Impotence

Published on 02/03/2015 by admin

Filed under Endocrinology, Diabetes and Metabolism

Last modified 02/03/2015

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CHAPTER 45

Impotence

1. What is impotence?

2. Do men with ED have disturbances in other sexual functions?

3. Is impotence common?

4. How does a normal erection occur?

5. Explain the role of the nervous system in achieving erection.

6. Explain the hormonal aspects of erection.

Nervous system stimuli release neurotransmitters that reverse the tonic smooth muscle constriction maintained by norepinephrine, endothelin, and other vasoconstrictive factors. The most important of these are the potent vasodilators nitric oxide (NO) and prostaglandin E1 (PGE1). In addition to neural sources, NO is derived from endothelial cells, and this may explain why endothelial integrity may be necessary for maintenance of an erection. NO works by increasing cyclic guanosine monophosphate (cGMP) and causing a decrease in intracellular calcium. This results in relaxation of vascular smooth muscle cells secondary to dissociation of actin-myosin. The role of testosterone in erectile function remains complex and controversial. Testosterone has a critical role in stabilizing intracavernosal NO synthase, and for fully satisfactory sexual function, a “normal” quotient of testosterone must be present. Testosterone is also the main hormonal mediator of male libido; this means that deficiency can have a psychologic impact on erectile function. Regardless, some men with testosterone levels below the reference limit still have normal erections. Testosterone replacement is therefore not guaranteed to cure ED in hypogonadal men, nor is it indicated in men with normal testosterone levels but impaired sexual function.

7. What vascular changes in the penis result in erection?

8. What types of nerves and neurotransmitters play a role in penile erection?

9. How does detumescence occur?

10. What are the common causes of impotence?

11. What lifestyles are associated with impotence?

12. Besides diabetes mellitus, what are the three most common endocrine causes of impotence?

13. Describe the most common drugs known to induce impotence.

14. Which antihypertensive agents should be used in patients with impotence?

15. What is “stuttering” impotence? What is its significance?

16. What historical information helps to separate organic from psychogenic impotence?

True psychogenic impotence is uncommon and should be a diagnosis of exclusion. Questions that may help to separate psychogenic from organic impotence are listed in Table 45-1. A detailed history assessing for contributing physical and psychiatric conditions can also help with this distinction. These include obesity, hypertension, hyperlipidemia, atherosclerosis, diabetes mellitus or other endocrinopathy, neurologic disease, prior pelvic surgery or irradiation, trauma, Peyronie’s disease, substance abuse, depression, or the aforementioned medications. A detailed social history is also important and includes assessment of stressors and the patient’s coping mechanisms, concomitant psychosexual problems such as premature ejaculation, and relationship dynamics with partners.

TABLE 45-1.

ORGANIC VERSUS PSYCHOGENIC IMPOTENCE

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  ORGANIC PSYCHOGENIC
Was onset abrupt? No Yes
Is impotence stress dependent? No Yes
Is libido preserved?* Yes No
Do you have morning erections? No Yes
Do you have orgasms? Yes No