Does Extralaryngeal Branching Have An Impact on the Rate of Postoperative Transient or Permanent Recurrent Laryngeal Nerve Palsy?

Background This prospective study assessed the prevalence of the extralaryngeal branching of the recurrent laryngeal nerve (RLN) and its impact on the incidence of postoperative transient or permanent RLN palsy. Methods Total or hemithyroidectomy was performed in 115 patients, with a total of 195 RLNs displayed. The RLN extralaryngeal branches were routinely identified and preserved. The postoperative course of each patient was evaluated. Outcomes of patients with and without branching RLN were compared. Results In all, 36 of 195 (18.5%) nerves showed extralaryngeal branching: 27 cases (25.5%) on the right and 9 on the left side (10.1%; p = 0.0088). Trifurcation of the RLN was identified in two dissections (1%). Bilateral bifurcations were observed in 3 of 80 (3.7%) patients. We reported four (2.1%) unilateral permanent RLN palsies, eight cases of unilateral transient nerve palsy (4.1%), and one bilateral transient RLN injury (0.6%). The comparative analysis of postoperative outcomes between branched and non-branched RLNs revealed that the anatomical variation was more frequently associated both with unilateral permanent RLN palsy (relative risk, 13.25; 95% confidence interval, 1.42-123.73; p = 0.0204) and unilateral transient RLN palsy (relative risk, 7.36; 95% confidence interval, 1.84-29.4; p = 0.0061). The only case of bilateral transient RLN injury was associated with a nonrecurrent inferior laryngeal nerve. Conclusions Branched RLNs represent a risk factor both for transient and permanent nerve palsy after surgery. Awareness of this anatomical variation and its routine investigation are essential during thyroid surgery to limit its relevant impact on postoperative RLN injury rate.