Recreational drugs are a major cause of erection problems and the number one problem drug is tobacco. Experiments show that even two cigarettes will markedly decrease the blood flow to the penis if…

The Effects of Disease States and Drugs on Erections

  Cardiovascular Disease is the most common cause of ED and is due to endothelial dysfunction. Studies have demonstrated that two million people have…

Intracavernosal smooth muscle tone is by far the most important determinant of intracavernosal blood flow. Approximately half of the cavernosal volume is composed of smooth muscle, with the remainder consisting of either lacunar spaces…

Penile prostheses are divided into 3 general types: malleable (semirigid), mechanical, and inflatable devices. The malleable devices are made of silicone rubber and several models contain a central intertwined metallic core. The mechanical device is…

Bilateral sympathectomy at the L2 level has resulted in ejaculatory dysfunction in about 40% of patients. High bilateral retroperitoneal lymphadenectomy causes an even higher percentage of emission failures. Retrograde ejaculation is…

Physiology of Emission, Ejaculation, & Orgasm

Different mechanisms are involved in erection, emission, ejaculation, and orgasm, and these events can be dissociated from one another (eg, a frequent complaint…

One of the most dramatic changes in urology has been the introduction of intracavernous injection of vasoactive drugs for the diagnosis and treatment of ED. A list of drugs that have been…

The vacuum constriction device consists of a plastic cylinder connected directly or by tubing to a vacuum-generating source (manual or battery-operated pump). After the penis is engorged by the negative pressure, a constricting ring…

Isolated stenosis or occlusion of the extrapenile arteries is amenable to surgical repair. Restoration of potency has been reported after surgery of the internal iliac and internal pudendal arteries. Currently, the most commonly used…

Alprostadil, the synthetic formulation of PGE1, is the only pharmacologic agent approved by the FDA for the management of ED via intracavernous and transurethral routes. Alprostadil stimulates adenyl cyclase to increase intracellular levels…

Sildenafil citrate (Viagra, Pfizer Pharmaceuticals) is a selective inhibitor of phosphodiesterase-5 (PDE5), the enzyme that breaks down the intracellular second messenger of erection cGMP and thus enhances penile erection. The clinical efficacy and safety…

Referral to endocrinology is recommended for patients with thyroid, adrenal, pituitary or hypothalamic dysfunction. The urologist should be aware that aging men with ED may show a variety of symptoms when hypogonadism coexists:…

Although the penile prosthesis remains one of the most effective treatments for all types of ED, nonsurgical management has replaced prosthetic surgery as the preferred choice in the last decade. Both specific…

A. Nocturnal Penile Tumescence (NPT) Test
Nocturnal erections occur in healthy males of all ages. Of the nocturnal erections, about 80% occur during REM sleep. The average man has 3-5 episodes of…

A detailed medical and psychosexual history and a thorough physical examination are the most important steps in the differential diagnosis of sexual dysfunction. Interviewing the partner, if available, is very helpful…

Other causes may affect one or more of the factors controlling the erectile mechanism. Because of the lack of scientific studies, however, their precise pathogenetic relationship remains speculative.

A. Drugs
Many…

The anatomic mechanism of penile erection was discovered in the 1980s by electron microscopy of corrosion penile casts made in the flaccid state and during erection (_{Fournier et al, 1987; Banya et al,…}

In the Massachusetts Male Aging Study, a community-based survey of men between 40 and 70 years of age, 52% of respondents reported some degree of ED: 17% mild, 25% moderate, and 10% complete.…

Male sexual dysfunction, denoting the inability to achieve a satisfactory sexual relationship, may involve inadequacy of erection or problems with emission, ejaculation, or orgasm.

Erectile dysfunction (impotence) is the inability to obtain or maintain…

The tunica of the corpora cavernosa is a bilayered structure with multiple sublayers. The inner circular bundles support and contain the cavernous tissue. From this inner layer radiate intracavernosal pillars that…

Innervation of the Penis

The autonomic spinal erection center is located in the intermediolateral nuclei of the spinal cord at levels S₂-S₄ and T₁₂-L₂. Nerve fibers from the thoracolumbar (sympathetic) and sacral (parasympathetic)…

During sexual stimulation, NO released from nerve ending and endothelium diffuses into the trabecular and arterial smooth-muscle cells to activate guanylyl cyclase, which catalyzes the formation of second messenger cyclic guanosine monophosphate…

Androgens are essential for male sexual maturity. Testosterone regulates gonadotropin secretion and muscle development; dihydrotestosterone mediates all other aspects of male sexual maturation, including hair growth, acne, male pattern baldness, and spermatogenesis. In…

by Tom F. Lue, MD

A better understanding of male sexual dysfunction has been made possible by innovative laboratory and clinical research in the mechanism, neurophysiology, and pharmacology of penile erection. Erectile…