Pelvic intraoperative neuromonitoring during robotic-assisted low anterior resection for rectal cancer

Intraoperative Neuromonitoring for Pediatric Pelvic Tumors

Background

Tumors of the pre-sacral and sacral spaces are a rare occurrence in children. Total tumor excision is required due to the significant risk of relapse in the event of partial surgery, but the surgical procedure may lead to postoperative problems such as urinary, sexual, and anorectal dysfunctions. Intraoperative neuromonitoring (IONM) has gained popularity in recent years as a strategy for preventing the onset of neurologic impairments by combining several neurophysiological techniques. The aim of our study is to describe the experience of Bambino Gesù Children's Hospital in the use of IONM in pediatric pelvic surgery.

Materials and Methods

The data of patients treated for pelvic malignancies at Bambino Gesù Children's Hospital from 2015 to 2019 were retrospectively collected. All patients were assessed from a neurologic and neuro-urologic point of view at different time-points (before and immediately after surgery, after 6 months, and 1-year follow-up). They were all monitored during a surgical procedure using multimodal IONM including transcranial motor evoked potentials (TcMEP), triggered-EMG (t-EMG), pudendal somatosensory evoked potentials (PSSEP), and bulbocavernosus reflex (BCR).

Results

During the study period, ten children underwent pelvic tumor removal at our Institution. In all cases, intraoperative neurophysiological recordings were stable and feasible. The preservation of neurophysiological response at the same intensity during surgical procedures correlated with no new deficits for all neurophysiological techniques.

Discussion

Although the impact of the IONM on surgical strategies and clinical follow-up is unknown, this preliminary experience suggests that the appropriate use of several neurophysiological techniques can influence both the radicality of pelvic tumor removal and the neurological and urological outcome at clinical follow-up. Finally, because of the highly complex anatomy and inter-individual variances, this is especially useful in this type of surgery.

Analysis of risk factors for pulmonary infection in patients with minimally invasive esophagectomy

Clinical manifestations of patients with pulmonary infection after minimally invasive esophagectomy were analyzed. A total of 500 patients undergoing minimally invasive esophagectomy in Sichuan Cancer Hospital and Institute from January 2015 to December 2016 were consecutively selected, among which 124 patients with pulmonary infection after surgery were taken as the infection group, and the remaining 376 patients were taken as the control group. The clinical data of all patients were collected. The pulmonary infection rate after minimally invasive esophagectomy was calculated, and clinical factors with difference were analyzed using the multivariate logistic regression analysis. There were significant differences in age, long-term smoking history, presence or absence of concurrent basic diseases and vital capacity (P<0.01). The application time of antibiotics and antacids and hospitalization duration in the infection group were obviously longer than those in the control group (P<0.01). Age, long-term smoking history, vital capacity, application time of antibiotics and antacids, hospitalization duration and concurrent diabetes mellitus/coronary heart disease/diseases of respiratory system increase the risk of postoperative pulmonary infection in patients with esophageal cancer, and age, long-term smoking history, diabetes mellitus, diseases of respiratory system and hospitalization duration are independent risk factors for pulmonary infection in patients after minimally invasive esophagectomy.

Robot-guided neuromapping during nerve-sparing taTME for low rectal cancer

PURPOSE

Intraoperative pelvic neuromapping with electrophysiological evaluation of autonomic nerve preservation during robotic total mesorectal excision (TME) for rectal cancer is conventionally performed by the bedside assistant with a hand-guided probe. Our goal was to return autonomy over the neuromonitoring process to the colorectal surgeon operating the robotic console.

METHODS

A recently described prototype microfork electrostimulation probe was evaluated intraoperatively during abdominal robotic-assisted transanal TME (taTME) surgery for low rectal cancer in three consecutive male patients.

RESULTS

An intraoperative video demonstrates the good control and maneuverability of the prototype probe with electrophysiological confirmation of bilateral pelvic autonomic nerve preservation.

CONCLUSIONS

This study presents the first in situ application of a new microfork probe for fully robot-guided neuromapping in three patients undergoing TME surgery for low rectal cancer.

Novel multi-image view for neuromapping meets the needs of the robotic surgeon

BACKGROUND

Pelvic intraoperative neuromonitoring during nerve-sparing robot-assisted total mesorectal excision (RTME) is feasible. However, visual separation of the neuromonitoring process from the surgeon console interrupts the workflow and limits the usefulness of available information as the procedure progresses. Since the robotic surgical system provides multi-image views in the surgeon console, the aim of this study was to integrate cystomanometry and internal anal sphincter electromyography signals to aid the robotic surgeon in his/her nerve-sparing technique.

METHODS

We prospectively investigated 5 consecutive patients (1 male, 4 females) who underwent RTME for rectal cancer at our institution in 2017. The robotic surgery was performed using the da Vinci Xi combined with pelvic intraoperative neuromapping with real-time electromyography and cystomanometry signal transmission by multi-image view during RTME.

RESULTS

The adapted two-dimensional pelvic intraoperative neuromonitoring imaging successfully simulcasted to the surgeon console view in all 5 cases. The technical note is complemented by an intraoperative video.

CONCLUSIONS

This report demonstrates the technical feasibility of an improved neuromonitoring process during nerve-sparing RTME. Robotic neuromapping can be fully visualized from the surgeon console.

Application of a newly designed microfork probe for robotic-guided pelvic intraoperative neuromapping

Introduction:

Robotic-assisted total mesorectal excision (TME) with pelvic intraoperative neuromapping was recently accomplished. However, neuromapping is conventionally conducted by a hand-guided laparoscopic probe. We introduce a prototype microfork probe to make robotic-guided neuromapping feasible.

Experiments and Technical Setup:

Two porcine experiments with nerve-sparing TME surgery were performed. A newly designed prototype bipolar microfork probe was inserted intraabdominally and guided with the robotic forceps. Intermittent neuromapping was then conducted and neuromonitoring data integrated in the surgeon console viewer.

Conclusion:

Robotic-guided neuromapping is shown to be feasible and fully controllable from the surgeon console.

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.

Postprocessing algorithm for automated analysis of pelvic intraoperative neuromonitoring signals

Two dimensional pelvic intraoperative neuromonitoring (pIONM®) is based on electric stimulation of autonomic nerves under observation of electromyography of internal anal sphincter (IAS) and manometry of urinary bladder. The method provides nerve identification and verification of its’ functional integrity. Currently pIONM® is gaining increased attention in times where preservation of function is becoming more and more important. Ongoing technical and methodological developments in experimental and clinical settings require further analysis of the obtained signals. This work describes a postprocessing algorithm for pIONM® signals, developed for automated analysis of huge amount of recorded data. The analysis routine includes a graphical representation of the recorded signals in the time and frequency domain, as well as a quantitative evaluation by means of features calculated from the time and frequency domain. The produced plots are summarized automatically in a PowerPoint presentation. The calculated features are filled into a standardized Excel-sheet, ready for statistical analysis.

Best practice: surgeon driven application in pelvic operations

In applied biomedical engineering and medical industry the transfer of established technology towards customers’ needs is essential for successful development and therefore business opportunities. In chronological order, we can show the transfer of scientific results of neurophysiological research into an existing neuromonitoring system and product which can be used by non-experts in medical technology in the operating room environment. All neurophysiology functions were realized in an intuitive graphical user interface. To stimulate the autonomous nerves, a specialized parameter paradigm was used, different from motor nerve stimulation. In the background, a complex signal processing algorithm recorded smooth muscle and bladder manometry data in synchronized time and automatically detected neurophysiological signals. The acquired data was then presented in real-time. With this effort a complex scientific task could be simplified to a Yes/No statement to the end-user. Beside all the reduction of complexity, the scientific challenge was still obtained, as raw-data is still possible to be recorded.

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.

Surface Electromyography Reliably Records Electrophysiologically Evoked Internal Anal Sphincter Activity: A More Minimally Invasive Approach for Monitoring Extrinsic Innervation

BACKGROUND

Even in the case of minimally invasive pelvic surgery, sparing of the autonomic nerve supply is a prerequisite for maintaining anal sphincter function. Internal anal sphincter (IAS) innervation could be electrophysiologically identified based on processed electromyographic (EMG) recordings with conventional bipolar needle electrodes (NE). This experimental study aimed for the development of a minimally invasive approach via intra-anal surface EMG for recordings of evoked IAS activity.

METHODS

Six male pigs underwent nerve-sparing low anterior rectal resection. Electric autonomic nerve stimulations were performed under online-processed EMG of the IAS. EMG recordings were simultaneously carried out with conventional bipolar NE as the reference method and newly developed intra-anal surface electrodes (SE) in different designs.

RESULTS

In all experiments, the IAS activity could be continuously visualized via EMG recordings based on NE and SE. The median number of bipolar electric stimulations per animal was 27 (range 5-52). The neurostimulations resulted in significant EMG amplitude increases for both recording types [NE: median 3.0 µV (interquartile range, IQR 2.8-3.5) before stimulation vs. 7.1 µV (IQR 3.9-13.8) during stimulation, p < 0.001; SE: median 3.6 µV (IQR 3.1-4.3) before stimulation vs. 6.8 µV (IQR 4.8-10.3) during stimulation, p < 0.001].

CONCLUSIONS

Intra-anal SE enabled reliable EMG of electrophysiologically evoked IAS activity similar to the conventional recording via NE. The transfer of the method to access platforms for transanal total mesorectal excision or robotics may offer a practical more minimally invasive approach for monitoring extrinsic innervation.

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.