Development of a simple model of extrinsic denervation of the small bowel in mouse

Reconstructing topography and extent of injury to the superior mesenteric artery plexus in right colectomy with extended D3 mesenterectomy: a composite multimodal 3-dimensional analysis

Background

Superior mesenteric artery plexus (SMAP) injury is reported to cause postoperative intractable diarrhea after pancreatic/colonic surgery with extended lymphadenectomy. This study aims to describe the SMAP microanatomy and extent of injury after right colectomy with extended D3 mesenterectomy for cancer.

Methods

Three groups (I) anatomical dissection, (II) postmortem histology, and (III) surgical specimen histology were included. Nerve count and area were compared between groups II and III and paravascular sheath thickness between groups I and II. 3D models were generated through 3D histology, nanoCT scanning, and finally through 3D printing.

Results

A total of 21 specimens were included as follows: Group (I): 5 (3 females, 80–93 years), the SMAP is a complex mesh surrounding the superior mesenteric artery (SMA), branching out, following peripheral arteries and intertwining between them, (II): 7 (5 females, 71–86 years), nerve count: 53 ± 12.42 (38–68), and area: 1.84 ± 0.50 mm2 (1.16–2.29), and (III): 9 (5 females, 55–69 years), nerve count: 31.6 ± 6.74 (range 23–43), and area: 0.889 ± 0.45 mm2 (range 0.479–1.668). SMAP transection injury is 59% of nerve count and 48% of nerve area at middle colic artery origin level. The median values of paravascular sheath thickness decreased caudally from 2.05 to 1.04 mm (anatomical dissection) and from 2.65 to 1.17 mm (postmortem histology). 3D histology models present nerve fibers exclusively within the paravascular sheath, and lymph nodes were observed only outside. NanoCT-derived models reveal oblique nerve fiber trajectories with inclinations between 35° and 55°. Two 3D-printed models of the SMAP were also achieved in a 1:2 scale.

Conclusion

SMAP surrounds the SMA and branches within the paravascular sheath, while bowel lymph nodes and vessels lie outside. Extent of SMAP injury on histological slides (transection only) was 48% nerve area and 59% nerve count. The 35°–55° inclination range of SMAP nerves possibly imply an even larger injury when plexus excision is performed (lymphadenectomy). Reasons for later improvement of bowel function in these patients can lie in the interarterial nerve fibers between SMA branches.

Stool dynamics after extrinsic nerve injury during right colectomy with extended D3-mesenterectomy

INTRODUCTION

To improve oncological outcome in right colon cancer surgery, an extended mesenterectomy (D3) is under evaluation. In this procedure, all tissue anterior and posterior to the superior mesenteric vessels from the middle colic to ileocolic artery origin is removed, causing injury to the superior mesenteric nerve plexus. The aim was to study the effects of this injury on bowel dynamics and quality of life (QoL).

METHODS

Patients undergoing right colectomy with conventional D2- and extended D3-mesenterectomy were asked to record stool number and consistency for 60 d after surgery and complete questionnaires regarding QoL and bowel function (BF) before and after recovery from surgery. We compared early postoperative stool dynamics and long-term QoL in the groups and presented graphs depicting the temporal profile of stool numbers and consistency.

RESULTS

Thirty-three patients operated with a D3-resection and 12 patients with a D2-resection participated. The results revealed significantly higher stool numbers in the D3-group until day 26, with significantly more loose-watery stools until day 40. The most pronounced difference was found on day 9 (Mean difference in the total number of stools: 2.25 stools/day, p=.004. Mean difference in loose-watery stools/day: 2.81 p<.001). About 25% in the D2- and 69.7% in the D3-group reported having more than three stools/day in the early postoperative phase. There were no differences in long-term QoL and BF between the groups except in stool consistency (p=.039).

DISCUSSION/CONCLUSIONS

Denervation following extended D3-mesenterectomy leads to transitory reduced consistency and increased frequency. It does not affect long-term QoL or BF.

Bowel function and quality of life after minimally invasive colectomy with D3 lymphadenectomy for right-sided colon adenocarcinoma

BACKGROUND

Changes in bowel function after right-sided colectomy are not well understood compared to those associated with left-sided colectomy or rectal resection. In particular, there are concerns about bowel function after right-sided colectomy with complete mesocolic excision, which has become popular in the West.

AIM

To evaluate the functional outcomes of patients who underwent right-sided colectomy with D3 lymphadenectomy for colon cancer.

METHODS

Functional data from patients who underwent minimally invasive right-sided colectomy for colon cancer from October 2017 to September 2018 were prospectively collected. Functional outcomes were evaluated preoperatively and at 3, 6, 12, and 18 mo postoperatively.

RESULTS

Prior to surgery, 57 patients answered the questionnaire, and 47 responded at three months, 52 at 6 mo, 52 at 12 mo, and 25 at 18 mo postoperatively. Most scales of quality of life and bowel function improved significantly over time. Urgency persisted to a high degree throughout the period without a significant change over time. The use of medications for defecation was about 10% over the entire period. Gas (P = 0.023) and fecal frequency (P < 0.001) increased, and bowel dysfunction group (P = 0.028) was more common among patients taking medication. At six months, resected bowel and colon lengths were significantly different as a risk factor between the dysfunction group and the no dysfunction group [odd ratio (OR): 1.095, P = 0.026; OR: 1.147, P = 0.031, respectively] in univariate analysis, but not in multivariate analysis.

CONCLUSION

Despite D3 lymphadenectomy, most bowel symptoms improved over time after right-sided colectomy using a minimally invasive approach, and continuous medication was needed in only approximately 10% of patients.

Bowel function and quality of life after superior mesenteric nerve plexus transection in right colectomy with D3 extended mesenterectomy

BACKGROUND

The aim of this study was to ascertain the impact of injury to the superior mesenteric nerve plexus caused by right colectomy with D3 extended mesenterectomy as performed in the prospective multicenter trial: "Safe Radical D3 Right Hemicolectomy for Cancer through Preoperative Biphasic Multi-detector Computed Tomography" in which all soft tissue surrounding the superior mesenteric vessels from the level of the middle colic artery to that of the ileocolic artery was removed.

METHODS

Bowel function and gastrointestinal quality of life in two consecutive cohorts that underwent right colectomy with and without D3 extended mesenterectomy were compared. Main outcome measures were the Diarrhea Assessment Scale (DAS) and Gastrointestinal Quality of Life Index (GIQLI). The data were collected prospectively through telephone interviews.

RESULTS

Forty-nine patients per group, comparable for age, sex, length of bowel resected but with significantly shorter follow-up time in the experimental group, were included. There was no difference in total DAS scores, subscores or additional questions except for higher bowel frequency scores in the D3 group (p = 0.02). Comparison of total GIQLI scores and subscales showed no difference between groups. Regression analysis with correction for confounding factors showed 0.48 lower bowel frequency scores in the D2 group (p = 0.022). Within the D3 group presence of jejunal arteries cranial to the D3 dissection area showed 1.78 lower DAS scores and 0.7 lower bowel frequency scores.

CONCLUSIONS

Small bowel denervation after right colectomy with D3 extended mesenterectomy leads to increased bowel frequency but does not impact gastrointestinal quality of life. Individual anatomical variants can affect postoperative bowel function differently despite standardized surgery.