Anatomic Study Of Recurrent Laryngeal Nerves (RLNs) Under Laparoscopy Via Breast Approach

Objective:There is a higher rate of injuring the RLNs and the parathyroid glands during laparoscopic thyroidectomy(LT) given that a sufficient maneuverable space can hardly be created.Identification of RLNs is proposed as an initial step of LT.In an attempt to improve the outcome of the LT,a careful anatomic study of RLNs was performed under laparoscopy approached by breast method and it aims to provide statistic and anatomic evidence for exposure and preservation of RLNs during the procedures.Result was analyzed for safe RLNs identification.Method:20 adult cadavers without neck malformations or deteriorations of neck structures were collected at random for study.30 cases of LT via breast approach performed in 1^st Affiliated Hospital of Jinan University,Guangzhou were non-randomly selected.Anatomy of the RLNs and the neurovascular relationship between laryngeal branches and inferior thyroid artery(ITA) as well as thyroid cartilage were observed and statistically analyzed.The best angle of lens and optic fibers adjustment,and proper length of lens insertion during surgeries for RLNs exposure were suggested as a conclusion.Results:(1) Dissection of RLNs of 20 cadavers(40 RLNs) revealed four types of RLNs configurations, 22 RLNs(55%) comprised two distinct branches.5 different types of RLNs branching were identified during the 30 cases of LT,33 RLNs(55%) comprised two distinct branches.(2) Observation of RLNs in 20 cadavers and during 30 cases of LT revealed nerves bifurcation into laryngeal branch and extralaryngeal branch.The laryngeal branch,before entering the larynx, divided into anterior divisions and posterior divisions near cricothyroid articulation.Distances were measured between the inferior horn of thyroid cartilage and RLN before its entrance into the larynx.Table 3 gives the lists of data which were assessed by T-test and showed there was no statistic significance(P＞0.05).(3) Neurovascular relationtship between RLN and ITA is highly variable.Only 3 types of variations could be documented in this study.Details were listed in Table 4.1-4.2 and statistic significance was indicated after being assessed by T-test(P＜0.05).(4) Stablized the lens at the horizontal level,30 cases of RLNs were exposed during LTs.During exposure of left RLNs,length of lens insertion was(17.07±1.31 cm),angle(clockwise) between lens and optic fibers was(36.63±6.32 degrees).During exposure of right RLNs,length of lens insertion was(14.87±1.41 cm),angle(clockwise) between lens and optic fibers was(27.97±4.33 degrees).Conclusions:(1) Management of RLN during LT via breast approach is different from that of conventional open surgery.(2) LT via breast approach is safe and feasible from the perspective of favorable cosmetic outcome which satisfies female patients.(3) Identify the RLNs during LT with proper insertion length of the lens and adjusting the lens and optic fibers into the best angle can help reduce the rate of RLN injury for a successful LT outcome.(4) The study provided surgeons with statistic and anatomic evidence for exposure and preservation of RLNs during LT.