The penis - Peyronie's disease and erectile dysfunction

Peyronie's disease is a fibrotic disease of the corpus cavernosa that produces penile shortening, significant and severe curvature on erection, penile pain and erectile dysfunction. Peyronie's disease occurs in 3% of US white males and is symptomatic in approximately 1%.

The cause of Peyronie's disease has not been clearly elucidated, but theories include penile trauma with subsequent scarring as well as genetic and developmental abnormalities. Patients in their late 40s and early 50s are the most likely to suffer from Peyronie's disease, which usually begins as painful erections and subsequently dorsal penile curvature. The course of the disease is approximately 12-18 months during which time the curvature may change and sexual function may be affected by this curvature. In patients with impaired coital function because of penile curvature, treatment may be necessary. Treatment during the period of plaque evolution should be medical and not surgical. Initial medical therapy consists of potassium para-amino benzoate (Potaba) or colchicine and vitamin E.

These agents modify scar tissue composition and plaque formation. Direct treatment with injection therapy using verapamil injection or newer agents such as uAnterferon may also be helpful in some patients.

In those patients in whom function continues to be compromised, curvature of the penis continues to be
severe, or ED precludes satisfactory coitus, surgical intervention may be necessary. In patients with inadequate erectile function from veno-occlusive abnormalities or poor arterial inflow, penile prosthesis with penile straightening may be required.

The three-piece inflatable penile prosthesis is the best choice for these patients as straightening procedures known as modeling are best performed with these more rigid inflatable rods.

Results of penile prosthesis implantation in Peyronie's patients are similar to those in patients without Peyronie's disease although penile shortening may be more prevalent in this group of patients.

In patients with continued satisfactory erectile function with PDE-5 inhibitors or without, penile straightening
procedures may be performed without the use of penile prosthesis. The first procedure designed to provide penile straightening in these patients was the Nesbit procedure or penile plication. With this procedure, an area of tunica albuginea opposite the area of curvature is plicated in the operating room in the presence of an artificial erection until penile curvature is overcome and the penis is straightened.

This procedure, which usually does not affect erectile function, is highly successful in penile straightening. Because it produces penile shortening, patients with severe penile curvative may be unsatisfied with the ultimate postoperative result.

In patients with severe penile curvature or with narrowing of the penis on erection (hourglass deformity), incision of the area of curvature with an artificial erection in the operating room followed by placement of an artificial graft at the area of curvature may provide straightening and preserve penile length and erectile function.

Grafts currently used include artificial substances such as porcine submucosal material, vein, dermis cadaveric pericardium and other acceptable graft materials.

Adverse events from this surgery include penile numbness, recurrent curvature and ED. Ultimate outcomes, however, are satisfactory in most patients who can then return to normal coital functioning with or without the assistance of oral erectogenic agents.

Future directions

The treatment of ED was revolutionized by the introduction of sildenafil in 1998. Newer agents recently introduced to the market will provide additional options for the treatment of patients with ED. Newer PDE3 inhibitors such as vardenafil and tadalafil will be supplemented by central nervous system acting agents for stimulating erectile function. The first of these agents, apomorphine SL, is currently approved and in use in Europe. It stimulates dopamine receptors in the erectile center of mid brain and has been demonstrated in phase 3 clinical trials to be effective in producing erectile function with minimal side effects. Newer injectable agents are also being investigated including novel potassium channel opening agents that require no refrigeration and produce little penile discomfort. Topical preparations of PGE1 have completed clinical trials and will soon be available for general use.

Active research is underway to evaluate the feasibility and effectiveness of gene therapy for ED. Gene therapy to restore NOS concentrations, endothelial function, potassium channel function in the corpus cavernosum smooth muscle appears, in animal models, to be an excellent method for restoring erectile function lost through diabetes, hypercholesterolemia, and other vascular causes. This mode of therapy may provide a long term solution for many patients with ED.

Despite the strides made in pharmacological treatment, many patients will still require penile construction with penile prostheses. The currently available penile prostheses have been modified and improved over the past 25 years to provide safe, reliable reconstruction for penile abnormalities and ED with low expected complications and morbidity, and high patient satisfaction.

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