Revista Anatomy ok 28/9/07 11:04 Página 111 Eur J Anat, 11 (2): 111-118 (2007) Localisation of hypogastric nerves and pelvic plexus in relation to rectal cancer surgery I. Bissett1, A. Zarkovic2, P. Hamilton2 and S. Al-Ali2 1- Department of Surgery, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand 2- Department of Anatomy with Radiology, Faculty of Medical and Health Sciences, University of Auckland, Auc- kland, New Zealand SUMMARY mm below a line joining the upper surfaces of two acetabula. This study shows that extrafas- Urinary, bowel, and sexual dysfunction caused cial excision does not damage the hypogastric by iatrogenic lesions of the pelvic plexus nerves or the pelvic plexuses and provides a remain a common complication of radical way to radiologically assess the proximity of a pelvic surgery. Preservation of these nerves tumour to the pelvic plexus. Such knowledge during surgery is hampered by their poor aids in preoperative planning to reduce the visualisation within the pelvic cavity and their incidence of post-operative pelvic autonomic small size. Recently, increased awareness of dysfunction. the high incidence of post-operative autonom- ic dysfunction has led to the development of nerve-sparing surgical techniques. This study Key words: Anatomy – Pelvic plexus – Col- aims to expand our knowledge of the anatomy orectal surgery – Rectal neoplasms of the pelvic plexus, to contribute to further enhancement of nerve sparing surgical tech- INTRODUCTION niques. Dissections of the hypogastric nerves and pelvic plexuses were performed on 10 The importance of the hypogastric nerves cadavers. We showed that nerves from the and the pelvic plexuses has only become clear pelvic plexus that supply the rectum can be over the last few years, during which time mobilised to a length of 10-15 mm and thus many authors have reported a high incidence can be identified and safely divided, leaving of urinary and sexual dysfunction following the pelvic plexus intact following the extrafas- rectal excision (Balslev and Harling, 1983; cial excision of the rectum. Likewise, the Gerstenberg et al., 1980; Hjortrup et al., hypogastric nerves, which are enveloped in a 1984; Hojo et al., 1989; Kinn and Ohman, layer of parietal fascia, also remain intact. The 1986; La Monica et al., 1985; Neal et al., fascia containing the hypogastric nerves was 1981; Santangelo et al., 1987; Williams and separated from the fascia propria by a loose Slack, 1980). Lepor et al. (1985) identified the areolar layer. Pelvic plexuses measured about nerves responsible for potency and described 30 by 30 mm in size. Radiological images their course in the pelvis based on serial giant showed the plexuses to be positioned about 5 sections of the pelvis of a cadaver. Other stud- Correspondence to: Mr. Ian Bissett. Department of Surgery, University of Auckland, Level 12, Room 12.087, Auckland City Hospital Support Building, Park Road, Grafton, Auckland, New Submitted: February 23, 2007 Zealand. Phone: +64 9 373 7599 ext 89820; Fax: +64 9 377 9656. E-mail: i.bis- Accepted: July 5, 2007 [email protected] 111 Revista Anatomy ok 28/9/07 11:04 Página 112 I. Bissett, A. Zarkovic, P. Hamilton and S. Al-Ali ies of the pelvic nerves followed, leading to The study included 10 adult, unembalmed the development of several descriptions of sur- cadavers (9 male and 1 female) aged 52-85 gical techniques aimed at preserving the years who required a post-mortem. Patients nerves (Havenga et al., 1996; Heald, 1997; who had previously undergone pelvic surgery Maas et al., 1998; Moriya et al., 1995). Some or who had been dead for more than 36 hours studies involved microscopic dissection of were excluded. The post-mortem was initially foetal tissue where the nerves are thicker and performed by the pathologist leaving the are surrounded by a small amount of connec- pelvic organs intact. Dissection of the pelvis tive tissue (Fritsch, 1989). Baader and Her- was performed immediately following the rmann (2003) investigated the pelvic pathologist’s post-mortem examination. In autonomic nerves in adults and their implica- addition, gross and microdissection using a tions in pelvic surgery. Despite advances in surgical stereomicroscope was carried out on a nerve-sparing surgery, the pelvic plexus further two formalin-preserved sagittally sec- remains liable to iatrogenic injury due to the tioned hemi- and whole male pelvises. small size of the individual nerve fibers, the First, extrafascial dissection of the rectum depth and narrowness of the pelvis, which can was performed on all specimens. The dissec- hinder precise surgical access, and confusion tion involved operating through the midline relating to the anatomical description and sur- incision that had already been performed for gical nomenclature of these structures. In the post-mortem. The dissection began at the addition, authors have often described the aortic bifurcation and continued directly on pelvic autonomic nerves as web-like in struc- the rectal fascia propria. The extrafascial dis- ture and as lying in different fascial planes. In section was continued up to the “lateral liga- particular, the relationship of the nerves to the ments” of the rectum. In this study, the fascia propria has profound implications in “lateral ligaments” refer to the condensation of surgery for rectal cancer. Radiological identifi- endopelvic connective tissue encountered on cation of the position of the pelvic plexus the anterolateral aspect of the dissection in the would also allow preoperative assessment of extrafascial plane below the peritoneal reflec- tumour proximity to the plexuses, facilitating tion. They contain the autonomic nerves pass- decision making and the planning of surgery. ing to the rectum from the pelvic plexuses The aims of this study are: (Rutegard et al., 1997). To confirm the integrity of the pelvic Mobilization of the rectum anterior to plexuses and hypogastric nerves after extrafas- these attachments was then carried out. The cial excision (EFE) in rectal surgery length of the nerves from their exit from the To identify the length and position of the pelvic plexus on the parietal fascia to the point nerves passing from the pelvic plexuses to the of their entry into the fascia propria after rectum during EFE mobilization of the rectum was measured in To identify the position of the pelvic millimeters using a calliper. The position of plexuses in relation to a known radiological the uppermost nerve fibres in the “lateral lig- landmark ament” was then determined in relation to the To clarify the site of the hypogastric nerves lateral peritoneal reflection, and a plane in the retrorectal fascial planes. through the tip of the greater trochanter. The distance from the most superior nerve to the peritoneum on the lateral side of the rectum MATERIALS AND METHODS was measured in millimeters. The greater trochanter was then palpated through the skin Ethical approval for this study was granted on each side and a Kirschner wire inserted by the Auckland Ethics Committee. The transversely immediately above it until the cadavers used in this study were bequeathed to point was visible in the pelvic cavity. The dis- the Department of Anatomy with Radiology tance in millimeters from the tip of the wire under the terms of the New Zealand Human to the uppermost nerve of the “lateral liga- Tissue Act (1964) for teaching and research. ment” was measured on each side. Consent was obtained from the immediate rel- Next, the pelvic plexuses were identified atives of the deceased. The present work con- on the pelvic sidewall after extrafascial exci- forms to the provision of the Declaration of sion of the rectum. The vertical and horizon- Helsinki in 1995, as revised in Edinburgh tal dimensions of the plexuses were measured 2000. in millimeters with a calliper and recorded. 112 Revista Anatomy ok 28/9/07 11:04 Página 113 Localisation of hypogastric nerves and pelvic plexus in relation to rectal cancer surgery Radio-opaque skin staples were attached to Dissection of the formalin-preserved male the upper, lower, anterior and posterior bor- hemi-pelvis was commenced at the bifurcation ders of the pelvic plexuses. An AP X-ray of the of the common iliac vessels, where the hypogas- pelvis was performed to demonstrate the posi- tric nerve was located descending in the tion of the pelvic plexuses in the bony skele- retroperitoneal fascia. It was followed to its ter- ton. The midpoints of the pelvic plexuses were mination at the postero-superior surface of the plotted on the X-rays by finding the point of pelvic plexus. A second contribution to the transection of lines drawn through the skin pelvic plexus was identified as pelvic splanch- staples. A line was then drawn joining the nic nerves contributing to the postero-inferior upper surface of the acetabulum on both sides. plexus. Further dissection of the formalin-pre- The distance from the midpoint of the pelvic served whole male pelvis involved cutting the plexus to the upper acetabular line was then pubic bones medial to the acetabula and remov- measured for each side on the X-ray films. ing the anterior border of the pelvic bowl. Fol- After removal of the rectum and measure- lowing identification and gross dissection of ment of the pelvic plexuses, the parietal fascia the hypogastric nerves, the pelvic peritoneum enveloping the superior hypogastric plexus was removed and the pelvic plexus microscopi- immediately anterior to the aortic bifurcation cally dissected within