Anatomical Studies On The TME Related Perirectal Fascias And Pelvic Autonomic Nerves In Male

Total mesorectal excision (TME) is a new surgical technology successfully combining the outcomes of radical cure of the malignant disease and pelvic autonomic nerve preservation (PANP). The method which extirpates the rectum and mesorectum "en-bloc" from the perirectal fascias has greatly reduced the local recurrence rate of tumor. At the same time, PANP efficiently maintain the micturition and sex function of male cancer patients post operation. Reasonable surgical technology should be applied on the basis of accurate anatomical theory. Properly realization of the TME and the PANP depend on exact and profound understanding of the perirectal fascias and the pelvic autonomic nerves. The present acknowledgement of these structure, however, remain in confusion, which impair the correctness of the TME and the clinical outcome post operation. The condition urges us to solve the problem through the clinical anatomical study. In these studies, the regional anatomical observation on fixed cadaver, the laparoscopic observation on living body, as well as the imageological observation such as the computed tomography (CT) and the magnetic resonance imaging (MRI) on cadaver and living body were used to elucidate the anatomical configurations of the mesorectum contained perirectal fascias and the pelvic autonomic nerves, as well as the relationship between them.Part. 1 Anatomical studies on the perirectal fascias1. Objectives: To elucidate the anatomical nature of the layers, the spaces and the components of the TME related perirectal fascias.2. Materials and methods: Ten fixed male hemi-pelvises in middle sagittal plane were dissected and observed.3. Results3.1 The perirectal tissue layersThe tissue layers around the rectum could be identified in sagittal plane posteroanteriorly as the peritoneum, the visceral layer of the pelvic fascia (VLPF), the neural fascia layer (NFL), the parietal layer of the pelvic fascia (PLPF), and the sacral periosteum. The mesorectum were composed of the posterior part formed by the VLPF coated perirectal adipose tissue, and the anterior part as the posterior leaf of the DenonviUiers fascia. There was a separate "neural fascia layer" between the mesorectum and the pre-sacral fascia, which contained the hypogastric nerve (HN) and the inferior hypogastirc plexus (IHP) and had special function and structure.3.2 The perirectal fascial spacesLocated between the mesorectum and the NFL, the retro-rectal space (RRS) extended laterally to the rectum as the space between the IHP and the mesorectum, anteriorly to the rectum as the space between the double leaves of the DenonviUiers fascia. Located between the NFL and the pre-sacral fascia (PSF), the pre-sacral space (PSS) extended laterally to the rectum as the space between the IHP and the pelvic wall muscles, anteriorly to the rectum as the space posterior to the seminal vesicle. There were distinct anatomical landmarks individually in the two spaces.3.3 The perirectal fascial componentsThe adhesion fascia (AF) was a solo structure linked the fascias anterior and posterior and an anatomical landmark in the RRS. The lateral rectal ligament (LRL) was the NFL coated branches of the IHP to the rectum. The middle rectal artery (MRA) drilled through the IHP and ran in, rather than under the LRL. The retro-sacral fascia (RSF) was a part of the NFL which fused anteriorly with the mesorectum at the level of the 4th sacral vertebra. The anterior leaf of the DenonviUiers fascia (ALDF) is extension of the NFL and adhered tightly to the rectourethral muscle at the apex of prostate. The posterior leaf of the DenonviUiers fascia (PLDF) is extension of themesorectum.4. Conclusions4.1 The annular distribution pattern of the perirectal fascias around the center of the rectumThe fascias distributed around the rectum in 3 layers. The inner layer is the VLPF, including the postero-lateral VLPF (the fascia propria) and the anterior PLDF. The middle layer is the NFL, including the postero-lateral NFL and the anterior ALDF. The outer layer is the PLPF, including the postero-lateral PSF and the anterior envelopes of the seminal vesicle and the prostate.4.2 The annular distribution pattern of the perirectal fascial spacesThe fascial spaces distributed around the rectum in 2 layers. Central and between the mesorectum and the NLF is the RRS > which extended lateral to the rectum as the space between the IHP and the mesorectum, anteriorly to the rectum as the space between the double leaves of the Denonvilliers fascia. Peripheral and between the NFL and the pre-sacral fascia (PSF) is the PSS, which extended laterally to the rectum as the space between the IHP and the pelvic wall muscles, anteriorly to the rectum as the space posterior to the seminal vesicle.4.3 The optimal surgical plane in the TME was the retro-rectal space and its extending spaces lateral and anterior to the rectumThe ideal surgical plane combined the TME and the PANP was the RRS and its extension lateral and anterior to the rectum, i.e. the RRS posterior to, the space between the IHP and the mesorectum lateral to and the space between the double leaves of the Denonvilliers fascia anterior to the rectum. In addition, the retro-rectal dissection plane was divided by the RSF into the RRS proximal and the PSS distal.Part. 2 Anatomical studies on the pelvic autonomic nerves1. Objectives: To elucidate the anatomical nature of the TME related pelvicautonomic nerves in male.2. Materials and methods: Ten fixed male hemi-pelvises in middle sagittal plane and 2 hemi-pelvises removed of the ilium were Dissected and Observed.3. Results3.1 The distribution nature of the pelvic autonomic nerves around the IHP corePelvic autonomic nerves (PAN) distributed and functioned around the IHP core, which was the projecting target of different PAN, and the origin of different neural branches to the pelvic viscera. The detail was as follows. The minority of the left and right trunk of the abdominal aortic plexus (AAP) joined together to form the inferior mesenteric plexus (IMP), the majority of them formed the superior hypogastric plexus (SHP). The SHP divided into a pair of hypogastric nerves (HN) in front of the sacral promontory. The HN received the fibers from the pelvic splanchnic nerves arising from the anterior roots of the 2nd to the 4th sacral nerves, and the fibers from the sacral splanchnic nerve originated from the 4th sacral sympathetic ganglion, and formed the IHP. The IHP then sent out efferent branches to the pelvic viscera.3.2 The AAP and the IMPThere was a neural fiber free "skylight" around the origin of the inferior mesenteric artery (IMA), where no fibers of the AAP and the IMP were seen. The crossing of the left trunk of the AAP and the IMA varies greatly. The left trunk of the AAP adhered closer to the IMA than the aorta.3.3 The SHP and the HNThe SHP adhered to the sacral promontory and was prone to be injured. The 3rd sacral vertebra is the turning point of the topographic relation between the HN and the mesorectum. The HN located posteriorly and laterally to the rectum respectively, above and under the level of the 3rd sacral vertebra. On the lateral pelvic wall at the level of the 2nd to the 3rd sacral vertebra, the HN adjoined the ureter, both could be acted as the landmarks to located each other.3.4 The PSNThe PSN originated from the anterior roots of the 2nd to the 4th sacral nerves, among which the 3rd sacral nerve originated PSN was the most conspicuous. The PSN located postero-laterally to the IHP and ran accompanied by the outer part of the MRA. The PSN displayed distinct appearances as the nerve roots, the nerve trunks, the nerve branches and the nerve terminals when running from the center to the periphery.3.5 The SSNThe SSN was arisen mainly from the 4th sacral sympathetic ganglion.3.6 The IHP3.6.1 At the level from the 3rd sacral vertebra to the coccyx, the main body of the IHP located in the sagittal plane lateral to the mesorectum. The seminal vesicle implied the center of the IHP. The IHP is an even cavernous nerve board without any sublayers. The HN, the PSN and the SSN are direct contribution of the IHP.3.6.2 The efferent branches of IHP included the ones to the bladder, the prostate, the rectum and the genital organs. The vesical branch ran along the ureter and the inferior vesical artery. The prostatic branch extended directly from the vesical branch. One part of the rectal branch ran laterally towards the mesorectum in the LRL, while the other drilled through the PLDF into the anterior wall of the rectum. The genital-urinary branch, the neurovascular bundle (NVB) ran in the lateral part of the ALDF.4. ConclusionsThe follow are the sites where the PAN is prone to injury, and the proper countermeasure.4.1 Ligation of the IMA: preservation of the left trunk of the AAP. Toavoid the AAP injured, it is advisable to ligate the vessel at the neural fiber free "skylight" at the origin of the IMA. The optimal surgical plane was between the IMA and the neural fibers when dissecting the sigmoid mesocolon.4.2 Dissection posterior to the rectum: preservation of the SHP andthe HN. The operation should be far away from the sacral promontory to avoid injury of the vicinal HN. Making sure that the surgical plane is in the RRS and the HN locate posterior to the operating area. Dissecting close to the mesorectum and the midline. The HN and the ureter may act as the landmarks each other.4.3 Dissection lateral to the rectum: preservation of the IHP and the PSN. Excessively traction of the mesorectum might deform the local structure and result in accidental injury of the IHP or the PSN. Exciding the LRL in the RRS median to the IHP. Paying much attention to the slim PSN around the MRA when dissecting the lymph nodes along the artery.4.4 Dissection anterior to the rectum: preservation of the NVB.Making sure that the surgical plane between the two leaves of the Denonvilliers fascia. Operating medianly to avoid injury of the peripheral NVB. Cutting the anterior rectal branch of IHP close to the PLDF.Part. 3 Laparoscopic studies in living body1. Objectives: To observe the appearances of the perirectal fascias and the pelvic autonomic nerves in the living body and found the difference between the cadaver and the living body. To find proper anatomical landmarks in the laparoscopic total mesorectal exicion (LTME).2. Materials and methods: According to sequence of the 6 dissecting procedure, the LTME records of 2 male rectal cancer patients were observed and analyzed.3. Results3.1 Exploration: The fascial adhesion between the sigmoid mesocolon and the peritoneum on the lateral abdominal wall, the sites where the ureters run down over the general iliac vessels, the dentate line of the peritoneal reflexion in the rectovesical pouch could be seen.3.2 Dissection lateral to the colon: the "yellow-white boundary" adipose tissue in the sigmoid mesocolon and the lateral peritoneum could be seen.3.3 Cutting the inferior mesenteric vessel: the "skylight" posterior to the sigmoid mesocolon was constructed by the IMA, the aorta and the posterior verge of the sigmoid mesocolon. The left ureter could be seen through the skylight.3.4 Dissection lateral to the rectum: the LRL is a rectal "pedicle". There were slim neural fibers joining the LRL from the later pelvic wall. The bleeding sites in the LRL might suggest the presence of the MRA.3.5 Dissection posterior to the rectum: the shining mesorectum could be see anterior to the RRS, displaying a bilobed appearance. The adhesion fascia and the recto-sacral fascia could be seen.3.6 Dissection anterior to the rectum: the seminal vesicle was covered by the ALDF, which resembled the NFL in appearance. The nature of the PLDF resembled the mesorectum.4. Conclusions4.1 There are sameness and difference between the living body and the cadaver in anatomical appearance4.1.1 The shining mesorectum displayed a typical "bilobed" sign at the back of its distal part. The NFL adhered to the mesorectum poteriorly.4.1.2 The loose-dense-loose tissue change in the RRS is implication of the adhesion fascia.4.1.3 After cutting the RSF, the surgical plane varied from the RRS to the PSS.4.1.4 There were neural fibers joined the LRL which was a thick "pedicle".4.1.5 It was hard to find the MRA in living body. The bleeding sites in the LRL might suggest the presence of the MRA.4.1.6 It was hard to find the PAN when the TME principle was abided by strictly.4.1.7 The ALDF and the PLDF resembled the NFL and the mesorectumrespectively in appearance.4.2 Anatomical landmarks in the LTMEThe "yellow-white boundary" might act as the landmark in the dissection lateral to the colon. The bifurcation of the aorta was the landmark to locate the IMA origin and the proper site of "skylight" posterior to the sigmoid mesocolon. The available landmarks in the RRS are the shining bilobed mesorectum, as well as the superior rectal artery and the hypogastric nerve when seeing.Part. 4 Imageological studies1. Objectives: To verify the anatomical observations in cadaver and living body and explore the methodology of tumor TNM staging and operating project evaluating imageologically.2. Materials and methods: Two healthy male adult underwent CT and MRI imaging at the level of pelvises. One fixed male pelvis was scanned by MRI scanner. The images were compared.3. Results3.1 The MRI image displayed the mesorectum and the NFL around it. The mesorectm is the high density signal structure around the rectum resembled to the adipose tissue. The fascia propria which displayed best in the traverse image is a low density signal line around the mesorectum. The line was highlighted by the NFL around the posterior part of the mesorectum.3.2 The shape and the topography of the mesorectum could be seen varied in CT image.3.3 The Denonvilliers fascia displayed as a low density signal layer between the prostate and the rectum. Disruption in the low density signal layer anterior and disturbance of the vessels and nerves antero-lateral to the rectum, might imply the extentison of tumor out of the mesorctum.3.4 The recto-sacral fascia displayed as low density signal strip extending from the NRL, which stretched from at the level of the 3rd or the 4th vertebra down to the posterior wall of the rectum.3.5 The IHP was high density signal network in the sagittal plane, while lineal, bead like structures in the traverse and coronal plane.3.6 The CT and MRI image could hardly to display the LRL, which was also difficult to identify by virtue of the MRA.3.7 Every layer in the rectal wall displayed clearly in the T2 weighted MRI image.4. ConclusionsMany key anatomical structures, especially the mesorectum, the neural fascia layer, the Denonvilliers fascia and the inferior hypogastric plexus, were visible clearly in MRI image. The MRI image is of clinical worth in tumor TNM staging and evaluation of operation protocol. Consecutive traverse CT scanning was an appropriate method to monitor the changes of the shape and topography of the mesorectum, which was helpful to understand the perirectal structures.Part.5 Applied anatomy on ureter protection in LTME.1. Objectives: To make certain the anatomical basis underlying the protection of ureters in the LTME.2. Materials and methods: Ten fixed male adult cadaver were dissected and observed on anatomical relationship the left ureter and the key structures in the LTME, such as the IMA, the sigmoid mesocolon, the mesorectum, and the lateral rectal ligament.3. Results3.1 The left ureter adjoined the operating area at the level of the IMA origin, the bifurcation of the left general iliac artery.3.2 The distances between the left ureter and the IMA origin, the root of the sigmoid mesocolon at the level of the bifurcation of the left general iliac artery, as well as the superior rectal artery at the level of the sacral promontory are (33.76±10.90) mm, (18.26±6.70) mm, (17.96±7.24) mm respectively. The width of the sigmoid mesocolon at the level of the sacral promontory was (45.69±8.26) mm.4. ConclusionsIt is wise to keep safe distance to the ureter in every operating stage in the LTME. The safe distances are 33.76±10.90mm and 18.26±6.70mm respectively at the level of the IMA origin and the root of the sigmoid mesocolon. The dissection lateral to the rectum should be close to the mesorectum to avoid injury of the ureter. It is dangerous to stop bleeding by electric coagulation aimlessly on the lateral pelvic wall.