Intraurethral Therapy

The effectiveness of injectable intracorporal forms of therapy over the last 15 years has encouraged the development of more acceptable and appealing delivery systems for these medications. Some men are opposed to the use of a needle placed in the penis to deliver medication, and this has contributed to the high dropout rate for patients who are prescribed intracorporal injections. Medicated urethral system for erections (MUSE) was introduced in early 1997 as an alternative method of delivering PGE1 to the erectile bodies. After urination, an applicator is placed about 1.5 in. into the urethra. After pushing a button, a pellet of PGE1 approximately the size of a grain of rice is deposited in the urinary tract. Absorption occurs in the corpus spongiosum; through venous communications between the corpus spongiosum and the corpora cavernosa, some of this medication gains entry into the erectile bodies. PGE1 then acts on the adenosine triphosphate system to decrease intracellular calcium and relax the penile smooth-muscle cells. Because of this direct action, intact innervation of the erectile mechanism is not necessary. To enhance delivery of this compound into the erectile body, a constricting band (ACTIS) at the base of the penis should be used. Penile, urethral, testicular, and perineal pain may be seen in up to 50% of the patients. Although hypotension and syncope rarely occur, this medication should be nonetheless applied while sitting to avoid falling. The effectiveness of MUSE at providing an erection that can be used for intercourse is in the range of 30% to 40%.

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A MUSE-induced erection is rarely rigid but may be described as a swollen penis that does not buckle when it is used for vaginal penetration with some assistance. MUSE may be useful in some patients following radical prostatectomy, who have not responded to type V phosphodiesterase inhibitors. This medication has also been used in conjunction with oral medication to provide additional support when adequate rigidity is not provided by one treatment alone. In addition, the use of MUSE with a previously placed penile implant has provided some increase in girth and length as engorgement of the glans penis and corpus spongiosum readily occurs with its use. Such increases in size, however, have only been in the range of 1 cm and each application costs approximately $20.

Vacuum Erection Devices

Vacuum erection therapy as a treatment for impotence had been used sporadically with homemade devices until the pioneering work of Geddings Osbon, who obtained Food and Drug Administration (FDA) approval for such a device in 1982. Over the next decade, primarily through the efforts of the Osbon Corporation, these constriction devices became a definite player in the treatment of erectile failure. Initial reports of Witherington and Nadig et al. have claimed success and satisfaction in over 90% of the patients using these devices. In a series of 45 patients of Gilbert and Gingell, 84% reported adequate rigidity, but only 27% were satisfied with the device. This experience was reinforced by Earle et al., who reported a satisfaction rate as low as 9%. The key to patient satisfaction with this treatment is the careful instruction of patients and adequate practice in removing the ring from the cylinder before the seal at the penoscrotal junction is broken to allow maintenance of penile rigidity. Common reported side effects include pain on ejaculation, inability to ejaculate, petechiae or bruising of the penis, and numbness during erection. Partners will frequently relate that the resulting erection is unpleasantly cold. The recommended maximum time period that the constriction ring may remain in place is 30 minutes. Even if this device is left on for longer periods—i.e., if the patient falls asleep with the ring in place—blood flow will continue at a very slow rate, but this volume is usually adequate to prevent necrosis of the penis.

The major advantage of the vacuum device is its relative margin of safety when compared to pharmacologic or surgical treatments of erectile dysfunction. Serious problems such as skin necrosis have only occurred with misuse. The relative safety of vacuum devices has encouraged the FDA to remove them from the list of prescribed devices, and they are now sold over the counter. Older patients in a stable marital relationship, who have failed in restoring erections with the use of medications, tend to choose the vacuum device when they are not inclined toward the surgical placement of a penile prosthesis.

Penile Prostheses

Effective penile prostheses were first introduced to the impotence marketplace in the early 1970s. Prior to this, there was no effective treatment for the unfortunate patient who had significant erectile dysfunction. Since less aggressive forms of treatment such as vacuum devices and medications were introduced, the market share of penile prostheses has become smaller; however, they do provide a predictable and reliable means of restoring erectile function, and the satisfaction rate among patients and partners who use penile prostheses has been the highest of all treatment modalities for erectile dysfunction, in the level of 85%. The small percentage of patients who report disappointment with this modality typically have unrealistic expectations regarding penile size, sensitivity, and arousal. Malfunctions may occur due to either wearing of parts or breakdown of the coverings of the erectile body or the skin of the scrotum, with the resulting extrusion of prosthetic parts. A recent multicenter study of 372 patients with the AMS-700 CX (American Medical Systems) prosthesis shows a mechanical reliability of:

  • 92% at 3 years,
  • 85% at 5 years,
  • 71% at 10 years.

Patient selection, proper sizing, placement by an experienced surgeon, and prompt attention to problems that may develop are of paramount importance in assuring success and satisfaction. Silicone and polyurethane used in the construction of these devices have not had detrimental effects on the body as shown in studies of patients with breast implants. Despite this, the FDA mandated that AMS and the Mentor Corporation conduct prospective clinical trials to document the safety, efficacy, and patient satisfaction of these devices. These studies have provided no evidence related to the presence of these foreign bodies, which would be considered detrimental to the patient’s health. In the past, while infection of a penile prosthesis has been uncommon—in the range of 1% to 3%—when it occurs, however, it is a catastrophic occurrence that necessitates immediate removal of the device. Recent experience with salvage procedures in which the infected prosthesis is removed completely, the wound thoroughly cleansed, and a new device placed at the same procedure, has shown successful outcomes in about 82% of the patients with up to eight years of followup.

An additional advantage of these devices is that they can be satisfactorily placed in patients following external beam therapy or brachytherapy for prostate cancer. They are also sometimes placed in patients following radical prostatectomy in conjunction with an artificial urinary sphincter, which is used to control incontinence if it develops following this procedure.