Surgical Skills Course March 2006

What role do accessory pudendal arteries play in the recovery of erectile function after radical prostatectomy?

Fernando P. Secin, MD, PhD; and Bertrand Guillonneau, MD
Department of Urology, Sidney Kimmel Center for Prostate and Urologic Cancers, <br>
Memorial Sloan-Kettering Cancer Center, New York, NY

The urology community has seen a unique evolution in the surgical approach to the prostate thanks to the advent of the laparoscopic technique. Initially taken with skepticism, laparoscopic radical prostatectomy (LRP), with or without robotic assistance, has gained remarkable popularity and is now widely implemented at specialized centers worldwide.

The video-endoscopic magnification lens has increased the view of the operating field 10-fold, enhancing our understanding of often unrecognized pelvic structures, such as accessory pudendal arteries (APAs). In a recent LRP series, either apical or lateral APAs (figure 1) were identified in 30% of patients undergoing LRP, and these arteries were preserved 83% of the time. Although it is impossible to make fair comparisons between open and laparoscopic surgery, the Johns Hopkins Hospital, a center of excellence with longstanding experience in prostate surgery, reported a 4% identification and a 75% preservation rate for large lateral APAs in an open prostatectomy series.

Currently, no unequivocal link has been established between APA preservation and postsurgical functional outcomes, such as erectile function and continence. However, anatomical and retrospective clinical data indicate a possible connection.
In classical anatomy, the arterial supply to the penis is thought to originate from the internal pudendal artery alone; however, contemporary anatomic studies reveal a more complex network of arteries supplying the penis, and APA play an important role. The reported incidence of APAs is variable and seems to depend on the means used to identify them. Cadaveric dissection studies typically report an incidence as high as 70%, but the incidence falls to 7% and 4% in radiographic and open radical prostatectomy series, respectively.
Breza and colleagues reported an incidence of 70% based on 10 cadaveric dissections. In their study, all APAs originated from intrapelvic arteries, and in 6 of the 7 cadavers with APAs, these arteries contributed to penile irrigation. In one case, the APA constituted the only blood supply to the left cavernous body.

Similarly, Benoit and colleagues emphasized the contribution of APAs not only to cavernous body irrigation but also to urethral irrigation. They found 33 APAs in 20 cadavers. The APAs originated from pelvic arteries in more than 80% of cadavers, and half of them branched from the inferior vesical artery. The APAs originating from inferior vesical arteries gave branches to the bladder, prostate, and external urethral sphincter. When these arteries were present, the main arterial supply of the urethral sphincter arose from them. After piercing the levator ani, the APAs usually gave multiple branches, 70% of which were cavernous arteries, usually destined for both corpora. In addition, when both internal pudendal arteries and APAs were present on the same side, anastomoses in the root of the penis occurred 70% of the time.
As a result of these findings, there has been increasing emphasis on the role that APAs may play in erectile function and potency following pelvic surgery. Besides neurologic causes, a vasculogenic etiology has been proposed for impotence following nerve-sparing radical prostatectomy. Mulhall and colleagues retrospectively evaluated 96 patients with excellent preoperative erectile function who underwent bilateral, nerve-sparing surgery and did not receive pharmacological support for erectile dysfunction in the initial 12 months after surgery. Of these patients, 59% had some degree of arterial insufficiency as assessed by cavernosometry or penile ultrasonography. Only one third of the patients with confirmed arterial insufficiency recovered erections suitable for penetration.

Droupy and colleagues performed intraoperative transrectal color Doppler studies on patients scheduled to undergo RRP. Pharmacologically induced erections demonstrated that the hemodynamic changes in the pudendal and accessory pudendal arteries were similar to those described in the cavernous arteries, supporting the concept that APAs play a role in penile erection. More recently, Rogers and colleagues compared patients who underwent nerve-sparing RRP with concomitant preservation of large APAs to those who underwent surgery without arterial preservation. Vascular preservation more than doubled the probability of regaining potency, and the procedure was associated with a statistically significant shorter time to regain potency.

In conclusion, since our hypotheses are based on anatomical and retrospective clinical data, we must concede that the functional role of APAs is yet to be determined. Prospective studies are currently underway at our institution to address this question.

QUESTIONS

Question 1
Why is the variation in the incidence of APA so wide?

a.  Method of diagnosis
b.  Only intrapelvic APAs are observed in surgery
c.  Only large lateral APAs are visualized in open surgery
d.  Lens magnification, dry field, and a more thorough dissection of the apex allows better identification of APAs in laparoscopic surgery
e.  All of the above

Correct answer: E
“Cadaveric dissection studies typically report an incidence as high as 70%,[5] but the incidence falls to 7% [7] and 4% [3, 4] in radiographic and open radical prostatectomy series, respectively.” This is fairly reasonable, because, diagnosis accuracy will certainly impact on APA identification. Small APAs will be less likely to be identified with arteriograms, and APAs running outside the pelvic cavity will never be observed during laparoscopic surgery.

Question 2
What is basis of the current evidence regarding the relationship between APAs and improved functional outcomes after prostatectomy?

a.  Cadaveric dissections
b.  Prospective clinical studies
c.  Retrospective clinical data
d.  Both a and c are correct
e.  All of the above

Correct answer: D
This is a field that warrants further research. Cadaveric dissections, doppler studies and retrospective data suggest a relationship between APA and functional outcomes, however, further studies are needed to assess that.

Question 3
The reported arteriogenic arterial insufficiency after radical prostatectomy is estimated to be:

a.  Less than 25%
b.  25–50%
c.  50–75%
d.  75–100%
e.  Depends on APA preservation

Correct answer: C
Dr. John Mulhall and colleagues retrospectively evaluated 96 patients with excellent preoperative erectile function who underwent bilateral, nerve-sparing surgery and did not receive pharmacological support for erectile dysfunction in the initial 12 months after surgery. [12] Of these patients, 59% had some degree of arterial insufficiency as assessed by cavernosometry or penile ultrasonography. Only one third of the patients with confirmed arterial insufficiency recovered erections suitable for penetration.

Question 4
Anatomy studies have shown APA contribution to penile irrigation when present is:

a.  Less than 20%
b.  20–40%
c.  40–60%
d.  60–80%
e.  Over 80%

Correct answer: E
Breza and colleagues reported an incidence of 70% based on 10 cadaveric dissections [6]. In their study, all APAs originated from intrapelvic arteries, and in 6 of the 7 cadavers with APAs, these arteries contributed to penile irrigation. In one case, the APA constituted the only blood supply to the left cavernous body.

Question 5
Which of the following statements is correct?

a.  Identification of both apical and lateral APAs in LRP is approximately 30% with a preservation rate over 80%.
b.  Identification of lateral APAs in open prostatectomy series is approximately 4% with a preservation rate of 75%.
c.  It is impossible to make fair comparisons between open and laparoscopic series
d.  Only prospective studies will determine the role of APAs in functional outcomes after prostatectomy
e.  All of the above

Correct answer: E
Answer A is based on studies done at Memorial Sloan Kettering Cancer Center, led by Dr. Bertrand Guillonneau, while answer b. has been demonstrated by Roger and colleagues. It is impossible to make fair comparisons between open and laparoscopic series because no head to head comparisons have ever been done. Only prospective studies will determine the role of APAs in functional outcomes after prostatectomy.

References

• Secin FP,  Karanikolas N,  Kuroiwa K,  Vickers A,  Touijer K, Guillonneau B. Positive surgical margins and accessory pudendal artery preservation during laparoscopic radical prostatectomy. Eur Urol 2005, 48:786-92.
• Secin FP,  Karanikolas N,  Touijer AK,  Salamanca JI,  Vickers AJ, Guillonneau B. Anatomy of accessory pudendal arteries in laparoscopic radical prostatectomy. J Urol 2005, 174:523-6.
• Rogers CG,  Trock BP, Walsh PC. Preservation of accessory pudendal arteries during radical retropubic prostatectomy: surgical technique and results. Urology 2004, 64:148-51.
• Polascik TJ, Walsh PC. Radical retropubic prostatectomy: the influence of accessory pudendal arteries on the recovery of sexual function. J Urol 1995, 154:150-2.
• Benoit G,  Droupy S,  Quillard J,  Paradis V, Giuliano F. Supra and infralevator neurovascular pathways to the penile corpora cavernosa. J Anat 1999, 195:605-15.
• Breza J,  Aboseif SR,  Orvis BR,  Lue TF, Tanagho EA. Detailed anatomy of penile neurovascular structures: surgical significance. J Urol 1989, 141:437-43.
• Rosen MP,  Greenfield AJ,  Walker TG,  Grant P,  Guben JK,  Dubrow J et al. Arteriogenic impotence: findings in 195 impotent men examined with selective internal pudendal angiography. Young Investigator's Award. Radiology 1990, 174:1043-8.
• Gray RR,  Keresteci AG,  St Louis EL,  Grosman H,  Jewett MA,  Rankin JT et al. Investigation of impotence by internal pudendal angiography: experience with 73 cases. Radiology 1982, 144:773-80.
• Bahren W,  Gall H,  Scherb W,  Stief C, Thon W. Arterial anatomy and arteriographic diagnosis of arteriogenic impotence. Cardiovasc Intervent Radiol 1988, 11:195-210.
• Aboseif SR,  Breza J,  Orvis BR,  Lue TF, Tanagho EA. Erectile response to acute and chronic occlusion of the internal pudendal and penile arteries. J Urol 1989, 141:398-402.
• Mulhall JP, Graydon RJ. The hemodynamics of erectile dysfunction following nerve-sparing radical retropubic prostatectomy. Int J Impot Res 1996, 8:91-4.
• Mulhall JP,  Slovick R,  Hotaling J,  Aviv N,  Valenzuela R,  Waters WB et al. Erectile dysfunction after radical prostatectomy: hemodynamic profiles and their correlation with the recovery of erectile function. J Urol 2002, 167:1371-5.
• Droupy S,  Hessel A,  Benoit G,  Blanchet P,  Jardin A, Giuliano F. Assessment of the functional role of accessory pudendal arteries in erection by transrectal color Doppler ultrasound. J Urol 1999, 162:1987-91.