Objective: To investigate the influence of endoscopic thyroidectomy on the voice and swallowing function of patients after surgery for thyroid tumor performed under effective protection of the recurrent laryngeal nerve.  
Methods: The clinical data of 205 patients undergoing thyroid surgery from January 2017 to June 2018 were retrospectively analyzed. Of the patients, 115 cases underwent endoscopic thyroid surgery via areolar approach (endoscopic group) and 90 cases underwent open thyroid surgery (open group), and all cases were subjected to subtotal or total unilateral lobectomy plus intraoperative nerve monitoring. The changes in voice and swallowing function in the two groups of patients before and after surgery were analyzed by using both subjective and objective evaluation indexes. Subjective evaluation indexes included voice disturbance index scale (VHI), voice GRBAS classification and swallowing disorder score (SIS); the objective indicators included the fundamental frequency (F0), fundamental frequency perturbation (jitter), amplitude perturbation (shimmer), and maximum vocalization time (MPT).
Results: In terms of subjective evaluation indexes, voice and swallowing disorders occurred in some of the patients in both groups at 1 month after surgery; all of the patients in open group with voice and swallowing disorders recovered to the normal states, while some patients in endoscopic group remained with swallowing disorders at 3 months after surgery; the incidence rates of swallowing disorders at 1 month and 3 months after surgery in endoscopic group were higher than those in open group (both P<0.01). As for objective evaluation indicators, the F0 values were decreased in both groups of patients at 1 month after surgery compared with the preoperative value (both P<0.05), but all recovered to the normal states at 3 months after surgery. No significant changes in jitter, shimmer and MPT occured in both groups of patients at 1 month and 3 months after surgery compared with their preoperative values (all P>0.05).
Conclusion: Voice and swallowing disorders will occur in some patients after either endoscopic or open thyroid surgery, which in most cases will recover within 3 months after surgery. The time to swallowing function recovery is relatively prolonged in patients following endoscopic surgery, which may be probably associated with neck adhesion and fixation after operation.