Erectile Dysfunction Causes (Etiology of ED)

The etiology of erectile dysfunction includes anything that can disrupt the progression of events that result in erection.  This can be due to various factors which can be organic, physiologic, endocrine, and psychogenic in nature. The etiology of erectile dysfunction is defines under two categories, medical and non medical. Some patients have also proved that organic factors are associated with psychogenic ones. Diseases such as multiple sclerosis, diabetes, trauma to the spinal chord; cardiovascular disorders etc can affect the nervous, cardiovascular or hormonal functions or produce a change in the smooth muscle tissue. The following four factors are quintessential for en erection to take place.

• Smooth functioning of the nervous system which conducts nerve impulses in the brain, spinal chord and male reproductive organ.
• Arteries near corpora cavernosa with healthy functions.
• Healthy functioning of smooth muscles and fibrous tissues within the corpora cavernosa
• Ample supply of nitric oxide in the male reproductive organ

The causes of erectile dysfunction can be categorized as:

• Medical
• Non-medical

MEDICAL CAUSES:

1. Vascular diseases associated with erectile dysfunction
2. Systemic diseases associated with erectile dysfunction
3. Neurogenic diseases associated with erectile dysfunction
4. Respiratory disease associated with erectile dysfunction
5. Endocrine conditions associated with erectile dysfunction
6. Penile conditions associated with erectile dysfunction
7. Psychiatric conditions associated with erectile dysfunction
8. Nutritional states associated with erectile dysfunction
9. Hematologic diseases associated with erectile dysfunction
10. Surgical procedures associated with erectile dysfunction
11. Medications associated with erectile dysfunction
12. Trauma to the male reproductive organ /Penile fracture

NON-MEDICAL CAUSES:

• Alcohol dependence
• Smoking
• Obesity

MEDICAL CAUSES INCLUDES:

1.    Vascular diseases associated with erectile dysfunction

Atherosclerosis- It is a disease of the arteries which occurs due to progressive deposition of fat debris resulting in thickening and hardening of the walls of the arteries. If the blood vessels in the male organ for reproduction are healthy, they help in getting and maintaining an erection. The arteries that reach the male organ for reproduction come via the abdomen and branch out into smaller branches before reaching the male organ for reproduction. The rush of blood from the heart to the male organ for reproduction results in a pressure that slows down the exit of blood from the male organ for reproduction. This helps to sustain erection. If the arteries are clogged with fat, it can result in poor blood supply to the male organ for reproduction resulting in loss of erection.

 

• Peripheral vascular disease- Also termed as peripheral arterial disease (PAD), it is narrowing of blood vessels in the limbs. Though more common in legs, there are also reports of this occurring in arms. It is also a potent marker of adverse cardiovascular prognosis. This disease occurs due to a blockage in the arteries which is termed ischemia. If the blockage is lower down in the arteries that supply blood to the lower limbs, it can cause pain in the thighs but if the blockage is above the groin, it can cause pain in the gluteal region (buttocks).This results in impotency due to improper blood supply.
• Myocardial infarction- This is a disease in which the myocardium (heart muscle) undergoes necrosis (death) due to prolonged ischemia. It is caused by narrowing of epicardial blood vessels due to atheromatous plaques. This results in platelet aggregation, thrombus formation, fibrin accumulation, hemorrhage into the plaque, and varying degrees of vasospasm which leads to myocardial infarction. Again due to deficiency of blood under such scenario, erectile dysfunction occurs. Also post myocardial infarction where the person has a near death experience, it can lead to depression which leads to decrease in his libido.
• Arterial hypertension/High blood pressure- The statistics for hypertension differ such that a man who has had moderate hypertension for twenty years may be at a lower risk for erectile dysfunction than a young man who has had very serious hypertension for only a few months. But high blood pressure can damage the small arteries of the male organ for reproduction. These damaged arteries are repaired by the body but the new repaired arteries have better resistance to sudden rush of blood, resulting in decreased supply of blood to the male reproductive organ. It also results in the smooth muscles losing their ability to relax which results in poor blood supply to the male organ for reproduction. It also causes a decrease in the testosterone levels. Testosterones play an important role in sexual arousal. Hypertension also decreases the level of zinc in the body. Zinc is responsible in the synthesis of testosterones.
• Prostate cancer treatment- Though prostrate cancer does not cause ED, its treatments can result in erectile dysfunction. If during prostatectomy, nerve sparing technique is used, the patient can recover within a year, but in a non-nerve sparing technology, recovery is unlikely to happen due to permanent damage to the nerves. Also post radiation therapy, patients have observed ED, which can be treated.

2.   Systemic diseases associated with erectile dysfunction

• Diabetes mellitus- During erection, the enzyme neuronal nitric oxide synthetase (nNOS) releases nitric oxide at the nerve endings of the male sexual organ. This cause an increase in the blood flow of the male sexual organ and relaxation of the penile smooth- muscle resulting in an erection. The increased blood flow further activates eNOS in penile blood vessels which continues the release of NO due to which the relaxation continues and full erection is maintained. In case of diabetes, sugar in the blood does not get broken down due to which it is high in O-GlcNAc. O-GlcNAc is a blood sugar that is present in the circulation of hyperglycemic patients. This sugar hinders the normal chain of events by inhibiting the activation of eNOS. This affects the release of NO which prevents the smooth muscles from relaxing.
• Scleroderma- is a progressive autoimmune disorder that affects the skin and connective tissue including blood vessels. During this disorder, there are alterations in the arteries and arterioles due accumulation of debris which results in vascular dysfunction. ED in scleroderma is due to this resultant fibrosis and impaired circulation.
• Renal failure/ end-stage renal disease (ESRD) – In the case of this disease the patient’s kidney functionS so poorly that it can prove fatal. It cannot be treated with conventional medical treatments such as drugs and doctors opt for dialysis or kidney transplant. During this disease there is acceleration of arthrosclerosis which results in vasculogenic erectile dysfunction. Majority of patients display cavernosal artery occlusive disease, resulting in erectile dysfunction.
• Liver cirrhosis- Liver is responsible for the removal of many hormones including estrogen. This disease results in hypogonadism which results in an imbalance in the level of estrogen and testosterones where the level of estrogen goes up and the level of testosterones come down. As stated above, testosterones are responsible for initiating sexual arousals and decrease in their level results in a fall in the libido. High level of estrogen results in redistribution of body fat which results in the man acquiring feminine characters. The patient’s abdomen becomes paunchy as the chest enlarges in the form of breasts and there is decrease in the muscle mass.
• Idiopathic hemochromatosis- This is a recessive disorder which results in abnormal accumulation of iron in the parenchymal organs, due to excessive absorption of iron form food. This excessive absorption can lead to organ toxicity. This disorder results in liver cirrhosis and diabetes which in turn cause erectile dysfunction.(Refer the notes above)
• Cancer - In different cancers, the malignant cells tend to damage the nerve cells of the pelvis resulting in erectile dysfunction.
• Cancer Treatment- Cancer patients while undergoing cancer treatments can suffer from erectile dysfunction due to the affects of surgeries or therapies.
• Surgery -Prostrate cancer which may lead to prostrate surgery can cause nerve damage. Similarly during testicular surgery, trauma to the arteries or veins can result in ED.
• Hormone therapy - the patient has to undergo hormone therapy or surgeries which affect the sexual organs.
• Radiation therapy– This form of therapy has shown better effect to cure cancer. But is also exposes the pelvis to radiations which can damage the nerves.
• Chemotherapy- This can reduce the amount of testosterone produced.
• Dyslipidemia- This is a disorder that is characterized by elevation in the plasma cholesterol, triglycerides (TGs) or both which can lead to development of arteriosclerosis. Also termed as hyperlipidemia, it can impair erectile functioning by affecting the endothelial and smooth muscle cells of the male sexual organ. Corpus cavernosum gets impaired due to oxidized low-density lipoproteins. The high level serum cholesterol and reduced high density lipoprotein cholesterol are among the factors that cause ED.

3.    Neurogenic diseases associated with erectile dysfunction

• Epilepsy- Also termed as seizure, it is a series of uncontrolled electrical activity in the brain that can cause physical convulsions, minor physical signs and thought disturbances. Patients of epilepsy suffer from erectile dysfunction due to various factors which could be emotional or physical in nature. These patients suffer from poor self esteem and social phobia which does not let them interact with the opposite sex. They are also concerned that sexual activity may trigger a seizure as it involves hyperventilation and physical exertion. Along side these psychological factors, they are also caused due to neuralgic and endocrine factors. The treatment of this disease through antiepilectic drugs (AED’s) decrease the level of testosterones in blood which results in decreased libido.

• Stroke- Also termed as CVA (cerebrovascular accident) is sudden death of some brain cells due to lack of oxygen when the blood supply to the brain in interrupted by blockage or rupture of an artery to the brain. As a result of this disease the patient may suffer from temporary loss of speech, paralysis of a side of the body or weakness of muscles. This can affect the libido or during paralysis the patient may suffer from erectile dysfunction. Depression and strained relationships with the partner post an attack is also said to be a cause of erectile dysfunction.
• Multiple sclerosis- this is an autoimmune disease of the central nervous system in which the immune system attacks myelin that serves as a nerve insulator and helps in the transmission of nerve signals. The clinical features of this disease are marked by numbness, weakness, loss of muscle coordination along with problems of vision, speech and bladder control. When erection occurs as a part of genital stimulation, the stimulus “bypass” the brain as they occur using the nerves of the spinal chord. So a patient who is suffering for multiple sclerosis may find it easy to achieve erections due to physical stimulation but not through foreplay or erotic situations or vice versa.
• Guillain-Barré syndrome- also called as acute inflammatory demyelinating polyneuropathy (AIDP) is an autoimmune disorder in which the body’s immune system attacks the peripheral nerves. Since the peripheral nerves residing in the brain and the spinal chord are most gravely affected, the brain cannot send stimulus for increased supply of blood to the male sexual organ resulting in loss of erection.
• Alzheimer disease- this incurable, degenerative disease, termed as dementia, is characterized by impairment of memory due to damage of the nerves. Alzheimer patients post the age of 60 also display erectile dysfunction and loss of libido due to peripheral nerve damage. Due to this the nerves around the male sexual organ do not get any stimulus to initiate erection.
• Parkinson’s disease- This is an autonomic disease associated with a loss of dopaminergic nigrostriatal neurons which manifests itself in the form of tremors which are barely noticeable and later become more pronounced. In this case also, the nerves around the male sexual organ do not receive stimulus from the brain or the spinal chord to stimulate erection leading to erectile dysfunction.

4.    Respiratory disease associated with erectile dysfunction

• Chronic obstructive pulmonary disease- is a disease in which due to chronic bronchitis (blockage of airways in the lungs) and emphysema (shortness of breath), there is obstruction of air flow through the airways which is usually permanent and progressive over time. Patients usually suffer from dyspnea (shortness of breath), cough and medicinal side effects which can result in loss of libido. This gets worse as they suffer form decreases self esteem resulting in fear of sexual failure. All this can have a psychological effect on their erection.
• Sleep apnea- is an obstruction that occurs when soft tissues in the back of the throat collapse and block the airway during sleep. Due this there is lack of oxygen which hampers the blood flow to the male sexual organ which results in erectile dysfunction.

5.    Endocrine conditions associated with erectile dysfunction

• Thyroid disorder- Men suffering from hyper or hypothyroidism usually rend to suffer from erectile dysfunction. In hyperthyroidism, the body produces excess hormones which in turn produce toxins which can cause erectile dysfunction. In the case of hypothyroidism, the body’s BMR (Basal Metabolic Rate) goes down which can cause obesity. Obesity is accompanied by various complications which cause erectile dysfunction.

Hypogonadism- This is a term in which there is decreased functioning of the testes. Though this can happen due to a series of underlying causes, its clinical features include erectile dysfunction due decreased level of testosterones.

• Diabetes- (refer above)

6.    Penile conditions associated with erectile dysfunction

• Peyronie disease- In this disease a plaque, or hard lump, forms within the male sexual organ. The plaque, a flat plate of scar tissue, develops on top or bottom side of the male sexual organ, inside a thick membrane called the tunica albuginea, which envelopes the erectile tissues. Initially this plaque begins as a localized inflammation and later develops into a hardened scar. This can cause pain in the male reproductive organ and abnormal curvature of the male reproductive organ. The patient may experience an erection but the abnormal curvature does not allow him to have an intercourse with his partner.

• Hypospadias- It is an abnormality of anterior urethral and penile development in which the urethral opening is ectopically located on the ventrum (toward the belly) of the male reproductive organ proximal (near the point of attachment) to the tip of the glans male reproductive organ, which, in this condition, is awkwardly opened out. This can be surgically corrected but during this time, patients experience loss of erection.
• Priapism- It is a condition wherein a patient experiences persistent painful erection which is not related to sexual arousal. This occurs when a part of the circulatory system like blood, blood vessels or nerves affect the course of normal blood flow. Subsequently the patient suffers form an involuntary prolonged erection unrelated to sexual stimulation which does not get relieved even by climax. This can exist for a long time resulting in extensive tissue damage to male reproductive organ and erectile dysfunction, if not treated on time.

7.    Psychiatric conditions associated with erectile dysfunction

• Depression- For a healthy sexual life a person need to be a in a healthy mental state. To get sexually aroused a person needs to be attracted and motivated. Once a person is depressed, he is withdrawn, loses temper easily, is self conscious and apathetic which results in loss of sexual desire. Due to this the male reproductive organ fails to maintain an erection. People who are prone to depression also suffer from social-anxiety problem. So when they finally get some sexual interactions, the anxiety around sex may inhibit the patient’s reaction.
• Widower syndrome- This is termed as a psychological problem in which a person feels guilty about cheating on his deceased spouse resulting in lack of erection. It is also observed in divorced men who have not participated in sexual intercourse for a long time. Some also say that this could be due to side effect of prolonged inactivity of the male reproductive organ. The tissues of the male reproductive organ get oxygen during erection which is important to keep them healthy. During the REM phase of sleep men have frequent erections which result in large quantity of blood and oxygen being brought into the male reproductive organ which oxygenate the tissues. As they age, there is a marked decrease in the nocturnal erection which results in the male reproductive organ getting less supply of oxygen. Inactivity of the male reproductive organ for a long period of time just compounds the problem leading to inability in having an erection.
• Performance anxiety- During this disorder the person gets highly anxious about his performance resulting in loss of libido. This is said to be due to excess rush of blood to the brains, resulting in decreased blood supply to the male reproductive organ resulting in the male reproductive organ continuing to be flaccid even after physical stimulation.
• Posttraumatic stress disorder- This psychiatric disorder is a long lasting response of the patient to a traumatic event. This event could be frightening, life threatening, or mentally disturbing due to which the person keeps relieving them mentally. Due to this they tend to avoid people, places or other things that remind them of the past bad experience. They also become extremely sensitive to normal life (hyperarousal). Due to all this, the person may slip into depression. This results in loss of libido and erectile dysfunction.

8.    Nutritional states associated with erectile dysfunction

• Malnutrition- Studies have shown that thiamin, a water soluble b-complex vitamin is vital in the optimization of nerve and energy transmission throughout the body. Deficiency of this vitamin has proved that the person may suffer from tremors; loss of concentration and in very extreme and rare cases may result in loss of erection. This condition can be reversed but taking vitamin supplements.
• Selenium- This trace element is an antioxidant and a part of the enzyme glutathione peroxidase. It metabolizes hydroperoxides formed from polyunsaturated fatty acids. It is also a part of enzymes that deiodinate thyroid hormones. More than half the selenium in a male is located in the testicles and seminal fluid ducts. Decrease in the level of selenium results in low sperm count and can lead to erectile dysfunction. Chicken, legumes, cereals and meat are rich sources of selenium.
• Zinc deficiency- This is another trace element that is necessary to maintain normal serum testosterone. Deficiency of this mineral restricts the pituitary gland from releasing luteinizing and follicle stimulating hormones which are responsible for stimulation of testosterone production. It also functions as an inhibitor to the aromatase enzyme which converts testosterones into excess estrogen. With age, there is an imbalance between the testosterone and estrogen ratio. Higher estrogen activities result in the patient getting effeminate, gaining weight and loosing his libido. Also testosterones play a major role in sexual arousal, so decrease in their level due to zinc deficiency leads to erectile dysfunction. Beef, lamb, pork, crabmeat, turkey, lobster, legumes, pumpkin seeds, string bean and salmon are rich in zinc.

9.    Hematologic diseases associated with erectile dysfunction

• Sickle cell anemia- is an inherited blood disorder that affects red blood cells. This is caused by an abnormal hemoglobin called as hemoglobin S. This hemoglobin, which is “S” shaped distorts the shape of oxygen blood cells. The distorted blood cells are crescent shaped, representing a sickle.  These fragile, sickle-shaped cells deliver less oxygen to the body’s tissues. They can also clog more easily in small blood vessels, and break into pieces that disrupt healthy blood flow. All this can cause priapism which results in erectile dysfunction.
• Leukemia- This is a cancer of the white blood cells in which the growth and development of the white blood cells (leukocytes) is abnormal. In this case, the white blood cells block the outflow of blood from the male reproductive organ which results in erectile dysfunction. It can also lead to priapism. In fact, in some cases, the only clinical feature of acute myeloid leukemia could be priapism.

10.    Surgical procedures associated with erectile dysfunction

Erection can takes place only if the sequence of events takes place in proper order. As stated above, these events include stimulus to the nerve and circulation of blood. The nerve route includes impulses passing between the brain, spinal chord and the area around the male reproductive organ. The blood circulation includes response in the muscle, fibrous tissues, veins and arteries in and around corpora cavernosa. While performing surgeries, the muscle, arteries, veins and nerves around the male reproductive organ may get damaged, resulting in erectile dysfunction. Besides this, chemotherapy and radiation also result in loss if erection. The following surgeries can result in this disorder.

1. Procedures on the brain and spinal cord
2. Retroperitoneal or pelvic lymph node dissection
3. Aortoiliac or aortofemoral bypass
4. Abdominal perineal resection
5. Surgical removal of the prostate for cancer
6. Surgical treatment of the prostate for benign disease
7. Proctocolectomy
8. Radical prostatectomy
9. Transurethral resection of the prostate
10. Cryosurgery of the prostate
11. Cystectomy

11.    Medications associated with erectile dysfunction

Antidepressants- These are a class of selective serotonin reuptake inhibitor (SSRI’s) which are primarily known as antidepressants which are used to treat depression. These along with atypical antidepressants target neurotransmitters such as serotonin, norepinephrine and dopamine. Since the action of these neurotransmitters is inhibited, the brain stops sending stimulus to the nerves around the male reproductive organ which results in loss of erection.

• Antipsychotics- These drugs are also commonly called as tranquilizers and administered to patients suffering from serious psychiatric disorders such as schizophrenia, bipolar disorder and alcohol and drug addiction. Once administered, they act by blocking dopaminergic transmission within the brain. They are neurotransmitters that send messages across the brain. Once their action is inhibited, they not only result in erectile dysfunction but also cause premature climax, no climax, decrease in libido and priapism.
• Antihypertensives- Patients who are on any hypertensive drugs for long experience erectile dysfunction. This is attributed to the fact that the primary actions of these drugs are inhibiting the bindings of the norepinephrines to the receptors on the membrane of vascular smooth muscle cells. This results in the muscles undergoing vasodilatation leading to decrease peripheral vascular resistance which results in decreased blood pressure. Since the blood pressure is decreased, the rush of blood to the male reproductive organ is lowered, which results in arresting the action of erection.
• Drugs such as Cimetidine and Finasteride- Cimetidine are a histamine H2-receptor antagonist which inhibits the production of acid in the stomach. It is used to treat peptic ulcers. But this drug also acts on the smooth muscle of the erectile corpus cavernosa of the male organ for reproduction and relaxes them which results in loss of erectile dysfunction. Similarly Finasteride is a form of antiandrogen which inhibits the action of testosterone. With a decrease of the male hormone, men experience loss of libido and erectile dysfunction.
• 5-Alpha reductase inhibitors- These are a group of antandrogenic drugs that are used in the treatment of benign prostatic hyperplasia (BPH) and androgenic (or androgenetic) alopecia. These drugs inhibit the conversion of testosterone to dihydrotestosterone. Dihydrotestosterones is the principle regulator of nitric oxide and cGMP (Cyclic guanosine monophosphate), which are responsible for penile erection.
• Cholesterol-lowering agents- Called as statins, these drugs are used to lower level of plasma cholesterol in the body. Since cholesterol is important for the production of testosterones, it’s important to maintain a healthy level of this in the body. Cholesterol lowering agents inhibit the action of cholesterol which results in a decrease in the level of testosterone.

12.    Trauma to the male organ for reproduction /Penile fracture.

• Trauma, either blunt or sharp- on or around the male organ for reproduction can result in erectile dysfunction. Patients who have suffered trauma on the pelvic region from a blunt injury can suffer from hemodynamic (movement of blood) impairment that can result in abnormal venous drainage or arterial supply. These patients may suffer from corporeal veno-occlusive dysfunction, cavernous artery insufficiency. In both the cases, the movement of the oxygenated and deoxygenated blood gets hindered. Most of these injuries occur to sportsmen who play without appropriate protective perineal equipment. Sharp injury may permanently damage the nerves around the male organ for reproduction.

• Fracture- This is penile fracture is the traumatic rupture of the corpus cavernosum. It is considered as a urologic emergency. Sudden trauma to the male organ for reproduction or twisting the male organ for reproduction while in an erect state can unplug the male organ for reproduction partially from the thin tunica albuginea. This is termed as fractured male organ for reproduction. This can involve one or more corpora and an associated injury to the penile urethra may occur. In both the cases, the injury is usually permanent.

NON – MEDICAL CAUSES INCLUDES:

There are various lifestyle disorders that can cause erectile dysfunctions which are-

• Alcohol dependence- There are many theories regarding alcohol consumption and its effect on the erection of a man. Researchers have observed that long term dependency and alcohol abuse can affect the production of testosterone and shrink the testes (testicular atrophy). Alcoholism can also cause hypogonadism. Hypogonadism is a disorder of the sex glands in which they produce little or no hormones. Conditions like diabetes and hypertension can aggravate because of alcohol abuse. These conditions are strongly linked to alcohol abuse. Alcohol can also react with certain drugs to produce an adverse event which can include erectile dysfunction.
• Smoking- Smoking for over a long duration is also said to be the culprit in making men suffer from ED. Men who have smoked for a long time can suffer from arthrosclerosis which occurs due to build up of plaques in the arteries. Smoking can also cause arterial lesions. Vasoconstriction (constriction of blood vessels) may further drop the flow of blood to the male organ for reproduction, within the arteries as a result of direct nicotine intake. The can also be excessive blood flow out of the male organ for reproduction which can inhibit erection. In case of a healthy male, during sexual stimulation, the veins constrict to withhold to blood in order to sustain erection. Nicotine in the blood impairs the constriction of veins due to which the veins dilate and the blood flows out.  This results in impairments of the valves which trap the blood in the male organ for reproduction This results in inhibition of erection.
• Obesity- This disease bring along with it a lot of other diseases including hypertension, diabetes, arthrosclerosis and cancer, all of which are among the leading causes of erectile dysfunction. Obesity can be hereditary, drug initiated, due to psychological imbalance or idiopathic. This disorder also increases the chance of decline in testosterone levels as it can create hormonal imbalance. It can also lead to inferiority complex which also results in loss of libido. The good thing is that patients who have undergone weight loss have experienced an in increase in their libido and erection without the help of a drug.

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