Effect of intra-operative autonomic nerve stimulation on pelvic nerve preservation during radical laparoscopic proctectomy

From basic to clinical: Anatomy of Denonvilliers' fascia and its application in laparoscopic radical resection of rectal cancer

The total mesorectal excision (TME) approach has been established as the gold standard for the surgical treatment of middle and lower rectal cancer. This approach is widely accepted to minimize the risk of local recurrence and increase the long-term survival rate of patients undergoing surgery. However, standardized TME causes urogenital dysfunction in more than half of patients, thus lowering the quality of life of patients. Of note, pelvic autonomic nerve damage during TME is the most pivotal cause of postoperative urogenital dysfunction. The anatomy of the Denonvilliers' fascia (DVF) and its application in surgery have been investigated both nationally and internationally. Nevertheless, controversy exists regarding the basic to clinical anatomy of DVF and its application in surgery. Currently, it is a hotspot of concern and research to improve the postoperative quality of life of patients with rectal cancer through the protection of their urinary and reproductive functions after radical resection. Herein, this study systematically describes the anatomy of DVF and its application in surgery, thus providing a reference for the selection of surgical treatment modalities and the enhancement of postoperative quality of life in patients with middle and low rectal cancer.

Pelvic Intraoperative Neuromonitoring Prevents Dysfunction in Patients With Rectal Cancer: Results From a Multicenter, Randomized, Controlled Clinical Trial of a NEUROmonitoring System (NEUROS)

OBJECTIVE

This NEUROmonitoring System (NEUROS) trial assessed whether pelvic intraoperative neuromonitoring (pIONM) could improve urogenital and ano-(neo-)rectal functional outcomes in patients who underwent total mesorectal excisions (TMEs) for rectal cancer.

BACKGROUND

High-level evidence from clinical trials is required to clarify the benefits of pIONM.

METHODS

NEUROS was a 2-arm, randomized, controlled, multicenter clinical trial that included 189 patients with rectal cancer who underwent TMEs at 8 centers, from February 2013 to January 2017. TMEs were performed with pIONM (n=90) or without it (control, n=99). The groups were stratified according to neoadjuvant chemoradiotherapy and sex, with blocks of variable length. Data were analyzed according to a modified intention-to-treat protocol. The primary endpoint was a urinary function at 12 months after surgery, assessed with the International Prostate Symptom Score, a patient-reported outcome measure. Deterioration was defined as an increase of at least 5 points from the preoperative score. Secondary endpoints were sexual and anorectal functional outcomes, safety, and TME quality.

RESULTS

The intention-to-treat analysis included 171 patients. Marked urinary deterioration occurred in 22/171 (13%) patients, with significantly different incidence between groups (pIONM: n=6/82, 8%; control: n=16/89, 19%; 95% confidence interval, 12.4-94.4; P =0.0382). pIONM was associated with better sexual and ano-(neo)rectal function. At least 1 serious adverse event occurred in 36/88 (41%) in the pIONM group and 53/99 (54%) in the control group, none associated with the study treatment. The groups had similar TME quality, surgery times, intraoperative complication incidence, and postoperative mortality.

CONCLUSION

pIONM is safe and has the potential to improve functional outcomes in rectal cancer patients undergoing TME.

Association between urinary function and resected pattern of the autonomic nerve system after transanal total mesorectal excision for rectal cancer

AIM

Transanal total mesorectal excision (TaTME) is expected to improve the quality of total mesorectal excision as well as preserve urinary function. We aimed to study the frequency and risk factors of urinary dysfunction in rectal cancer patients after TaTME. Moreover, we analysed the association between urinary function and resected pattern of the autonomic nerve system (ANS) in TaTME.

METHOD

We retrospectively analysed 231 patients who underwent TaTME at our hospital from 2013 to 2018. Independent risk factors for urinary dysfunction were assessed by multivariate analysis. Urinary dysfunction was defined as a condition that requires urethral catheterisation. We intraoperatively judged and classified the preserved or resected pattern of ANS into four categories.

RESULTS

The rate of urinary dysfunction after TaTME was 12.1% at discharge. Multivariate analysis revealed that beyond TME and ANS resection were the two major independent risk factors for urinary dysfunction. Total ANS preservation had reduced rates of urinary dysfunction, and all patients were free from catheterisation 6 months post-surgery. There was a higher rate of urinary dysfunction in total ANS resection than in partial ANS resection at 6 months post-surgery.

CONCLUSION

This study showed that urinary function after TaTME was associated with resection of the ANS. Furthermore, the rate of urinary dysfunction and recovery time were closely related to the pattern of ANS resection.

Identification of the surgical indication line for the Denonvilliers' fascia and its anatomy in patients with rectal cancer

Background

The high rate of urogenital dysfunction after traditional total mesorectal excision (TME) has caused doubts among scholars on the standard fashion of dissection. We have proposed the necessity to preserve the Denonvilliers’ fascia in patients with rectal cancer. However, how to accurately locate the Denonvilliers’ fascia is unclear. This study aimed to explore anatomical features of the Denonvilliers’ fascia by comparing autopsy findings and observations of surgical videos so as to propose a dissection method for the preservation of pelvic autonomic nerves during rectal cancer surgery.

Methods

Five adult male cadaver specimens were dissected, and surgical videos of 135 patients who underwent TME for mid‐low rectal cancer between January 2009 and February 2019 were reviewed to identify and compare the structure of the Denonvilliers’ fascia.

Results

The monolayer structure of the Denonvilliers’ fascia was observed in 5 male cadaver specimens, and it was located between the rectum, the bottom of the bladder, the seminal vesicles, the vas deferens, and the prostate. The Denonvilliers’ fascia was originated from the rectovesical pouch (or rectum‐uterus pouch), down to fuse caudally with the rectourethral muscle at the apex of the prostate, and fused to the lateral ligaments on both sides. The fascia was thinner on the midline with a thickness of 1.06 ± 0.10 mm. The crown shape of the Denonvilliers’ fascia was slightly triangular, with a height of approximately 5.42 ± 0.16 cm at midline. Nerves were more densely distributed in front of the Denonvilliers’ fascia than behind, especially on both sides of it. Under laparoscopic view, the Denonvilliers’ fascia was originated at the lowest point of the rectovesical pouch (or rectum‐uterus pouch), with a thickened white line which was a good mark for identifying the Denonvilliers’ fascia.

Conclusion

Identification of the surgical indication line for the Denonvilliers’ fascia could help us identify the Denonvilliers’ fascia, and it would improve our ability to protect the pelvic autonomic function of patients undergoing TME for rectal cancer.

Urinary dysfunction in patients with rectal cancer: a prospective cohort study

AIM

Urinary dysfunction is one of many complications after treatment for rectal cancer. The aim of this study was to evaluate the prevalence of patient-reported urinary dysfunction at the time of diagnosis and at 1-year follow-up and to assess the risk factors linked to urinary incontinence.

METHOD

Patients with newly diagnosed rectal cancer were included in the QoLiRECT study between 2012 and 2015. Questionnaires from the time of diagnosis and 1-year follow-up were analysed, with 1085 and 916 patients, respectively, eligible for analysis. Regression analyses were made to investigate possible risk factors for incontinence. The patient cohort was also compared with a cohort from the Swedish general population.

RESULTS

At baseline, the prevalence of urinary dysfunction (14% of women, 8% of men) was similar to that in the general population. At 1-year follow-up, 20% of patients experienced urinary incontinence (29% of women, 14% of men). Emptying difficulties were experienced by 46% (41% of women, 49% of men) and urgency by 58% across both sexes. Abdominoperineal excision and urinary dysfunction at baseline were found to be independent risk factors for incontinence at 1-year follow-up. Among patients who were continent at baseline, risk factors were female sex, physical inactivity at baseline, comorbidity and abdominoperineal excision.

CONCLUSION

Urinary dysfunction is frequent among patients with rectal cancer, with up to a two-fold increase in symptoms 1 year after diagnosis. Unfortunately, few factors are modifiable and these results stress the importance of informing patients of possible outcomes related to urinary dysfunction after treatment for rectal cancer.

Intraoperative monitoring of pelvic autonomic nerves during laparoscopic low anterior resection of rectal cancer

Background

Some patients with low rectal cancer experience anorectal and urogenital dysfunctions after surgery, which can influence the long-term quality of life. In this study, we aimed to protect nerve function in such scenarios by performing intraoperative monitoring of pelvic autonomic nerves (IMPAN).

Patients and methods

We retrospectively investigated a series of 87 patients undergoing laparoscopic low anterior resection of rectal cancer. Nerve-sparing was evaluated both visually and electrophysiologically. IMPAN was performed by stimulating the pelvic autonomic nerves under processed electromyography of the internal anal sphincter. Urination, defecation, sexual function, and the quality of life were evaluated using validated and standardized questionnaires preoperatively and at follow-up, 12 months after surgery.

Results

Among a total of 87 patients (53 male and 34 female patients), IMPAN with simultaneous electromyography of the internal anal sphincter was performed in 58 (66.7%) patients. Bilateral positive IMPAN results for both measurements, indicating successfully confirmed pelvic autonomic nerve preservation, were obtained in 45 (51.7%) patients. No significant difference was found in terms of urogenital and anorectal functions between preoperative and postoperative patients with bilateral positive IMPAN (P>0.05). Compared to preoperative patients with IMPAN (unilateral) or without IMPAN, these patients exhibited higher International Prostate Symptom Score, a lower International Index of Erectile Function-5, and a lower Female Sexual Function Index score at 12 months postoperatively (P<0.05).

Conclusion

IMPAN is an appropriate method with which to laparoscopically protect nerve function.

Transcutaneous sacral nerve stimulation for intraoperative verification of internal anal sphincter innervation

BACKGROUND

The current standard for pelvic intraoperative neuromonitoring (pIONM) is based on intermittent direct nerve stimulation. This study investigated the potential use of transcutaneous sacral nerve stimulation for non-invasive verification of pelvic autonomic nerves.

METHODS

A consecutive series of six pigs underwent low anterior rectal resection. For transcutaneous sacral nerve stimulation, an array of ten electrodes (cathodes) was placed over the sacral foramina (S2 to S4). Anodes were applied on the back, right and left thigh, lower abdomen, and intra-anally. Stimulation using the novel method and current standard were performed at different phases of the experiments under electromyography of the autonomic innervated internal anal sphincter (IAS).

KEY RESULTS

Transcutaneous stimulation induced increase of IAS activity could be observed in each animal under specific cathode-anode configurations. Out of 300 tested configurations, 18 exhibited a change in the IAS activity correlated with intentional autonomic nerve damage. The damage resulted in a significant decrease of the relative area under the curve of the IAS frequency spectrum (P<.001). Comparison of the IAS spectra under transcutaneous and direct stimulation revealed no significant difference (after rectal resection: median 5.99 μV•Hz vs 7.78 μV•Hz, P=.12; after intentional nerve damage: median -0.27 μV•Hz vs 3.35 μV•Hz, P=.29).

CONCLUSIONS AND INFERENCES

Non-invasive selective transcutaneous sacral nerve stimulation could be used for verification of IAS innervation.

Risk Factor Analysis for Newly Developed Urogenital Dysfunction after Total Mesorectal Excision and Impact of Pelvic Intraoperative Neuromonitoring-a Prospective 2-Year Follow-Up Study

AIM

Urogenital dysfunction is a common sequela following total mesorectal excision for rectal cancer. This prospective study analyzed potential risk factors and investigated the impact of pelvic intraoperative neuromonitoring.

METHOD

Included were 85 patients undergoing total mesorectal excision for rectal cancer, 43 under the control of pelvic intraoperative neuromonitoring. Urogenital function was assessed with validated questionnaires within a 2-year follow-up period. Potential risk factors were identified by multivariate analysis.

RESULTS

Overall, approximately one-third of treated patients suffered from new onset of urinary dysfunction. Initially, half of the sexually active patients were affected by sexual dysfunction; after 2 years, almost three quarters were affected. In the pelvic intraoperative neuromonitoring group, urinary and sexual dysfunction rates including minor and major disturbances were significantly lower (2-year follow-up 20% vs. 51% (p = 0.004) and 56% vs. 90% (p = 0.010)). Throughout the survey, non-performance of pelvic intraoperative neuromonitoring was found to be an independent risk factor. Neoadjuvant chemoradiotherapy was identified as an independent predictor for urogenital dysfunction in the further course one and 2 years after surgery.

CONCLUSION

Pelvic intraoperative neuromonitoring is associated with significantly lower rates of urinary and sexual dysfunction in the short and long run, whereas neoadjuvant chemoradiotherapy has a negative impact only in the long run.

Extracorporeal Stimulation of Sacral Nerve Roots for Observation of Pelvic Autonomic Nerve Integrity: Description of a Novel Methodological Setup

INTRODUCTION

Neurophysiologic monitoring can improve autonomic nerve sparing during critical phases of rectal cancer surgery.

OBJECTIVES

To develop a system for extracorporeal stimulation of sacral nerve roots.

METHODS

Dedicated software controlled a ten-electrode stimulation array by switching between different electrode configurations and current levels. A built-in impedance and current level measurement assessed the effectiveness of current injection. Intra-anal surface electromyography (sEMG) informed on targeting the sacral nerve roots. All tests were performed on five pig specimens.

RESULTS

During switching between electrode configurations, the system delivered 100% of the set current (25 mA, 30 Hz, 200 μs cathodic pulses) in 93% of 250 stimulation trains across all specimens. The impedance measured between single stimulation array contacts and corresponding anodes across all electrode configurations and specimens equaled 3.7 ± 2.5 kΩ. The intra-anal sEMG recorded a signal amplitude increase as previously observed in the literature. When the stimulation amplitude was tested in the range from 1 to 21 mA using the interconnected contacts of the stimulation array and the intra-anal anode, the impedance remained below 250 Ω and the system delivered 100% of the set current in all cases. Intra-anal sEMG showed an amplitude increase for current levels exceeding 6 mA.

CONCLUSION

The system delivered stable electric current, which was proved by built-in impedance and current level measurements. Intra-anal sEMG confirmed the ability to target the branches of the autonomous nervous system originating from the sacral nerve roots.

SIGNIFICANCE

Stimulation outside of the operative field during rectal cancer surgery is feasible and may improve the practicality of pelvic intraoperative neuromonitoring.

Genito-urinary sequelae after carcinological rectal resection: What to tell patients in 2017

Although we have seen revolutionary changes with multi-disciplinary management of patients with rectal cancer, the evaluation of genito-urinary sequelae remains of great concern. Precise pre-operative evaluation with validated scores allows detection of urinary disorders in 16 to 23% of patients, and sexual disorders in nearly 35% of men and 50% of women. Regardless of the surgical approach, it is fundamental to respect the autonomic innervation during total mesorectal excision in order to prevent these sequelae. Identification of these nerves can be facilitated by intra-operative neuro-stimulation. In spite of these precautions, de novo urinary sequelae are observed in nearly 33% of patients and bladder evacuation disorders in 25% of patients. Advanced age, pre-operative urinary disorders, female gender, and abdomino-perineal resection are independent risk factors for urinary sequelae. Early post-operative urodynamic abnormalities might be predictive of these sequelae and justify early physiotherapy. Likewise, sexual sequelae such as erectile and/or ejaculatory disorders, dyspareunia and lubrication deficits result in de novo cessation of sexual activity in 28% of men and 18% of women. Advanced age, neo-adjuvant radiation therapy, and abdomino-perineal resection are independent risk factors for sexual dysfunction. Pharmacotherapy with sildenafil has proven useful in the treatment of erectile disorders. Genito-urinary and ano-rectal sequelae occur concomitantly in more than one of ten patients, suggesting a potential common pathophysiology.

Surgeons' assessment of internal anal sphincter nerve supply during TaTME - inbetween expectations and reality

Background: Intraoperative identification of nerve fibers heading from the inferior rectal plexus (IRP) to the internal anal sphincter (IAS) is challenging. The transanal total mesorectal excision (TaTME) is said to better preserve pelvic autonomic nerves. The aim of this study was to investigate the nerve identification rates during TaTME by transanal visual and electrophysiological assessment.

Material and methods: A total of 52 patients underwent TaTME for malignant conditions. The IRP with its posterior branches to the IAS and the pelvic splanchnic nerves (PSN) were visually assessed in 20 patients (v-TaTME). Electrophysiological nerve identification was performed in 32 patients using electric stimulation under processed electromyography of IAS (e-TaTME).

Results: The indication profile for TaTME was comparable between the v-TaTME and the e-TaTME group. The identification of IRP was more meaningful under electrophysiological assessment than under visual assessment for the left pelvic side (81% vs. 45%, p = 0.008) as well as the right pelvic side (78% vs. 45%, p = 0.016). The identification rates for PSN did not significantly differ between both groups, respectively (81% vs. 75%, p = 0.420 and 84% vs. 70%, p = 0.187).

Conclusions: The transanal approach facilitated visual identification of IAS nerve supply. In combination with electrophysiological nerve assessment the identification rate almost doubled. For further insights functional data are needed.

Continuous intraoperative monitoring of pelvic autonomic nerves during TME to prevent urogenital and anorectal dysfunction in rectal cancer patients (NEUROS): a randomized controlled trial

Background

Urinary, sexual and anorectal sequelae are frequent after rectal cancer surgery and were found to be related to intraoperative neurogenic impairment. Neuromonitoring methods have been developed to identify and preserve the complex pelvic autonomic nervous system in order to maintain patients’ quality of life. So far no randomized study has been published dealing with the role of neuromonitoring in rectal cancer surgery.

Methods/design

NEUROS is a prospective two-arm randomized controlled multicenter clinical trial comparing the functional outcome in rectal cancer patients undergoing total mesorectal excision (TME) with and without pelvic intraoperative neuromonitoring (pIONM). A total of 188 patients will be included. Primary endpoint is the urinary function measured by the International Prostate Symptom Score. Secondary endpoints consist of sexual, anorectal functional outcome and safety, especially oncologic safety and quality of TME. Sexual function is assessed in females with the Female Sexual Function Index and in males with the International Index of Erectile Function. For evaluation of anorectal function the Wexner-Vaizey score is used. Functional evaluation is scheduled before radiochemotherapy (if applicable), preoperatively (baseline), before hospital discharge, 3 and 6 months after stoma closure and 12 months after surgery. For assessment of safety adverse events, the rates of positive resection margins and quality of mesorectum are documented.

Discussion

This study will provide high quality evidence on the efficacy of pIONM aiming for improvement of functional outcome in rectal cancer patients undergoing TME.

Trial registration

Clinicaltrials.gov: NCT01585727. Registration date is 04/25/2012

Electrophysiology-based quality assurance of nerve-sparing in laparoscopic rectal cancer surgery: Is it worth the effort?

BACKGROUND

After low anterior resection for rectal cancer, visual assessment of pelvic autonomic nerve preservation can be difficult due to the complexity of neuroanatomy, as well as surgery- and patient-related factors. The present study aimed to evaluate nerve-sparing quality assurance using the laparoscopic neuromapping (LNM) technique.

METHODS

We prospectively investigated a series of 30 patients undergoing laparoscopic low anterior resection. Nerve-sparing was evaluated both visually and electrophysiologically. LNM was performed using stimulation of pelvic autonomic nerves under simultaneous cystomanometry and processed electromyography of the internal anal sphincter. Urogenital and anorectal functions were evaluated using validated and standardized questionnaires preoperatively, at short-term follow-up, and at mid-term follow-up at a median of 9 months (range 6-12 months) after surgery.

RESULTS

One patient reported new onset of urinary dysfunction, and another patient reported new onset of anorectal dysfunction. Of the 20 sexually active patients, five reported sexual dysfunction. Visual assessment by laparoscopy confirmed complete nerve preservation in 28 of 30 cases. For prediction of urinary and anorectal function, LNM sensitivity, specificity, positive and negative predictive value, and overall accuracy were each 100 %. LNM with combined assessment for prediction of sexual function yielded a sensitivity of 80 %, specificity of 93 %, positive predictive value of 80 %, negative predictive value of 93 %, and overall accuracy of 90 %.

CONCLUSIONS

LNM is an appropriate method for reliable quality assurance of laparoscopic nerve-sparing.