A common and important cause of ED is vasculogenic. Many men with ED have comorbid conditions such as hyperlipidemia, hypercholesterolemia, tobacco abuse, diabetes mellitus, or coronary artery disease (CAD).  The Princeton III Consensus recommends screening men who present with ED for cardiovascular risk factors; ED may be the earliest presentation of atherosclerosis and vascular disease. 
Poor sleep patterns can be a contributing factor for erectile dysfunction, Mucher says. One review published in the journal Brain Research emphasized the intricate relationship between the level of sex hormones like testosterone, sexual function, and sleep, noting that testosterone levels increase with improved sleep, and lower levels are associated with sexual dysfunction. Hormone secretion is controlled by the body’s internal clock, and sleep patterns likely help the body determine when to release certain hormones.
On the horizon is gene therapy that would deliver genes that produce products or proteins that may not be functioning properly in the penile tissue of men with ED. Replacement of these proteins may result in improvement in erectile function. Experimental animal models have demonstrated improvement in erectile function with gene therapy. Human studies may also demonstrate success with this therapy. Gene therapy may take a long time for regulatory approval and public acceptance.
The most common inflatable prosthesis is the three-piece penile prosthesis. It is composed of paired cylinders, which doctors surgically insert inside the penis. Patients can expand the cylinders using pressurized fluid (see figure 3). Tubes connect the cylinders to a fluid reservoir and pump, which doctors also surgically implant. The reservoir is usually in the pelvis. A doctor places the pump in the scrotum. By pressing on the pump, sterile fluid transfers from the reservoir into the cylinders in the penis. An erection is produced primarily by expansion of the width of the penis, however, one model can increase in length a small amount also. Lock-out valves in the tubing prevent the fluid from leaving the cylinder until a release valve is pressed. By pressing the relief valve and gently squeezing the penis, the fluid within the cylinders transfers back into the reservoir.
It is important that all erectile dysfunction is reported to your doctor, as sometimes it can be an indicator of something physically wrong with you that has to be treated. Also, your doctor is in the best position to find the reason for your erectile dysfunction. Routine questions and tests will provide a guide to the cause and allow your doctor to decide what kind of treatment you might need to deal with it. This may involve referral to a specialist. Detailed information can be found at the website of the Impotence Association – www.sda.uk.net
One study examined the role of testosterone supplementation in hypogonadal men with ED. These men were considered nonresponders to sildenafil, and their erections were monitored by assessing nocturnal penile tumescence (NPT). After these men were given testosterone transdermally for 6 months, the number of NPTs increased, as did the maximum rigidity with sildenafil.  This study suggests that a certain level of testosterone may be necessary for PDE5 inhibitors to function properly.
In men of all ages, erectile failure may diminish willingness to initiate sexual relationships because of fear of inadequate sexual performance or rejection. Because males, especially older males, are particularly sensitive to the social support of intimate relationships, withdrawal from these relationships because of such fears may have a negative effect on their overall health.
The lab testing obtained for the evaluation of erectile dysfunction may vary with the information obtained on the health history, physical examination, and recent lab testing. A testosterone level is not necessary in all men; however, a physician will order labs to determine a patient's testosterone level if other signs and symptoms of hypogonadism (low testosterone) such as decreased libido, loss of body hair, muscle loss, breast enlargement, osteoporosis, infertility, and decreased penile/testicular size are present.
Effective treatment for erectile dysfunction is available, and for most men will allow the return to a fulfilling sex life. The side effects of the treatment for erectile dysfunction vary depending on the treatment that is used. Some may interrupt the spontaneity of sexual activity. For example, PDE-5 inhibitors typically need to be taken one hour before sex. Side effects may include headaches, indigestion, vasodilation, diarrhoea and blue tinge to vision. Other treatments such as penile injections may cause pain at the injection site, or an erection that will not go down. Treatment options need to be carefully discussed with your doctor to determine which one is best suited to you.
The appropriate evaluation of all men with erectile dysfunction should include a medical and detailed sexual history (including practices and techniques), a physical examination, a psycho-social evaluation, and basic laboratory studies. When available, a multidisciplinary approach to this evaluation may be desirable. In selected patients, further physiologic or invasive studies may be indicated. A sensitive sexual history, including expectations and motivations, should be obtained from the patient (and sexual partner whenever possible) in an interview conducted by an interested physician or another specially trained professional. A written patient questionnaire may be helpful but is not a substitute for the interview. The sexual history is needed to accurately define the patient's specific complaint and to distinguish between true erectile dysfunction, changes in sexual desire, and orgasmic or ejaculatory disturbances. The patient should be asked specifically about perceptions of his erectile dysfunction, including the nature of onset, frequency, quality, and duration of erections; the presence of nocturnal or morning erections; and his ability to achieve sexual satisfaction. Psychosocial factors related to erectile dysfunction should be probed, including specific situational circumstances, performance anxiety, the nature of sexual relationships, details of current sexual techniques, expectations, motivation for treatment, and the presence of specific discord in the patient's relationship with his sexual partner. The sexual partner's own expectations and perceptions should also be sought since they may have important bearing on diagnosis and treatment recommendations.
Not to give your already stressed-out dude one more thing to worry about, but stress is the cause of 20 percent of all erectile problems, from one-off boner blunders to a lingering inability to get and maintain an erection. Of course, sex difficulties are just the tip of the stress-induced health problem iceberg — sustained stress can also lead to insomnia, stomach troubles, chest pains, anxiety, and more severe health issues in the long term.
Erectile dysfunction may be an unpleasant condition that no one really wants to talk about, failing to acknowledge it won’t make the problem go away. Your best defense against health problems like this is to learn everything you can about it so you can tackle the problem at the root. If you’re ready to stop living in embarrassment about your sexual function, become an advocate for yourself and your own health and talk to your doctor.
If you have symptoms of ED, it’s important to check with your doctor before trying any treatments on your own. This is because ED can be a sign of other health problems. For instance, heart disease or high cholesterol could cause ED symptoms. With a diagnosis, your doctor could recommend a number of steps that would likely improve both your heart health and your ED. These steps include lowering your cholesterol, reducing your weight, or taking medications to unclog your blood vessels.
Appallingly little is known about the prevalence of erectile dysfunction in the United States and how this prevalence varies according to individual characteristics (age, race, ethnicity, socioeconomic status, and concomitant diseases and conditions). Data on erectile dysfunction available from the 1940's applied to the present U.S. male population produce an estimate of erectile dysfunction prevalence of 7 million.
The male erectile response is a vascular event initiated by neuronal action and maintained by a complex interplay between vascular and neurological events. In its most common form, it is initiated by a central nervous system event that integrates psychogenic stimuli (perception, desire, etc.) and controls the sympathetic and parasympathetic innervation of the penis. Sensory stimuli from the penis are important in continuing this process and in initiating a reflex arc that may cause erection under proper circumstances and may help to maintain erection during sexual activity.
Instead of the hesitation with which he had accosted the cardinal a quarter of an hour before, there might be read in the eyes of the young king that will against which a struggle might be maintained, and which might be crushed by its own impotence, but which, at least, would preserve, like a wound in the depth of the heart, the remembrance of its defeat.
#6 It’s performance anxiety. Many men suffer from performance anxiety, and that’s another reason you can’t get hard. Simply put, you’re too nervous to get your dick up. And that’s okay, it happens! This is likely to happen if you haven’t had sex in a while or if you’re starting up with a new partner. Sex is supposed to be fun, but worrying over your prowess between the sheets can make sex the exact opposite of what’s it’s supposed to be. [Read: 13 ways to overcome sexual anxiety and perform]
"Data shows the longer you ride, the higher your chance of developing ED in terms of distance per week," Gittens says. If you cycle for exercise or socialization, you don't have to necessarily give it up, just make some modifications. Gittens suggests riding for shorter distances, giving yourself a rest every once in a while, finding a comfortable seat, and getting a bike that’s sized appropriately.
How soon the drugs start working ranges from 15 to 60 minutes. Neither Viagra nor Levitra will work if you take them after a meal, which blocks their absorption. However, neither Cialis nor Stendra interact with food this way. The onset time determines how soon you can engage in intercourse. Stendra and daily-use Cialis are closest to being an "on demand" erectile drug; using the others requires more planning.
Dr Kenny du Toit is a urologist practicing in Rondebosch, Cape Town. He is also consultant at Tygerberg hospital, where he is a senior lecturer at Stellenbosch University. He is a member of the South African Urological Association, Colleges of Medicine South Africa and Société Internationale d’Urologie. Board registered with both the HPCSA (Health professions council of South Africa) and GMC (General medical council UK). He has a keen interest in oncology, kidney stones and erectile dysfunction.http://www.dutoiturology.co.za
The dorsal artery provides for engorgement of the glans during erection, whereas the bulbourethral artery supplies the bulb and the corpus spongiosum. The cavernous artery effects tumescence of the corpus cavernosum and thus is principally responsible for erection. The cavernous artery gives off many helicine arteries, which supply the trabecular erectile tissue and the sinusoids. These helicine arteries are contracted and tortuous in the flaccid state and become dilated and straight during erection. 
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.
Both ED and low testosterone (hypogonadism) increase with age. The incidence of the latter is 40% in men aged 45 years and older.  Testosterone is known to be important in mood, cognition, vitality, bone health, and muscle and fat composition. It also plays a key role in sexual dysfunction (eg, low libido, poor erection quality, ejaculatory or orgasmic dysfunction, reduced spontaneous erections, or reduced sexual activity). 
2 inability of the adult male to achieve or sustain a penile erection or, less commonly, to ejaculate after achieving an erection. Several forms are recognized. Functional impotence has a psychological basis. Organic impotence includes vasculogenic, neurogenic, endocrinic, and anatomical factors. Anatomical impotence results from physically defective genitalia. Atonic impotence involves disturbed neuromuscular function. Poor health, old or advancing age, drugs, smoking, trauma, and fatigue can induce impotence. Also called erectile dysfunction, impotency. impotent, adj.
The first stem cell study for the treatment of ED was published in 2004. This study used embryonic stem cells to treat ED. At this time, there is a total of 36 published basic studies assessing stem cell therapy for ED, with two clinical trials. The mechanism of action of stem cells is to generate angiogenesis with subsequent increase in cavernosal smooth muscle cells within the corporal bodies.46
The association between low testosterone and ED is not entirely clear. Although these 2 processes certainly overlap in some instances, they are distinct entities. Some 2-21% of men have both hypogonadism and ED; however, it is unclear to what degree treating the former will improve erectile function.  About 35-40% of men with low testosterone see an improvement in their erections with testosterone replacement; however, almost 65% of these men see no improvement. 
Most of us are raised to believe that men are ravenous sex-beasts, eternally horny and only pretending to be a part of polite society so that they can find some new crevice to jam their Jeremy Irons into. So the first time we cross paths (and genitals) with a guy who can't get an erection, many of us immediately panic and assume that the problem must be us. We must be profoundly unsexy. After all, what could else possibly stop these hormone-addled maniacs from getting an erection?
Martha K Terris, MD, FACS is a member of the following medical societies: American Cancer Society, American College of Surgeons, American Institute of Ultrasound in Medicine, American Society of Clinical Oncology, American Urological Association, Association of Women Surgeons, New York Academy of Sciences, Society of Government Service Urologists, Society of University Urologists, Society of Urology Chairpersons and Program Directors, and Society of Women in Urology
Psychological processes such as depression, anxiety, and relationship problems can impair erectile functioning by reducing erotic focus or otherwise reducing awareness of sensory experience. This may lead to inability to initiate or maintain an erection. Etiologic factors for erectile disorders may be categorized as neurogenic, vasculogenic, or psychogenic, but they most commonly appear to derive from problems in all three areas acting in concert.
Vacuum constriction devices may be effective at generating and maintaining erections in many patients with erectile dysfunction and these appear to have a low incidence of side effects. As with intracavernosal injection therapy, there is a significant rate of patient dropout with these devices, and the reasons for this phenomenon are unclear. The devices are difficult for some patients to use, and this is especially so in those with impaired manual dexterity. Also, these devices may impair ejaculation, which can then cause some discomfort. Patients and their partners sometimes are bothered by the lack of spontaneity in sexual relations that may occur with this procedure. The patient is sometimes also bothered by the general discomfort that can occur while using these devices. Partner involvement in training with these devices may be important for successful outcome, especially in regard to establishing a mutually satisfying level of sexual activity.
There have been some studies to suggest that a placebo effect that improves ED may work for some men. One study found that men taking an oral placebo pill showed as much improvement in ED symptoms as men who took actual medication to improve ED. Conversely, men who were given therapeutic suggestions to improve ED did not see signs of symptom improvement.
For many men, there is no direct factor involved in erectile dysfunction other than the natural process or aging. As men age, the testosterone hormone decreases in productivity and circulation. Basically, the body is saying that the man has done his job, especially if he has had children. During this time of drawdown on testosterone, men may experience weaker erections, more difficulty in achieving erections, and more difficulty in maintaining erections.
You’ve heard of—and probably experienced—the numbing effect alcohol has on your mind, body, and (unfortunately) penis. If you fail to rise to the occasion on a regular basis and you're drinking has gone from occassional weekend binge to a Monday through Friday ordeal, consider cutting back—way back. Heavy drinking proportionately increases your risk of ED, according to research from the Indian Journal of Psychiatry.