Anatomical study of the left superior mediastinal lymphatics for tracheal branches of left recurrent laryngeal nerve-preserving mediastinoscope-assisted surgery in esophageal cancer

Histological study of the thin membranous dense connective tissues around the curving portion of the bilateral recurrent laryngeal nerves

OBJECTIVE/AIM

We aimed to demonstrate the anatomical relationship between the recurrent laryngeal nerves (RLNs), thin membranous dense connective tissue (TMDCT [e.g., the visceral or vascular sheaths around the esophagus]), and the lymph nodes around the esophagus at the curving portion of the RLNs for rational and efficient lymph node dissection.

METHODS

Transverse sections of the mediastinum at 5 mm or 1 mm intervals were obtained from four cadavers. Hematoxylin and eosin staining and Elastica van Gieson staining were performed.

RESULTS

The visceral sheaths could not be clearly observed the curving portions of the bilateral RLNs, which were observed on the cranial and medial side of the great vessels (aortic arch and right subclavian artery [SCA]). The vascular sheaths could be clearly observed. The bilateral RLNs diverged from the bilateral vagus nerves, which ran along with the vascular sheaths, went up around the caudal side of the great vessels and the vascular sheath, and ran cranially on the medial side of the visceral sheath. Visceral sheaths were not observed around the region containing the left tracheobronchial lymph nodes (No. 106tbL) or the right recurrent nerve lymph nodes (No. 106recR). The regions containing the left recurrent nerve lymph nodes (No. 106recL) and the right cervical paraesophageal lymph nodes (No. 101R) were observed on the medial side of the visceral sheath, with the RLN.

CONCLUSION

The recurrent nerve, which branched off from the vagus nerve descending along the vascular sheath, ascended the medial side of the visceral sheath after inversion. However, no clear visceral sheath could be identified in the inverted area. Therefore, during radical esophagectomy, the visceral sheath along No. 101R or 106recL may be recognized and available.

Morbidity After Esophagectomy With Three-Field Lymph Node Dissection in Patients With Esophageal Cancer: Looking for the Best Predictive Model

Purpose

Esophagectomy with three-field lymphadenectomy (3FLD) is a potentially curative treatment option for resectable esophageal cancer (EC), which is associated with significant morbidity. Risk scores are useful for patient assessment; this study compares 7 different scores and indexes to find the best model for predicting morbidity in patients undergoing 3FLD.

Methods

Six years of data from January 2010 to January 2016 were reviewed, patients with EC who underwent 3FLD were retrospectively scored using 4 predictive scores and 3 predictive index models. Postoperative morbidity was assessed according to the extended Clavien-Dindo classification. The outcomes were the presence and severity of morbidity. Validation was performed by calculating the area under the ROC curve and by the assessment of collinearity among the variables independently associated with morbidity in the overall model to determine the best predictive model.

Results

We included 230 patients were included in the final analysis. Complications after 3FLD occurred in 168 patients (73%; minor complications, n = 96 [41%]; major complications, n=72 [31%]). The AUC values (<0.7) indicated that all scores and indexes had poor discrimination power in predicting the presence and severity of morbidity. Overall, the Steyerberg score was associated with the lowest risk of misestimation in predicting morbidity (P = 0.0330).

Conclusion

No score or index could predict the presence or severity of morbidity after 3FLD with good discrimination power. Age (>68 years) was the most critical factor affecting morbidity. The Steyerberg score model, based on the addition and subtraction of risk values was the best model for predicting morbidity after 3FLD.

Comparative study of three types of lymphadenectomy along the left recurrent laryngeal nerve by minimally invasive esophagectomy

Background

The objective of this study was to compare three kinds of lymphadenectomy methods along the recurrent laryngeal nerve (RLN) and assess the safety and effectiveness of the new method.

Methods

A total of 194 patients with esophageal cancer who underwent minimally invasive esophagectomy (MIE) at our institution from May 2013 to May 2017 were analyzed retrospectively. According to the method of lymphadenectomy along the left RLN, the patients were divided into three groups: 75 cases underwent the conventional method (A group), 80 cases the skeletonized method (B group) and 39 cases the modified Bascule method (C group). The number of dissected lymph nodes and surgical outcomes were recorded and compared to identify differences among the three groups.

Results

The frequency of metastasis to the LRLN lymph node was 18.6% among all patients, and 12%, 20% and 28% in groups A, B and C, respectively. The number of harvested lymph nodes (total/chest/LRLN/LRLN+) in group B and group C were significantly greater than that of group A, but not significant between group B and group C. The hoarseness rate in group C was 15.4%, which was lower than the rate in group B (21.3%) and higher than the rate in group A (13.3%), but there was no statistical significance.

Conclusions

The new method for lymphadenectomy along the left RLN during MIE in the semi‐prone position is safe and reliable. It provides sufficient lymph node dissection along the left RLN.

Histological study of the thin membranous structure made of dense connective tissue around the esophagus in the upper mediastinum

BACKGROUND

The structure of the fascia in upper mediastinum has already been reported from gross anatomical viewpoints by Sarrazin. But it is necessary to understand meticulous anatomy for thoracoscopic or mediastinoscopic surgery. So herein, we investigate histologically the thin membranous structure made of dense connective tissues.

METHODS

Semi-sequential transverse sections of the mediastinum were obtained from three cadavers. Hematoxylin and eosin staining, Elastica van Gieson staining, and Masson trichrome staining were performed to identify the presence and location of the thin membranous structure made of dense connective tissues.

RESULTS

The "visceral sheath" and "vascular sheath," as previously described by Sarrazin, were observed histologically. These two thin membranous structures do not surround the esophagus and trachea cylindrically. In addition, the "visceral sheath" on the right side of the upper mediastinum was unclear in comparison to the left side. The "visceral sheath" (on the left side) gradually became unclear, and seemed to almost disappear; the esophagus was found to be very close to the thoracic duct on the caudal side of the bifurcation of the trachea. Although the left recurrent nerve was located inside the "visceral sheath" in all cadavers, the left recurrent nerve lymph nodes were located inside the "visceral sheath" in cadaver 1 and between the "visceral sheath" and "vascular sheath" in cadaver 3.

CONCLUSION

The "visceral sheath" around the esophagus in the upper mediastinum was histologically demonstrated; however, the findings were not constant.