Impotence
Impotence
Definition
Impotence, often called erectile dysfunction, is the inability to achieve or maintain an erection long enough to engage in sexual intercourse.
Description
Under normal circumstances, when a man is sexually stimulated, his brain sends a message down the spinal cord and into the nerves of the penis. The nerve endings in the penis release chemical messengers, called neurotransmitters, that signal the corpora cavernosa (the two spongy rods of tissue that span the length of the penis) to relax and fill with blood. As they expand, the corpora cavernosa close off other veins that would normally drain blood from the penis. As the penis becomes engorged with blood, it enlarges and stiffens, causing an erection. Problems with blood vessels, nerves, or tissues of the penis can interfere with an erection.
Causes and symptoms
It is estimated that up to 20 million American men frequently suffer from impotence and that it strikes up to half of all men between the ages of 40 and 70. Doctors used to think that most cases of impotence were psychological in origin, but they now recognize that, at least in older men, physical causes may play a primary role in 60% or more of all cases. In men over the age of 60, the leading cause is atherosclerosis, or narrowing of the arteries, which can restrict the flow of blood to the penis. Injury or disease of the connective tissue, such as Peyronie's disease, may prevent the corpora cavernosa from completely expanding. Damage to the nerves of the penis, from certain types of surgery or neurological conditions, such as Parkinson's disease or multiple sclerosis, may also cause impotence. Men with diabetes are especially at risk for impotence because of their high risk of both atherosclerosis and a nerve disease called diabetic neuropathy.
Certain types of blood pressure medications, antiulcer drugs, antihistamines, tranquilizers (especially before intercourse), antifungals (hetoconazole), antipsychotics, antianxiety drugs, and antidepressants, known as selective serotonin reuptake inhibitors (SSRIs, including Prozac and Paxil), can interfere with erectile function. Smoking, excessive alcohol consumption, and illicit drug use may also contribute. In rare cases, low levels of the male hormone testosterone may contribute to erectile failure. Finally, psychological factors, such as stress, guilt, or anxiety, may also play a role, even when the impotence is primarily due to organic causes.
Diagnosis
The doctor also obtains a thorough medical history to find out about past pelvic surgery, diabetes, cardiovascular disease, kidney disease, and any medications the man may be taking. The physical examination should include a genital examination, a measurement of blood flow through the penis, hormone tests, and a glucose test for diabetes.
In some cases, nocturnal penile tumescence testing is performed to find out whether the man has erections while asleep. Healthy men usually have about four or five erections throughout the night. The man applies a device to the penis called a Rigiscan before going to bed at night, and the device can determine whether he has had erections. (If a man is able to have normal erections at night, this suggests a psychological cause for his impotence.)
Treatment
Years ago, the standard treatment for impotence was an implantable penile prosthesis or long-term psychotherapy. Although physical causes are now more readily diagnosed and treated, individual or marital counseling is still an effective treatment for impotence when emotional factors play a role. Fortunately, other approaches are now available to treat the physical causes of impotence.
Medications
The first line and by far the most common treatment today is with the prescription drug sildenafil citrate, sold under the brand name Viagra. An estimated 20 million prescriptions for the pill have been filled since it was approved by the FDA in March 1998. It is also the most effective treatment with a success rate of more than 60%. The drug boosts levels of a substance called cyclic GMP, which is responsible for widening the blood vessels of the penis. In clinical studies, Viagra produced headaches in 16% of men who took it, and other side effects included flushing, indigestion, and stuffy nose.
The primary drawback to Viagra, which works about an hour after it is taken, it that the FDA cautions men with heart disease or low blood pressure to be thoroughly examined by a physician before obtaining a prescription.
In the summer of 2002, two investigational drugs were announced to become available in the near future to also treat erectile dysfunction. Vardenafil and tadalafil both helped men who also had such conditions as diabetes, high blood pressure and benign prostatic hypertrophy. The drugs are awaiting final FDA approval.
Vardenafil and tadalafil belong to the same group of chemical compounds as sildenafil, namely phos-phodiesterase type 5 (PDE-5) inhibitors. Some men cannot benefit from sildenafil or the two newer PDE-5 inhibitors because they have low levels of nitric oxide. British investigators reported in late 2002 that three different types of compounds are being studied as possible medications for men with low levels of nitric oxide. They are Rho-kinase inhibitors, soluble guanylate cyclase activators, and nitric oxide-releasing PDE-5 inhibitors.
Other medications under investigation as treatments for impotence are topical agents. Topical means that they are applied externally to the skin rather than being injected or taken by mouth. If approved, these drugs would provide a noninvasive alternative for men who cannot take sildenafil or other oral medications for impotence.
Injection therapy involves injecting a substance into the penis to enhance blood flow and cause an erection. The Food and Drug Administration (FDA) approved a drug called alprostadil (Caverject) for this purpose in July of 1995. Alprostadil relaxes smooth muscle tissue to enhance blood flow into the penis. It must be injected shortly before intercourse. Another, similar drug that is sometimes used is papaverine—not yet been approved by the FDA for this use. Either drug may sometimes cause painful erections or priapism (uncomfortable, prolonged erections) that must be treated with a shot of epinephrine.
Alprostadil may also be administered into the urethral opening of the penis. In MUSE (medical urethral system for erection), the man inserts a thin tube the width of a vermicelli noodle into his urethral opening and presses down on a plunger to deliver a tiny pellet containing alprostadil into his penis. The drug takes about 10 minutes to work and the erection lasts about an hour. The main side effect is a sensation of pain and burning in the urethra, which can last about five to 15 minutes.
Mechanical and surgical treatments
Another approach is vacuum therapy. The man inserts his penis into a clear plastic cylinder and uses a pump to force air out of the cylinder. This forms a partial vacuum around the penis, which helps to draw blood into the corpora cavernosa. The man then places a special ring over the base of the penis to trap the blood inside it. The only side effect with this type of treatment is occasional bruising if the vacuum is left on too long.
Implantable penile prostheses are usually considered a last resort for treating impotence. They are implanted in the corpora cavernosa to make the penis rigid without the need for blood flow. The semirigid type of prosthesis consists of a pair of flexible silicone rods that can be bent up or down. This type of device has a low failure rate but, unfortunately, it causes the penis to always be erect, which can be difficult to conceal under clothing.
The inflatable type of device consists of cylinders that are implanted in the corpora cavernosa, a fluid reservoir implanted in the abdomen, and a pump placed in the scrotum. The man squeezes the pump to move fluid into the cylinders and cause them to become rigid. (He reverses the process by squeezing the pump again.) While these devices allow for intermittent erections, they have a slightly higher malfunction rate than the silicon rods.
Men can return to sexual activity six to eight weeks after implantation surgery. Since implants affect the corpora cavernosa, they permanently take away a man's ability to have a natural erection.
In rare cases, if narrowed or diseased veins are responsible for impotence, surgeons may reroute the blood flow into the corpus cavernosa or remove leaking vessels. However, the success rate with these procedures has been very low, and they are still considered experimental.
Gene therapy
A newer investigational approach to the treatment of erectile dysfunction is gene therapy. As of late 2002, several preclinical studies have shown promise, but none of the gene-based strategies so far have yet been tested for safety.
Alternative treatment
A number of herbs have been promoted for treating impotence. The most widely touted herbs for this purpose are Coryanthe yohimbe (available by prescription as yohimbine, with the trade name Yocon) and gingko (Gingko biloba ), although neither has been conclusively shown to help the condition in controlled studies. In addition, gingko carries some risk of abnormal blood clotting and should be avoided by men taking blood thinners such as coumadin. Other herbs promoted for treating impotence include true unicorn root (Aletrius farinosa ), saw palmetto (Serenoa repens ), ginseng (Panax ginseng ), and Siberian ginseng (Eleuthrococcus senticosus ). Strychnos Nux vomica has been recommended, especially when impotence is caused by excessive alcohol, cigarettes, or dietary indiscretions, but it can be very toxic if taken improperly, so it should be used only under the strict supervision of a physician trained in its use.
Prognosis
With proper diagnosis, impotence can nearly always be treated or managed successfully. Unfortunately, fewer than 10% of impotent men seek treatment.
Prevention
There is no specific treatment to prevent impotence. Perhaps the most important measure is to maintain general good health and avoid atherosclerosis by exercising regularly, controlling weight, controlling hypertension and high cholesterol levels, and avoiding smoking. Avoiding excessive alcohol intake may also help.
Resources
BOOKS
Beers, Mark H., MD, and Robert Berkow, MD, editors. "Erectile Dysfunction." Section 17, Chapter 220. In The Merck Manual of Diagnosis and Therapy. Whitehouse Station, NJ: Merck Research Laboratories, 2004.
Miller, Lucinda G., and Wallace J. Murray, editors. Herbal Medicinals: A Clinician's Guide. Binghamton, N.Y.: Haworth Press, 1999.
Pelletier, Kenneth R., MD. The Best Alternative Medicine, Part II. "CAM Therapies for Specific Conditions: Impotence." New York: Simon & Schuster, 2002.
PERIODICALS
Campbell, Adam. "Soft Science: The Exclusive World on Which Sex Supplements may Help and Which Won't." Men's Health May 2002: 100.
Cellek, S., R. W. Rees, and J. Kalsi. "A Rho-Kinase Inhibitor, Soluble Guanylate Cyclase Activator and Nitric Oxide-Releasing PDE5 Inhibitor: Novel Approaches to Erectile Dysfunction." Expert Opinion on Investigational Drugs 11 (November 2002): 1563-1573.
Christ, G. J. "Gene Therapy for Erectile Dysfunction: Where Is It Going?" Current Opinion in Urology 12 (November 2002): 497-501.
Cowley, Geoffrey. "Looking Beyond Viagra." Newsweek April 24, 2000: 77.
Gresser, U., and C. H. Gleiter. "Erectile Dysfunction: Comparison of Efficacy and Side Effects of the PDE-5 Inhibitors Sildenafil, Vardenafil and Tadalafil—Review of the Literature." European Journal of Medical Research 7 (October 29, 2002): 435-446.
"Is Viagra Safe?" Internal Medicine Alert June 29, 2002: 90.
Norton, Patrice G.W. "Investigational Drugs in Erectile Dysfunction. (Vardenafil, Tadalafil)." Internal Medicine News June 1, 2002: 50.
Yap, R. L., and K. T. McVary. "Topical Agents and Erectile Dysfunction: Is There a Place?" Current Urology Reports 3 (December 2002): 471-476.
"Yohimbe Tree Bark: Herbal Viagra Better Gotten by Rx." Environmental Nutrition February 1999: 8.
ORGANIZATIONS
American Foundation for Urologic Disease. 1128 North Charles Street, Baltimore, MD 21201. (410) 468-1800.
American Urological Association (AUA). 1120 North Charles Street, Baltimore, MD 21201. (410) 727-1100. 〈www.auanet.org〉.
Center for Biologics Evaluation and Research (CBER), U. S. Food and Drug Administration (FDA). 1401 Rockville Pike, Rockville, MD 20852-1448. (800) 835-4709 or (301) 827-1800. 〈www.fda.gov/cber〉.
Impotence Institute of America, Impotents Anonymous. 10400 Little Patuxent Parkway, Suite 485, Columbia, MD 21044-3502. (800) 669-1603.
National Kidney and Urologic Diseases Information Clearinghouse. 3 Information Way, Bethesda, MD 20892-3580. (800) 891-5390.
KEY TERMS
Alprostadil— A smooth muscle relaxant sometimes injected into the penis or applied to the urethral opening to treat impotence.
Atherosclerosis— A disorder in which plaques of cholesterol, lipids, and other debris build up on the inner walls of arteries, narrowing them.
Corpus cavernosum (plural, corpora cavernosa)— One of two rods of spongy tissue in the penis that become engorged with blood in order to produce an erection.
Gene therapy— A menthod of treating a disorder by replacing damaged or abnormal genes with normal ones. Some researchers think that gene therapy may offer a new way to treat impotence.
Neurotransmitters— Chemicals that modify or help transmit impulses between nerve synapses.
Papaverine— A smooth muscle relaxant sometimes injected into the penis as a treatment for impotence.
Peyronie's disease— A disease resulting from scarring of the corpus cavernosa, causing painful erections.
Topical— A type of medication that is applied to a specific and limited area of skin, and affects only the area to which it is applied.
Urethra— The small tube that drains urine from the bladder, as well as serving as a conduit for semen during ejaculation in men.
Viagra— Trade name of an orally administered drug for erectile failure first cleared for marketing in the United States in March 1998. Its generic name is sildenafil citrate.
Impotence
Impotence
Definition
Impotence, also known as erectile dysfunction, is the inability to achieve or maintain an erection long enough to engage in sexual intercourse.
Description
Under normal circumstances, when a man is sexually stimulated, his brain sends a message down the spinal cord and into the nerves of the penis. The nerve endings in the penis release chemical messengers, called neurotransmitters, that signal the arteries that supply blood to the corpora cavernosa (the two spongy rods of tissue that span the length of the penis) to relax and fill with blood. As they expand, the corpora cavernosa close off other veins that would normally drain blood from the penis. As the penis becomes engorged with blood, it enlarges and stiffens, causing an erection. Problems with blood vessels, nerves, or tissues of the penis can interfere with an erection.
Causes & symptoms
It is estimated that as many as 20 million American men frequently suffer from impotence and that it strikes up to half of all men between the ages of 40 and 70. Doctors used to think that most cases of impotence were psychological in origin, but they now recognize that, at least in older men, physical causes may play a primary role in 60% or more of all cases. In men over the age of 60, the leading cause is atherosclerosis , or narrowing of the arteries, which can restrict the flow of blood to the penis. Injury or disease of the connective tissue, such as Peyronie's disease, may prevent the corpora cavernosa from completely expanding. Damage to the nerves of the penis from certain types of surgery or neurological conditions, such as Parkinson's disease or multiple sclerosis , may also cause impotence. Men with diabetes are especially at risk for impotence because of their high risk of both atherosclerosis and a nerve disease called diabetic neuropathy.
Some drugs, including certain types of blood pressure medications, antihistamines, tranquilizers (especially when taken before intercourse), and antidepressants known as selective serotonin reuptake inhibitors (SSRIs, including Prozac and Paxil) can interfere with erections. Smoking , excessive alcohol consumption, and illicit drug use may also contribute. In some cases, low levels of the male hormone testosterone may contribute to erectile failure. Finally, such psychological factors as stress , guilt, or anxiety , may also play a role, even when the impotence is primarily due to organic causes.
Diagnosis
When diagnosing the underlying cause of impotence, the doctor begins by asking the man a number of questions about when the problem began, whether it only happens with specific sex partners, and whether he ever wakes up with an erection. (Men whose dysfunction occurs only with certain partners or who wake up with erections are more likely to have a psychological cause for their impotence.) Sometimes, the man's sex partner is also interviewed. In some cases, domestic discord may be a factor.
The doctor also obtains a thorough medical history to find out about past pelvic surgery, diabetes, cardiovascular disease, kidney disease, and any medications the man may be taking. The physical examination should include a genital examination, hormone tests, and a glucose test for diabetes. Sometimes a measurement of blood flow through the penis may be taken.
Alternative health practitioners often forgo such extensive testing and rely on information obtained from the patient. Usually the fact that the man cannot get or maintain an erection is reason enough to begin alternative or holistic therapy.
Treatment
A number of herbs have been promoted for treating impotence. The most widely touted is yohimbe (Corynanthe yohimbe ), derived from the bark of the yohimbe tree native to West Africa. It has been used in Europe for about 75 years to treat erectile dysfunction. The FDA approved yohimbe as a treatment for impotence in the late 1980s. It is sold as an over-the-counter dietary supplement and as a prescription drug under brand names such as Yocon, Aphrodyne, Erex, Yohimex, Testomar, Yohimbe, and Yovital.
There is no clear medical research that indicates exactly how or why yohimbe works in treating impotence. It is generally believed that yohimbe dilates blood vessels and stimulates blood flow to the penis, causing an erection. It also prevents blood from flowing out of the penis during an erection. It may also act on the central nervous system, specifically the lower spinal cord area where sexual signals are transmitted. Studies show it is effective in 30–40% of men with impotence. It is primarily effective in men with impotence caused by vascular, psychogenic (originating in the mind), or diabetic problems. It usually does not work in men whose impotence is caused by organic nerve damage. In healthy men without impotence, yohimbe in some cases appears to increase sexual stamina and prolong erections.
The usual dosage of yohimbine (yohimbe extract) to treat erectile dysfunction is 5.4 mg three times a day. It may take three to six weeks for it to take effect. Most commercially available supplements don't contain enough yohimbe to be effective. Doctors recommend obtaining a prescription for yohimbe to get enough active ingredient for success.
Ginkgo (Ginkgo biloba ) is also used to treat impotence, although it has not been shown to help the condition in controlled studies and probably has more of a psychological effect. In addition, ginkgo carries some risk of abnormal blood clotting and should be avoided by men taking such blood thinners, as coumadin. Other herbs promoted for treating impotence include true unicorn root (Aletrius farinosa ), saw palmetto (Serenoa repens ), ginseng (Panax ginseng ), and Siberian ginseng (Eleuthrococcus senticosus ). Nux vomica (Strychnos nux-vomica ) has been recommended, especially when impotence is caused by excessive alcohol, cigarettes, or dietary indiscretions. Nux vomica can be very toxic if taken improperly, so it should be used only under the strict supervision of a physician trained in its use.
There are quite a few Chinese herbal remedies for impotence, usually combinations of herbs and sometimes such animal parts as deer antler and sea horse.
Allopathic treatment
Years ago, the standard treatment for impotence was a penile implant or long-term psychotherapy . Although physical causes are now more readily diagnosed and treated, individual or marital counseling is still an effective treatment for impotence when emotional factors play a role. Fortunately, other approaches are now available to treat the physical causes of impotence.
The most common treatment today is with the prescription drug sildenafil citrate, sold under the brand name Viagra. An estimated 20 million prescriptions for the pill have been filled since it was approved by the FDA in March 1998. It is also the most effective treatment, with a success rate of more than 60%. The drug boosts levels of a substance called cyclic GMP, which is responsible for widening the blood vessels of the penis. In clinical studies, Viagra produced headaches in 16% of men who took it, and other side effects included flushing, indigestion , and stuffy nose.
The primary drawback to Viagra, which works about an hour after it is taken, is that the FDA cautions men with heart disease or low blood pressure to be thoroughly examined by a physician before obtaining a prescription. At least 130 men have died while taking Viagra. Shortly after use of the drug skyrocketed, concerns were expressed over cardiovascular effects from Viagra. However, studies reported in 2002 that sildenafil had no effect on cardiac symptoms in older men who used it. Instead, cardiac events reported with use of Viagra are more likely the result of the physical demands of sexual activity in patients using the drug who were already at higher risk for cardiovascular disease.
In the summer of 2002, two investigational drugs were announced to become available in the near future to also treat erectile dysfunction. Vardenafil and tadalafil both helped men who also had such conditions as diabetes, high blood pressure and benign prostatic hypertrophy. The drugs are awaiting final FDA approval.
Vardenafil and tadalafil belong to the same group of chemical compounds as sildenafil, namely phosphodiesterase type 5 (PDE-5) inhibitors. Some men cannot benefit from sildenafil or the two newer PDE-5 inhibitors because they have low levels of nitric oxide. British investigators reported in late 2002 that three different types of compounds are being studied as possible medications for men with low levels of nitric oxide. They are Rho-kinase inhibitors, soluble guanylate cyclase activators, and nitric oxide-releasing PDE-5 inhibitors.
Other medications under investigation as treatments for impotence are topical agents. Topical means that they are applied externally to the skin rather than being injected or taken by mouth. If approved, these drugs would provide a noninvasive alternative for men who cannot take sildenafil or other oral medications for impotence.
Other traditional therapies for impotence include vacuum pump therapy, injection therapy involving injecting a substance into the penis to enhance blood flow, and a penile implantation device. In rare cases, if narrowed or diseased veins are responsible for impotence, surgeons may reroute the blood flow into the corpus cavernosa or remove leaking vessels.
A newer approach to the treatment of erectile dysfunction is gene therapy. As of late 2002, several preclinical studies have shown promise, but none of the gene-based strategies so far have yet been tested for safety.
Expected results
With proper diagnosis, impotence can nearly always be treated or coped with successfully. Unfortunately, fewer than 10% of impotent men seek treatment.
Prevention
There is no specific treatment to prevent impotence. Perhaps the most important measure is to maintain general good health and avoid atherosclerosis by exercising regularly, controlling weight, controlling hypertension and high cholesterol levels, and not smoking. Avoiding excessive alcohol intake may also help.
Resources
BOOKS
"Erectile Dysfunction." Section 17, Chapter 220 in The Merck Manual of Diagnosis and Therapy, edited by Mark H. Beers, MD, and Robert Berkow, MD. Whitehouse Station, NJ: Merck Research Laboratories, 1999.
Miller, Lucinda G., and Wallace J. Murray, eds. Herbal Medicinals: A Clinician's Guide. Binghamton, N.Y.: Haworth Press, 1999.
Pelletier, Kenneth R., MD. The Best Alternative Medicine, Part II, "CAM Therapies for Specific Conditions: Impotence." New York: Simon & Schuster, 2002.
Robbers, James E., and Varro E. Tyler. Tyler's Herbs of Choice: The Therapeutic Use of Phytomedicinals. Binghamton, N.Y.: Haworth Press, 1998.
Ryan, George. Reclaiming Male Sexuality: A Guide to Potency, Vitality, and Prowess. New York: M. Evans and Co., 1997.
PERIODICALS
Campbell, Adam. "Soft Science: The Exclusive World on Which Sex Supplements May Help and Which Won't." Men's Health (May 2002): 100.
Cellek, S., R. W. Rees, and J. Kalsi. "A Rho-Kinase Inhibitor, Soluble Guanylate Cyclase Activator and Nitric Oxide-Releasing PDE5 Inhibitor: Novel Approaches to Erectile Dysfunction." Expert Opinion on Investigational Drugs 11 (November 2002): 1563–1573.
Christ, G. J. "Gene Therapy for Erectile Dysfunction: Where Is It Going?" Current Opinion in Urology 12 (November 2002): 497–501.
Cowley, Geoffrey. "Looking Beyond Viagra." Newsweek (April 24, 2000): 77.
Gresser, U., and C. H. Gleiter. "Erectile Dysfunction: Comparison of Efficacy and Side Effects of the PDE-5 Inhibitors Sildenafil, Vardenafil and Tadalafil—Review of the Literature." European Journal of Medical Research 7 (October 29, 2002): 435–446.
"Is Viagra Safe?" Internal Medicine Alert (June 29, 2002): 90. Norton, Patrice G.W. "Investigational Drugs in Erectile Dys-function. (Vardenafil, Tadalafil)." Internal Medicine News (June 1, 2002): 50.
Yap, R. L., and K. T. McVary. "Topical Agents and Erectile Dysfunction: Is There a Place?" Current Urology Reports 3 (December 2002): 471–476.
"Yohimbe Tree Bark: Herbal Viagra Better Gotten by Rx." Environmental Nutrition (February 1999): 8.
ORGANIZATIONS
American Foundation for Urologic Disease. 1128 North Charles Street, Baltimore, MD 21201. (800) 242-2383. <http://www.afud.org>.
American Urological Association (AUA). 1120 North Charles Street, Baltimore, MD 21201. (410) 727-1100. <www.auanet.org>.
Center for Biologics Evaluation and Research (CBER), U. S. Food and Drug Administration (FDA). 1401 Rockville Pike, Rockville, MD 20852-1448. (800) 835-4709 or (301) 827-1800. <www.fda.gov/cber>.
Impotence Institute of America, Impotents Anonymous. 10400 Little Patuxent Parkway, Suite 485, Columbia, MD 21044-3502. (800) 669-1603.
National Kidney and Urologic Diseases Information Clearing-house. 3 Information Way, Bethesda, MD 20892-3580. 800-891-5390. http://www.niddk.nih.gov/health/kidney/nkudic.htm.
OTHER
"Yohimbine." Drkoop.com. http://www.drkoop.com/hcr/drugstory/pharmacy/leaflets/english/d01386a1.asp.
Ken R. Wells
Rebecca J. Frey, PhD
impotence
Erections of the penis occur for sexual purposes and also during the night during REM (rapid eye movement) sleep. Impotence is usually understood to mean a lack of sufficient firmness and stiffness of the penis at the time of sexual intercourse. For a normal sexual erection the following events must occur: (i) There needs to be sufficient sexual stimulus. This can be sexy mind pictures, seeing one's partner naked, the smell of one's partner or the touch of one's partner, and these stimuli are particularly intense with a new partner. Impotence often occurs at a time of life when these various stimuli are less attractive than before.(ii) As the penis starts to become erect there is a relaxation of muscle fibres in the walls of the penile arteries, and as a result there is increased blood flow into the penis. In older men with high blood pressure and hardening of the arteries this increased blood flow occurs less readily.(iii) At the same time as more blood enters the penis there is relaxation of muscle fibres inside the twin erectile bodies (corpora cavernosa) in response to nitric oxide released from nerve endings within them. As a result of the increased blood flow and relaxation of corpora cavernosal muscle there is an increased pressure within the erectile bodies, and this shuts off exit veins from the penis, thus the erect penis is firm and warm. We now know that the health of the erectile muscle is maintained by periodic perfusion with warm arterial blood. When the penis is soft and cold and containing only a little venous blood the oxygen tension within the corpora cavernosa is very low. If periodic erections do not occur there is progressive damage to the erectile muscle which is gradually replaced by fibrous tissue and becomes less responsive to nitric oxide. Thus, there is truth in the saying ‘Use it or lose it’.
There are a number of physical causes for erectile failure. Damage to the local peripheral nerves or blood vessels, injury or disease of the spinal cord, ageing, conditions causing narrowing or obstruction of the blood vessels, neurological disorders, hormonal deficiencies, diabetes, and some drugs can all have this effect. Local conditions leading to impotence include priapism — a persistent and painful erection, which may result for reasons not fully understood in permanent erectile failure — and Peyronie's disease, which causes the penis to bend to one side during erection. However, although it is now recognized that physical factors may contribute to a far greater number of cases of impotence than previously supposed, in many cases the aetiology is psychological. Like other apparently reflex physical actions, erection can be affected by the state of mind of the individual. Given that sexual interaction is an emotionally-laden area of life, impotence may occur especially in situations which are felt to be particularly stressful and in which there is considerable pressure on the male to ‘perform’, for example on the first occasion with a new partner. A considerable percentage of men experience intermittent and situational impotence.
Failure of sexual power is still regarded as a slur on the manhood of an individual and is very seldom admitted to, in spite of being perhaps one of the most common of sexual difficulties. So sensitive a subject is it that men tend not to take the problem to their general practitioners but seek out various forms of private assistance. The aid to failing manhood once offered by dubious quacks in newspaper small advertisements is now offered by ‘Well Man’ clinics and similar institutions via explicit advertisements in the quality papers covering several column inches, and indeed on World Wide Web pages.
There are a number of procedures which the physician can deploy to assess erectile function and to determine whether the failure is psychological in origin or whether there is some organic cause. Simple measures are ascertaining whether erections take place during sleep (using a mercury-in-rubber strain gauge) or in response to erotic materials, though the first is not always practicable and the second may not be personally or culturally acceptable. If erection occurs, this does not totally exclude physical causes, but strongly suggests psychological causation. Other means of investigation are seldom as non-invasive. Moreover, investigations into penile blood flow during erection and other vascular phenomena, and on the nerve system of the penis, show rather contradictory results, which limit their usefulness as tests.
Injections into the corpora cavernosa may be used as a diagnostic procedure to assess erectile response, and have been enthusiastically taken up by some practitioners as a treatment. This appears to be effective in cases where there is a neurological reason for erectile failure, and some cases of psychological origin also respond to this treatment, but there are problems in cases with severe damage to the blood supply.
For psychogenic impotence, or when there are contributing psychological factors, the central problem is usually to overcome the negative pattern established by performance anxiety. Use of ‘sensate focus’ techniques may be advised, encouraging the man to engage in various forms of pleasurable touching and stimulation without obligation to attain an erection and attempt penetrative intercourse. For premature ejaculation, the use of ‘stop-start’ (reaching a state of high arousal, ceasing stimulation, and then resuming) and ‘squeeze’ techniques (firmly squeezing the tip of the penis to prevent ejaculation), though requiring much repetition in order to break the old habit and establish the new, has been shown to be of some benefit. Sometimes the impotence is due to deeper and more longstanding problems for which psychotherapy may be advised.
Recently, various medicines have been found to exaggerate the nitric oxide stimulus that relaxes the corpora cavernosal muscle. The medicine in most general use in the UK in the 1990s was self-injection of prostaglandin or alternatively a urethral prostaglandin pellet. However, oral tablets containing a phospho-diesterase inhibitor, sildenifil, (trade name Viagra) are nearly as effective and have become the first line treatment throughout the world. An interesting side-effect, experienced by 5–10% of men is an alteration in the perception of light and this is explained by sildenifil inhibiting also phosphdiesterase-6, which is found in cells in the retina of the eye. When men experience this side effect, light may appear brighter or objects may appear with a blueish tinge. In general, however, sildenifil has been shown to be very safe and although there has been a scare about heart attacks the numbers reported are no different from the numbers that would have been expected in a population of similar age who have not taken the drug. Another new tablet that is now available contains apomorphine, and in contrast to sildenifil works by influencing chemical pathways in the hypothalamus in the brain, again, like sildenifil, only in the context of sexual stimulation. There are several sildenifil-like and other tablets being developed and these and other so-called Quality-of-life drugs are causing major funding problems for health care systems.
If all else fails, there is the possibility of implanting a penile prosthesis — a simple plastic splint, or an inflatable implant, — but there is rarely a good case for this, certainly in no more than 1% of patients, and most of them would be paraplegic.
The problem of impotence is best — and most often — addressed in a multidisciplinary clinic, including psycho–sexual counsellors, psychologists, endocrinologists, and urogenital surgeons.
Impotence is often considered to be one of the prices paid for leading a modern, urbanized, and ‘unnatural’ life, and to bear some causal relation to the changing social role of women. Anxiety about the ability to manifest manhood by sustaining an erection, however, appears to have been prevalent throughout history, during which few women enjoyed anything like the social and economic power now delineated as so threatening. Accusations of manhood stolen by witchcraft and charms for its restoration suggest that in apparently ‘simpler’ societies erection was not necessarily a reliable biological reflex, and that impotence should, perhaps, be seen as one of the prices humanity has paid for becoming self-conscious — indeed, human.
Lesley A. Hall, and Tim Hargreave
See urogenital system.See also coitus; ejaculation; penis.
impotent
im·po·tent / ˈimpətnt/ • adj. 1. unable to take effective action; helpless or powerless: he was seized with an impotent anger.2. (of a man) abnormally unable to achieve a sexual erection. ∎ (of a male animal) unable to copulate.DERIVATIVES: im·po·tence n.im·po·ten·cy n.im·po·tent·ly adv.
impotent
Impotence
357. Impotence
- Chatterly, Sir Clifford paraplegic from the war, unable to satisfy his wife sexually. [Br. Lit.: D. H. Lawrence Lady Chatterly’s Lover in Benét, 559]