Erectile dysfunction (ED) is the inability to get or keep an erection firm enough to have sexual intercourse. It is also referred as impotence.
Signs and Symptoms
Erectile dysfunction is characterized by the regular or repeated inability to obtain or maintain an erection. It is analyzed in several ways:
Surgical intervention for a number of conditions may remove anatomical structures necessary to erection, damage nerves, or impair blood supply. Erectile dysfunction is a common complication of treatments for prostate cancer, including prostatectomy and destruction of the prostate by external beam radiation, although the prostate gland itself is not necessary to achieve erection. As far as inguinal hernia surgery is concerned, in most cases, and in the absence of postoperative complications, the operative repair can lead to a recovery of the sexual life of patients with preoperative sexual dysfunction, while, in most cases, it does not affect patients with a preoperative normal sexual life. ED can also be associated with bicycling due to both neurological and vascular problems due to compression.
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. 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.
A useful and simple way to distinguish between physiological and psychological impotence is to determine whether the patient ever has an erection. If never, the problem is likely to be physiological; if sometimes (however rarely), it could be physiological or psychological. The current diagnostic and statistical manual of mental diseases has included a listing for impotence.
Duplex ultrasound : Duplex ultrasound is used to evaluate blood flow, venous leak, signs of atherosclerosis, and scarring or calcification of erectile tissue. Injecting prostaglandin, a hormone-like stimulator produced in the body, induces erection. Ultrasound is then used to see vascular dilation and measure penile blood pressure.
Penile nerves function : Tests such as the bulbocavernosus reflex test are used to determine if there is sufficient nerve sensation in the penis. The physician squeezes the glans (head) of the penis, which immediately causes the anus to contract if nerve function is normal. A physician measures the latency between squeeze and contraction by observing the anal sphincter or by feeling it with a gloved finger inserted past the anus.
Nocturnal penile tumescence (NPT) : It is normal for a man to have five to six erections during sleep, especially during rapid eye movement (REM). Their absence may indicate a problem with nerve function or blood supply in the penis. There are two methods for measuring changes in penile rigidity and circumference during nocturnal erection: snap gauge and strain gauge. A significant proportion of men who have no sexual dysfunction nonetheless do not have regular nocturnal erections.
Penile biothesiometry : This test uses electromagnetic vibration to evaluate sensitivity and nerve function in the glans and shaft of the penis.
Dynamic infusion cavernosometry (DICC) : technique in which fluid is pumped into the penis at a known rate and pressure. It gives a measurement of the vascular pressure in the corpus cavernosum during an erection.
Corpus cavernosometry : Cavernosography measurement of the vascular pressure in the corpus cavernosum. Saline is infused under pressure into the corpus cavernosum with a butterfly needle, and the flow rate needed to maintain an erection indicates the degree of venous leakage. The leaking veins responsible may be visualised by infusing a mixture of saline and x ray contrast medium and performing a cavernosogram In Digital Subtraction Angiography (DSA), the images are acquired digitally.
Magnetic resonance angiography (MRA) : This is similar to magnetic resonance imaging. Magnetic resonance angiography uses magnetic fields and radio waves to provide detailed images of the blood vessels. Doctors may inject a "contrast agent" into the patient's bloodstream that causes vascular tissues to stand out against other tissues. The contrast agent provides for enhanced information regarding blood supply and vascular anomalies.
Treatment depends on the causes.
Exercise, particularly aerobic exercise during midlife is effective for preventing ED; exercise as a treatment is under investigation.For tobacco smokers, cessation results in a significant improvement.
Oral pharmacotherapy and vacuum erection devices are first-line treatments,followed by injections of drugs into the penis, and penile implants.
Oral medication : Phosphodiesterase type 5 inhibitors. The cyclic nucleotide phosphodiesterases constitute a group of enzymes that destroy the cyclic nucleotides cyclic adenosine monophosphate and cyclic guanosine monophosphate (cGMP). Phosphodiesterases exist in different molecular forms and are unevenly distributed throughout the body. One of the forms of phosphodiesterase is termed PDE5, and inhibiting PDE5 increases the amount of cGMP available in the blood supply to the penis, thus increasing blood flow. The PDE5 inhibitors sildenafil (Viagra), vardenafil (Levitra) and tadalafil (Cialis) are prescription drugs which are taken orally.
Injected medication : Another treatment regimen is injection therapy. One of the following drugs is injected into the penis: papaverine, phentolamine, and prostaglandin E1.
Pumps : A vacuum erection device helps draw blood into the penis by applying negative pressure. This type of device is sometimes referred to as penis pump and may be used just prior to sexual intercourse. Several types of FDA approved vacuum therapy devices are available with a doctor's prescription. When pharmacological methods fail, a purpose-designed external vacuum pump can be used to attain erection, with a separate compression ring fitted to the penis to maintain it. These pumps should be distinguished from other penis pumps (supplied without compression rings) which, rather than being used for temporary treatment of impotence, are claimed to increase penis length if used frequently, or vibrate as an aid to masturbation. More drastically, inflatable or rigid penile implants may be fitted surgically.