection occasionally is pretty normal as you get older. But if you have unreliable erections for a prolonged period of time – more than six months – this could suggest an early sign of physical problems such as cardiovascular disease or diabetes which could develop further so get yourself checked out.
Aging: There are two reasons why older men are more likely to experience erectile dysfunction than younger men. First, older men are more likely to develop diseases (such as heart attacks, angina, cardiovascular disease, strokes, diabetes mellitus, and high blood pressure) that are associated with erectile dysfunction. Second, the aging process alone can cause erectile dysfunction in some men by causing changes in the muscle and tissue within the penis.
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional medical advice, diagnosis or treatment and should not be relied on to make decisions about your health. Never ignore professional medical advice in seeking treatment because of something you have read on the WebMD Site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
×