Method

Colorectal cancer

In the field of coloproctological surgery, intraoperative neuromonitoring (known as pelvic intraoperative neuromonitoring – pIOM) is mainly used during resection of colorectal cancer in the course of a total mesorectal excision (TME). Here, both the rectum and the mesorectum are removed.

During resection of colorectal cancer, the surgeons work in different tissue layers in which there are also functionally relevant nerves that are sometimes very difficult to see. The complex structures of the autonomic nervous system make nerve-sparing surgery difficult. In addition, in advanced cases there is infiltration of the surrounding highly innervated tissue layers, which further complicates localisation of the nerves.

Neuromonitoring during TME of colorectal cancer

>> To monitor the anorectal function, electrodes are placed on the internal and external anal sphincter at the beginning of surgery.

>> Electrophysiological function control is carried out by electrical stimulation of the inferior hypogastric plexus and the pelvic splanchnic nerves.

>> This in turn results in an increase in the activity of the innervated smooth muscles, which is recorded with electrodes placed in or on the muscle (electromyography – EMG).

>> The measurement of muscle activity and thus their intact innervation can also be determined indirectly. Thus, the activity of the detrusor muscle is measured by a change in pressure in the bladder.

>> The characteristic changes in the EMG and pressure signals are automatically detected and made audible through a loudspeaker and visualised on a display.

>> Postoperative preservation of sexual function after removal of colorectal cancer is indicated by bilateral positive signals at the bladder and rectum.^[1]

Maintaining quality of life despite complete removal of colorectal cancer

Therefore, it is possible to identify autonomic nerve structures during the resection of colorectal cancer and to monitor their function.^[2–5] The aim of this monitoring is to avoid intraoperative nerve injuries in this area. Damage to the pelvic autonomic nerves during resection of colorectal cancer can, in the worst case, lead to urogenital and anorectal dysfunction and even loss of function, further worsening the patients’ quality of life.^[6]

The monitoring of nerve function is documented and stored by a software during TME of colorectal cancer, as in other neuromonitoring applications (such as thyroidectomy). This makes it possible to evaluate pelvic neuromonitoring after resection of colorectal cancer and, if necessary, follow-up therapy can be started in a targeted manner.

References

1. Kneist, W. et al. Intraoperative Monitoring of Bladder and Internal Anal Sphincter Innervation: A Predictor of Erectile Function following Low Anterior Rectal Resection for Rectal Cancer? Results of a Prospective Clinical Study. Dig. Surg. 30, 459–465 (2013).

2. Kneist, W., Kauff, D. W., Naumann, G. & Lang, H. Resection rectopexy—laparoscopic neuromapping reveals neurogenic pathways to the lower segment of the rectum: preliminary results. Langenbecks Arch. Surg. 398, 565–570 (2013).

3. Kauff, D. W. et al. Evaluation of two-dimensional intraoperative neuromonitoring for predicting urinary and anorectal function after rectal cancer surgery. Int. J. Colorectal Dis. 28, 659–664 (2013).

4. Kneist, W., Stelzner, S., Hanke, L. I. & Wedel, T. Inferior rectal plexus is no longer isolated in no man’s land: An encouraging outlook with TaTME. coloproctology 39, 85–87 (2017).

5. Kauff, D. W., Lang, H. & Kneist, W. 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. J. Gastrointest. Surg. 21, 1038–1047 (2017).

6. Lent, V. & Junginger, T. Nervenstörungen der Harnblasen- und Sexualfunktionen nach Rektumresektionen und -exstirpationen. CHAZ 12, 257–261 (2011).