|
Erectile dysfunction,
sometimes called "impotence," is
the repeated inability to get or
keep an erection firm enough for
sexual intercourse. The word
"impotence" may also be used to
describe other problems that
interfere with sexual
intercourse and reproduction,
such as lack of sexual desire
and problems with ejaculation or
orgasm. Using the term erectile
dysfunction makes it clear that
those other problems are not
involved.
Erectile dysfunction, or ED,
can be a total inability to
achieve erection, an
inconsistent ability to do so,
or a tendency to sustain only
brief erections. These
variations make defining ED and
estimating its incidence
difficult. Estimates range from
15 million to 30 million,
depending on the definition
used. According to the National
Ambulatory Medical Care Survey (NAMCS),
for every 1,000 men in the
United States, 7.7 physician
office visits were made for ED
in 1985. By 1999, that rate had
nearly tripled to 22.3. The
increase happened gradually,
presumably as treatments such as
vacuum devices and injectable
drugs became more widely
available and discussing
erectile function became
accepted. Perhaps the most
publicized advance was the
introduction of the oral drug
sildenafil citrate (Viagra) in
March 1998. NAMCS data on new
drugs show an estimated 2.6
million mentions of Viagra at
physician office visits in 1999,
and one-third of those mentions
occurred during visits for a
diagnosis other than ED.
In older men, ED usually has
a physical cause, such as
disease, injury, or side effects
of drugs. Any disorder that
causes injury to the nerves or
impairs blood flow in the penis
has the potential to cause ED.
Incidence increases with age:
About 5 percent of 40-year-old
men and between 15 and 25
percent of 65-year-old men
experience ED. But it is not an
inevitable part of aging.
ED is treatable at any age,
and awareness of this fact has
been growing. More men have been
seeking help and returning to
normal sexual activity because
of improved, successful
treatments for ED. Urologists,
who specialize in problems of
the urinary tract, have
traditionally treated ED;
however, urologists accounted
for only 25 percent of Viagra
mentions in 1999.
How does an erection occur?
The penis contains two
chambers called the corpora
cavernosa, which run the length
of the organ (see figure 1). A
spongy tissue fills the
chambers. The corpora cavernosa
are surrounded by a membrane,
called the tunica albuginea. The
spongy tissue contains smooth
muscles, fibrous tissues,
spaces, veins, and arteries. The
urethra, which is the channel
for urine and ejaculate, runs
along the underside of the
corpora cavernosa and is
surrounded by the corpus
spongiosum.
Erection begins with sensory
or mental stimulation, or both.
Impulses from the brain and
local nerves cause the muscles
of the corpora cavernosa to
relax, allowing blood to flow in
and fill the spaces. The blood
creates pressure in the corpora
cavernosa, making the penis
expand. The tunica albuginea
helps trap the blood in the
corpora cavernosa, thereby
sustaining erection. When
muscles in the penis contract to
stop the inflow of blood and
open outflow channels, erection
is reversed.
 |
|
Figure 1.
Arteries (top) and veins
(bottom) penetrate the
long, filled cavities
running the length of
the penis—the corpora
cavernosa and the corpus
spongiosum. Erection
occurs when relaxed
muscles allow the
corpora cavernosa to
fill with excess blood
fed by the arteries,
while drainage of blood
through the veins is
blocked. |
What causes erectile dysfunction
(ED)?
Since an erection requires a
precise sequence of events, ED
can occur when any of the events
is disrupted. The sequence
includes nerve impulses in the
brain, spinal column, and area
around the penis, and response
in muscles, fibrous tissues,
veins, and arteries in and near
the corpora cavernosa.
Damage to nerves, arteries,
smooth muscles, and fibrous
tissues, often as a result of
disease, is the most common
cause of ED. Diseases—such as
diabetes, kidney disease,
chronic alcoholism, multiple
sclerosis, atherosclerosis,
vascular disease, and neurologic
disease—account for about 70
percent of ED cases. Between 35
and 50 percent of men with
diabetes experience ED.
Lifestyle choices that
contribute to heart disease and
vascular problems also raise the
risk of erectile dysfunction.
Smoking, being overweight, and
avoiding exercise are possible
causes of ED.
Also, surgery (especially
radical prostate and bladder
surgery for cancer) can injure
nerves and arteries near the
penis, causing ED. Injury to the
penis, spinal cord, prostate,
bladder, and pelvis can lead to
ED by harming nerves, smooth
muscles, arteries, and fibrous
tissues of the corpora cavernosa.
In addition, many common
medicines—blood pressure drugs,
antihistamines, antidepressants,
tranquilizers, appetite
suppressants, and cimetidine (an
ulcer drug)—can produce ED as a
side effect.
Experts believe that
psychological factors such as
stress, anxiety, guilt,
depression, low self-esteem, and
fear of sexual failure cause 10
to 20 percent of ED cases. Men
with a physical cause for ED
frequently experience the same
sort of psychological reactions
(stress, anxiety, guilt,
depression). Other possible
causes are smoking, which
affects blood flow in veins and
arteries, and hormonal
abnormalities, such as not
enough testosterone.
How is ED diagnosed?
Patient History
Medical and sexual histories
help define the degree and
nature of ED. A medical history
can disclose diseases that lead
to ED, while a simple recounting
of sexual activity might
distinguish among problems with
sexual desire, erection,
ejaculation, or orgasm.
Using certain prescription or
illegal drugs can suggest a
chemical cause, since drug
effects account for 25 percent
of ED cases. Cutting back on or
substituting certain medications
can often alleviate the problem.
Physical Examination
A physical examination can give
clues to systemic problems. For
example, if the penis is not
sensitive to touching, a problem
in the nervous system may be the
cause. Abnormal secondary sex
characteristics, such as hair
pattern or breast enlargement,
can point to hormonal problems,
which would mean that the
endocrine system is involved.
The examiner might discover a
circulatory problem by observing
decreased pulses in the wrist or
ankles. And unusual
characteristics of the penis
itself could suggest the source
of the problem—for example, a
penis that bends or curves when
erect could be the result of
Peyronie's disease.
Laboratory Tests
Several laboratory tests can
help diagnose ED. Tests for
systemic diseases include blood
counts, urinalysis, lipid
profile, and measurements of
creatinine and liver enzymes.
Measuring the amount of free
testosterone in the blood can
yield information about problems
with the endocrine system and is
indicated especially in patients
with decreased sexual desire.
Other Tests
Monitoring erections that occur
during sleep (nocturnal penile
tumescence) can help rule out
certain psychological causes of
ED. Healthy men have involuntary
erections during sleep. If
nocturnal erections do not
occur, then ED is likely to have
a physical rather than
psychological cause. Tests of
nocturnal erections are not
completely reliable, however.
Scientists have not standardized
such tests and have not
determined when they should be
applied for best results.
Psychosocial
Examination
A psychosocial examination,
using an interview and a
questionnaire, reveals
psychological factors. A man's
sexual partner may also be
interviewed to determine
expectations and perceptions
during sexual intercourse.
How is ED treated?
Most physicians suggest that
treatments proceed from least to
most invasive. For some men,
making a few healthy lifestyle
changes may solve the problem.
Quitting smoking, losing excess
weight, and increasing physical
activity may help some men
regain sexual function.
Cutting back on any drugs
with harmful side effects is
considered next. For example,
drugs for high blood pressure
work in different ways. If you
think a particular drug is
causing problems with erection,
tell your doctor and ask whether
you can try a different class of
blood pressure medicine.
Psychotherapy and behavior
modifications in selected
patients are considered next if
indicated, followed by oral or
locally injected drugs, vacuum
devices, and surgically
implanted devices. In rare
cases, surgery involving veins
or arteries may be considered.
Psychotherapy
Experts often treat
psychologically based ED using
techniques that decrease the
anxiety associated with
intercourse. The patient's
partner can help with the
techniques, which include
gradual development of intimacy
and stimulation. Such techniques
also can help relieve anxiety
when ED from physical causes is
being treated.
Drug Therapy
Drugs for treating ED can be
taken orally, injected directly
into the penis, or inserted into
the urethra at the tip of the
penis. In March 1998, the Food
and Drug Administration (FDA)
approved Viagra, the first pill
to treat ED. Since that time,
vardenafil hydrochloride (Levitra)
and tadalafil (Cialis) have also
been approved. Additional oral
medicines are being tested for
safety and effectiveness.
Viagra, Levitra, and Cialis
all belong to a class of drugs
called phosphodiesterase (PDE)
inhibitors. Taken an hour before
sexual activity, these drugs
work by enhancing the effects of
nitric oxide, a chemical that
relaxes smooth muscles in the
penis during sexual stimulation
and allows increased blood flow.
While oral medicines improve
the response to sexual
stimulation, they do not trigger
an automatic erection as
injections do. The recommended
dose for Viagra is 50 mg, and
the physician may adjust this
dose to 100 mg or 25 mg,
depending on the patient. The
recommended dose for either
Levitra or Cialis is 10 mg, and
the physician may adjust this
dose to 20 mg if 10 mg is
insufficient. A lower dose of 5
mg is available for patients who
take other medicines or have
conditions that may decrease the
body's ability to use the drug.
Levitra is also available in a
2.5 mg dose.
None of these PDE inhibitors
should be used more than once a
day. Men who take nitrate-based
drugs such as nitroglycerin for
heart problems should not use
either drug because the
combination can cause a sudden
drop in blood pressure. Also,
tell your doctor if you take any
drugs called alpha-blockers,
which are used to treat prostate
enlargement or high blood
pressure. Your doctor may need
to adjust your ED prescription.
Taking a PDE inhibitor and an
alpha-blocker at the same time
(within 4 hours) can cause a
sudden drop in blood pressure.
Oral testosterone can reduce
ED in some men with low levels
of natural testosterone, but it
is often ineffective and may
cause liver damage. Patients
also have claimed that other
oral drugs—including yohimbine
hydrochloride, dopamine and
serotonin agonists, and
trazodone—are effective, but the
results of scientific studies to
substantiate these claims have
been inconsistent. Improvements
observed following use of these
drugs may be examples of the
placebo effect, that is, a
change that results simply from
the patient's believing that an
improvement will occur.
Many men achieve stronger
erections by injecting drugs
into the penis, causing it to
become engorged with blood.
Drugs such as papaverine
hydrochloride, phentolamine, and
alprostadil (marketed as
Caverject) widen blood vessels.
These drugs may create unwanted
side effects, however, including
persistent erection (known as
priapism) and scarring.
Nitroglycerin, a muscle
relaxant, can sometimes enhance
erection when rubbed on the
penis.
A system for inserting a
pellet of alprostadil into the
urethra is marketed as Muse. The
system uses a prefilled
applicator to deliver the pellet
about an inch deep into the
urethra. An erection will begin
within 8 to 10 minutes and may
last 30 to 60 minutes. The most
common side effects are aching
in the penis, testicles, and
area between the penis and
rectum; warmth or burning
sensation in the urethra;
redness from increased blood
flow to the penis; and minor
urethral bleeding or spotting.
Research on drugs for
treating ED is expanding
rapidly. Patients should ask
their doctor about the latest
advances.
Vacuum Devices
Mechanical vacuum devices cause
erection by creating a partial
vacuum, which draws blood into
the penis, engorging and
expanding it. The devices have
three components: a plastic
cylinder, into which the penis
is placed; a pump, which draws
air out of the cylinder; and an
elastic band, which is placed
around the base of the penis to
maintain the erection after the
cylinder is removed and during
intercourse by preventing blood
from flowing back into the body
(see figure 2).
 |
|
Figure 2.
A vacuum-constrictor
device causes an
erection by creating a
partial vacuum around
the penis, which draws
blood into the corpora
cavernosa. Pictured here
are the necessary
components: (a) a
plastic cylinder, which
covers the penis; (b) a
pump, which draws air
out of the cylinder; and
(c) an elastic ring,
which, when fitted over
the base of the penis,
traps the blood and
sustains the erection
after the cylinder is
removed. |
One variation of the vacuum
device involves a semirigid
rubber sheath that is placed on
the penis and remains there
after erection is attained and
during intercourse.
Surgery
Surgery usually has one of three
goals:
- to implant a device that
can cause the penis to
become erect
- to reconstruct arteries
to increase flow of blood to
the penis
- to block off veins that
allow blood to leak from the
penile tissues
Implanted devices, known as
prostheses, can restore erection
in many men with ED. Possible
problems with implants include
mechanical breakdown and
infection, although mechanical
problems have diminished in
recent years because of
technological advances.
Malleable implants usually
consist of paired rods, which
are inserted surgically into the
corpora cavernosa. The user
manually adjusts the position of
the penis and, therefore, the
rods. Adjustment does not affect
the width or length of the
penis.
Inflatable implants consist
of paired cylinders, which are
surgically inserted inside the
penis and can be expanded using
pressurized fluid (see figure
3). Tubes connect the cylinders
to a fluid reservoir and a pump,
which are also surgically
implanted. The patient inflates
the cylinders by pressing on the
small pump, located under the
skin in the scrotum. Inflatable
implants can expand the length
and width of the penis somewhat.
They also leave the penis in a
more natural state when not
inflated.
 |
|
Figure 3.
With an inflatable
implant, erection is
produced by squeezing a
small pump (a) implanted
in a scrotum. The pump
causes fluid to flow
from a reservoir (b)
residing in the lower
pelvis to two cylinders
(c) residing in the
penis. The cylinders
expand to create the
erection. |
Surgery to repair arteries
can reduce ED caused by
obstructions that block the flow
of blood. The best candidates
for such surgery are young men
with discrete blockage of an
artery because of an injury to
the crotch or fracture of the
pelvis. The procedure is almost
never successful in older men
with widespread blockage.
Surgery to veins that allow
blood to leave the penis usually
involves an opposite
procedure—intentional blockage.
Blocking off veins (ligation)
can reduce the leakage of blood
that diminishes the rigidity of
the penis during erection.
However, experts have raised
questions about the long-term
effectiveness of this procedure,
and it is rarely done.
Hope through Research
Advances in suppositories,
injectable medications,
implants, and vacuum devices
have expanded the options for
men seeking treatment for ED.
These advances have also helped
increase the number of men
seeking treatment. Gene therapy
for ED is now being tested in
several centers and may offer a
long-lasting therapeutic
approach for ED.
The National Institute of
Diabetes and Digestive and
Kidney Diseases (NIDDK) sponsors
programs aimed at understanding
the causes of erectile
dysfunction and finding
treatments to reverse its
effects. NIDDK's Division of
Kidney, Urologic, and
Hematologic Diseases supported
the researchers who developed
Viagra and continue to support
basic research into the
mechanisms of erection and the
diseases that impair normal
function at the cellular and
molecular levels, including
diabetes and high blood
pressure.
Points to Remember
- Erectile dysfunction
(ED) is the repeated
inability to get or keep an
erection firm enough for
sexual intercourse.
- ED affects 15 to 30
million American men.
- ED usually has a
physical cause.
- ED is treatable at all
ages.
- Treatments include
psychotherapy, drug therapy,
vacuum devices, and surgery.
For
More Information
American Urological
Association (AUA)
1000 Corporate Boulevard
Linthicum, MD 21090
Phone: 1–866–RING–AUA (746–4282)
or 410–689–3700
Fax: 410–689–3800
Email:
aua@auanet.org
Internet:
www.auanet.org
www.urologyhealth.org
AUA can refer you to a urologist
in your area.
American Diabetes
Association (ADA)
Attn: National Call Center
1701 North Beauregard Street
Alexandria, VA 22311
Phone: 1–800–DIABETES (342–2383)
Internet:
www.diabetes.org
ADA can help you find a doctor
who specializes in diabetes care
in your area.
American Association of
Sex Educators, Counselors, and
Therapists (AASECT)
P.O. Box 1960
Ashland, VA 23005–1960
Phone: 804–752–0026
Fax: 804–752–0056
Internet:
www.aasect.org
Check the AASECT website to find
a certified sexuality educator,
counselor, or therapist in your
area.
The U.S. Government does not
endorse or favor any specific
commercial product or company.
Trade, proprietary, or company
names appearing in this document
are used only because they are
considered necessary in the
context of the information
provided. If a product is not
mentioned, the omission does not
mean or imply that the product
is unsatisfactory.
National Kidney and Urologic
Diseases Information
Clearinghouse
3 Information Way
Bethesda, MD 20892–3580
Phone: 1–800–891–5390
TTY: 1–866–569–1162
Fax: 703–738–4929
Email:
nkudic@info.niddk.nih.gov
Internet:
www.kidney.niddk.nih.gov
The National Kidney and
Urologic Diseases Information
Clearinghouse (NKUDIC) is a
service of the National
Institute of Diabetes and
Digestive and Kidney Diseases (NIDDK).
The NIDDK is part of the
National Institutes of Health of
the U.S. Department of Health
and Human Services. Established
in 1987, the Clearinghouse
provides information about
diseases of the kidneys and
urologic system to people with
kidney and urologic disorders
and to their families, health
care professionals, and the
public. The NKUDIC answers
inquiries, develops and
distributes publications, and
works closely with professional
and patient organizations and
Government agencies to
coordinate resources about
kidney and urologic diseases.
Publications produced by the
Clearinghouse are carefully
reviewed by both NIDDK
scientists and outside experts.
This publication was reviewed by
Arnold Melman, M.D., Montefiore
Medical Center, Bronx, NY; and
Mark Hirsch, M.D., U.S. Food and
Drug Administration.
This publication is not
copyrighted. The Clearinghouse
encourages users of this
publication to duplicate and
distribute as many copies as
desired. |
