General Description
Impotence, or erectile dysfunction (ED), is the inability of a male
to sustain an erection sufficient for sexual intercourse. It may
be a total inability to achieve an erection, an inconsistent ability
to do so, or a tendency to sustain only brief erections. Experts
believe impotence affects between 10 and 15 million American men.1
Although ED may be caused by psychological or emotional factors,
most cases have a physical cause such as disease, injury, or drug
side effects. Any disorder that impairs blood flow to the penis
has the potential to cause impotence. Although the incidence of
impotence increases with age (about 5 percent of men at age 40 experience
ED, compared to 15 to 25 percent at age 65), it is not an inevitable
part of aging. At all ages, impotence is treatable through a variety
of methods, including psychotherapy, drug therapy, vacuum devices,
and surgery.
Contributing factors
Erection begins with sensory and mental stimulation. Impulses
from the brain cause muscles in the penis to relax, allowing blood
to fill two chambers (the corpora cavernosa) that run the length
of the organ, causing it to expand. An elastic sheath, called
the tunica albuginia, helps trap blood inside the corpora cavernosa,
thereby sustaining erection. Erection is reversed when muscles
in the penis contract, stopping the inflow of blood and opening
the outflow channels. Since an erection requires a sequence of
events (including nerve impulses in the brain, spinal column,
and the area of the penis; and responses in muscles, fibrous tissues,
and blood vessels), impotence can occur when any of the events
is disrupted.
Damage to arteries, smooth muscles, and fibrous tissues, often
as a result of disease or injury to the penis, spinal cord, prostate,
bladder, or pelvis, is the most common cause of impotence. About
70 percent of ED cases are caused by diseases such as diabetes,
kidney disease, chronic alcoholism, multiple sclerosis, atherosclerosis,
and vascular disease. Between 35 and 50 percent of men with diabetes
experience impotence. ED can also result when surgery (for example,
prostate surgery) injures nerves and arteries near the penis.
Many common medications, including blood pressure medications,
antihistamines, antidepressants, tranquilizers, appetite suppressants,
and ulcer drugs, produce impotence as a side effect.
Other possible causes of impotence are smoking, which affects
blood flow in the veins and arteries; hormonal abnormalities,
such as insufficient testosterone; and psychological factors such
as stress, anxiety, guilt, depression, low self-esteem, and fear
of sexual failure. Experts believe that psychological factors
cause 10 to 20 percent of ED cases.1 Although
such factors are broadly associated with more than 80 percent
of impotence cases, they are usually secondary reactions to underlying
physical causes.
Conventional treatment
Most physicians suggest that treatments for impotence proceed
along a path moving from least invasive to most invasive. This
means eliminating or cutting back on any harmful drugs is considered
first. Psychotherapy and behavior modifications are considered
next, followed by vacuum devices, oral drugs, injected drugs,
and surgically implanted devices (and, in rare cases, surgery
involving veins or arteries). Psychotherapy, which involves techniques
that decrease anxiety associated with intercourse, is most often
used to treat psychologically based ED. Such techniques can also
help relieve anxiety in people with physical impotence.
Drugs for treating impotence 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 approved
sildenafil citrate (Viagra) as an oral pill for treatment of ED.
Taken one hour before sexual activity, sildenafil works by enhancing
the effects of nitric oxide, a chemical in the body that relaxes
the penis during sexual stimulation, allowing increased blood
flow. Sildenafil does not trigger an automatic erection as injected
drugs do. Oral administration of the amino acid L-arginine boosts
nitric oxide levels and may improve sexual function in ED caused
by low nitric oxide production.2 Oral testosterone
may benefit men with impotence caused by low natural testosterone
production. Injection drugs, which work by widening blood vessels
in the penis, can be very effective in treating ED, but they may
cause side effects such as scarring and persistent erection (priapism).
Mechanical vacuum devices cause erection by creating a partial
vacuum around the penis, drawing blood into the organ. An elastic
band is placed around the base of the penis to maintain erection
during intercourse by preventing blood from flowing back into
the body. Surgically implanted devices, known as prostheses, can
also be used to restore erection. These include malleable rods,
which can be manually adjusted to manipulate the postition of
the penis, and inflatable devices, which use a small pump to draw
fluid from a small reservoir and expand the length and width of
the penis. In a small number of cases, surgical procedures may
be performed to open obstructed arteries and increase blood flow
to the penis or to block veins that carry blood away from the
organ.
Nutritional/lifestyle considerations
A number of dietary and lifestyle factors can play a role in improving
sexual potency. Tobacco, alcohol, and caffeine can contribute
to impotence and should be avoided. Studies have shown that exercises
that strengthen the pelvic muscles (such as Kegel exercises) can
provide satisfactory improvement in many ED cases.3
Because stress can be an important factor in ED, relaxation techniques
are helpful for many men. Several nutrients such as zinc,4,5
vitamin A, vitamin E, and niacin, which contribute to hormone
production and circulatory health, play important roles in healthy
sexual function. Preliminary studies indicate that DHEA, a hormone
marketed as a dietary supplement, may improve sexual potency in
some men.6,7 Although a number of herbs (yohimbe,
Ginkgo biloba, tribulus, ginseng, green oats, muira puama, damiana,
et al.) are reputed to have aphrodisiac effects, most of these
claims lack scientific support. However, some studies suggest
that yohimbe,8-12 ginkgo,13
ginseng,14 and tribulus15
may have some value in improving sexual function. |
