After Total Mesorectal Excision
Christoph A. Maurer
C.A. Maurer ( u)
Surgical Department, Kantonsspital, Rheinstrasse 26, 4410 Liestal, Switzerland
e-mail: christoph.maurer@ksli.chAbstract
The autonomous pelvic nerves are in close contact to the visceral pelvic fascia that surrounds the mesorectum. The concept of total mesorectal excsion (TME) in rectal cancer treatment has led to a substantial improvement of autonomous pelvic nerve preservation. Consecutively, this highly precise and sharp dissection technique under direct vision reduces the problem of accidental bladder denervation from 50–60% with conventional rectal cancer surgery to less than 20% with TME and the problem of postoperative impotence from 70–100% to less than 30%. The learning curve in this technically demanding procedure plays a major role with regard to a satisfying nerve preservation. The laparoscopic approach for TME allows to obtain similarly favorable results with regard to postoperative urogenital function, at least for tumors situated in the middle and upper third of the rectum, compared with open surgery. The present paper describes and depictures in detail the anatomy and the pathophysiology of autonomic pelvic nerves, the surgical technique for nerve preservation and gives a short overview of the results in the literature including own data.
Introduction
Rectal cancer is the number one cancer with regard to the incidence of abdom- inal malignancies [26, 32]. The two main problems of rectal cancer surgery are local recurrence and pelvic autonomic nerve damage. Whereas enormous efforts have been made recently to improve local recurrence rates, only few studies have investigated postoperative urinary and sexual function, which has a large impact on the patients’ postoperative quality of life. This chapter focuses on the issue of pelvic autonomic nerve function, particularly in the context of total mesorectal excision (TME) [2, 9, 20]. As described in detail elsewhere in this book, the TME technique is characterized by a sharp dissection between the parietal and visceral planes of the pelvic fascia, resulting in a complete removal of the rectum together
Recent Results in Cancer Research, Vol. 165Springer-Verlag Berlin Heidelberg 2005c
with the mesorectum. Compared to conventional rectal resection, TME is more extensive and radical, and therefore has a potentially adverse effect on pelvic nerve preservation. On the other hand, TME is a more precise technique, respecting the anatomical planes and preserving the autonomic pelvic nerves that are adjacent to the resection plane.
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Anatomy and Pathophysiology of Autonomic Pelvic Nerves
A plexus of sympathetic nerves lies in extraperitoneal connective tissue on the anterior aspect of the aorta and surrounds the origin of the inferior mesenteric artery. This inferior mesenteric plexus (upper part) and the superior hypogastric plexus (lower part) of the preaortic plexus is preserved by ligating and dividing the inferior mesenteric artery not flush to the aorta but 1–2 cm from its aortic origin. Hence, a “preaortic strip” is avoided, except when indicated by lymph node involvement at this site. Resection of the superior hypogastric plexus and/or re- section of the hypogastric nerve on both sides will cause retrograde ejaculation since the reflectory activation of urinary bladder sphincter during ejaculation is lost. The superior hypogastric plexus divides in the manner of an inverted Y into
Figure 1. Anatomy of autonomous pelvic nerves
Table1.Autonomicpelvicnervestructuresandconsequencesoflostfunctioncorrespondingtositeofnervedamage SiteofnervedamageNervefailureBladderdisorderMalegenitaldisorderFemalegenitaldisorderAnalsphincterdisorder SuperiorhypogastricplexusSpartiallyIncontinenceRetrogradeDiminishedorgasmNone bothsides(partial)ejaculation N.hypogastricusonesideSpartiallyNoneEv.retrogradeNoneNone onesideejaculation Nn.hypogastricibothsidesSpartiallyIncontinenceRetrogradeDiminishedorgasmNone bothsides(partial)ejaculation InferiorhypogastricplexusonesideS+PScompletelyVoidingdisorderIncompleteIncompleteNone onesideerection+ejaculationerection/lubrication InferiorhypogastricplexusbothsidesS+PScompletelyAtonia,severeLackofLackofIncontinenceI–II bothsidesvoidingdisordererection+ejaculationerection/lubrication NeurovascularbundleonesideS+PScompletelyNoneIncompleteIncompleteNone onesideerection+ejaculationerection/lubrication NeurovascularbundlebothsidesS+PScompletelyNoneLackofLackofNone bothsideserection+ejaculationerection/lubrication S,pelvicsympatheticnerve;PS,pelvicparasympatheticnerve.
a pair of hypogastric nerves, each of which may be a single nerve or an elongated network of anastomosing fibers, which run to the side walls of the pelvis, where they merge with parasympathetic fibers (Nn. erigentes, “the erigent pillar” ac- cording to Heald) from the second to fourth sacral nerve roots and fibers from the sacral sympathetic ganglia to form the inferior hypogastric plexus on each side (Fig. 1). This almost rectangular plaque of nervous tissue is firmly attached to the anterolateral aspect of the mesorectum on both sides, i.e. between 10 and 2 o’clock, due to nerve branches directly entering the mesorectum for autonomic innerva- tion of the rectum. These nerve fibers together with an inconsistently (less than 20%) found small artery (the middle rectal artery) must be carefully dissected;
meanwhile the inferior hypogastric plexus itself must be preserved. Damage to the latter on one side will cause (temporary) voiding difficulties of the urinary bladder and at least diminished erection and ejaculation or diminished vaginal lubrication and arousal; damage on both sides will lead to denervated bladder re- quiring catheterism, and impotence/dyspareunia. Communicating predominantly parasympathetic nerves between bilateral splanchnic nerves may take over an im- portant function in patients with hemilateral nerve damage [31]. Neurovascular bundles from the inferior hypogastric plexus and internal iliac vessel branches pass forwards from their posterolateral relationship to seminal vesicles, prostate and bladder, as the lateral edges of Denonvilliers’ fascia, and they need to be preserved as the fascia is resected with the rectum [1, 6, 11, 18]. Autonomic pelvic nerve structures and loss of their function corresponding to the site of nerve damage are summarized in Table 1.
Urinary and Sexual Function After Conventional Rectal Cancer Surgery
For many years severe urogenital dysfunction has been accepted as normal faith following rectal cancer surgery. Reasons for the high rates of denervated bladder and impotence (Table 2) were the anatomy and pathophysiology of autonomic pelvic nerves that were only poorly understood by surgeons, and the commonly used blunt dissection technique. There was even a period where some surgeons recommended stripping the aorta and the iliac vessels for an increase in radicality.
Nowadays, we know that this is not only of no benefit with regard to survival, but it deteriorates quality of life substantially.
Table 2. Urinary and male sexual function after conventional rectal cancer surgery
Author Year No. of Bladder Loss of Lack of
patients dysfunction erection ejaculation
Kinn and Ohman [14] 1986 22 50% 80% n.a.
Cunsolo et al. [3] 1990 46 57% 59% 59%
Hojo et L; [10] 1991 134 58% 69% 81%
Koukouras et al. [15] 1991 40 n.a. 53% 30%
Nerve Preservation Using the Total Mesorectal Excision Technique
Recent studies reported improved urinary and sexual function (Table 3) in com- parison to older data (Table 2). We hypothesized that this improvement is the result of the introduction and growing acceptance of the TME technique [8, 9, 20, 22].
Therefore, we analyzed our own series of 133 patients with resected rectal cancer between November 1993 and September 1998 at the university of Bern [21]. The TME technique was introduced in 1995. A questionnaire regarding preoperative and current urogenital function was sent to all 87 patients who were alive in De- cember 1998. Sixty patients answered reliably to the questionnaire: 29 patients in group 1 underwent conventional rectal cancer surgery from 1993 to 1995, and 31 patients in group 2 underwent mesorectal excision from 1996 to 1998. Three out of 31 patients in group 2 had only partial mesorectal excision. There was no significant difference between group 1 and group 2 regarding gender, tumor lo- cation, tumor stage, radiation therapy, or surgical complications. However, group 2 patients had a significantly higher median age at operation (71.2 vs. 63.9 years) and smaller distance of anastomosis from anal verge (4.7 vs. 6.4 cm) than group 1 patients. Regarding urinary function both groups were similar. Regarding male sexual function, however, the ability to achieve orgasm and to ejaculate was signif- icantly better preserved in the TME patients (group 2) than in the conventionally operated patients (group 1). Overall, the postoperative deterioration in male sex- ual function was significantly more common in group 1 (Fig. 2). The high rate of preexisting sexual disorders in both groups needs to be mentioned.
Table 3. Urinary and male sexual function after introduction of TME
Author Year No. of Bladder Loss reduction Lack
patients dysfunction of erection of ejaculation
Enker [4] 1992 42 5% 13% 24%
Leveckis et al. [17] 1995 20 15% 19% NA
Havenga et al. [7] 1996 136 32% 17% 42%
Maas et al. [19] 1998 47 28% 11% 42%
Saito et al. [30] 1998 91 26% 24% 45%
Nesbakken et al. [25] 2000 27 13%a 28% 43%
Nagawa et al. [24] 2001 22 27% 45% 45%
Maurer et al. [21] 2001 19 21%a 55% 30%
Quah et al. [28] 2002 37 3% 24% 19%
Pocard et al. [27] 2002 9 0% 44% 11%
Kim et al. [13] 2002 68 26% 25% 38%
aWomen additionally included.
Figure 2. Frequency of six different features of male genital function in group 1 (conventional rectal surgery) and group 2 (total mesorectal excision; TME) before and after operation. Preop., before operation; postop., after operation. *p<0.05, † p<0.001 (χ2test). (From [21], with permission of Blackwell Science)
Impact of Learning Curve on Pelvic Autonomic Nerve Preservation
In a recent personal series (unpublished data) of 45 low anterior resections (30 of them with coloanal reconstruction) and eight abdominoperineal resections for rectal cancer from July 2002 to December 2004, none of these patients had to be sent home with a urinary catheter and only one male patient complained of diminished erection and ejaculation. Rectal dissection in this patient was more difficult because of previous rectal surgery. A second male patient with hemilateral pelvic nerve resection resulting from direct tumor infiltration was no longer sexually active before operation and did not complain of sexual dysfunction postoperatively. All other patients did not experience any alteration in urinary or sexual function.
These data strongly suggest further improvement of the author’s precision of the nerve-sparing TME technique when compared to our recently published results [21]. Similarly good results were reported by Quah et al. for open rectal cancer surgery [28]: 0/40 required long-term intermittent self-catheterization, 3/22 men had erectile dysfunction and 1/22 were unable to ejaculate.
After introduction of TME, Junginger et al. were able to identify and preserve
the pelvic autonomic nerves in 60%, 94% and 92% within the first 50 patients, the
second 50 patients and the third 50 patients, respectively [12]. Correspondingly,
the frequency of bladder voiding disturbance requiring catheterization decreased
from 26% to 2% and 4%, respectively.
Intraoperative parasympathetic nerve stimulation with penile tumescence mon- itoring may be an aid to less experienced pelvic surgeons and may help in learning to identify and preserve autonomic nerves during total mesorectal excision [5].
Nerve Preservation and Laparoscopic Total Mesorectal Excision
Evidence is growing that laparoscopically resected patients with rectal cancer do at least not worse than open resected patients in terms of long-term survival [16, 23].
Therefore, the next question must address urinary and sexual function following laparoscopic rectal cancer surgery. In a retrospective analysis of a randomized trial comparing open versus laparoscopic rectal cancer resection, 7/15 (47%) sexually active men in the laparoscopic group reported impotence or impaired ejaculation compared with only 1/22 patients having an open operation (p <0.01) [28]. The authors concluded that especially in patients with low rectal cancers or bulky tu- mors, autonomic nerve preservation is more difficult to achieve by the laparoscopic approach, probably because of insufficient tension on the planes that have to be dissected. Similarly, Rullier et al. reported loss of sexual function in 8 out of 18 male patients (44%) following laparoscopic intersphincteric resection for mid and low rectal cancers [29]. Further studies will have to show whether laparoscopy will be able to overcome this problem in future.
Conclusion
The autonomous pelvic nerves are in close contact with the visceral pelvic fas- cia, the “holy plane” that surrounds the mesorectum. The growing acceptance of the concept of total mesorectal excision in rectal cancer treatment has led to a substantial improvement in autonomous pelvic nerve preservation. Consecu- tively, postoperative genital function—and to a lesser extent the urinary function, too—is significantly better preserved after TME than after conventional rectal cancer surgery. The learning curve in this highly precise and technically demand- ing procedure plays a major role with regard to satisfactory nerve preservation.
The laparoscopic approach for TME makes it possible to obtain similarly favorable results in terms of postoperative urogenital function, at least for tumors situated in the middle and upper third of the rectum.
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