The Author
  Richard F. Spark, M.D., F.A.C.E. is an Associate Clinical Professor of Medicine at Harvard Medical School and Director of the Steroid Research Lab at Boston’s Beth Israel Deaconess Medical Center, where he continues an active research program. The author of two other books on male sexuality and fertility, he has written for The New York Times Magazine and The New Republic on health related issues and has published widely in major medical journals. A Fellow of the American College of Endocrinology and the American College of Physicians, and a member of the Endocrine Society, the Andrology Society, and the Federation of Clinical Research, he has a private practice in Chestnut Hill, Massachusetts.

  Criticism
  The book contains a wealth of information related to men’s sexual health, with merely a few minor shortcomings worth mentioning:
       1)  “Impotence” with its negative connotation suggesting weakness, is used throughout the book. The terms “erectile difficulty (ED)” or  “erectile dysfunction” would have been preferable; the latter of these is only used a few times.
       2) According to the book cover, Dr. Sparks’ wants to address men in general and of all age groups. However, the focus is largely on heterosexual men, ignoring the homosexual population. Sex is often described as heterosexual sex between a man and his female partner, and none of the case stories or references to couples mentions homosexual men and couples.
       3) As a sex therapist who helps clients focus on intimacy and pleasure without emphasizing sexual performance, some of the remarks I disagree with: “.... Ideally, the duration of thrusting will be sufficient to allow the man and his partner to achieve orgasm at about the same time (page 49).” It is implied that not only should one “ideally” achieve orgasm during sexual activity, but also it is desirable to climax simultaneously. This is in direct contrast to the messages I usually extend to my clients: that it is O.K. to have sex without climaxing at all, that instead of focusing on performance and goals such as “achieving” orgasm, it is more important to simply enjoy the existing intimacy between partners, whatever form it may take. The statement “… the sexual act does not end with penetration. Ejaculation must occur (page 76)” is a strong argument and in my opinion not true.
       4) References to only selected chapters are listed in the back and without numerical links in the text. This makes it impossible to identify the exact origins of some of the statements made. In the section on the risk of heart disease and sex, I was surprised that a recent study by Mueller et al. (1996) was not cited. Research has shown that patients after a myocardial infarction (MI) benefit from enrolling into a cardiovascular rehabilitation program. The low risk of triggering a MI during sexual activity is nearly unchanged whether one has a history of heart disease or not. Regular exercise can reduce the risk even further.
       5) Incorrect terms such as “alpha impulses (page 25)”, “nerves of the alpha type (page 253)” and “alpha signals (page 253)” are used to describe physiological events during arousal/erections. Maybe the author intended to present complex cellular events in an easy, understandable language, but I believe that he has introduced confusing terms. Also, the substances nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) are incorrectly described as having separate effects on smooth muscle cells (pages 26 and 104, table 11.1). To my knowledge, as described in my appendix which follows, NO exerts its effects through the intracellular second messenger cGMP, and therefore the two substances act through one and the same mechanism. Using correct terms, and based on recent research the mechanism of tumescence/detumescence is described in the appendix.
        The reasons why Viagra is not recommended (contraindicated) for people taking nitrates should have been mentioned following the section “…. Men who routinely use a class of medication called nitrates like nitroglycerine or isosorbide (Isordil), commonly prescribed to prevent or alleviate a form of heart pain called angina pectoris, should not take Viagra. No ifs, ands, or buts (page 117).” The paragraph ends here. In my opinion, an explanation, such as that given in the appendix related to why Viagra should be avoided in these cases would have been appropriate.
 

  Positive Comments
  Sexual Health For Men deserves much praise. Dr. Sparks clearly is a very experienced endocrinologist with a thorough understanding of the function of male hormones. His section on the origin, release, metabolism and function of male hormones such as testosterone, dihydrotestosterone (DHT), dehydroepiandrosterone (DHEA), and anabolic steroids is captivating, and the reader learns how male hormones affect prostate growth, hair loss, muscle mass and other bodily changes. It becomes clear how popular drugs such as Finasteride (Proscar, Propecia) exert their effects in the male body. This section of the book is truly educational, and the clinical vignettes make it entertaining.

  The chapters on different treatment options for erectile difficulties, such as penile injection, vacuum devices, and penile implants are informative as well. The author offers thorough and richly illustrated explanations for how individual treatment options function. The book constitutes a valuable source of information for readers who want to learn about contemporary treatment for erectile dysfunctions.

   Two other sections deserve praise: the chapters on the prostate and its problems, including prostate cancer; and the chapter on fertility. Again, readers may find valuable and up-to-date information on these topics, including detailed descriptions of physical exams, tests and treatment options.

  In a separate chapter, The Lure of Alternative Medicine, Dr. Spark offers a fair discussion of why some alternative medicines work and others do not. Ginseng, Vitamin E, Zinc, Yohimbine, and over-the-counter male hormones such as androstendione and DHEA are thoroughly discussed.

  The book ends with a discussion on normal ageing, the issue of whether or not to restore youthful hormone levels in mature men, and finally an outlook on what is next for men in the new millennium.

  Conclusion
  Sexual Health For Men is truly a complete guide, an important and up-to-date resource for information about this wide topic. My praise for this substantial book far exceeds my criticisms. I recommend Sexual Health For Men highly.
 
 
 

  Appendix by Dr. Owens: Physiological cellular events during arousal/erections:
  The smooth muscle cells in segments of the penis (corpora cavernosa) can either 1) relax, thereby allowing increased blood flow to the penis, or tumescence, or they can 2) contract, resulting in detumescence, or the flaccid state of the penis. Both events may be initiated in different ways, and it is ultimately the degree of contraction or relaxation of these smooth muscle cells that determines whether the penis is flaccid or erect.

  Nerves to the penis release the neurotransmitter noradrenaline (a catecholamine), causing stimulation of alpha-receptors on the surface of adjacent smooth muscle cells. This leads to smooth muscle cell contraction, allowing only limited blood flow into the penis, which is now in the flaccid state, or undergoes detumescence if it was previously erect. Catecholamines can also be released during stressful situations associated with sexual activity such as fear of failure, performance anxiety, anger, shame, or embarrassment (Goldstein, 2000). Or they may be released in painful situations such as genital pain from infection of the prostate, epididymitis, and Peyronie’s disease, or non-genital pain such as headache (Goldstein, 2000). In either case, smooth muscle cells are stimulated to contract, resulting in reduced blood flow to the penis and detumescence.

  To complicate matters further, different types of alpha-receptors (alpha-1 and alpha-2-subtypes) are located not only on the smooth muscle cells, but also directly adjacent on the nerve-buds, from where catecholamines and other neurotransmitters are released. From this location alpha-receptors modify how much of the transmitter substance is released from the nerves, and then reaches the smooth muscle cells (Crenshaw and Goldberg, 1996).

  By blocking alpha-receptors on the smooth muscle cells with drugs like phentolamine (Regitine, Vasomax, mentioned on page 136), contraction of the smooth muscle cells can be prevented or at least reduced, allowing an erection to persist longer. This is why the drug phentolamine is effective in the treatment of ED and is currently being tested for possible FDA-approval as such a treatment option (Goldstein, 2000). The drug is already used as a blood pressure lowering medication for people with pheochromocytoma, a condition where excess catecholamines are produced in the body.

  Alpha-2-receptors are blocked by Yohimbine, an alkaloid obtained from the bark of the African tree, Coryanthe yohimbe (Crenshaw and Goldberg, 1996; Morales, 2000). For over a century Yohimbine has been used as an aphrodisiac, and only recently has it become clear that Yohimbine has central effects (in the brain), increasing sexual arousal, as well as peripheral effects, blocking the catecholamine induced contractility in the smooth muscle of the penis (Bancroft, 2000). Alpha-2 receptors are located throughout the body on blood vessels and in the intestines as well, which explains some of the side effects (indigestion, nausea, dizziness, headache) experienced following the intake of Yohimbine (Crenshaw and Goldberg, 1996).

  There are other ways smooth muscle cells in the penis can relax, resulting in an erection: During sexual arousal penile nerves release nitric oxide (NO), which activates the smooth muscle cells to release the messenger cyclic guanosine monophosphate (cGMP) inside the cells. It is this messenger signal which tells the contractile proteins inside the smooth muscle cells to stop contracting and to relax. The more of the messenger cGMP that is available inside the cells, the more they relax, and the more blood is channeled to the penis through widened pass ways, causing tumescence and erection.

  Viagra enhances erections by increasing cGMP levels in erectile tissue smooth muscle cells. It increases the amount of intracellular cGMP by inhibiting its breakdown through the enzyme type 5 phosphodiesterase (PDE 5). Viagra only works in men who are sexually aroused (take a Viagra, mow the lawn, and nothing happens) and who produce some cGMP on their own. The drug can enhance a minor erection by making sure that the cGMP produced stays around in the cells for a while longer, instead of being removed by PDE 5. For men taking heart medication such as nitrates, Viagra can fatally potentiate the medicine effect and the cGMP released upon medicine intake may be increased to dangerous levels, causing a potentially deadly drop in blood pressure. It is important to emphasize that this only applies to situations where men take Viagra while simultaneously being on nitrates, and that Viagra otherwise is a safe drug to use. It is of utmost importance that Viagra is prescribed by a doctor and is not shared or taken without a doctor’s consent.
 

References:
        Bancroft, J. (2000) Effects of alpha-2 blockade on sexual response: experimental studies with Delequamine (RS15385); International Journal of Impotence Research; Vol. 12, Suppl. 1, S64-S69
        Crenshaw, T. L. & Goldberg, J. P. (1996) Sexual Pharmacology. Drugs That Affect Sexual Function. W. W. Norton & Company. New York. London; ISBN: 0-393-70144-1
        Goldstein, I. (2000) Oral phentolamine: an alpha-1, alpha-2 adrenergic antagonist for the treatment of erectile dysfunction; International Journal of Impotence Research; Vol. 12, Suppl. 1, S75-S80
        Morales, A. (2000) Yohimbine in erectile dysfunction: the facts; International Journal of Impotence Research; Vol. 12, Suppl. 1, S70-S74
        Muller, J.E. et al. (1996) Triggering myocardial infarction by sexual activity. Low absolute risk and prevention by regular physical exertion; Journal of the American Medical Association; 275, 1405-1409