Mechanical devices for the treatment of erectile dysfunction
ROY WITHERINGTON, M.D. is professor of surgery and chief of urology at the Medical College of Georgia School of Medicine, Augusta. Dr. Witherington received his medical degree from the Medical College of Georgia, served an internship at Walter Reed Army Medical Center, Washington, D. C., and completed a residency in urology at the Medical College of Georgia.
Almost all men with erectile dysfunction can be successfully treated. External erection devices are safe and effective for the management of partial impotence. if external devices fail to produce adequate penile engorgement or if they cannot be used, invasive treatments are available. Penile implants remain the gold standard for the management of erectile impotence, especially complete impotence. A satisfaction rate of 80 to 90 percent can be expected with all of the currently available implants. Attention to surgical detail and proper patient selection usually produce an excellent functional and anatomic result.
More than 2.5 percent of men in the United States have erectile impotence. With the therapeutic options available today, this condition can be adequately managed in almost all cases.
The causes of erectile impotence may be organic, psychologic or both (Table 1). Organic problems account for at least 85 percent of cases, and psychologic problems are responsible for about 10 percent of cases. Less than 5 percent of impotent men have no apparent cause for their erectile dysfunction.
In many patients, more than one factor may be operative. For example, diabetic men with erectile dysfunction often have both autonomic neuropathy and vascular occlusive disease. Furthermore, organic and psychologic causes frequently coexist. In patients with organic impotence, repeated inability to sustain an erection long enough to complete the sexual act leads to frustration and anticipation of failure. A psychologic factor then acts synergistically with the organic cause to worsen the problem.
Potentially useful procedures for the evaluation of erectile dysfunction are listed in Table 2. In most patients, a careful history, a complete physical examination and several basic laboratory tests complete blood count, urinalysis, biochemical profile) are sufficient.
If the cause of erectile dysfunction is obvious after the initial work-up, appropriate management can be initiated. If the cause is not obvious, more detailed evaluation should be performed. In such cases, laboratory studies should include a glucose tolerance test and determination of serum levels of pituitary gonadotropins, testosterone and prolactin.
Psychologic evaluation is probably indicated when the cause of impotence is not obvious. The Minnesota Multiphasic Personality Inventory is usually adequate for screening. If gross aberrations are detected, more detailed psychologic evaluation is mandatory.
Measurement of nocturnal penile tumescence (NPT) can be done using either a Snap-gauge (Dacomed Corp., Minneapolis, Minn.) or an electronic monitoring device. Normally, men have several firm erections during rapid-eye-movement sleep; absence of such erections indicates a probable organic cause of impotence. For the most accurate results, NPT monitoring should be performed on three different nights.
A basic neurologic examination should be performed at the time of the initial history and physical examination. If the findings are abnormal, more detailed neurologic evaluation is indicated.
Measurement of brachial and penile blood pressures allows calculation of the penile:brachial index. An index of less than 0.75 suggests a vascular cause of impotence. Injection of 60 mg of papaverine or 20 to 50 [micro]g of prostaglandin [E.sub.1] into either corpus cavernosum normally produces an erection that will be sustained for at least 30 minutes if penile blood flow is normal. Thus, absence of a sustained erection following injection of these vasoactive drugs usually indicates penile vascular insufficiency.
Some impotent patients require more detailed invasive vascular studies, including pelvic arteriography, dynamic cavernosometry and dynamic cavernosography. Arteriography is indicated when vascular occlusive lesions are suspected and surgical revascularization might be a feasible method of management. Dynamic cavernosometry and cavernosography measure penile blood flow characteristics. These studies are indicated in relatively young men who have a protracted history of inability to maintain good quality erections and in whom venous shunting of blood f rom the corpora is considered likely.
Generally, the work-up should be tailored to the individual patient. In most patients with erectile dysfunction, a costly, detailed evaluation is not necessary.
In addition to mechanical aids, such as vacuum constriction devices and penile implants, many methods for managing erectile dysfunction currently exist. Psychologic therapy is useful when no organic cause of impotence can be identified. Drug therapy with yohimbine (Aphrodyne, Yocon, Yohimex) indirectly enhances parasympathetic activity and is occasionally beneficial in men with mild partial impotence. Testosterone replacement therapy may be useful in men with low serum testosterone levels.
Intracavernosal injection of vasoactive drugs (Figure 1) is beneficial in patients with impotence resulting from neurologic disease, as long as penile blood supply is adequate. Vasoactive drugs produce erections by relaxing smooth muscle in the spongy tissue of the penis. Blood flow is increased, producing engorgement of erectile tissue. Simultaneously, venous outflow is decreased because of compression of peripherally positioned emissary veins against the corporeal tunica albuginea.
In selected patients, surgical revascularization may allow restoreltion of blood supply to the penis. Obvious abnormal venous leaks can be obliterated surgically in certain patients. Finally, resection of a prolactin-secreting pituitary tumor may correct erectile dysfunction in a few cases.
Mechanical devices for the management of erectile dysfunction include externally positioned splints, constriction bands, vacuum constriction devices and penile implants. Over the years, many types of external splints have been available, but none have been entirely satisfactory. Vacuum constriction devices have gained acceptance only during the past decade.(1-3)
The modern era of implants began in 1973 with the introduction of the inflatable penile prosthesis. Use of a semirigid silicone rod implant was first reported in 1975. Both types of implants have been improved, and several highly reliable prostheses are now available.
A number of external vacuum constriction devices are used in the tatment of erectile impotence (Table 3 and Figures 2, 3 and 4). All of these mechanical aids for erection are patented, and the Food and Drug Administration permits their sale. A prescription is necessary to purchase most of these devices.
Most vacuum constriction devices consist of a vacuum chamber, a pump, connector tubing and penile constriction bands. The vacuum chamber is large enough to fit over the erect penis. A connector tube runs to the pump from a small opening at the closed end of the chamber. An elastic constriction band, available in several sizes and types, is placed around the base of the chamber. Water-soluble lubricant is applied to the open end of the cylinder and to the entire penis. The chamber is placed over the flaccid penis, and an airtight seal is obtained (Figure 5).
Vacuum is applied with the pump to create negative pressure within the chamber. This negative pressure pulls blood into the penis and produces either erectile augmentation or an erection-like state (Figure 6). After adequate tumescence is achieved, the elastic band is guided from the chamber onto the base of the penis to cause entrapment of blood. The chamber is removed, and the erection-like state is maintained long enough to permit intercourse (Figure 7). Currently, it is recommended that the constriction band not be left on the penis for more than 30 minutes. If a longer period of tumescence is required, the constriction band can be removed for a few minutes and repeat erection achieved.
Good results have occurred with vacuum constriction systems. Nadig and associates(4) reported on the use of a vacuum constriction device in 35 men with organic impotence. Thirty-two of these men achieved an erection-like state, and 2 7 obtained a penile longitudinal rigidity of greater than 450 g of buckling force. Four of the five men who had less than adequate penile buckling force were still able to have satisfactory intercourse. Eighty percent of the patients were satisfied with the vacuum constriction device and used it regularly.
Osbon Medical Systems, Ltd. (Augusta, Ga.), distributor of the Erecaid System, surveyed more than 2,000 users of their device.(3) The average age of these men was 65 years, and most had used the device for less than one year. Before using the device, 74 percent of the men either had no erection or had a feeble erection that made vaginal penetration impossible. Ninety-two percent of the Erecaid system users could achieve an erection-like state that was adequate for satisfactory intercourse, and 78 percent had sexual intercourse at least every two weeks. Twenty-five percent were occasionally able to have satisfactory intercourse without using the device. About one week (or four practice sessions) was required to learn to use the device successfully. The seasoned user needed only two and one-half minutes to achieve an erection-like state suitable for intercourse. Most of the men described improvement in self-image and a solid relationship with their sexual partner.
All of the currently available vacuum constriction systems are reusable. Following use, each device should be cleaned and stored according to the distributor’s instructions.
In men with complete impotence, vacuum constriction devices achieve tumescence, but only distal to the point of constriction. Consequently, the penis pivots at its base, in some cases preventing intromission. However, many men with complete impotence are able to use vacuum constriction devices successfully, despite lack of tumescence proximal to the constriction band.
One potential problem with vacuum constriction systems is that the constriction band prevents normal antegrade ejaculation; consequently, sudden, painful distention of the bulbous urethra may occur. However, painful ejaculation is rarely described by device users.
If unsatisfactory erections occur after insertion of a penile implant or after intracavernosal injection of vasoactive drugs, use of a constriction band or a vacuum constriction system may augment the erection.(5) Following removal of penile implants, external devices have often been used successfully. In many instances, the devices have worked so well that users have refused to undergo surgical replacement of penile prostheses.
Vacuum constriction systems should be used with caution in patients who are receiving anticoagulant therapy or who have a blood dyscrasia. However, many men on anticoagulants use the devices successfully. Most vacuum constriction systems require both hands, although all of them can be used with the assistance of the sexual partner. Precoital application of any vacuum constriction device permits foreplay that may enhance the total sexual experience for both partners.
No significant complications from vacuum constriction systems have been reported among compliant users. Specifically, urethral stricture, spongy tissue fibrosis, penile skin necrosis and penile gangrene have not been encountered. However, patience is necessary to learn to use any of the vacuum constriction systems properly. At first, the devices may appear cumbersome. Initial use may cause some penile pain and ecchymosis. Persistent users have progressively less difficulty manipulating the devices, and the time required for them to achieve an erection or erection-like state lessens. Potential users should be advised not to give up easily.
Implantation of a penile prosthesis is the treatment of choice in most cases of complete impotence. However, once a prosthesis is implanted, irreversible damage to erectile tissue occurs. For this reason, implantation is not recommended as first-line treatment of mild to moderate partial impotence. Also, the glans is not rendered turgid by an implant.
Noninflatable Implants. Several types of semirigid, malleable (Figure 8) and articulating (Figure 9) implants are available (Table 4). All of these prostheses come in various diameters and lengths.
Inflatable Implants. Three types of inflatable implants are available Table 5). The three-component device has two cylinders, a reservoir and a pump plus tubing with connectors that permit assembly (Figures 10 and 11). The two-component implant is composed of two cylinders and a reservoir/pump combination plus connector tubing (Figure 12). The third type is a single-component, self-contained cylindrical unit (Figure 13).
The older three-component devices have several advantages. First, the erection produced closely resembles a normal erection. Second, these devices are completely concealed. Finally, the satisfaction rate from the use of three-component inflatable implants is generally high.
The three-component devices are somewhat difficult to insert, and in time they all malfunction. However, newer designs have significantly reduced the incidence of malfunction; in most cases, malfunctions can be easily and successfully corrected.
The newer two-part prostheses are similar to the three-part devices, but they are easier to insert, since a reservoir does not have to be placed in the properitoneal space. However, the long-term effectiveness of these devices is not yet known.
The completely self-contained units are easy to insert. They are fairly easy to conceal, and they produce erections that resemble normal ones. However, these implants are not as soft and pliable as multi-component prostheses, and in some instances they do not deflate well.
Underlying conditions necessitating the use of a penile implant are listed in Table 6. Most penile implantations are performed on men 40 to 70 years of age. Complications associated with implantation procedures include infection, pain, erosion, extrusion, breakage, malposition and malfunction. Inflatable devices can malfunction for many reasons, but the most common cause is leakage of fluid from a cylinder. Significant infection occurs in about 2 percent of implant recipients; when present, infection usually necessitates removal of the device. Bothersome pain occurs in about 3.5 percent of patients and occasionally leads to removal of the implant.
The number of implant failures increases with time, as would be expected with any mechanical device. Noninflatable devices can be expected to work well for at least seven to ten years, and the newer inflatable implants can be expected to function for five to ten years. Fortunately, most malfunctions can be corrected with relative ease and with the expectation of an additional five to ten years of trouble-free functioning.
Presently, the satisfaction rate for noninflatable implants is about 80 percent. When inflatable implants are used, a satisfactory outcome is expected in 80 to 90 percent of patients. Before a penile implant is inserted, patients should understand that the device only produces an erection: neither ejaculation nor orgasm is guaranteed. In the absence of unrealistic expectations, a well-placed implant should allow the impotent man to enjoy an active, healthy sex life indefinitely.
1. Witherington R. External aids for treatment of
impotence. J Urol Nurs 1987;6:10-6.
2. Witherington R. Suction device therapy in
the management of erectile impotence. Urol
Clin North Am 1988; 15:123-8.
3. Witherington R. Vacuum constriction device
for management of erectile impotence. J Urol
4. Nadig PW, Ware JC, Blumoff R. Noninvasive
device to produce and maintain an erection-like
state. Urology 1986;27:126-31.
5. Marmar JL, Debenedictis TJ, Praiss DE. The
use of a vacuum constrictor device to augment
a partial erection following an intracavernous
injection. J Urol 1988;140:975-9.
TABULAR DATA OMITTED
COPYRIGHT 1991 American Academy of Family Physicians
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