The inferior hypogastric plexus: A different view

Dissection of the Sympathetic Nerves Around the Mesorectum at the Abdominopelvic Border

Introduction Along the border between the abdominal cavity and pelvis are nervous structures that belong to the autonomous nervous system, which is delicate. These can be easily injured during regional surgical procedures such as the total mesorectal excision, where the preservation of the nervous structures should be one of the main objectives. In our study, we aimed to dissect all the sympathetic nerve formations listed at the abdominopelvic border and to present their formation, anatomical routes, and relations, as well as the surgical importance of their preservation. Method We performed anatomical dissections on eight 60- to 75-year-old cadavers (three male and five female) in the Dissection Laboratory of Carol Davila University of Medicine and Pharmacy, Bucharest, ROM. We sectioned each pelvis along the right pararectal line and exposed the hypogastric plexuses and their branches, following their pathways toward the pelvic viscera. Results We highlight the main nervous structures in the pelvis, namely the paravertebral sympathetic ganglion chain, which continues into the pelvis with the sacral ganglion chain, and the prevertebral component of the abdominal sympathetic system, represented by the superior hypogastric plexus and its continuation via the hypogastric nerves toward the inferior hypogastric plexuses. We followed the pathway of the superior hypogastric plexus from its origin down to its bifurcation into the two hypogastric nerves. We then followed the nerves into the pelvis and observed the formation of the inferior hypogastric plexuses, from which branches emerged toward the pelvic organs. Along the way, we point out anatomical landmarks that are crucial in an attempt to spare these nervous structures during regional surgical procedures. Conclusions While performing surgeries such as rectal resection with the excision of the mesorectum, radical hysterectomy, and radical prostatectomy, a thorough knowledge of the sympathetic nerve structures that pass from the abdominal cavity into the pelvis is required to spare pelvic innervation. In such a context, the dissection and anatomical assessment of regional sympathetic nerves can prove to be crucial in establishing operative protocols.

The distribution of the inferior hypogastric plexus in female pelvis

Elements that comprise the inferior hypogastric plexus are difficult to expose, intricate, and highly variable and can easily be damaged during local surgical procedures. We aimed to highlight, through dissection, the origin, formation, and distribution of the hypogastric nervous structures and follow them in the female pelvis. We performed detailed dissections on 7 female formalin-fixed cadavers, focusing on structures surrounding the pelvic organs. For each hemipelvis, we removed the peritoneum from the pelvic floor, and after we identified the hypogastric nerves, we continued our dissection towards the inferior hypogastric plexuses, following the branches of the latter. Laterorectally, the hypogastric nerves form the inferior hypogastric plexus, a variable structure - nervous lamina, neuronal network (more frequently), or sometimes a combination of them. We identified three components of the inferior hypogastric plexus. The anterior bundle travels towards the base of the urinary bladder, the middle part innervates the uterus and the vagina, and the posterior segment provides the innervation of the rectum. The plexus can be identified after removing the pelvic peritoneum and the subperitoneal adipose tissue. Intraoperatively, the structures can be preserved by using an immediately-subperitoneal dissection plane. The variable branches are relatively well-organized around the pelvic vessels, supplying the urinary bladder, the genital organs, and the rectum. The ureter is surrounded by some branches, especially in its last segment, and it also receives innervation directly from the hypogastric nerve. Close to the viscera, the nerves enter neurovascular plexuses, making the intraoperative separation of the nerves and the vessels virtually impossible.

A step towards stereotactic navigation during pelvic surgery: 3D nerve topography

Background

Long-term morbidity after multimodal treatment for rectal cancer is suggested to be mainly made up by nerve-injury-related dysfunctions. Stereotactic navigation for rectal surgery was shown to be feasible and will be facilitated by highlighting structures at risk of iatrogenic damage. The aim of this study was to investigate the ability to make a 3D map of the pelvic nerves with magnetic resonance imaging (MRI).

Methods

A systematic review was performed to identify a main positional reference for each pelvic nerve and plexus. The nerves were manually delineated in 20 volunteers who were scanned with a 3-T MRI. The nerve identifiability rate and the likelihood of nerve identification correctness were determined.

Results

The analysis included 61 studies on pelvic nerve anatomy. A main positional reference was defined for each nerve. On MRI, the sacral nerves, the lumbosacral plexus, and the obturator nerve could be identified bilaterally in all volunteers. The sympathetic trunk could be identified in 19 of 20 volunteers bilaterally (95%). The superior hypogastric plexus, the hypogastric nerve, and the inferior hypogastric plexus could be identified bilaterally in 14 (70%), 16 (80%), and 14 (70%) of the 20 volunteers, respectively. The pudendal nerve could be identified in 17 (85%) volunteers on the right side and in 13 (65%) volunteers on the left side. The levator ani nerve could be identified in only a few volunteers. Except for the levator ani nerve, the radiologist and the anatomist agreed that the delineated nerve depicted the correct nerve in 100% of the cases.

Conclusion

Pelvic nerves at risk of injury are usually visible on high-resolution MRI with dedicated scanning protocols. A specific knowledge of their course and its application in stereotactic navigation is suggested to improve quality of life by decreasing the likelihood of nerve injury.

Electronic supplementary material

The online version of this article (10.1007/s00464-018-6086-3) contains supplementary material, which is available to authorized users.

Expression of Glial Cell Line-Derived Neurotrophic Factor (GDNF) and the GDNF Family Receptor Alpha Subunit 1 in the Paravaginal Ganglia of Nulliparous and Primiparous Rabbits

PURPOSE

To evaluate the expression of glial cell line-derived neurotrophic factor (GDNF) and its receptor, GDNF family receptor alpha subunit 1 (GFRα-1) in the pelvic (middle third) vagina and, particularly, in the paravaginal ganglia of nulliparous and primiparous rabbits.

METHODS

Chinchilla-breed female rabbits were used. Primiparas were killed on postpartum day 3 and nulliparas upon reaching a similar age. The vaginal tracts were processed for histological analyses or frozen for Western blot assays. We measured the ganglionic area, the Abercrombie-corrected number of paravaginal neurons, the cross-sectional area of the neuronal somata, and the number of satellite glial cells (SGCs) per neuron. The relative expression of both GDNF and GFRα-1 were assessed by Western blotting, and the immunostaining was semiquantitated. Unpaired two-tailed Student t -test or Wilcoxon test was used to identify statistically significant differences (P≤0.05) between the groups.

RESULTS

Our findings demonstrated that the ganglionic area, neuronal soma size, Abercrombie-corrected number of neurons, and number of SGCs per neuron were similar in nulliparas and primiparas. The relative expression of both GDNF and GFRα-1 was similar. Immunostaining for both GDNF and GFRα-1 was observed in several vaginal layers, and no differences were detected regarding GDNF and GFRα-1 immunostaining between the 2 groups. In the paravaginal ganglia, the expression of GDNF was increased in neurons, while that of GFRα-1 was augmented in the SGCs of primiparous rabbits.

CONCLUSIONS

The present findings suggest an ongoing regenerative process related to the recovery of neuronal soma size in the paravaginal ganglia, in which GDNF and GFRα-1 could be involved in cross-talk between neurons and SGCs.

Anatomic relationships of the pelvic autonomic nervous system in female cadavers: clinical applications to pelvic surgery

BACKGROUND

The integrity of the pelvic autonomic nervous system is essential for proper bowel, bladder, and sexual function.

OBJECTIVE

The purpose of this study was to characterize the anatomic path of the pelvic autonomic system and to examine relationships to clinically useful landmarks.

STUDY DESIGN

Detailed dissections were performed in 17 female cadavers. Relationships of the superior hypogastric plexus to aortic bifurcation and midpoint of sacral promontory were examined; the length and width of plexus was documented. Path and width of right and left hypogastric nerves were recorded. The origin and course of the pelvic splanchnic nerves were documented. Individual nerve tissue that contributed to the inferior hypogastric plexus was noted. Relative position of nerves to arteries, viscera, and ligaments was documented. In a subset of specimens, biopsy specimens were obtained to confirm gross findings by histologic analysis. Descriptive statistics were used for data analyses and reporting.

RESULTS

In all specimens, the superior hypogastric plexus was embedded in a connective tissue sheet within the presacral space, just below the peritoneum. In 14 of 17 specimens (82.4%), the plexus formed a median distance of 21.3 mm (range, 9-40 mm) below aortic bifurcation; in the remaining specimens, it formed a median distance of 25.3 mm (range, 20.5-30 mm) above bifurcation. In 58.8% of specimens, the superior hypogastric plexus was positioned to the left of midline. The median length and width of the plexus was 39.5 (range, 11.5-68) mm and 9 (range, 2.5-15) mm, respectively. A right and left hypogastric nerve was identified in all specimens and formed a median distance of 23 mm (range, 5-32 mm) below the promontory. The median width of the hypogastric nerve was 3.5 mm (range, 3-4.5 mm) on the right and 3.5 mm (range, 2-6.5 mm) on the left. The median distance from midportion of uterosacral ligament to the closest nerve branch was 0.5 mm (range, 0-4.5 mm) on right and 0 mm (range, 0-27.5 mm) on left. In all specimens, the inferior hypogastric plexus was formed by contributions from the hypogastric nerves and branches from S3 and S4. In 47.1% of hemipelvises, S2 branches contributed to the plexus. The sacral sympathetic trunk contributed to the plexus in 16 of 34 hemipelvises where this structure was identified. The inferior hypogastric plexus formed 1-3 cm lateral to the rectum and upper third of the vagina. From this plexus, 1-3 discrete branches coursed deep to the ureter toward the bladder. A uterine branch that coursed superficial to the ureter followed the ascending branch of the uterine artery. An S4 branch was found directly attaching to lateral walls of the rectum in 53% of specimens. Pelvic splanchnic nerves merged into the inferior hypogastric plexus on the lower and medial surface of the coccygeus muscle. Histologic analysis confirmed neural tissue in all tissues that were sampled.

CONCLUSION

Anatomic variability and inability to visualize the small caliber fibers that comprise the inferior hypogastric plexus grossly likely underlines the reasons that some postoperative visceral and sexual dysfunction occur in spite of careful dissection and adequate surgical technique. These findings highlight the importance of a discussion with patients about the risks that are associated with interrupting autonomic fibers during the preoperative consent.

Role of Estrogens in the Size of Neuronal Somata of Paravaginal Ganglia in Ovariectomized Rabbits

We aimed to determine the role of estrogens in modulating the size of neuronal somata of paravaginal ganglia. Rabbits were allocated into control (C), ovariectomized (OVX), and OVX treated with estradiol benzoate (OVX + EB) groups to evaluate the neuronal soma area; total serum estradiol (E2) and testosterone (T) levels; the percentage of immunoreactive (ir) neurons anti-aromatase, anti-estrogen receptor (ERα, ERβ) and anti-androgen receptor (AR); the intensity of the immunostaining anti-glial cell line-derived neurotrophic factor (GDNF) and the GDNF family receptor alpha type 1 (GFRα1); and the number of satellite glial cells (SGCs) per neuron. There was a decrease in the neuronal soma size for the OVX group, which was associated with low T, high percentages of aromatase-ir and neuritic AR-ir neurons, and a strong immunostaining anti-GDNF and anti-GFRα1. The decrease in the neuronal soma size was prevented by the EB treatment that increased the E2 without affecting the T levels. Moreover, there was a high percentage of neuritic AR-ir neurons, a strong GDNF immunostaining in the SGC, and an increase in the SGCs per neuron. Present findings show that estrogens modulate the soma size of neurons of the paravaginal ganglia, likely involving the participation of the SGC.

Careful Dissection of the Distal Ureter Is Highly Important in Nerve-sparing Radical Pelvic Surgery: A 3D Reconstruction and Immunohistochemical Characterization of the Vesical Plexus

Objective

Radical hysterectomy with pelvic lymphadenectomy (RHL) is the preferred treatment for early-stage cervical cancer. Although oncological outcome is good with regard to recurrence and survival rates, it is well known that RHL might result in postoperative bladder impairments due to autonomic nerve disruption. The pelvic autonomic network has been extensively studied, but the anatomy of nerve fibers branching off the inferior hypogastric plexus to innervate the bladder is less known. Besides, the pathogenesis of bladder dysfunction after RHL is multifactorial but remains unclear. We studied the 3-dimensional anatomy and neuroanatomical composition of the vesical plexus and describe implications for RHL.

Materials and Methods

Six female adult cadaveric pelvises were macroscopically dissected. Additionally, a series of 10 female fetal pelvises (embryonic age, 10–22 weeks) was studied. Paraffin-embedded blocks were transversely sliced in 8-μm sections. (Immuno) histological analysis was performed with hematoxylin and eosin, azan, and antibodies against S-100 (Schwann cells), tyrosine hydroxylase (postganglionic sympathetic fibers), and vasoactive intestinal peptide (postganglionic parasympathetic fibers). The results were 3-dimensionally visualized.

Results

The vesical plexus formed a group of nerve fibers branching off the ventral part of the inferior hypogastric plexus to innervate the bladder. In all adult and fetal specimens, the vesical plexus was closely related to the distal ureter and located in both the superficial and deep layers of the vesicouterine ligament. Efferent nerve fibers belonging to the vesical plexus predominantly expressed tyrosine hydroxylase and little vasoactive intestinal peptide.

Conclusions

The vesical plexus is located in both layers of the vesicouterine ligament and has a very close relationship with the distal ureter. Complete mobilization of the ureter in RHL might cause bladder dysfunction due to sympathetic and parasympathetic denervation. Hence, the distal ureter should be regarded as a risk zone in which the vesical plexus can be damaged.

Optimal plane for nerve sparing total mesorectal excision, immunohistological study and 3D reconstruction: an embryological study

AIM

Genito-urinary complications are frequent after rectal surgery and are often due to nerve damage. The relationship between the pelvic nerves and surgical planes are unclear. The aim of the study was to determine the relationship between the inferior hypogastric plexus and the fascia of the lateral pelvic wall and between Denonvilliers' fascia and the efferent branches of the inferior hypogastric plexus.

METHOD

Computer-assisted anatomical dissection was used. Serial histological sections were made from six human foetuses and a male adult. Sections were stained with haematoxylin and eosin, Masson's trichrome and immunostainings. The sections were then digitalized and reconstructed in three dimensions.

RESULTS

The inferior hypogastric plexus was situated in a virtual space between the fascia propria of the rectum and the fascia on the upper surface of the levator ani. During the lateral dissection, the optimal surgical plane is the plane of the fascia propria of the rectum. We located Denonvilliers' fascia in three dimensions. It plays the role of a protective sheet for the neurovascular bundle. The optimal plane for nerve preservation is situated behind Denonvilliers' fascia.

CONCLUSION

This study has enabled a clear visualization of the optimal planes to perform total mesorectal excision while ensuring nerve preservation. Three-dimensional visualization clearly helps to bridge the gap between histological examination and the findings of surgery.

Colorectal and uterine movement and tension of the inferior hypogastric plexus in cadavers

BACKGROUND

Hypotheses on somatovisceral dysfunction often assume interference by stretch or compression of the nerve supply to visceral structures. The purpose of this study is to examine the potential of pelvic visceral movement to create tension of the loose connective tissue that contains the fine branches of the inferior hypogastric nerve plexus.

METHODS

Twenty eight embalmed human cadavers were examined. Pelvic visceral structures were displaced by very gentle 5 N unidirectional tension and the associated movement of the endopelvic fascia containing the inferior hypogastric plexus that this caused was measured.

RESULTS

Most movement of the fascia containing the inferior hypogastric plexus was obtained by pulling the rectosigmoid junction or broad ligament of the uterus. The plexus did not cross any vertebral joints and the fascia containing it did not move on pulling the hypogastric nerve.

CONCLUSIONS

Uterine and rectosigmoid displacement produce most movement of the fascia containing the hypogastric nerve plexus, potentially resulting in nerve tension. In the living this might occur as a consequence of menstruation, pregnancy or constipation. This may be relevant to somatovisceral reflex theories of the effects of manual therapy on visceral conditions.

Where does pelvic nerve injury occur during rectal surgery for cancer?

AIM

Optimal treatment of rectal adenocarcinoma involves total mesorectal excision with nerve-preserving dissection. Urinary and sexual dysfunction is still frequent following these procedures. Improved knowledge of pelvic nerve anatomy may help reduce this and define the key anatomical zones at risk.

METHOD

The MEDLINE database was searched for available literature on pelvic nerve anatomy and damage after rectal surgery using the key words 'autonomic nerve', 'pelvic nerve', 'colorectal surgery', and 'genitourinary dysfunction'. All relevant French and English publications up to May 2010 were reviewed. Reviewed data were illustrated using 3D reconstruction of the foetal pelvis.

RESULTS

The ligation of the inferior mesenteric artery and dissection of the retrorectal space can cause damage to the superior hypogastric plexus and/or hypogastric nerve. Anterolateral dissection in the 'lateral ligament' area and division of Denonvilliers' fascia can damage the inferior hypogastric plexus and efferent pathways. Perineal dissection can indirectly damage the pudendal nerve.

CONCLUSIONS

In most cases, the pelvic nerves can be preserved during rectal surgery. Complete oncological resection may require dissection close to the nerves where the tumour is located anterolaterally where it is fixed and when the pelvis is narrow.

Endometriosis: the elusive epiphenomenon

The denervation-reinnervation view proposes that retrograde menstruation results from loss of normal, fundocervical polarity caused by injuries to uterine nerves. Injuries may be sporadic (following vaginal delivery) or recurrent (after persistent straining during defaecation) creating very different appearances at laparoscopy. Clinical symptoms of pelvic pain, menstrual problems, dyspareunia, and dysmenorrhoea result from aberrant reinnervation that may occur with, or without deposits of pelvic endometriosis. Endometrium, delivered by retrograde menstruation, adheres to any injured tissues in the lower pelvis. Classical 'endometriosis' is largely an epiphenomenon to underlying processes of denervation and reinnervation.

Pelvic floor stimulation: what are the good vibrations?

OBJECTIVE

The aim of this study was to determine if two different whole body vibration, sinusoidal vibration (SV) and stochastic resonance vibration (SRV), using various intensities lead to a reactive activation of pelvic floor muscles.

STUDY DESIGN

We compared the pelvic floor muscle response of a healthy control group with that of a post partum group with weakened pelvic floor contraction. Activation effects of stochastic resonance vibration and sinusoidal vibration with six increasing vibration intensities were investigated using pelvic floor EMG and compared to activity during rest and maximum voluntary contraction.

RESULTS

Both whole body vibration systems were able to activate pelvic floor muscles significantly depending on vibration intensity. Generally, the SRV achieved a significantly higher activation than maximum voluntary contraction, especially in women post partum and using a frequency of 6-12 Hz.

CONCLUSION

SRV, compared to SV, leads to higher pelvic floor muscle activation in subjects with weakened pelvic floor muscles and achieves higher pelvic floor activation than maximum voluntary contraction alone. Neurourol. Urodynam. 28:405-410, 2009. (c) 2009 Wiley-Liss, Inc.

Design and development of a new facility for teaching and research in clinical anatomy

This article discusses factors in the design, commissioning, project management, and intellectual property protection of developments within a new clinical anatomy facility in the United Kingdom. The project was aimed at creating cost-effective facilities that would address widespread concerns over anatomy teaching, and support other activities central to the university mission-namely research and community interaction. The new facilities comprise an engaging learning environment and were designed to support a range of pedagogies appropriate to the needs of healthcare professionals at different stages of their careers. Specific innovations include integrated workstations each comprising of a dissection table, with removable top sections, an overhead operating light, and ceiling-mounted camera. The tables incorporate waterproof touch-screen monitors to display images from the camera, an endoscope or a database of images, videos, and tutorials. The screens work independently so that instructors can run different teaching sessions simultaneously and students can progress at different speeds to suit themselves. Further, database access is provided from within an integrated anatomy and pathology museum and display units dedicated to the correlation of cross-sectional anatomy with medical imaging. A new functional neuroanatomy modeling system, called the BrainTower, has been developed to aid integration of anatomy with physiology and clinical neurology. Many aspects of the new facility are reproduced within a Mobile Teaching Unit, which can be driven to hospitals, colleges, and schools to provide appropriate work-based education and community interaction.

Variability in superior hypogastric plexus morphology and its clinical applications: a cadaveric study

BACKGROUND

The superior hypogastric plexus (SHP) that is formed anterior to the aorta and the sacral promontory and is located anterior to the L5-S1 vertebrae, normally continues as the inferior hypogastric plexus. Several variations have been described from a single trunk to a plexiform arrangement.

MATERIALS AND METHODS

The SHP was dissected in 35 formalized cadavers.

RESULTS

A single thin and rounded nerve was found in 17.14% of subjects. The type of a wide reticular formation was observed in 28.57% of specimens. Interestingly, a band-like nerve trunk consisting of nerve bundles connected with loose connective tissue was evident in 22.85% of cadavers. Eventually, two distinct nerves at a short distance with each other were found in 31.44% of subjects. Furthermore, we found that branches of the major and minor splanchnic nerves contributed to SHP constitution. We provided, additionally, the topographic anatomy of the SHP with regard to the sacral promontory and the abdomen midline.

CONCLUSION

A detailed knowledge of the course, the morphology, the various forms and the topography of the SHP is of outmost significance for several clinical specialties.