Laparoscopic pelvic neuromonitoring permits superior nerve-sparing Technical and electrophysiological aspects of the open and laparoscopic approach

Introduction: The study aimed to evaluate two-dimensional pelvic intraoperative neuromonitoring (pIONM) in laparoscopic nerve-sparing colorectal surgery compared to the open procedure. Methods: From a consecutive series a total of 64 patients undergoing either pIONM controlled laparoscopic (LAP group, n=32) or open nerve-sparing surgery (OPEN group, n=32) was investigated prospectively. In all procedures pIONM was carried out based on bipolar electric stimulations of pelvic autonomic nerves under continuous electromyography of the internal anal sphincter and cystomanometry. Results: In contrast to open surgery, the laparoscopic approach enabled pIONM under permanent visual control with more selective neurostimulation and tracing of neurogenic pathways due to camera angle adjustments, illumination and magnification effects. The median electromyographic amplitude increase during neurostimulation was 4.3 μV (interquartile range (IQR) 2.3-7.5) for the LAP group and 1.9 μV (IQR 0.9-4.8) for the OPEN group (p<0.001). Conclusion: Laparoscopy in combination with two-dimensional pIONM may offer technical and electrophysiological advantages over the open procedure. The evoked electromyographic signal as a surrogate parameter indicates a potential improvement of nerve-sparing with the laparoscopic approach.