Erectile Dysfunction
(ED, Impotence)

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What is erectile dysfunction?

Erectile dysfunction (ED) is defined as the persistent inability to achieve or maintain a penile erection sufficient for satisfactory sexual performance. A breakdown occurs in the normal physiology that allows the penis to fill with blood, become firm and erect, and then become flaccid after ejaculation or because sexual stimulation has stopped. Impotence is a term no longer used to describe the inability to maintain an erection.

Erectile dysfunction can cause stress and relationship troubles and can be the sign of an underlying medical condition. Although many men find it uncomfortable or awkward to discuss erectile dysfunction with their health care professional, persistent erectile dysfunction should trigger a visit to your doctor.

For a normal erection to occur, the arteries to the penis must be able to deliver blood, hormone levels need to be optimized, and there needs to be an appropriate psychological state. If any of these systems do not function properly, an erection may not occur.

There are two spongy areas within the penis, called the corpus cavernosum, that are capable of becoming engorged with blood. With proper sexual stimulation, either physical or emotional, hormones trigger the release of nitrous oxide at nerve endings in the penis to dilate blood vessels and allow arterial blood to be pumped into these spongy tissues causing the penis to become erect. With continued sexual stimulation, the muscles at the base of the penis start to contract preventing blood from entering or escaping the penis, increasing its firmness. Once either ejaculation occurs or stimulation stops, the muscles relax, allowing the blood to leave the penis.

What causes erectile dysfunction?

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Before an erection can occur, numerous organ systems in the body need to function properly. Should any or all systems fail, erectile dysfunction may result. These systems include the brain, hormone release, muscles, nerves, arteries, veins, and emotional response.

The hypothalamus and pituitary glands in the brain need to function to stimulate the testes to produce the testosterone required for libido (sexual drive or desire). Injury, stroke, or a tumor may affect brain function. Hypogonadism (hypo=less + gonad=testicle), trauma, or surgery may result in failure of the testes to produce testosterone.

Nerve supply to the penis needs to be intact. Nerves can be damaged by trauma or surgery, especially after prostate surgery. Poorly controlled diabetes can lead to peripheral neuropathy and failure of nerves that support an erection. Multiple sclerosis is associated with erectile dysfunction.

Adequate blood supply needs to be delivered to the penis. Blood supply can be affected by trauma or surgery. More commonly, blood supply is restricted because of peripheral vascular disease or hardening of the arteries, the same scenario that can lead to heart attack and stroke. Patients with erectile dysfunction have a high likelihood of also having coronary artery disease. Risk factors include high blood pressure, high cholesterol, smoking, and diabetes.

The muscles and tissues of the penis need to be capable of accepting the increased blood supply required to produce an erection. Damage due to trauma or surgery may be the underlying cause of a flaccid penis.

An appropriate emotional and psychological state is required to achieve an erection. Mental and emotional problems that could lead to erectile dysfunction include depression, mental disorders, stress, and performance anxiety. Side effects from selective serotonin reuptake inhibitors (SSRI antidepressants) like fluoxetine (Prozac), sertraline (Zoloft), paroxetine (Paxil), citalopram (Celexa), and escitalopram (Lexapro) can also be a factor in erectile dysfunction.

Medically Reviewed by a Doctor on 3/18/2014

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