Risk factors for transient vocal cord palsy after thyroidectomy.

BACKGROUND Transient recurrent laryngeal nerve palsy affects to 5-10 per cent of patients after extracapsular thyroidectomy. This prospective study assessed the impact of surgical injury and extralaryngeal branching of the inferior laryngeal nerve (ILN) on vocal cord dysfunction (VCD). METHODS Total thyroidectomy or lobectomy was performed in 188 patients, with 302 ILNs at risk. The anatomy of the ILN and degree of injury to the nerve, based on the Laryngeal Nerve Injury Score (LNIS), were recorded. Fibreoptic laryngoscopy was performed a mean(s.d.) of 10.6(4.1) days after thyroidectomy. RESULTS Some 37.4 per cent of ILNs showed extralaryngeal branching. In all, 10.9 per cent of patients developed VCD; 4.3 per cent had paresis and 6.6 per cent paralysis. All paretic and all but one paralytic cords recovered fully after 61(17) days. VCD was more frequently associated with branched than non-branched ILNs (15.8 versus 8.1 per cent; P = 0.022). Injuries were more common in branched nerves (mean(s.e.m.) total LNIS 0.94(0.08) versus 0.51(0.05); P < 0.001). Branched nerves were more likely to be associated with VCD (odds ratio 2.2 (95 per cent confidence interval 1.1 to 4.5)). CONCLUSION Branched ILNs suffer more surgical injuries and are twice as likely to be associated with VCD.