Clinical advantages and neuroprotective effects of monitor guided fang's capillary fascia preservation right RLN dissection technique

Abstract

Objective: To investigate the feasibility and advantages of Fang's capillary fascia preservation right recurrent laryngeal nerve (RLN) dissection technique (F-R-RLN dissection) with preservation of the capillary network and fascia between the RLN and common carotid artery for greater neuroprotective efficiency compared with traditional techniques.

Methods: We retrospectively analyzed 102 patients with papillary thyroid carcinoma undergoing right level VI lymph node dissection in our department from March 2021 to January 2022. Sixty patients underwent F-R-RLN dissection (the experimental group) and 42 patients underwent standard dissection (the control group). The intraoperative electrical signal amplitude ratios of the RLN, the number of dissected lymph nodes, and the preservation rates of the parathyroid glands were recorded and compared between the two groups.

Results: The electrical signal amplitude ratio of the lower neck part point of the RLN to the upper laryngeal inlet point in the experimental group was significantly lower than the ratio in the control group (p = 0.006, Z-score = -2.726). One patient suffered transient RLN paralysis in both groups, but this resolved within 1 month after operation. There were no significant differences between the two groups in terms of the number of level VIa or level VIb lymph nodes dissected, nor in the rate of preservation of the parathyroid glands.

Conclusions: F-R-RLN dissection is a thorough dissection technique that is effective at preventing an electrical signal amplitude decrease in the RLN, and at preventing RLN paralysis by preserving its blood supply.

Keywords: lymph node dissection; neuroprotective; parathyroid preservation; recurrent laryngeal nerve; thyroid cancer.

Figure 1

Course of the right recurrent laryngeal nerve (RLN): the right RLN runs obliquely with its inferior side closer to the common carotid artery. Level VIb, limited by the nerve and trachea, is shaped as a triangle with its top on the upper side.

Figure 2

Technique of Fang’s capillary fascia preservation right recurrent laryngeal nerve (F-R-RLN) dissection. (A) Dissecting superficial lymph connective tissue of RLN and cutting the lateral border of level VIa (the purple line in the figure). The green arrow points to the V1 electrical signal monitor point from the vagus nerve and the yellow arrow points to the R1 electric signal monitor point from the RLN. (B) Sparing RLN laterally to the superior and inner side of the common carotid artery and dissecting level VIb lymph connective tissue (the green line in the figure). (C) Preserving the capillary network encased by the fascia between the RLN and the common carotid artery and dissecting level VI lymph connective tissue (the red line in the figure). The blue arrow points to the R2d in the upper laryngeal inlet part. The purple arrow points to the R2p in the lower neck part. Laryngeal body is dislocated to the left and upper side in order to expose level VIb and therefore the esophagus is shifted to the right side of the trachea..

Figure 3

Operative field after Fang’s capillary fascia preservation right recurrent laryngeal nerve (F-R-RLN) dissection technique: the capillary network encased by fascia between the RLN and the common carotid artery and the branches of RLN running laterally are preserved.

Figure 4

Preservation of inferior parathyroid gland during Fang’s capillary fascia preservation right recurrent laryngeal nerve (F-R-RLN) dissection technique. (A) Inspect the inferior parathyroid glands (the white arrow) and its blood supply (blue arrow) after raising the lobe. (B) Protect and raise sternothyroid ligament outwards and downwards, creating a fan-like shape, in which the vertex is formed by the parathyroid and the parathyroid blood vessels; the sternothyroid ligament is intact. Black arrow: the right lobe of thyroid; white arrow: the inferior right parathyroid gland; blue arrow: the blood supply of parathyroid gland; yellow arrow: the recurrent laryngeal nerve (RLN).