Feasibility and efficacy of preserving internal branch of superior laryngeal nerve in endoscopic surgery for hypopharyngeal squamous cancer: an observational study

Abstract

Objective: This study was performed to investigate the feasibility of preservation of internal branch of superior laryngeal nerve(ibSLN) during transoral endoscopic surgery for hypopharyngeal squamous cancer(HSCC) and the influence on patient's swallowing function after operation. Methods: From May 2020 to June 2021, the data of 29 HSCC patients who required for transoral endoscopic surgery in the Department of Otorhinolaryngology Head and Neck Surgery, the Second Xiangya Hospital of Central South University were prospectively included, and the included patients were divided into two groups randomly by lottery. According to whether ibSLN was actively dissected during operation, they were divided into ibSLN preservation group (n=15) and control group (n=14, without ibSLN preservation). Operation time, intraoperative hemorrhage, intraoperative neck dissection, postoperative radiotherapy, postoperative recurrence within 1 year, retention and swallowing function, the recovery of oral soft diet and the quality of life were compared between two groups. SPSS 25.0 software was used for statistical analysis. Results: The study included 29 eligible patients, including 25 males and 4 females.The age ranged from 42 to 67 (56.07±5.93) years. There were no significant differences(P>0.05) between 2 groups in the following data,including age(t=-0.56), gender(χ2=0.01), TNM stage(T stageχ2=0.29, N stage χ2=0.02), pathological diagnosis(χ2=0.03), preoperative swallowing function(χ2=0.00) and M. D. Anderson Dysphagia Inventory(MDADI) score(global t=0.55, emotional t=0.16, functional t=0.60, physical t=0.64), operation time(t=1.62) and intraoperative hemorrhage(t=-1.46), intraoperative neck dissection(χ2=0.01), postoperative radiotherapy(χ2=0.32), postoperative recurrence within 1 year(P>0.050). The swallowing function was evaluated by water swallowing test after operation. The swallowing function of ibSLN preservation group was better than control group, and the difference between two groups was statistically significant on the 1st (χ2=4.44, P=0.035), 5th (χ2=4.24, P=0.039) and 7th (χ2=4.55, P=0.033) day after operation. On the 14th day after operation, the MDADI scores of patients in the ibSLN preservation group were higher than those in the control group in global (t=2.45, P=0.021), functional (t=2.54, P=0.017) and physical (t=2.24, P=0.034) dimensions, except for emotional dimension (t=1.89, P=0.070). The median time of oral soft diet(U=23.00, P<0.001), normal oral diet(U=21.00, P<0.001) and the nasogastric tube removal time (U=18.50, P<0.001) in ibSLN preservation group was 2 days, 5 days and 6 days respectively, earlier than that in control group, which had statistically significant difference. Conclusion: Our results show that it is feasible to preserve the ibSLN during HSCC transoral endoscopic surgery, which can achieve rapid recovery of postoperative swallowing function.