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Impotence

Course Authors

John E. Morley, M.D.

During the last three years, Dr. Morley has received grant/research support from Vivus, Merck & Co., Upjohn, B. Braun McGaw, Bayer Corp and Nestec, Ltd. He has also served on the Speakers' Bureau for LXN, Organon, Ross, Pharmacia & Upjohn, Glaxo Wellcome, Hoechst Marion Roussel, Searle, Merck & Co., Roche, Bristol-Myers Squibb, Novartis, Pratt, B. Braun McGaw, Pfizer and Parke-Davis. This presentation will include discussion of commercial products and services.

Estimated course time: 1 hour(s).

Albert Einstein College of Medicine – Montefiore Medical Center designates this enduring material activity for a maximum of 1.0 AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

In support of improving patient care, this activity has been planned and implemented by Albert Einstein College of Medicine-Montefiore Medical Center and InterMDnet. Albert Einstein College of Medicine – Montefiore Medical Center is jointly accredited by the Accreditation Council for Continuing Medical Education (ACCME), the Accreditation Council for Pharmacy Education (ACPE), and the American Nurses Credentialing Center (ANCC), to provide continuing education for the healthcare team.

 
Learning Objectives

Upon completion of this Cyberounds®, you should be able to:

  • Describe the common causes of impotence

  • Understand the approach to diagnosing the causes of impotence

  • Review the available treatment choices for impotence.

 

Impotence (or the more politically correct term, erectile dysfunction) is defined as the inability to obtain an erection adequate for intercourse on two-thirds of the attempts. Impotence is a common, treatable condition of older males and it can be useful to let patients know this, since bringing up the issue can encourage elderly male patients who might otherwise be reluctant to mention their concern. Most of the treatments can be -- and are -- carried out by primary care physicians.

Physiology of an Erection

Penile erections occur when the smooth muscle of the corpora cavernosa relaxes, resulting in blood entering the penis. Nitric oxide is the major smooth muscle dilatory neurotransmitter involved in producing a penile erection (See Figure 1).

Figure 1.

Figure 1

Impotence Is a Common Condition

p>It is estimated that impotence occurs in 10 to 20 million persons in the U.S.A.(1) Impotence occurs in one-third of persons over 40 years of age who are seeing a physician for another medical condition.(2) The Massachusetts Male Aging Study(3) reported that the combined rate of minimal, moderate and complete impotence in males 40 to 70 years was 52%. Age, vascular disease, medications, diabetes and depression were the strongest variables associated with impotence.

The Impotence Top 10 List

  1. Most impotence is due to organic causes
  2. The most common cause of impotence is vascular disease
  3. Tobacco is the most important "street drug" to cause impotence
  4. Thiazide diuretics are the most common prescription drug, worldwide, to cause impotence
  5. Peripheral sensory neuropathy is associated with a loss of erection following vaginal penetration
  6. Males with vascular impotence are at a marked increased risk for developing myocardial infarction
  7. Persons who can obtain an erection with their mistress but not with their wife do not necessarily have psychogenic impotence
  8. Intra-urethral infusion is a treatment for impotence
  9. Sildenafil is the treatment of choice for most men with impotence
  10. Older persons treated for impotence need advice about safe sex techniques

Causes of Impotence

In one study 86% of all impotence was demonstrated to be organic.(2) The most common cause of impotence is vascular disease.(4) The vascular disease can be either arterial or venous. The frequency of venous leaks, resulting in the inability to maintain an erection adequate for intercourse, increase with aging. Aging is also associated with decreased penile oxygenation, leading to increased smooth muscle fibrosis. Tobacco smoking is associated with an increased incidence of impotence.(5) Smoking two cigarettes is sufficient to prevent an erection obtained by intracorporeal injection of papaverine.(6) Nicotine infusion prevents carvenoscal nerve stimulated erections in dogs. Other drugs that are associated with impotence include alcohol and heroin. Autonomic neuropathy, due to diabetes or other causes, can result in impotence. Diabetes also causes impotence by accelerating vascular disease. Because of sensory neuropathy, it is difficult to maintain adequate erections after vaginal penetration. Persons who have a sensory neuropathy-associated impotence exhibit delayed penile evoked potentials (an electric shock to the penis is perceived only after a delay in the cerebral cortex).

Multiple sclerosis patients can present with "stuttering" impotence, i.e., impotence that is present for a few weeks, then goes away, only to return again. Over half of males with multiple sclerosis have impotence as their first presenting symptom. Medications are a common cause of impotence. Worldwide, thiazide diuretics are the most common medication causing impotence.

Table 1. Drugs Associated with Impotence

Anticholinergic
Atropine
Scopolamine

Anticonvulsant
Phenytoin
Carbamcezepine

Antidepressant
Amitriptidine
Imipramine
Doxepin
Nortriptidine
Fluoxetine

Antihypertensive
Thiazide
Clonidine
Metoprolol
Propranalol
Hydralazine
Captopril
Diltiazem

Antipsychotic
Chlorpormazine
Haloperidol

H2 receptor antagonist
Cimetidine
Ranitidine

Narcotic
Codeine
Methadone

Sedatives
Alcohol
Barbiturates

Miscellaneous
Ketoconazole
Cemiodarone
Digoxin
Fenfluramine
Interferon
Naproxen
Metoclopramide

Other Organic Causes of Impotence

Thyroid disease (both hypo- and hyper-thyroidism) causes impotence. Hyperprolactinemia also causes impotence. Decreased testosterone is more commonly associated with decreased libido than with impotence.

Other organic causes of impotence include cerebrovascular accidents and spinal cord lesions (ischemic, traumatic, tumors and spinal stenosis).

Depression is an important cause of impotence and all impotent males should be screened for depression. Other psychogenic causes of impotence include:

  • Performance Anxiety: Often coexists with organic causes.
  • Widower's Syndrome: Inability to have intercourse following death of spouse because one is still grieving.
  • Madonna Complex: Inability to have intercourse with the mother of one's child.

It should be noted that the commonly listed textbook factors purported to differentiate between psychogenic and organic impotence can all occur with early organic impotence. These factors are early morning erections and ability to have intercourse with a new partner but not with an old partner.

Vascular Impotence Is Associated with Subsequent Major Vascular Disease

Studies by Virag et al.(7) demonstrated a strong retrospective association of impotence withsubsequent atherosclerotic events. Our study(8) showed a prospective association between vascular impotence, as measured by penile brachial pressure index (PBPI), and future myocardial infarction or stroke:

Table 2. Relationship of Penile Brachial Pressure Index (PBPI) to Vascular Disease.

PBPI
< 0.65 < or = 0.66 P
Myocardial Infarction 12%> 2% <0.05
Stroke 16% 3% <0.05
Any major vascular event 26% 5% <0.05

All patients with vascular impotence should be referred to a cardiologist for possible stress testing. All these patients should be counseled on appropriate atherosclerotic prevention techniques, i.e., stop smoking, treat hypertension, lower cholesterol.

Diagnosis of Impotence

The first step is to carry out an appropriate history and physical examination. The St. Louis University/Missouri Gateway Education Center/GRECC sexual history questionnaire developed by Fran Kaiser, M.D., can be obtained by clicking here.

Special tests that may be indicated for the diagnosis of impotence may include:

  • Fasting serum glucose
  • Thyroid function tests
  • Testosterone and prolactin [if libido is low or two or more questions are answered positively on the ADAM (Androgen Deficiency in Aging Males) questionnaire] Depression screen
  • Penile brachial pulse index: This is performed with a pediatric sphygmomanometer and a doppler stethoscope. Its use is controversial. However, it has had excellent clinical use for identifying vascular impotence and it is relatively cheap.

Figure 2.

Figure 2

Intracorporeal injections to observe erectile capacity Duplex doppler to carefully define arterial and venous blood flow. As specific treatments for vascular leakage do not exist at present this is an expensive test without any major benefit. Snap gauge--can be used to see if adequate erections occur during sleep. Nocturnal penile tumescence -- a research tool of questionable clinical use.

Management of Impotence

  • Refer clear-cut psychogenic impotence for psychological counseling, though some oral drugs such as yohimbine and Sudenafil® also work.
  • Treat depression if present.
  • Provide reassurance concerning organic nature of the disease and its treatability, where appropriate. Always counsel partner as well. Make sure you know who the potential partner is.
  • Penile protheses available:
    • Semirigid rods (while less used these days, they arestill the gold standard for the highly sexually active male)
    • Inflatable prostheses (poor five-year survival of prosthesis makes these less desirable)
  • Intracorporeal penile injections(9)
    • Alprostadil (PGE-1) -- only FDA improved agent
    • Papaverine
    • Phentolamine
  • Intraurethral injections (MUSE system) (injects alprostadil into the urethra--increased risk of hypotension over intracorporeal injections and has much lower success rate). An alternative that is more acceptable to some males.(9),(11)
  • Oral drugs:
    • The phosphodiesterase-5 inhibitor [sildenafil (Viagra®) is, at present, the treatment of choice for impotence. It is taken orally one hour prior to sexual activity. It provides good erections in 50 to 70% of men. Those men taking nitrates cannot use sildenafil because of risk of sudden death. The effect of 50 to 100 mg of sildenafil lasts for 12 to 20 hours. Other side effects include flushing, hypotension, headaches and visual disturbances. Two other phosphodiesterase inhibitors are under development at present. Historically, pentoxifyline, a non-specific phosphodiesterase inhibitor, was the first agent of this class to be used for erectile dysfunction.(14),(15) Males who are hypogonadal will have impaired activity of the nitric oxide synthase enzyme.
    • Zinc (placebo response; useful in very rare zinc deficient patient)
    • Yohimbine (for psychogenic impotence -- liver dysfunction is a major side effect). The use of this drug is not recommended.
    • Oral phentolamine and apomorphine SL (Uprima® -- in phase III trials for psychogenic impotence.(12),(13) Apomorphine is less effective than sildenafil.
  • Vacuum tumescence devices (excellent for older persons who want to have intercourse once a week or less often) (see Figures 3-5).

Figure 3.

Figure 3

Figure 4.

Figure 4

Figure 5.

Figure 5

Male impotence, particularly among older men, is a more common problem than most would think or, perhaps, like to think. It is most often successfully treated. Treatment can greatly improve the quality of life of elderly men (and women!) Your professional questions regarding impotence can actually be helpful, not "nosy" or improper. One of the best ways to broach what may for some be a delicate subject is to remark on just how common the problem is and take it from there.

Finally, it should be remembered that older persons may indulge in high risk sex practices just as young persons do. Thus, it is important to provide them with information concerning safe sex practices, including the use of condoms.


Footnotes

1Morley JE, Kaiser FE. Impotence: the internist\'s approach to diagnosis and treatment. Adv Int Med 38:151-168, 1993.
2Slag MF, Morley JE, Elson MK, et al. Impotence in medical clinic outpatients. JAMA 249:1736-1740, 1983.
3Feldman HA, Goldstein I, Hatzichristou DG, Krane RJ, McKinlay JB. Impotence and its medical and psychosocial correlates: results of the Massachusetts Male Aging Study. J Urol 151:54-61, 199.
4Kaiser FE, Viosca SP, Morley JE, Mooradian AD, Davis SS, Korenman SG. Impotence and aging: clinical and hormonal factors. J Amer Geriatr Soc 36:511-119, 1988.
5Condra M, Morales A, Owen JA, Surridge DH, Fenemore J. Prevalence and significance of tobacco smoking in impotence. Urol 27:495-498, 1986.
6Jeunemann KP, Lue TF, Luo JA, Benowitz NL, Abozeid M, Tanagho EA. The effect of cigarette smoking on penile erection. J Urol 138:438-441, 1987.
7Virag R, Bouilly P, Frydman D. Is impotence an arterial disorder? A study of arterial risk factors in 440 impotent men. Lancet 1(8422):181-4, 1985 Jan 26.
8Korenman SG, Morley JE, Kaiser FE, Mooradian AD, Viosca SP. Relationship of penile brachial pressure index to myocardial infarction and cerebrovascular accidents in older men. Amer J Med 84:445-448, 1988.
9Ishi N, Watanabe H, Irisawa et al. Intracavernous injection of prostaglandin E1 for the treatment of erectile impotence. J Urol 141:323, 1992.
11Padma-Nathan H, Hellsteom WJ, Kaiser FE, Labasky RF, Lue TF, Nolten WE, Norwood PC, Peterson CA, Shabsigh R, Tam PY, Place VA, Gesendheit N. Treatment of men with erectile dysfunction with transurethral alprostadil. Medicated Urethral System for Erection (MUSE) Study Group. New Eng J Med 336:1-7, 1997.
12Becker AJ, Stief CG, Schultheiss D, et al. Double-blind study on oral phentolamine as treatment for erectile dysfunction. J Urol 157:785, 1997.
13Heaton JP, Morales A, Adams MA, Johnson B, el-Rashidy R. Recovery of erectile function by oral administration of apomorphine. Urol 45:200, 1995.
14Jackson G. Sildenafil (ViagraR): new data, new confidence in treating erectile dysfunction in the cardiovascular patient. International Journal of Clinical Practice 56(2):75,2002 Mar.
15Wespes E, Amar E, Hatzichristou D, Montorsi F, Pryor J, Vardi Y. Guidelines on erectile dysfunction. European Urology 41(1):1-5,2002 Jan.