Clinical relevance and surgical anatomy of non-recurrent laryngeal nerve: 7 year experience

Abstract

Purpose: We report our clinical experience with non-recurrent inferior laryngeal nerve (NRLN).

Methods: We collected our data retrospectively during 7 years. Total thyroidectomies (TTEs; N = 626) and hemithyroidectomies (HTEs; N = 187) were performed in 766 patients (80.2% of women) by the same group of surgeons. 47 two-steps operations were performed. The total number of inferior laryngeal nerves at risk was 1,439 (725 right sided, 714 left sided). The nerves were always identified according to anatomical landmarks. We did not use intra-operative nerve monitoring.

Results: We found four right-sided NRLNs (0.55% of the right-sided nerves). NRLN arose directly from the vagus nerve, running transversally parallel to the trunk of the inferior thyroid artery in all our cases (type IIa). Combination with ipsilateral recurrent nerve and other non-recurrent types (I and III) were not observed. We observed unclear voicing postoperatively with fast spontaneous recovery in one NRLN case, while the voice quality and phonation were perfect in the remaining cases.

Conclusions: Thyroid surgeons should understand the variable topography of inferior laryngeal nerves. Non-recurrent laryngeal nerve is a vulnerable asymptomatic anatomical variation of recurrent laryngeal nerve. Optimal NRLN identification should be done prior to operation by routine X-ray and ultrasonography, based on abnormality of cervical vessels.