Causes of Impotence
By admin at 28 July, 2009, 4:39 pm
What is impotence?
Impotence, also known as erectile dysfunction (ED) is an inability to achieve or sustain a prolonged satisfactory erection during any sort of sexual activity. Impotence is different from other conditions that inhibit one’s ability to have sexual intercourse. Other sexual problems may include lack of desire as well as problems ejaculating or climaxing. This article’s primary focus is on the evaluation of Impotence in males.
How common is Impotence?
Impotence, or erectile dysfunction (ED), can vary in severity; some may be completely unable to achieve an erection, while others simply have an inability over time to have consistent full erections, while others might only be able to sustain short unsustainable erections. Studies show that many men are hesitant to discuss their problems of impotence with their doctors, therefore leading many to believe that this problem in society is under-diagnosed. However, taking into account this fact, experts have estimated that impotence (ED) affects up to 30 million men each year in The United States alone.
While ED can happen at any age, it is more common among the elderly, with only a very small percentage of young men being stricken with the problem. Research shows that by the time an average man reaches the age of 45, he has experienced at least one case of erectile dysfunction. According to studies performed by The Massachusetts Male Aging Study, complete impotence (the total inability to achieve an erection) increases from only an average of 5% in subjects aged 40 to around 15% for those aged 70 or older. Studies of population in the Netherlands have found that some degree of erectile dysfunction occurs in 20% of men between the ages of 50 and 54, and in 50% of men between the ages of 70 and 78. In 1999, The National Ambulatory Medical Care survey recorded 1,520,000 visits to the doctor for erectile dysfunction related problems.
What is the anatomy of a normal penis?
The penis is made up of two chambers, each known as the Corpora cavernosa. These chambers run along the length of the upper side of the penis (see figure 1 below). The urethra, which provides a canal by which urine runs through, as well as the fluid ejaculated by the penis, runs along the underside of the Corpora cavernosa. The Corpora cavernosa consists of a spongy tissue made up of smooth muscles, fibrous tissues, gaps, veins, and arteries. A membrane known as the albuginea, surrounds the exterior of the Corpora cavernosa. Veins located within the tunica albuginea allow for blood to be drained out of the penis.
How erections occur?
Erections always begin with some sort of sexual stimulation. This stimulation can be tactile (i.e. touching), or mental (i.e. sexual fantasies). Sexual stimulation creates electrical impulses to be carried along the nerves leading to the penis and causes these nerves to release nitric oxide, which in turn increases the productions of cyclic GMP (cGMP) in the smooth muscle cells of the Corpora cavernosa. This cGMP causes the smooth muscles of the Corpora cavernosa to relax, allowing uninhibited blood flow to and within the penis. This incoming blood flow fills the Corpora cavernosa, allowing the penis to expand and cause an erection.
How an erection is sustained?
The Pressure from the expanding of the penis causes the veins to compress (these same veins that are used to transport blood out of the penis) in the tunica albuginea, causing the blood to be trapped within the Corpora cavernosa, making it possible for an erection to be sustained. An erection is reversed at the moment the cGMP levels in the Corpora cavernosa fall, making the smooth muscles of the Corpora cavernosa to contract, and stopping the inward flow of blood. This, in turn, causes the veins which drain the blood away from the penis to open up. The levels of cGMP in the Corpora cavernosa decrease due to being destroyed by an enzyme known as phosphodiesterase type 5 (PDE5).
What causes erectile dysfunction (ED)?
The ability to achieve and sustain erections requires several things, including:
1. A healthy nervous system that is able to conduct nerve impulses in the brain, spinal column, and penis
2. Healthy arteries in and near the Corpora cavernosa,
3. Healthy smooth muscles and fibrous tissues within the Corpora cavernosa
4. Adequate levels of nitric oxide in the penis.
Should one or more of these characteristics not be met, erectile dysfunction can occur.
The causes of erectile dysfunction are as follows:
• Aging
There are two reasons why older men are more likely to experience erectile dysfunction than younger men. Firstly, older men are more prone to diseases such as heart attacks, angina, strokes, diabetes mellitus, and high blood pressure that are often times associated with erectile dysfunction. Secondly, erectile dysfunction can be caused simply by the natural process of aging, primarily by decreasing the compliance of tissues in the Corpora cavernosa. Though it has been suggested, it has not yet been proven that aging causes a decrease in the production of nitric oxide in the nerves that innervate the smooth muscles within the penis.
• Diabetes mellitus
On average, erectile dysfunction tends to develop 10 to15 years earlier in diabetic men than among men without signs of diabetes. In a random population study, which took men who have suffered from type I diabetes for more than 10 years, erectile dysfunction was reported by 55% of the men between the ages of 50 to 60 years old. This increased risk of erectile dysfunction among men with diabetes mellitus could be due to the earlier onset and greater severity of atherosclerosis that has been shown to limit the blood flow by narrowing the arteries and thereby limiting the blood flow to the penis. Without sufficient blood flow to the penis, an erection is simply not possible to achieve.
Diabetes mellitus has also been proven to cause erectile dysfunction by means of damaging both sensory and autonomic nerves; this condition is known as diabetic neuropathy. Smoking cigarettes, obesity, poor control of blood glucose levels, and having diabetes mellitus for a prolonged time further increases the risk of erectile dysfunction in men. Additionally, atherosclerosis and/or neuropathy causes ED in men, making many diabetic men develop a myopathy (muscular disease) as the cause of ED. This myopathy can cause a decrease of the compliance of muscles in the Corpora cavernosa which in turn causes the inability to initiate or maintain an erection. For additional information, please read the article on Diabetes.
• Hypertension (high blood pressure)
Through studies, it has been shown that patients with essential hypertension or arteriosclerosis have an increased risk of developing erectile dysfunction. Essential hypertension is the most common form of hypertension getting its name from the fact that it is not caused by another disease (unlike other types of hypertension which can be caused by kidney disease). It is not clearly known how essential hypertension is connected with erectile dysfunction. However, patients with essential hypertension have been found to have low production of nitric oxide by the arteries of the body, including the necessary arteries in the penis. For this reason, scientists now contribute erectile dysfunction to the decreased levels of nitric oxide which is caused by essential hypertension.
• Cardiovascular diseases
In the US, the most common cause of cardiovascular disease is atherosclerosis. Atherosclerosis is defined as the narrowing and hardening of arteries causing the reduction of blood flow and increasing blood pressure. It typically affects many arteries throughout the body, and has been proven to be aggravated by: hypertension, high blood cholesterol, smoking, and diabetes mellitus. Heart attacks are the result when coronary arteries (arteries that supply blood to the heart) are narrowed due to atherosclerosis. Should the same blockage of arteries caused by atherosclerosis affect the cerebral arteries, the result is a stroke in the brain.
This same logic holds true for the penis. When arteries are narrowed due to atherosclerosis, it causes much needed blood flow to not reach the penis and/or pelvic organs, problems can occur. Should there be inadequate blood flow to the penis, the lack of erection is the result. Research shows a very strong correlation between erectile dysfunction and the severity of atherosclerosis in the coronary artery. Thus, men who have a more severe atherosclerosis in the coronary artery tend to have a greater chance of having some type of erectile dysfunction. And, in turn, those with less severe cases tend to have a lower chance erectile dysfunction. Several panels of doctors have suggested men who have just been diagnosed with onset erectile dysfunction be immediately checked for coronary artery diseases (advanced coronary artery atherosclerosis that has not yet caused angina or a heart attack). For more information please read more on heart attacks in the Heart Attack Prevention article.
• Cigarette smoking:
Cigarette smoking aggravates atherosclerosis and can increase the risk for erectile dysfunction. For more information, please read the Smoking and Quitting Smoking article.
• Nerve or spinal cord damage:
Damage to the spinal cord and nerves in the pelvis can cause erectile dysfunction. Nerve damage can be caused by disease, trauma, or surgical procedures. Examples of damage include: injury to the spinal cord from an accident (automobile, falling on head), injury to the pelvic nerves from prostate surgery, multiple sclerosis (a neurological disease causing widespread nerve damage), and long-term diabetes mellitus.
• Substance abuse:
Marijuana, heroin, cocaine, and alcohol abuse have been proven to contribute to erectile dysfunction. Alcoholism, in addition to causing nerve damage, can lead to the atrophy of the testicles and lower testosterone levels. For more information, please visit the Drug Abuse Center.
• Low testosterone levels:
Testosterone (the primary sex hormone in men) is not only necessary for sex drive (libido) but also is necessary to maintain nitric oxide levels in the penis. Therefore, men with hypogonadism (diminished function of the testes resulting in low testosterone production) can suffer from low sex drives and erectile dysfunction.
• Medications
• Depression and anxiety
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