|
|
Erectile Dysfunction
Incidence & Prevalence
| Anatomy |
Physiology |
 |
Erectile dysfunction (ED) is the inability of a man to achieve
or maintain an erection sufficient for his sexual needs or the
needs of his partner. Most men experience this at some point
in their lives, usually by age 40, and are not psychologically
affected by it.
Some men, however, experience chronic,
complete erectile dysfunction (impotence), and others, partial
or brief erections. Frequent erectile dysfunction can cause
emotional and relationship problems, and often leads to
diminished self-esteem. Erectile dysfunction has many causes,
most of which are treatable, and is not an inevitable
consequence of aging.
Incidence and Prevalence
The term "erectile dysfunction" can mean the inability to
achieve erection, an inconsistent ability to do so, or the
ability to achieve only brief erections. These various
definitions make estimating the incidence of erectile
dysfunction difficult. According to the National Institutes of
Health in 2002, an estimated 15 million to 30 million men in
the United States experience chronic erectile dysfunction.
According to the National Ambulatory Medical Care Survey (NAMCS),
approximately 22 out of every 1000 men in the United States
sought medical attention for ED in 1999.
Incidence of the disorder increases with age. Chronic Erectile Dysfunction
affects about 5% of men in their 40s and 15–25% of men by the
age of 65. Transient ED and inadequate erection affect as many
as 50% of men between the ages of 40 and 70.
Diseases (e.g., diabetes, kidney disease, alcoholism,
atherosclerosis) account for as many as 70% of chronic ED
cases and psychological factors (e.g., stress, anxiety,
depression) may account for 10–20% of cases. Between 35 and
50% of men with diabetes experience ED.
Anatomy of the Penis
The internal structure of the penis consists of two
cylinder-shaped vascular tissue bodies (corpora cavernosa)
that run throughout the penis; the urethra (tube for expelling
urine and ejaculate); erectile tissue surrounding the urethra;
two main arteries; and several veins and nerves. The longest
part of the penis is the shaft, at the end of which is the
head, or glans penis. The opening at the tip of the glans,
which allows for urination and ejaculation, is the meatus.
Physiology of Erection
The physiological process of erection begins in the brain and
involves the nervous and vascular systems. Neurotransmitters
in the brain (e.g., epinephrine, acetylcholine, nitric oxide)
are some of the chemicals that initiate it. Physical or
psychological stimulation (arousal) causes nerves to send
messages to the vascular system, which results in significant
blood flow to the penis. Two arteries in the penis supply
blood to erectile tissue and the corpora cavernosa, which
become engorged and expand as a result of increased blood flow
and pressure.
Because blood must stay in the penis to maintain rigidity,
erectile tissue is enclosed by fibrous elastic sheathes
(tunicae) that cinch to prevent blood from leaving the penis
during erection. When stimulation ends, or following
ejaculation, pressure in the penis decreases, blood is
released, and the penis resumes its normal shape.
A medical examination may indicate neurological, vascular, or
hormonal disease, or Peyronie's disease. History of illness,
smoking, drug use, and hypertension can be ascertained with a
thorough examination of health history. Laboratory tests are
performed to identify the underlying cause.
|
1 |
2 |
3 |
Back to Top |
|
