Confirmation of an anatomic variation of the recurrent laryngeal nerve at site of entry into the larynx in Chinese population

ObjectiveThis study was aimed at analyzing the frequency of the newly reported variation and the frequency of postoperative palsy associated with three different kinds of known variations.MethodsWe conducted a retrospective study on the data of 2068 consecutive Chinese patients who underwent thyroidectomy. The study included 1362 left and 1507 right (2869 in total) RLNs.ResultsAmong all the RLNs, 548 were found to have variations at the laryngeal entry of the RLN. The most frequent variation was extralaryngeal branching (n = 322), followed by the fan-shaped branching (n = 201). Our newly identified variation was also noted in 25 of our patients. In these cases, the RLN entered the larynx from sites that were distant from the posterior cricothyroid joint. The distance from the entry of the RLN to the back of cricothyroid joints was over 5 mm. Compared to the rates reported from other countries, the rate of the first type of variation is lower, while that of the second type is higher. The frequency of the new variation has not been reported in other populations, but it is consistent with our previous finding. The incidence of postoperative palsy was greater for RLNs with the first and third types of variations than in the normal RLNs.ConclusionWe confirmed that the incidence of patients with the new type of variation of the RLN at the entry of the larynx was about 1% in Chinese. Awareness among surgeons regarding this variation is important to avoid postoperative palsy.