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

Abstract

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.

Letter to the editor concerning the article “Anatomy of the neural fibers at the superior mesenteric artery-a cadaver study”

“…In addition, they showed that two main nerve cords (one traveling ventrally and other traveling dorsally) are present along the SMA with an anti-clockwise rotation in a helical manner. We are gratified to note that these results concur with our recent results [2], confirming the hypothesis of a nonlinear course of this plexus, namely a helical trajectory of the nerves around the SMA.…”

Comments on Superior Mesenteric Artery First Approach for Right Colectomy

“…In our procedure, the extent of injury to the superior mesenteric nerve plexus is 48% of the area. 2 A study 3 has shown that the effect of such injury to the nerve plexus on the patient's bowel function is comparable to that of patients who have undergone traditional D2 mesenterectomy.…”

Visible Lymph Affluents in the D3 Volume: An MDCTA Pictorial Essay

“…The more and more accepted complete mesocolic excision with D3 lymphadenectomy for cancer [ 4 , 5 ], either by open access, laparoscopy or robotic surgery has shed new light on the lymphatic anatomy of the mesentery of the small and the large bowel. The D3 volume has been defined according to the landmarks of the superior mesenteric vein (SMV) and artery (SMA) and their principal affluents/branches [ 6 , 7 ]. The limits are as follows: 2 cm-distal to the origin of the ileocolic artery and cranial to the origin of the middle colic artery (MCA), 3 cm right to the right border of the SMV, and the left border of the SMA.…”

“…This volume includes the tissue in front and behind the mesenteric vessels, with the posterior limit of the fusion fascias of Treitz and Toldt. It is well known that the lymphatic plexuses are found here in the superficial submesothelial space and the deeper lymphovascular bundles within the mesenteric connective tissue lattice [ 6 , 7 , 8 ]. From the mesenteric collecting lymphatics, the lymph is carried to the central/preterminal superior mesenteric nodes around the corresponding artery [ 2 ].…”

“…Throughout the development of lymphangiology, the classical anatomical dissection [ 6 , 7 , 14 , 15 ] remains one of its cornerstones. Minute dissection can present even more delicate lymph vessels and lymph nodes, as well as the meshes which they form [ 7 , 14 , 15 ].…”