Anatomic variations of the pelvic floor nerves adjacent to the sacrospinous ligament: a female cadaver study

The minimally invasive sacrospinous fixation under visual guidance: An anatomical study

OBJECTIVE

Sacrospinous fixation is the gold standard procedure for management of apical pelvic organ prolapse by the vaginal route. However, there may be a relevant risk of neurovascular injury due to the proximity of neurovascular structures. We propose an anatomical study concerning the sacrospinous ligament with a new innovative minimally invasive technology using both a suture capturing device and a chip-on-the-tip endoscope to perform sacropinous fixation.

STUDY DESIGN

Bilateral sacrospinous fixation was performed in three female cadavers, in the course of the anatomical study conducted with a specific device (the Suture Capturing I Stitch™ Device) under real time visual guidance with a chip-on -the-tip endoscope, the NanoScope™ system.

RESULTS

Identification of ischial spine and sacrospinous ligament as well as feasibility of sacrospinous fixation under NanoScope™ control were always possible on both sides.

CONCLUSIONS

This new innovative minimally invasive technology using both a suture capturing device and a chip-on-the-tip endoscope is relevant and could be an advantage in terms of safety and better placement of the suture on the sacrospinous ligament.

Anatomy of the pudendal nerve in clinically important areas: a pictorial essay and narrative review

PURPOSE

The pudendal nerve is an anatomical structure arising from the ventral branches of the spinal roots S2-S4. Its complex course may be affected by surrounding structures. This may result in irritation or entrapment of the nerve with subsequent clinical symptoms. Aim of this study is to review the anatomy of the pudendal nerve and to provide detailed photographic documentation of the areas with most frequent clinical impact which are essential for surgical approach.

METHODS

Major medical databases were searched to identify all anatomical studies investigating pudendal nerve and its variability, and possible clinical outcome of these variants. Extracted data consisted of morphometric parameters, arrangement of the pudendal nerve at the level of roots, formation of pudendal nerve, position according to sacrospinal and sacrotuberal ligaments and its terminal branches. One female cadaver hemipelvis was dissected with common variability of separate course of inferior rectal nerve. During dissection photodocumentation was made to record course of pudendal nerve with focus on areas with recorded pathologies and areas exposed to iatrogenic damage during surgical procedures.

RESULTS

Narrative review was done to provide background for photodocumentation. Unique photos of course of the pudendal nerve was made in areas with great clinical significance.

CONCLUSION

Knowledge of anatomical variations and course of the pudendal nerve is important for examinations and surgical interventions. Surgically exposed areas may become a site for iatrogenic damage of pudendal nerve; therefore, unique picture was made to clarify topographic relations.

The anatomy of the sacrospinous ligament: how to avoid complications related to the sacrospinous fixation procedure for treatment of pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

Historically, the sacrospinous ligament (SSL) has been used to treat POP in order to restore the apical compartment through a posterior or an anterior vaginal approach. The SSL is located in a complex anatomical region, rich in neurovascular structures that must be avoided to reduce complications such as acute hemorrhage or chronic pelvic pain. The aim of this three-dimensional (3D) video describing the SSL anatomy is to show the anatomical concerns related to the dissection and the suture of this ligament.

METHODS

We conducted a research of anatomical articles about vascular and nerve structures located in the SSL region, in order to increase the anatomical knowledge and show the best placement of sutures to reduce complications related to SSL suspension procedures.

RESULTS

We showed the medial part of the SSL to be most suitable for the placement of the suture during SSL fixation procedures, in order to avoid nerve and vessel injuries. However, nerves to the coccygeus and levator ani muscle can course on the medial part of the SSL, the portion of the SSL where we recommended to pass the suture.

CONCLUSIONS

Knowledge of the SSL anatomy is crucial and during surgical training it is clearly indicated to stay far away (almost 2 cm) from the ischial spine to avoid nerve and vascular injuries.

Sacrospinous fixation: Review of relevant anatomy and surgical technique

Apical support is an important component of pelvic floor reconstruction for pelvic organ prolapse. Sacrospinous ligament fixation is a recognized procedure for apical support. Complications from sacrospinous ligament fixation include pain (buttock and leg) and bleeding. There is some debate as to the optimal location for placement of the sacrospinous fixation sutures. This review summarizes the neuroanatomy of the coccygeus sacrospinous ligament as it pertains to the sacrospinous ligament fixation procedure. An appreciation of the neuroanatomy will lead to a better understanding of methods to reduce operative complications and improve suture placement. This paper also describes a technique for the sacrospinous fixation procedure to better assist clinicians in dissecting the connective tissue off the ligament. Removing or clearing the connective tissue off the ligament will allow critical landmarks to be easily palpated and hence a more accurate placement of sutures. This in turn may reduce the risk of perioperative complications.

Comparison between anterior and posterior vaginal approach in apical prolapse repair in relation to anatomical structures and points of fixation to the sacrospinous ligament in fresh postmenopausal female cadavers

INTRODUCTION AND HYPOTHESIS

The high prevalence of pelvic organ prolapse (POP) in women requires attention and constant review of treatment options. Sacrospinous ligament fixation (SSLF) for apical prolapse has benefits, high efficacy, and low cost. Our objective is to compare anterior and posterior vaginal approach in SSLF in relation to anatomical structures and to correlate them with body mass index (BMI).

METHODS

Sacrospinous ligament fixation was performed in fresh female cadavers via anterior and posterior vaginal approaches, using the CAPIO®SLIM device (Boston Scientific, Natick, MA, USA). The distances from the point of fixation to the pudendal artery, pudendal nerve, and inferior gluteal artery were measured.

RESULTS

We evaluated 11 cadavers with a mean age of 70.1 ± 9.9 years and mean BMI 22.4 ± 4.6 kg/m². The mean distance from the posterior SSLF to the ischial spine, pudendal artery, pudendal nerve, and inferior gluteal artery were 21.18 ± 2.22 mm, 17.9 ± 7.3 mm, 19.2 ± 6.8 mm, and 18.9 ± 6.9 mm respectively. The same measurements relative to the anterior SSLF were 19.7 ± 2.7 mm, 18.6 ± 6.7 mm, 19.2 ± 6.9 mm, and 18.3 ± 6.7 mm. Statistical analysis showed no difference between the distances in the two approaches. The distances from the fixation point to the pudendal artery and nerve were directly proportional to the BMI.

CONCLUSIONS

There was no difference in the measurements obtained in the anterior and posterior vaginal approaches. A direct correlation between BMI and the distances to the pudendal artery and pudendal nerve was found.

Sacrospinous Ligament Fixation Using an Anchor Versus Suture-Capturing Device: A Prospective Cohort Study

OBJECTIVE

The aim of the study was to compare rates of persistent gluteal and posterior thigh pain, procedural efficacy, and postoperative complications at 1 year after sacrospinous ligament fixation using either an anchor-based or suture-capturing device.

METHODS

This prospective cohort study evaluated outcomes 1 year after operation in patients previously enrolled in a randomized controlled trial comparing an anchor-based versus suture-capturing device for sacrospinous fixation. Symptom scores were evaluated via Pelvic Floor Distress Inventory 20 and Pelvic Floor Impact Questionnaire 7. Pain was evaluated using the Numerical Rating Scale. Composite surgical failure was defined as prolapse beyond the hymen or C-point greater than one half down the vagina, vaginal bulge symptoms, or a need for prolapse retreatment via surgery or pessary management. Descriptive and bivariate statistics were performed.

RESULTS

Forty three (21 anchors, 22 sutures) of the original 47 patients (91%) returned for follow-up. The mean follow-up time was 15.4 months, age was 69 years old, body mass index was 30, and preoperative Pelvic Organ Prolapse Quantification stage was 2.7. No patients reported significant increase in pain at sacrospinous fixation site above baseline, and there was no significant difference in posterior thigh or gluteal pain on the side of fixation compared with baseline in the anchor-based or suture-capture groups (-0.2 ± 0.9 and -0.5 ± 1.6, respectively, P = 0.719). Two patients demonstrated surgical failure (anchor group) due to bulge symptoms (P = 0.233). The devices similarly improved Pelvic Floor Distress Inventory 20 (-71.0 ± 45.5 vs -66.3 ± 64.4, P = 0.652) and Pelvic Floor Impact Questionnaire 7 (-40.6 ± 62.4 vs -26.4 ± 65.7, P = 0.768) scores.

CONCLUSIONS

Persistent gluteal or posterior thigh pain and surgical failure is uncommon 12 months after sacrospinous fixation and was not associated with the type of fixation device.

The Anatomical Distribution of the Pudendal Nerve Block Injection: A Cadaveric Study

OBJECTIVE

The objective of this study was to assess the accuracy of commonly used injection locations of the pudendal nerve block by examining the proximity of the injected dye to the pudendal nerve in a cadaveric model.

METHODS

Pudendal block injections at 4 sites were placed transvaginally on 5 cadaveric pelvises. These sites were 1 cm proximal to the ischial spine (black dye), at the ischial spine (red dye), 1 cm distal to the ischial spine (blue dye), and 2 cm lateral and 2 cm distal to the ischial spine (green dye). The cadavers were dissected via a posterior approach.

RESULTS

We measured the shortest distance from the center of the dye-stained tissue to the pudendal nerve. As expected, the injections at the ischial spine (red) resulted in a distribution of dye closest to the pudendal nerve, averaging 3.0 ± 0.95 mm. Dyes at other sites were close to the nerve: 3.1 ± 1.00 mm (black), 3.6 ± 1.14 mm (blue), and 4.05 ± 1.28 mm (green).

CONCLUSIONS

Regardless of the injection site, all dyes were close the pudendal nerve, indicating accuracy. We observed wide variation in the dye distribution even though all injections were performed by the same provider, implicating lack of precision. Based on our findings, we propose that the most effective injection location is at the ischial spine because it is the closest to the pudendal nerve; however, all injections were within 4 mm of the pudendal nerve, suggesting that only 1 to 2 injections may be sufficient.

A Cadaveric Simulation Model to Teach Suture Placement During Sacrospinous Ligament Fixation

OBJECTIVES

The objectives of this study were to describe a cadaveric simulation model designed to teach sacrospinous ligament fixation (SSLF) and to assess trainee performance, comfort, and skill with suture placement.

METHODS

Nine invited participants from 3 institutions participated in cadaveric simulation training, consisting of a didactic lecture, technical demonstrations, and supervised execution of suture placement. Trainee self-perceived knowledge and confidence levels of SSLF were assessed before and after the educational intervention. Suture placement was assessed by expert faculty pelvic reconstructive surgeons. The number of attempts required by trainees for an anatomically safe suture placement was recorded. Participants completed a postintervention satisfaction survey.

RESULTS

All 9 participants correctly identified where an SSLF suture should be placed on a printed image before the educational intervention, but only 33% achieved anatomically safe suture placement on the first attempt (mean ± SD, 2.88 ± 2.10 attempts). Four participants (44%) reported comfort with independently performing SSLF before the course. Of these, three (75%) required more than 1 attempt for successful suture placement. Mean ± SD distance of SSLF suture from the ischial spine was 1.90 ± 0.59 cm. All participants reported that they found the training helpful in learning the surgical steps and anatomy related to SSLF and would recommend it to others.

CONCLUSIONS

A cadaveric simulation teaching model led to improved trainee-reported confidence with the operative steps and anatomy related to SSLF. Participants' prior knowledge of procedural steps and anatomy did not always transfer to adequate procedural skills for safe suture placement, suggesting the need for further simulation practice for fellow trainees.

Anatomical structures at risk using different approaches for sacrospinous ligament fixation

For 50 years now, sacrospinous ligament fixation (SSLF) has been used to treat pelvic organ prolapse consequent on altered integrity of the pelvic myofascial structures. It is usually performed vaginally, but it has recently been performed laparoscopically through either an anterior or a posterior approach, with the broad ligament as a landmark to differentiate the two. In the present study, these two laparoscopic approaches were assessed using Thiel-embalmed cadavers. The anterior and posterior approaches were compared in terms of the closest distance to anatomical structures at risk, including pelvic viscera, the obturator nerve, and vascular structures. The posterior approach was more often closer to the investigated vessels and the rectum. The obturator nerve and the ureter were close to both the anterior and posterior approaches. The urinary bladder was closer using the anterior approach. From an anatomical standpoint, therefore, the anterior laparoscopic approach for SSLF is more likely to cause injury to the urinary bladder, whereas the posterior approach is more prone to causing rectal and vessel injuries. This study illustrates, from a basic science perspective, the importance of combining fascia research, novel endoscopic or minimally invasive surgical exposures informed by anatomy, and contemporary trends in gynecology in order to improve patient outcomes. Clin. Anat. 33:522-529, 2020. © 2019 Wiley Periodicals, Inc.

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.

A new endoscopic minimal invasive approach for pudendal nerve and inferior cluneal nerve neurolysis: An anatomical study

AIM

To describe a new minimal invasive approach of the gluteal region which will permit to perform neurolysis of the pudendal and cluneal nerves in case of perineal neuralgia due to an entrapment of these nerve trunks.

METHOD

Ten transgluteal approaches were performed on five cadavers. Relevant anatomic structures were dissected and further described. Neurolysis of the pudendal nerve or cluneal nerves were performed. Landmarks for secure intraoperative navigation were indicated.

RESULTS

The first operative trocar for the camera was inserted with regards to the iliac crest in the deep gluteal space. With the aid of pneumodissection, the infragluteal plane was dissected. The piriformis muscle was identified as well as the sciatic and the posterior femoral cutaneous nerve. Consequently, the sciatic tuberosity was visualized together with the cluneal nerves. Hereafter, the second trocar was introduced caudal to the first one and placed on an horizontal line passing at the level of the coccyx, allowing access to the ischial spine and the visualization of the pudendal nerve and vessels. A third 5 mm trocar was then inserted medial from the first one, permitting to dissect and transsect the sacrospinous ligament. The pudendal nerve was subsequently transposed and followed on its course in the pudendal channel.

CONCLUSIONS

A reliable exploration of the gluteal region including identification of the sciatic, pudendal, and posterior femoral cutaneous nerves is feasible using a minimal invasive transgluteal procedure. Consequently, the transposition of the pudendal nerve and the liberation of the cluneal nerves can be performed.

Inferior gluteal and other nerves associated with sacrospinous ligament: a cadaver study

BACKGROUND

Reported rates of gluteal pain after sacrospinous ligament fixation range from 12-55% in the immediate postoperative period and from 4-15% 4-6 weeks postoperatively. The source of gluteal pain often is attributed to injury to the nerve to levator ani or pudendal nerve. The inferior gluteal nerve and other sacral nerve branches have not been examined thoroughly as potential sources of gluteal pain.

OBJECTIVES

The purpose of this study was to further characterize anatomy of the inferior gluteal nerve and other nerves that are associated with the sacrospinous ligament from a combined gluteal and pelvic approach and to correlate findings to sacrospinous ligament fixation.

STUDY DESIGN

Dissections were performed in female cadavers that had not been embalmed with gluteal and pelvic approaches. From a pelvic perspective, the closest structure to the superior border of the sacrospinous ligament midpoint was noted, and the sacral nerves that perforated the ventral surface of coccygeus muscle were examined. From a gluteal perspective, the closest distances from ischial spine to the pudendal, inferior gluteal, posterior femoral cutaneous, and sciatic nerves were measured. In addition, the closest distance from the midpoint of sacrospinous ligament to the inferior gluteal nerve and the origin of this nerve were documented. The thickness and height of the sacrospinous ligament at its midpoint were measured. Sacral nerve branches that coursed between the sacrospinous and sacrotuberous ligaments were assessed from both a pelvic and a gluteal approach. Descriptive statistics were used for data analysis.

RESULTS

Fourteen cadavers were examined. From a pelvic perspective, the closest structure to the superior border of sacrospinous ligament at its midpoint was the S3 nerve (median distance, 3 mm; range, 0-11 mm). Branches from S3 and/or S4 perforated the ventral surface of coccygeus muscles in 94% specimens. From a gluteal perspective, the closest structure to ischial spine was the pudendal nerve (median distance, 0 mm; range, 0-9 mm). Median closest distance from inferior gluteal nerve to ischial spine and to the midpoint of sacrospinous ligament was 28.5 mm (range, 6-53 mm) and 31.5 mm (range, 10-47 mm), respectively. The inferior gluteal nerve arose from dorsal surface of combined lumbosacral trunk and S1 nerves in all specimens; a contribution from S2 was noted in 46% of hemipelvises. At its midpoint, the sacrospinous ligament median thickness was 5 mm (range, 2-7 mm), and its median height was 14 mm (range, 3-22 mm). In 85% of specimens, 1 to 3 branches from S3 and/or S4 nerves pierced or coursed ventral to the sacrotuberous ligament and perforated the inferior portion of the gluteus maximus muscle.

CONCLUSIONS

Damage to the inferior gluteal nerve during sacrospinous ligament fixation is an unlikely source for postoperative gluteal pain. Rather, branches from S3 and/or S4 that innervate the coccygeus muscles and those coursing between the sacrospinous and sacrotuberous ligaments to supply gluteus maximus muscles are more likely to be implicated. A thorough understanding of the complex anatomy surrounding the sacrospinous ligament, limiting depth of needle penetration into the ligament, and avoiding extension of needle exit or entry point above the upper extent of sacrospinous ligament may reduce nerve entrapment and postoperative gluteal pain.

The Pudendal Nerve and Its Branches in Relation to Richter's Procedure

OBJECTIVE

Variations in the branching pattern of the pudendal nerve (PN) have been described in the literature. This study investigated these variations in order to comment on a safe area for the placement of a Richter's stitch.

METHODS

Richter's procedure was performed on nine unembalmed female cadavers and followed by dissection. PN dissections were done on another 20 embalmed female cadavers. Variations in the branching pattern of the PN were noted and the distance between the Richter's stitch placed and the PN/or the inferior rectal nerve (IRN) measured.

RESULTS

The IRN entered the gluteal region as a separate structure in 6/29 cases. The separate IRN was found to pass between 4.1 and 14.45 mm medial to the ischial spine in 18/29 cases. In one case, the Richter's stitch was found to pierce the IRN. The distance between the stitch and the PN and/or the IRN ranged from 0 to 17.8 mm.

CONCLUSIONS

To minimize the risk of nerve damage or entrapment, the Richter's stitch should be placed >20 mm from the ischial spine. This recommended area should be revised for different population groups, as variations might exist between groups.

Laparoscopic pudendal nerve decompression and transposition combined with omental flap protection of the nerve (Istanbul technique): technical description and feasibility analysis

BACKGROUND

We aimed in this study to investigate the efficacy of laparoscopic pudendal nerve decompression and transposition (LaPNDT) in the treatment of chronic pelvic pain due to pudendal neuralgia. Pudendal nerve entrapment (PNE) between the sacrospinous and sacrotuberous ligaments is the most frequent etiology. We describe the technical details, feasibility, and advantages of a laparoscopic approach in patients with PNE.

METHODS

Consecutive patients (n = 27) with a diagnosis of PNE underwent LaPNDT with omental flap protection in an effort to prevent re-fibrosis around the nerve in the long term. The degree of pain and pain impact were evaluated pre- and postoperatively using the visual analog pain scale (VAS) and the Impact of Symptoms and Quality of Life.

RESULTS

The mean (± standard deviation [SD]) follow-up of the 27 patients was 6.8 ± 4.2 months; 16 of the 27 were followed-up for more than 6 months. The mean (SD) operation time was 199.4 ± 36.1 (155-300) min, and the mean estimated blood loss was 39.7 ml. All patients were ambulated on the first postoperative day, and the mean (SD) hospitalization time was 2.1 ± 1.0 (1-6) days. The mean VAS scores of 27, 23, 16, and 6 patients were 1.5, 1.4, 1.6, and 2.0, postoperatively, at the first, third, sixth, and twelfth months (p < 0.0001). A more than reduction in VAS score (>80 %) was achieved in 13 of the 16 patients (81.2 %) who were followed-up for more than 6 months.

CONCLUSIONS

LaPNDT seems a feasible surgical modality for cautiously selected patients with PNE. In addition, using an omental flap for protection of the nerve is one of the most important technical advantages of laparoscopy. As a minimally invasive surgery, the laparoscopic approach can be technically feasible, with its promising preliminary results in the treatment of PNE. With further analysis, in the future it may open new frontiers for pudendal nerve neuromodulation as a new treatment modality in some intractable functional problems of the genitourinary tract.

Sacrospinous ligament fixation for pelvic organ prolapse in the era of vaginal mesh kits

PURPOSE OF REVIEW

To examine the sacrospinous ligament as a point of attachment for pelvic organ prolapse procedures, including vaginal mesh kits.

RECENT FINDINGS

Pelvic surgeons are increasingly employing the sacrospinous ligament as a point of attachment for biologic grafts and synthetic mesh kits during uterovaginal prolapse repairs. These techniques may have introduced a novel set of complications (mesh extrusion, erosion) in addition to those already known to occur in traditional sacrospinous ligament fixations. Except for limited short-term results, little data are available in the literature regarding surgical outcomes and complications for mesh and graft augmented repairs attached to the sacrospinous ligament.

SUMMARY

The sacrospinous ligament fixation is a well tolerated and effective procedure for suspension of the vaginal apex. Mesh augmentation using the sacrospinous ligament may improve objective prolapse recurrence, but complications still occur, including those specific to mesh placement.