© 1991 S. Kargcr AG. Basel 0 0 4 2 -1 I38/91/0463-0266S2.75/0
Urol Int 1991;46:266-274
Nerve Sparing and Continence Preservation during Radical Prostatectomy P. Narayan Department of Urology, University of California School of Medicine, San Francisco, Calif., USA
Key Words. Prostate cancer ■Nerve preservation • Continence preservation Abstract. Prostate cancer is one of the most common malignancies occurring in men. During the last decade, several advances have been made in decreasing the morbidity of surgical therapy. Two major advances have included an improved understanding of the physiology of erection and anatomy of pelvic parasympathetic nerves mediating erectile function. Surgical techniques of ‘nerve preservation’ during surgery can preserve postoperative potency in 50-70% of patients with localized prostate cancer. In others the use of intracorporal vasoactive agents, vacuum suction devices and surgical techniques can additionally improve potency. Knowledge of the various mech anisms contributing to continence have additionally enabled modifications in surgical techniques to enhance conti nence rates postoperatively. Currently postoperative continence after radical prostatectomy occurs in over 95% of patients.
Prostate cancer is one of the most common cancers occurring in men. During the last decade there has been a tremendous resurgence of interest in surgical therapy of prostate cancer, in large part because of an increased understanding of the pelvic anatomy and the develop ment of techniques to decrease incidence of the compli cations of surgery (specifically blood loss, impotence and incontinence). In addition, there is a greater emphasis on the need to treat early-stage cancer based on knowledge of progression and improvements in staging techniques and in selecting patients for surgery. Finally, advances in anesthetic techniques and perioperative care have con tributed to better results and decreased morbidity.
Indications Radical prostatectomy is a form of local therapy which produces the best results when performed for localized cancer; for cancer that is pathologically con fined to the prostate, 15-year survival rates are similar to
those of age-matched normal controls. Local recurrence following radical prostatectomy is low, in the range of 15-20% in long-term studies [Narayan and Jajodia, 1990], This chapter discusses technical nuances of radi cal prostatectomy that can help to reduce morbidity and improve quality of life after surgery. Several of these techniques were originally pioneered by Walsh and asso ciates [Walsh and Donker, 1982; Walsh et al., 1983; Walsh, 1987; Schlegel and Walsh, 1987]. Predominant complications of radical prostatectomy are blood loss during surgery, postoperative impotence and postopera tive incontinence. To decrease the incidence of these complications and devise techniques to prevent them, an accurate knowledge of anatomy and physiology is essen tial.
Neurophysiology of Erection and Continence Erectile function is mediated by a complex of sympa thetic, parasympathetic and somatic nerve fibers [deGroat and Steers, 1988]. The parasympathetic fibers are perhaps the most important to erectile function. These
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Introduction
fibers, which arise from the sacral 2nd, 3rd and 4th nerve roots, synapse in the hypogastric plexus and travel as cavernous nerves on either side of the prostate to enter the cavernous bodies of the penis (fig. 1); they are largely responsible for initiating the arterial and sinusoidal re laxation that begins tumescence. Sympathetic nerve fi bers, which are involved in mediating the detumescence phase of erectile function, arise from Tn through L3 tho racolumbar sympathetic ganglia and travel via both the cavernous and pudendal nerves to innervate the corpo real bodies. The fibers of the somatic nerves, which carry the tactile sensations from the penile skin, also arise from the S2, S3 and S4 sacral segments and travel via the pudendal nerves. The neural innervations of the various continence mechanisms are not completely understood. The detru sor muscle and ‘preprostatic sphincter’ are supplied by parasympathetic and sympathetic nerves. The striated muscle of the external sphincter is supplied by auto nomic nerves (thoracolumbar, sympathetic and sacral 2nd. 3rd and 4th parasympathetic) as well as by somatic nerves arising from the sacral 2nd, 3rd and 4th spinal segments. While some investigators believe that most neural pathways of the somatic supply of the urethral sphincter are via the internal pudendal nerve, others believe that some of this supply may occur via the pelvic nerves [Donker et al., 1976; Blacklock, 1976; Tanagho and Smith, 1968; Koyanagi 1980]. The physiology of voiding is complex and involves a coordinate process of detrusor contraction with simultaneous relaxation of in ternal and external sphincteric mechanisms. Studies have revealed that the process of voiding is mediated by both local reflex mechanisms and spinal- and corticalcontrolled mechanisms.
Surgical Anatomy Neural Pathways The sympathetic fibers that arise from the paraverte bral ganglia course between and around the aorta and inferior vena cava as they descend toward the superior hypogastric plexus, which is located at the level of T12 and S| anterior to the vertebral bodies (fig. 1). After pass ing through the superior hypogastric plexus, the sympa thetic fibers mingle with the parasympathetic fibers to course through the inferior hypogastric plexus, located on the surface of the bodies of the 2nd, 3rd and 4th sacral vertebrae behind the bladder. The condensation of fibers that arise from the inferior hypogastric plexus, termed
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Fig. 1. Neuroanatomy of the pelvic autonomic and somatic nerves.
the erectile or cavernous nerves, travels on either side of the prostate outside Denonvilliers’ fascia. At the level of the prostate, these nerves are normally about 0.5-1 cm away from the prostatic capsule. (When there is prostatic enlargement resulting from nodular hyperplasia or can cer, these nerves may be closer to the capsule.) Through out their course in the pelvis, these pelvic nerves give rise to branches that supply the bladder base, prostate, semi nal vesicles, ejaculatory duct and urethra. The pudendal nerve arises from the sacral 2nd, 3rd and 4th nerve roots, travels in Alcock’s canal and enters the perineum well below the prostate to supply the urethra and penis. It is not subject to injury during radical prostatectomy Anatomy o f Continence Mechanisms The base of the prostate is continuous with the detru sor muscle at the bladder base both externally and inter nally. Externally, the outer longitudinal layer of this muscle envelops the prostate anteriorly and laterally as a
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Interior vesical artery Detrusor lo o p --------Preprostatic sphincter Striated sphincter External sphincter
Ampulla of vas deferens Seminal vesicle Prostatic branch Urethra
sling or a loop (fig. 2). Internally, the deep trigonal mus cle extends downward into the prostate as a muscular sleeve surrounding the upper part of the prostatic ure thra. Sometimes termed the ‘preprostatic sphincter’, this sleeve - along with the inner circular fibers of the blad der neck - constitutes the internal sphincter mechanism in the male. The preprostatic musculature, made up of smooth muscle similar to that of the detrusor, is narrow posteriorly and fans out anteriorly. It ends close to the level of the verumontanum, where it meets the upper fibers of the striated urethral muscle, or ‘external sphinc ter’ (fig. 2). The upper third of the striated urethral mus cle is variable in length, sometimes extending up to the bladder neck and interdigitating with the fibers of the detrusor but more often ending at the level of the veru montanum. In the upper third it is prominent anteriorly, while in the lower two thirds it encircles the entire ure thra. The internal and external sphincter mechanisms are further enhanced in maintaining continence by the ‘bellows’ effects of the levator ani and perineal muscles of the urogenital triangle.
Arterial and Venous Anatomy of the Prostate Branches of the inferior vesical artery form the major arterial supply of the prostate. The prostatic branch is given off at the base of the prostate near the 5 and 7 o’clock positions (right and left) in the groove between the prostate and bladder neck (fig. 3). Perforating branches from this artery penetrate the prostatic capsule
Fig. 3. Posterior view of the bladder and prostate demonstrating the arterial supply of the prostate.
and then divide, supplying both the prostatic tissue and the prostatic urethra. The terminal portion of the infe rior vesical arteries courses downward and travels along with the cavernous nerves as part of the neurovascular bundle. Branches from these vessels form additional cap sular arteries of the prostate. The penis is normally supplied by the terminal branches of the internal pudendal artery (fig. 4), includ ing the perineal artery, the bulbourethral artery and the cavernous (deep) and dorsal (superficial) arteries of the penis [Breza et al., 1989; Tramier et al., 1981; Juskiewenski et al., 1982], Variations in arterial supply may result in an accessory internal pudendal artery forming an additional or sole blood supply to one side of the penis. The significance of this variation is that the acces sory pudendal artery may arise from the obturator, infe rior or superior vesical arteries. All of these latter vessels are subject to complete or partial injury during radical prostatectomy and cystoprostatectomy. Thus, there are vascular and neural considerations for impotence follow ing radical prostatectomy. The venous blood supply of the prostate is formed by the dorsal vein and the plexus of veins surrounding the prostate anteriorly and laterally (Santorini’s plexus). The deep dorsal vein is part of the intermediate venous sys tem draining the penis. After penetrating the urogenital diaphragm (which anteriorly is only a thin fascia), this vein divides into an anterior branch and several lateral branches (fig. 5). Veins from the anterior surface of the prostate and bladder wall coalesce to join the superficial branch of the dorsal vein complex that usually traverses
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Fig. 2. Anatomy of the sphincteric muscles in the male.
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the area between the two puboprostatic ligaments. The lateral branches of the dorsal vein complex travel on the lateral sides of the prostate and communicate with branches of the crural, obturator and internal pudendal veins. These branches eventually drain via the inferior vesical and hemorrhoidal veins into the internal iliac veins.
Technique of Nerve-Sparing Radical Prostatectomy The author has performed nerve-sparing operations in over 125 patients at UCSF and VAMC hospitals in San Francisco. The discussion and results in this paper are based on this experience. We perform all radical prostatectomies with the pa tient’s legs spread at an approximate 30-45° angle and resting on Kraus ‘airplane’ splints (AMSCO, Erie, Penn.). The perineum is positioned at the edge of the table, so that an assistant standing between the patient’s legs can provide perineal pressure at the time of vesi courethral anastomosis. This pressure enables the ure thral stump to be pushed in 1-2 cm, allowing easier access for a meticulous vesicourethral anastomosis. An important early step in radical prostatectomy is the achievement of a relatively bloodless field by adequate ligation of the dorsal vein complex. Dr. Walsh recom
Fig. 5. The venous drainage of the prostate.
mends bilateral temporary occlusion of the hypogastric arteries to minimize blood loss; we have used this tech nique on occasion, though not as a routine. To minimize blood loss from the dorsal vein complex, we first sutureligate the branches of the dorsal plexus on the anterior and lateral surfaces of the bladder neck and prostate (fig. 6) and then open the endopelvic fascia on either side and carefully incise the puboprostatic ligaments (fig. 7). These ligaments are superficial, and during their incision care must be taken not to injure branches of the dorsal vein complex directly behind them. The next step is to ligate the dorsal vein complex. If there is a prominent superficial branch, it is ligated first. The main complex is ligated using a large right-angle clamp passed from left to right or vice versa, using 0 Dexon or 2-0 PDS absorbable sutures (fig. 8). We prefer absorbable rather than silk sutures because the last occa sionally migrate into the urethral anastomotic repair and later cause irritative voiding symptoms. Because the proximity of the prostate to the pubic bone prevents division of the dorsal vein complex between ligatures, they are all tied close to the pubic bone. The previously placed sutures on the anterior and lateral surfaces of the bladder neck prevent back-bleeding during division of the dorsal vein complex. The dorsal vein is incised slowly and methodically, to avoid both slippage of the ligatures and inadvertent excision of the anterior pros-
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Fig. 4. The arterial supply of the penis and its variations.
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tatic capsule, which is close to the complex. If the liga tures on the dorsal vein slip during incision of the vein complex, the complex can be suture-ligated against the pubic wall fascia, using 2-0 chromic catgut on a UR4 or TT4 (semicircular) needle. When the dorsal vein com plex bleeds because of inadequate ligation or other ve nous injury, temporary hemostasis may be obtained by distal traction on the Foley catheter, which causes the prostate and anterior bladder neck to descend and com press the dorsal complex against the pubic bone. This maneuver may be used intermittently during ligation and division of the dorsal complex if bleeding becomes a problem. Following division of the dorsal vein complex, the urethra is transected. The urethral insertion into the prostate is variable [Weldon and Tavel, 1988]. It is often in the form of a notch, where there is a defect in the anterior prostate wall and the prostate covers the urethra less anteriorly than laterally and posteriorly. This knowl edge helps one to avoid transecting the apex of the pros tate laterally and posteriorly. The urethra is First incised anteriorly (fig. 9). The Foley catheter is then clamped; the proximal portion is used for traction, the distal end cut and removed. Trac tion on the Foley catheter exposes the posterior urethral wall so that it can be carefully incised. Just prior to com plete transection of the posterior urethral wall, we occa sionally place 2 sutures at the 3 and 9 o’clock positions; these sutures are later used for vesicourethral anasto
moses. We do this both because the posterior urethral wall is transected at a lower level than is the anterior wall (fig. 9, 10) and because the urethral striated muscu lature is less developed posteriorly than anteriorly and therefore the urethra tends to react more posteriorly. The apex of the prostate is then carefully dissected and, finally, the rectourethralis fibers are incised. These fi bers must be incised in the midline to prevent inadver tent injury to the cavernous nerves. The fibers are usually well visualized and can be incised under direct vision (fig. 10). Occasionally, however, the apex is ad herent and the fibers are not easily visualized; this is especially prevalent in patients who have had transure thral prostatectomy, in which the cancer is apical or there is scarring following multiple biopsies or prostati tis. Careful dissection in situ is necessary to avoid both leaving apical prostate behind and potential rectal injury (fig. 11). Once the apex is freed, the two constant vessels at the lateral edges must be carefully ligated (fig. 12). These vessels branch from the neurovascular bundle and are part of the vascular supply of the corpora, which is subject to injury during radical prostatectomy. Absorb able sutures, used to ligate these vessels, are preferred because they help prevent inadvertent ligation of nearby pelvic nerve fibers. Next, the lateral fascial attachments arc divided. Within this fascia there may be small and variable vascular branches travelling from the neurovas cular bundle to the prostate; these must also be ligated, as they are seen, using absorbable sutures (fig. 12). The
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Fig. 6. Suture ligation of the dorsal vein complex on the anterior surface of the bladder neck and prostate. Fig. 7. Ligated dorsal vein complex with intact endopelvic fascia (a) and opened endopelvic fascia with incised puboprostatic liga ments (b).
Nerve Sparing and Continence Preservation
Fig. 10. Incision of the rectourethralis fibers in situ to free the apex of the prostate.
prostate is then gently dissected off the rectum posteri orly in the midline. Once the urethra is completely tran sected, we perform 4 quadrant biopsies of the distal ure thral stump to document negative margins. Vascular pedicles of the prostate are then ligated - close to the prostate and away from the rectum, to avoid injury to the cavernous nerves (fig. 12). Attention is then directed at dissecting the bladder neck. A small incision is made in the groove between the bladder neck and the prostate. Meticulous dissection of the bladder neck will preserve most of the circular fibers, promoting preservation of the continence mechanism associated with the bladder neck (fig. 13). The posterior fibers of the bladder neck are part of the trigone and tend to retract inward after their incision. Care must be taken, therefore, not to tear the posterior
Fig. 9. Incision of the urethra.
Fig. 11. Alternative technique of dissection and incision of rec tourethralis fibers to free the apex of the prostate.
Fig. 12. Dissection of the lateral prostatic fascia.
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Fig. 8. Ligation of the dorsal vein complex.
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bladder wall. The ejaculatory ducts are identified in the midline and incised using large hemoclips. The seminal vesicles are then freed. Injury to autonomic fibers is avoided by confining the dissection close to the seminal vesicles and securing all proximal bleeding using electro cautery or hemoclips. At the tip of each seminal vesicle, there is a constant arterial supply, which should be care fully secured. Following removal of the prostate, we repair the blad der neck. Meticulous dissection of the prostate at the bladder neck prevents a posterior tear of the trigonal muscle and limits the extent of repair necessary. Prior to repair we routinely perform 4 quadrant biopsies of the bladder neck to ensure negative margins. If the defect is small, the bladder neck may be narrowed by a few approximating sutures of absorbable material (fig. 14a). If the patient has undergone a prior transurethral resec tion. has a large median lobe or has extensive prostatic cancer, the resultant defect in the bladder neck is re paired by approximation beginning posteriorly in the midline to provide a small circular bladder neck (fig. 14b). To ensure good mucosal-to-mucosal approxi mation during vesicourethral anastomosis, we evert the mucosa using 4 sutures of 4-0 chromic catgut. If the bladder musculature appears to be of poor quality or if extensive bladder neck repair is necessary, we tempo rarily divert the urine using bilateral single J stents (fig. 15). These stents are placed intraoperatively, exit through the bladder and anterior abdominal wall and are removed at 7-10 days postoperatively. In our experi ence, these stents reduce the volume of postoperative anastomotic drainage and may diminish fibrosis at the anastomotic area, promoting earlier and more complete recovery of continence.
Fig. 14. Repair of bladder neck, a Fish mouth technique, b Pos terior racquet handle technique.
Anastomosis of the urethra to the bladder is achieved using 7-8 absorbable sutures. We prefer 3-0 Maxon® (Davis and Geek). The anastomosis is performed over a 20 French Silastic catheter. Initial positioning of the patient with the legs extended on Kraus ‘airplane’ splints allows an assistant to place a sponge stick in the peri neum to push the urethra inward, resulting in a gain of 1-2 cm in urethral length and making the urethra acces sible for placement of urethral anastomotic sutures. Ad ditionally, the posterior sutures previously placed on the distal urethral margin enable some traction on the ure thra. In heavy patients with deep pelves, a wedge pubcctomy of the inner table of the pubic bones in the midline can help to improve visualization of the dorsal vein com plex and vesicourethral anastomoses.
Nerve-Sparing Radical Perineal Prostatectomy Radical perineal prostatectomy has two major advan tages over radical retropubic prostatectomy. One is im proved urethral visualization, which facilitates vesico urethral anastomosis. A second advantage is reduced blood loss, since the dissection is performed below the dorsal vein complex. Disadvantages include the need for a separate incision to perform pelvic lymphadenectomy and the difficulty of performing the lateral dissection in large prostates. During radical perineal prostatectomy, cavernous nerves can also be preserved by recognizing and preserving the lateral fascia of the prostate, which contains the neurovascular bundle (fig. 16). Other im portant steps include limiting the dissection close to the urethra and ligating vascular pedicles close to the pros tate. Continence preservation may, in fact, be enhanced
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Fig. 13. Dissection of the bladder neck.
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Fig. 15. Placement of single J temporary diversion stents in extensive bladder neck repair.
Fig. 16. Neurovascular bundles as observed during radical peri neal prostatectomy.
with meticulous urcthrovesical anastomoses. The suc cessful use of these techniques has been discussed re cently in the literature [Myers et al., 1987; Weiss et al., 1985],
leakage not present previously. Patients with risk factors such as older age (over 65), atherosclerosis, smoking and diabetes have only a 30-40% chance of preserving po tency, even if their cancer is at a low stage and nerves arc spared. Early postoperative treatment with nonsurgical therapies may help some patients, while penile implant surgery may be necessary in others. There has been concern among surgeons that nerve sparing may compromise the performance of an ade quate cancer operation. However, the cavernous nerves are located outside the prostate capsule and Denonvilliers’ fascia; therefore, in patients with cancer confined to the prostatic capsule, cavernous nerve sparing should have no impact on cancer control. Dr. Walsh and col leagues have also performed extensive pathological stud ies demonstrating this fact [Eggleston and Walsh, 1985; Walsh et al., 1987], In stage B-2 cancers, however, in which the incidence of extracapsular extension is high, we do not recommend nerve-sparing surgery. Occasion ally, in the young patient (under age 65), in whom pre operative biopsy has demonstrated probable absence of cancer on one side, we perform a unilateral preservation of the neurovascular bundle. Dr. Walsh has reported the successful use of this technique in preserving potency in 65% of men aged 50-65 years [Walsh et al., 1987], Our results have been lower, probably because most of our patients had additional risk factors for impotence.
Results of Nerve-Sparing Prostatectomy Results of nerve-sparing radical prostatectomy de pend on a number of factors. These include patient age. potency prior to surgery, cancer stage, history of smok ing, medication history and coexistent illness such as hypertension, atherosclerosis, diabetes and peripheral vascular disease. In low-stage cancers (A|-B|) in patients under 65 years with normal potency and minimal risk factors, we can achieve reasonable potency (erections satisfactory for vaginal penetration) in 50% of patients 3-6 months following surgery. In another 20-30%, par tial erections are achievable. In these patients, erection can be improved and made suitable for penetration by the use of vacuum suction devices and intracavernous injections of smooth muscle relaxants (papaverine hy drochloride or prostaglandin E|), and a-blockers (phentolamine) [Lue and Tanagho, 1987], Penile Doppler studies in these patients indicate damage to the vascular supply of the penis, including partial fibrosis of one or both cavernous arteries and varying degrees of venous
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The reported incidence of incontinence following radical prostatectomy varies from 0.5-15%. Stress in continence related to exertion is the most common form of incontinence; however, 3-5% of patients will have incontinence at rest and require an artificial sphincter or other means to achieve control. Because of the multifac torial mechanisms involved in continence, it is hard to define a specific cause of incontinence in any individual patient postoperatively. The techniques of radical pros tatectomy described herein have resulted in an overall incontinence rate of less than 10% in our patients. Severe incontinence has occurred only in 2% of these patients; mild stress incontinence is seen in 3-5% of patients and moderate stress incontinence in an addi tional 3%.
References Blacklock NJ: Surgical anatomy of the prostate; in Williams DI. Chisholm GD (eds); Scientific Foundations of Urology, ed 1. Chicago, Year Book Medical Publishers, 1976, vol II, sectil, chap 16, p 113. Breza J et al: Detailed anatomy of penile neurovascular structures: Surgical significance. J Urol 1989;141:437-443. deGroat WC, Steers WD: Neuroanatomy and neurophysiology of penile erection; in Tanagho EA, Lue TF, McClure RD (eds), Contemporary Management of Impotence and Infertility. Balti more. Williams & Wilkins, 1988. Donker PJ, Droes J, Th PM, Van Ulden BM: Anatomy of the mus culature and innervation of the bladder and the urethra; in Wil liams DI, Chisholm GD (eds): Scientific Foundations of Urolo gy, ed 1. Chicago, Year Book Medical Publishers, 1976, vol II, sect 1, chap 5, p 32. Eggleston JC, Walsh PC: Radical prostatectomy with preservation of sexual function: Pathological findings in the first 100 cases. J Urol 1985;134:1146-1148. Juskiewenski S, et al: A study of the arterial blood supply to the penis. Anat Clin 1982;4:101-107.
Koyanagi T: Studies on the sphincteric system located distally in the urethra: The external urethral sphincter revisited. J Urol 1980; 124:400-406. Lue TF, Tanagho EA: Physiology of erection and pharmacological management of impotence. J Urol 1987;137:829-836. Myers RP, Goellner JR, Cahill DR: Prostate shape, external striated urethral sphincter and radical prostatectomy: The apical dissec tion. J Urol 1987;138:543-550. Narayan P, Jajodia P: Prostatic oncology. Urologic care in the elder ly. Clin Geriatr Med 1990:6:131-161. Schlegel PN, Walsh PC: Neuroanatomical approach to radical cys tectomy with preservation of sexual function. J Urol 1987; 138: 1402-1406. Tanagho EA, Smith DR: Mechanism of urinary continence. 1. Embryologic, anatomic and pathologic considerations. J Urol 1968;100:640-646. Tramier D, et al: Radiological anatomy of the internal pudendal artery (a. pudenda interna) in the male. Anat Clin 1981 ;3:195— 200. Walsh PC, Donker P: Impotence following radical prostatectomy: Insight into etiology and prevention. J Urol 1982; 128:492— 494. Walsh PC, Epstein JL, Lowe FC: Potency following radical prosta tectomy with wide unilateral excision of the neurovascular bun dle. J Urol 1987;138:823-827. Walsh PC, Lepor H, Eggleston JC: Radical prostatectomy with pres ervation of sexual function: Anatomical and pathological con siderations. Prostate 1983;4:473-485. Walsh PC: Radical prostatectomy, preservation of sexual function, cancer control: The controversy. Urol Clin North Am 1987; 14: 553-573. Weiss JP, et al: Preservation of periprostatic autonomic nerves dur ing total perineal prostatectomy by intrafascial dissection. Urol ogy 1985;26:160-163. Weldon VE, Tavel FR: Potency-sparing radical perineal prostatecto my: Anatomy, surgical technique and initial results. J Urol 1988: 140:559-562.
P. Narayan, MD Department of Urology, U-575 University of California San Francisco, CA 94143-0738 (USA)
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Results of Continence Preservation
Urol Int 1991;46:266-274
Nerve Sparing and Continence Preservation during Radical Prostatectomy P. Narayan Department of Urology, University of California School of Medicine, San Francisco, Calif., USA
Key Words. Prostate cancer ■Nerve preservation • Continence preservation Abstract. Prostate cancer is one of the most common malignancies occurring in men. During the last decade, several advances have been made in decreasing the morbidity of surgical therapy. Two major advances have included an improved understanding of the physiology of erection and anatomy of pelvic parasympathetic nerves mediating erectile function. Surgical techniques of ‘nerve preservation’ during surgery can preserve postoperative potency in 50-70% of patients with localized prostate cancer. In others the use of intracorporal vasoactive agents, vacuum suction devices and surgical techniques can additionally improve potency. Knowledge of the various mech anisms contributing to continence have additionally enabled modifications in surgical techniques to enhance conti nence rates postoperatively. Currently postoperative continence after radical prostatectomy occurs in over 95% of patients.
Prostate cancer is one of the most common cancers occurring in men. During the last decade there has been a tremendous resurgence of interest in surgical therapy of prostate cancer, in large part because of an increased understanding of the pelvic anatomy and the develop ment of techniques to decrease incidence of the compli cations of surgery (specifically blood loss, impotence and incontinence). In addition, there is a greater emphasis on the need to treat early-stage cancer based on knowledge of progression and improvements in staging techniques and in selecting patients for surgery. Finally, advances in anesthetic techniques and perioperative care have con tributed to better results and decreased morbidity.
Indications Radical prostatectomy is a form of local therapy which produces the best results when performed for localized cancer; for cancer that is pathologically con fined to the prostate, 15-year survival rates are similar to
those of age-matched normal controls. Local recurrence following radical prostatectomy is low, in the range of 15-20% in long-term studies [Narayan and Jajodia, 1990], This chapter discusses technical nuances of radi cal prostatectomy that can help to reduce morbidity and improve quality of life after surgery. Several of these techniques were originally pioneered by Walsh and asso ciates [Walsh and Donker, 1982; Walsh et al., 1983; Walsh, 1987; Schlegel and Walsh, 1987]. Predominant complications of radical prostatectomy are blood loss during surgery, postoperative impotence and postopera tive incontinence. To decrease the incidence of these complications and devise techniques to prevent them, an accurate knowledge of anatomy and physiology is essen tial.
Neurophysiology of Erection and Continence Erectile function is mediated by a complex of sympa thetic, parasympathetic and somatic nerve fibers [deGroat and Steers, 1988]. The parasympathetic fibers are perhaps the most important to erectile function. These
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Introduction
fibers, which arise from the sacral 2nd, 3rd and 4th nerve roots, synapse in the hypogastric plexus and travel as cavernous nerves on either side of the prostate to enter the cavernous bodies of the penis (fig. 1); they are largely responsible for initiating the arterial and sinusoidal re laxation that begins tumescence. Sympathetic nerve fi bers, which are involved in mediating the detumescence phase of erectile function, arise from Tn through L3 tho racolumbar sympathetic ganglia and travel via both the cavernous and pudendal nerves to innervate the corpo real bodies. The fibers of the somatic nerves, which carry the tactile sensations from the penile skin, also arise from the S2, S3 and S4 sacral segments and travel via the pudendal nerves. The neural innervations of the various continence mechanisms are not completely understood. The detru sor muscle and ‘preprostatic sphincter’ are supplied by parasympathetic and sympathetic nerves. The striated muscle of the external sphincter is supplied by auto nomic nerves (thoracolumbar, sympathetic and sacral 2nd. 3rd and 4th parasympathetic) as well as by somatic nerves arising from the sacral 2nd, 3rd and 4th spinal segments. While some investigators believe that most neural pathways of the somatic supply of the urethral sphincter are via the internal pudendal nerve, others believe that some of this supply may occur via the pelvic nerves [Donker et al., 1976; Blacklock, 1976; Tanagho and Smith, 1968; Koyanagi 1980]. The physiology of voiding is complex and involves a coordinate process of detrusor contraction with simultaneous relaxation of in ternal and external sphincteric mechanisms. Studies have revealed that the process of voiding is mediated by both local reflex mechanisms and spinal- and corticalcontrolled mechanisms.
Surgical Anatomy Neural Pathways The sympathetic fibers that arise from the paraverte bral ganglia course between and around the aorta and inferior vena cava as they descend toward the superior hypogastric plexus, which is located at the level of T12 and S| anterior to the vertebral bodies (fig. 1). After pass ing through the superior hypogastric plexus, the sympa thetic fibers mingle with the parasympathetic fibers to course through the inferior hypogastric plexus, located on the surface of the bodies of the 2nd, 3rd and 4th sacral vertebrae behind the bladder. The condensation of fibers that arise from the inferior hypogastric plexus, termed
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Fig. 1. Neuroanatomy of the pelvic autonomic and somatic nerves.
the erectile or cavernous nerves, travels on either side of the prostate outside Denonvilliers’ fascia. At the level of the prostate, these nerves are normally about 0.5-1 cm away from the prostatic capsule. (When there is prostatic enlargement resulting from nodular hyperplasia or can cer, these nerves may be closer to the capsule.) Through out their course in the pelvis, these pelvic nerves give rise to branches that supply the bladder base, prostate, semi nal vesicles, ejaculatory duct and urethra. The pudendal nerve arises from the sacral 2nd, 3rd and 4th nerve roots, travels in Alcock’s canal and enters the perineum well below the prostate to supply the urethra and penis. It is not subject to injury during radical prostatectomy Anatomy o f Continence Mechanisms The base of the prostate is continuous with the detru sor muscle at the bladder base both externally and inter nally. Externally, the outer longitudinal layer of this muscle envelops the prostate anteriorly and laterally as a
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Interior vesical artery Detrusor lo o p --------Preprostatic sphincter Striated sphincter External sphincter
Ampulla of vas deferens Seminal vesicle Prostatic branch Urethra
sling or a loop (fig. 2). Internally, the deep trigonal mus cle extends downward into the prostate as a muscular sleeve surrounding the upper part of the prostatic ure thra. Sometimes termed the ‘preprostatic sphincter’, this sleeve - along with the inner circular fibers of the blad der neck - constitutes the internal sphincter mechanism in the male. The preprostatic musculature, made up of smooth muscle similar to that of the detrusor, is narrow posteriorly and fans out anteriorly. It ends close to the level of the verumontanum, where it meets the upper fibers of the striated urethral muscle, or ‘external sphinc ter’ (fig. 2). The upper third of the striated urethral mus cle is variable in length, sometimes extending up to the bladder neck and interdigitating with the fibers of the detrusor but more often ending at the level of the veru montanum. In the upper third it is prominent anteriorly, while in the lower two thirds it encircles the entire ure thra. The internal and external sphincter mechanisms are further enhanced in maintaining continence by the ‘bellows’ effects of the levator ani and perineal muscles of the urogenital triangle.
Arterial and Venous Anatomy of the Prostate Branches of the inferior vesical artery form the major arterial supply of the prostate. The prostatic branch is given off at the base of the prostate near the 5 and 7 o’clock positions (right and left) in the groove between the prostate and bladder neck (fig. 3). Perforating branches from this artery penetrate the prostatic capsule
Fig. 3. Posterior view of the bladder and prostate demonstrating the arterial supply of the prostate.
and then divide, supplying both the prostatic tissue and the prostatic urethra. The terminal portion of the infe rior vesical arteries courses downward and travels along with the cavernous nerves as part of the neurovascular bundle. Branches from these vessels form additional cap sular arteries of the prostate. The penis is normally supplied by the terminal branches of the internal pudendal artery (fig. 4), includ ing the perineal artery, the bulbourethral artery and the cavernous (deep) and dorsal (superficial) arteries of the penis [Breza et al., 1989; Tramier et al., 1981; Juskiewenski et al., 1982], Variations in arterial supply may result in an accessory internal pudendal artery forming an additional or sole blood supply to one side of the penis. The significance of this variation is that the acces sory pudendal artery may arise from the obturator, infe rior or superior vesical arteries. All of these latter vessels are subject to complete or partial injury during radical prostatectomy and cystoprostatectomy. Thus, there are vascular and neural considerations for impotence follow ing radical prostatectomy. The venous blood supply of the prostate is formed by the dorsal vein and the plexus of veins surrounding the prostate anteriorly and laterally (Santorini’s plexus). The deep dorsal vein is part of the intermediate venous sys tem draining the penis. After penetrating the urogenital diaphragm (which anteriorly is only a thin fascia), this vein divides into an anterior branch and several lateral branches (fig. 5). Veins from the anterior surface of the prostate and bladder wall coalesce to join the superficial branch of the dorsal vein complex that usually traverses
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Fig. 2. Anatomy of the sphincteric muscles in the male.
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the area between the two puboprostatic ligaments. The lateral branches of the dorsal vein complex travel on the lateral sides of the prostate and communicate with branches of the crural, obturator and internal pudendal veins. These branches eventually drain via the inferior vesical and hemorrhoidal veins into the internal iliac veins.
Technique of Nerve-Sparing Radical Prostatectomy The author has performed nerve-sparing operations in over 125 patients at UCSF and VAMC hospitals in San Francisco. The discussion and results in this paper are based on this experience. We perform all radical prostatectomies with the pa tient’s legs spread at an approximate 30-45° angle and resting on Kraus ‘airplane’ splints (AMSCO, Erie, Penn.). The perineum is positioned at the edge of the table, so that an assistant standing between the patient’s legs can provide perineal pressure at the time of vesi courethral anastomosis. This pressure enables the ure thral stump to be pushed in 1-2 cm, allowing easier access for a meticulous vesicourethral anastomosis. An important early step in radical prostatectomy is the achievement of a relatively bloodless field by adequate ligation of the dorsal vein complex. Dr. Walsh recom
Fig. 5. The venous drainage of the prostate.
mends bilateral temporary occlusion of the hypogastric arteries to minimize blood loss; we have used this tech nique on occasion, though not as a routine. To minimize blood loss from the dorsal vein complex, we first sutureligate the branches of the dorsal plexus on the anterior and lateral surfaces of the bladder neck and prostate (fig. 6) and then open the endopelvic fascia on either side and carefully incise the puboprostatic ligaments (fig. 7). These ligaments are superficial, and during their incision care must be taken not to injure branches of the dorsal vein complex directly behind them. The next step is to ligate the dorsal vein complex. If there is a prominent superficial branch, it is ligated first. The main complex is ligated using a large right-angle clamp passed from left to right or vice versa, using 0 Dexon or 2-0 PDS absorbable sutures (fig. 8). We prefer absorbable rather than silk sutures because the last occa sionally migrate into the urethral anastomotic repair and later cause irritative voiding symptoms. Because the proximity of the prostate to the pubic bone prevents division of the dorsal vein complex between ligatures, they are all tied close to the pubic bone. The previously placed sutures on the anterior and lateral surfaces of the bladder neck prevent back-bleeding during division of the dorsal vein complex. The dorsal vein is incised slowly and methodically, to avoid both slippage of the ligatures and inadvertent excision of the anterior pros-
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Fig. 4. The arterial supply of the penis and its variations.
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tatic capsule, which is close to the complex. If the liga tures on the dorsal vein slip during incision of the vein complex, the complex can be suture-ligated against the pubic wall fascia, using 2-0 chromic catgut on a UR4 or TT4 (semicircular) needle. When the dorsal vein com plex bleeds because of inadequate ligation or other ve nous injury, temporary hemostasis may be obtained by distal traction on the Foley catheter, which causes the prostate and anterior bladder neck to descend and com press the dorsal complex against the pubic bone. This maneuver may be used intermittently during ligation and division of the dorsal complex if bleeding becomes a problem. Following division of the dorsal vein complex, the urethra is transected. The urethral insertion into the prostate is variable [Weldon and Tavel, 1988]. It is often in the form of a notch, where there is a defect in the anterior prostate wall and the prostate covers the urethra less anteriorly than laterally and posteriorly. This knowl edge helps one to avoid transecting the apex of the pros tate laterally and posteriorly. The urethra is First incised anteriorly (fig. 9). The Foley catheter is then clamped; the proximal portion is used for traction, the distal end cut and removed. Trac tion on the Foley catheter exposes the posterior urethral wall so that it can be carefully incised. Just prior to com plete transection of the posterior urethral wall, we occa sionally place 2 sutures at the 3 and 9 o’clock positions; these sutures are later used for vesicourethral anasto
moses. We do this both because the posterior urethral wall is transected at a lower level than is the anterior wall (fig. 9, 10) and because the urethral striated muscu lature is less developed posteriorly than anteriorly and therefore the urethra tends to react more posteriorly. The apex of the prostate is then carefully dissected and, finally, the rectourethralis fibers are incised. These fi bers must be incised in the midline to prevent inadver tent injury to the cavernous nerves. The fibers are usually well visualized and can be incised under direct vision (fig. 10). Occasionally, however, the apex is ad herent and the fibers are not easily visualized; this is especially prevalent in patients who have had transure thral prostatectomy, in which the cancer is apical or there is scarring following multiple biopsies or prostati tis. Careful dissection in situ is necessary to avoid both leaving apical prostate behind and potential rectal injury (fig. 11). Once the apex is freed, the two constant vessels at the lateral edges must be carefully ligated (fig. 12). These vessels branch from the neurovascular bundle and are part of the vascular supply of the corpora, which is subject to injury during radical prostatectomy. Absorb able sutures, used to ligate these vessels, are preferred because they help prevent inadvertent ligation of nearby pelvic nerve fibers. Next, the lateral fascial attachments arc divided. Within this fascia there may be small and variable vascular branches travelling from the neurovas cular bundle to the prostate; these must also be ligated, as they are seen, using absorbable sutures (fig. 12). The
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Fig. 6. Suture ligation of the dorsal vein complex on the anterior surface of the bladder neck and prostate. Fig. 7. Ligated dorsal vein complex with intact endopelvic fascia (a) and opened endopelvic fascia with incised puboprostatic liga ments (b).
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Fig. 10. Incision of the rectourethralis fibers in situ to free the apex of the prostate.
prostate is then gently dissected off the rectum posteri orly in the midline. Once the urethra is completely tran sected, we perform 4 quadrant biopsies of the distal ure thral stump to document negative margins. Vascular pedicles of the prostate are then ligated - close to the prostate and away from the rectum, to avoid injury to the cavernous nerves (fig. 12). Attention is then directed at dissecting the bladder neck. A small incision is made in the groove between the bladder neck and the prostate. Meticulous dissection of the bladder neck will preserve most of the circular fibers, promoting preservation of the continence mechanism associated with the bladder neck (fig. 13). The posterior fibers of the bladder neck are part of the trigone and tend to retract inward after their incision. Care must be taken, therefore, not to tear the posterior
Fig. 9. Incision of the urethra.
Fig. 11. Alternative technique of dissection and incision of rec tourethralis fibers to free the apex of the prostate.
Fig. 12. Dissection of the lateral prostatic fascia.
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Fig. 8. Ligation of the dorsal vein complex.
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bladder wall. The ejaculatory ducts are identified in the midline and incised using large hemoclips. The seminal vesicles are then freed. Injury to autonomic fibers is avoided by confining the dissection close to the seminal vesicles and securing all proximal bleeding using electro cautery or hemoclips. At the tip of each seminal vesicle, there is a constant arterial supply, which should be care fully secured. Following removal of the prostate, we repair the blad der neck. Meticulous dissection of the prostate at the bladder neck prevents a posterior tear of the trigonal muscle and limits the extent of repair necessary. Prior to repair we routinely perform 4 quadrant biopsies of the bladder neck to ensure negative margins. If the defect is small, the bladder neck may be narrowed by a few approximating sutures of absorbable material (fig. 14a). If the patient has undergone a prior transurethral resec tion. has a large median lobe or has extensive prostatic cancer, the resultant defect in the bladder neck is re paired by approximation beginning posteriorly in the midline to provide a small circular bladder neck (fig. 14b). To ensure good mucosal-to-mucosal approxi mation during vesicourethral anastomosis, we evert the mucosa using 4 sutures of 4-0 chromic catgut. If the bladder musculature appears to be of poor quality or if extensive bladder neck repair is necessary, we tempo rarily divert the urine using bilateral single J stents (fig. 15). These stents are placed intraoperatively, exit through the bladder and anterior abdominal wall and are removed at 7-10 days postoperatively. In our experi ence, these stents reduce the volume of postoperative anastomotic drainage and may diminish fibrosis at the anastomotic area, promoting earlier and more complete recovery of continence.
Fig. 14. Repair of bladder neck, a Fish mouth technique, b Pos terior racquet handle technique.
Anastomosis of the urethra to the bladder is achieved using 7-8 absorbable sutures. We prefer 3-0 Maxon® (Davis and Geek). The anastomosis is performed over a 20 French Silastic catheter. Initial positioning of the patient with the legs extended on Kraus ‘airplane’ splints allows an assistant to place a sponge stick in the peri neum to push the urethra inward, resulting in a gain of 1-2 cm in urethral length and making the urethra acces sible for placement of urethral anastomotic sutures. Ad ditionally, the posterior sutures previously placed on the distal urethral margin enable some traction on the ure thra. In heavy patients with deep pelves, a wedge pubcctomy of the inner table of the pubic bones in the midline can help to improve visualization of the dorsal vein com plex and vesicourethral anastomoses.
Nerve-Sparing Radical Perineal Prostatectomy Radical perineal prostatectomy has two major advan tages over radical retropubic prostatectomy. One is im proved urethral visualization, which facilitates vesico urethral anastomosis. A second advantage is reduced blood loss, since the dissection is performed below the dorsal vein complex. Disadvantages include the need for a separate incision to perform pelvic lymphadenectomy and the difficulty of performing the lateral dissection in large prostates. During radical perineal prostatectomy, cavernous nerves can also be preserved by recognizing and preserving the lateral fascia of the prostate, which contains the neurovascular bundle (fig. 16). Other im portant steps include limiting the dissection close to the urethra and ligating vascular pedicles close to the pros tate. Continence preservation may, in fact, be enhanced
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Fig. 13. Dissection of the bladder neck.
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Fig. 15. Placement of single J temporary diversion stents in extensive bladder neck repair.
Fig. 16. Neurovascular bundles as observed during radical peri neal prostatectomy.
with meticulous urcthrovesical anastomoses. The suc cessful use of these techniques has been discussed re cently in the literature [Myers et al., 1987; Weiss et al., 1985],
leakage not present previously. Patients with risk factors such as older age (over 65), atherosclerosis, smoking and diabetes have only a 30-40% chance of preserving po tency, even if their cancer is at a low stage and nerves arc spared. Early postoperative treatment with nonsurgical therapies may help some patients, while penile implant surgery may be necessary in others. There has been concern among surgeons that nerve sparing may compromise the performance of an ade quate cancer operation. However, the cavernous nerves are located outside the prostate capsule and Denonvilliers’ fascia; therefore, in patients with cancer confined to the prostatic capsule, cavernous nerve sparing should have no impact on cancer control. Dr. Walsh and col leagues have also performed extensive pathological stud ies demonstrating this fact [Eggleston and Walsh, 1985; Walsh et al., 1987], In stage B-2 cancers, however, in which the incidence of extracapsular extension is high, we do not recommend nerve-sparing surgery. Occasion ally, in the young patient (under age 65), in whom pre operative biopsy has demonstrated probable absence of cancer on one side, we perform a unilateral preservation of the neurovascular bundle. Dr. Walsh has reported the successful use of this technique in preserving potency in 65% of men aged 50-65 years [Walsh et al., 1987], Our results have been lower, probably because most of our patients had additional risk factors for impotence.
Results of Nerve-Sparing Prostatectomy Results of nerve-sparing radical prostatectomy de pend on a number of factors. These include patient age. potency prior to surgery, cancer stage, history of smok ing, medication history and coexistent illness such as hypertension, atherosclerosis, diabetes and peripheral vascular disease. In low-stage cancers (A|-B|) in patients under 65 years with normal potency and minimal risk factors, we can achieve reasonable potency (erections satisfactory for vaginal penetration) in 50% of patients 3-6 months following surgery. In another 20-30%, par tial erections are achievable. In these patients, erection can be improved and made suitable for penetration by the use of vacuum suction devices and intracavernous injections of smooth muscle relaxants (papaverine hy drochloride or prostaglandin E|), and a-blockers (phentolamine) [Lue and Tanagho, 1987], Penile Doppler studies in these patients indicate damage to the vascular supply of the penis, including partial fibrosis of one or both cavernous arteries and varying degrees of venous
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The reported incidence of incontinence following radical prostatectomy varies from 0.5-15%. Stress in continence related to exertion is the most common form of incontinence; however, 3-5% of patients will have incontinence at rest and require an artificial sphincter or other means to achieve control. Because of the multifac torial mechanisms involved in continence, it is hard to define a specific cause of incontinence in any individual patient postoperatively. The techniques of radical pros tatectomy described herein have resulted in an overall incontinence rate of less than 10% in our patients. Severe incontinence has occurred only in 2% of these patients; mild stress incontinence is seen in 3-5% of patients and moderate stress incontinence in an addi tional 3%.
References Blacklock NJ: Surgical anatomy of the prostate; in Williams DI. Chisholm GD (eds); Scientific Foundations of Urology, ed 1. Chicago, Year Book Medical Publishers, 1976, vol II, sectil, chap 16, p 113. Breza J et al: Detailed anatomy of penile neurovascular structures: Surgical significance. J Urol 1989;141:437-443. deGroat WC, Steers WD: Neuroanatomy and neurophysiology of penile erection; in Tanagho EA, Lue TF, McClure RD (eds), Contemporary Management of Impotence and Infertility. Balti more. Williams & Wilkins, 1988. Donker PJ, Droes J, Th PM, Van Ulden BM: Anatomy of the mus culature and innervation of the bladder and the urethra; in Wil liams DI, Chisholm GD (eds): Scientific Foundations of Urolo gy, ed 1. Chicago, Year Book Medical Publishers, 1976, vol II, sect 1, chap 5, p 32. Eggleston JC, Walsh PC: Radical prostatectomy with preservation of sexual function: Pathological findings in the first 100 cases. J Urol 1985;134:1146-1148. Juskiewenski S, et al: A study of the arterial blood supply to the penis. Anat Clin 1982;4:101-107.
Koyanagi T: Studies on the sphincteric system located distally in the urethra: The external urethral sphincter revisited. J Urol 1980; 124:400-406. Lue TF, Tanagho EA: Physiology of erection and pharmacological management of impotence. J Urol 1987;137:829-836. Myers RP, Goellner JR, Cahill DR: Prostate shape, external striated urethral sphincter and radical prostatectomy: The apical dissec tion. J Urol 1987;138:543-550. Narayan P, Jajodia P: Prostatic oncology. Urologic care in the elder ly. Clin Geriatr Med 1990:6:131-161. Schlegel PN, Walsh PC: Neuroanatomical approach to radical cys tectomy with preservation of sexual function. J Urol 1987; 138: 1402-1406. Tanagho EA, Smith DR: Mechanism of urinary continence. 1. Embryologic, anatomic and pathologic considerations. J Urol 1968;100:640-646. Tramier D, et al: Radiological anatomy of the internal pudendal artery (a. pudenda interna) in the male. Anat Clin 1981 ;3:195— 200. Walsh PC, Donker P: Impotence following radical prostatectomy: Insight into etiology and prevention. J Urol 1982; 128:492— 494. Walsh PC, Epstein JL, Lowe FC: Potency following radical prosta tectomy with wide unilateral excision of the neurovascular bun dle. J Urol 1987;138:823-827. Walsh PC, Lepor H, Eggleston JC: Radical prostatectomy with pres ervation of sexual function: Anatomical and pathological con siderations. Prostate 1983;4:473-485. Walsh PC: Radical prostatectomy, preservation of sexual function, cancer control: The controversy. Urol Clin North Am 1987; 14: 553-573. Weiss JP, et al: Preservation of periprostatic autonomic nerves dur ing total perineal prostatectomy by intrafascial dissection. Urol ogy 1985;26:160-163. Weldon VE, Tavel FR: Potency-sparing radical perineal prostatecto my: Anatomy, surgical technique and initial results. J Urol 1988: 140:559-562.
P. Narayan, MD Department of Urology, U-575 University of California San Francisco, CA 94143-0738 (USA)
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Results of Continence Preservation
