The Identification of Recurrent Laryngeal Nerve by Injection of Blue Dye into the Inferior Thyroid Artery

Abstract

Background: Thyroidectomy creates a potential risk for injury of the recurrent laryngeal nerve (RLN). The identification and dissection of the RLN is the gold standard for preserving its function. Aim of the work: was to evaluate the value of injection of methylene blue dye into the inferior thyroid artery for help of the identification and dissection of RLN. Patients and Methods: This study included 60 selected patients who underwent thyroid surgery divided into 2 groups. In group A (30 patients) the branches of the inferior thyroid artery (ITA) near to the capsule of the thyroid lobe were isolated, and then 0.5 ml methylene blue dye was injected into the artery. In group B (30 patients) the RLN identified without help of dye to be compared with group A cases. Results: During injection of dye bleeding from the ITA occurred in 7 patients. The identification of the RLN within the painted tissue was succeeded 28 patients and failed in 2 patients due to extravasation of the dye. Regarding the amount of blood loss, there was a significant difference between the groups as the average amount of blood loss in group A was 85±22 ml (range 70-120) and in group B was 105±37 ml (range 90-160) P = 0.01. Also, by comparing the time taken for RLN identification in one side, there was a significant difference between the groups, as the median time taken for single RLN identification in each case in group A was 9±2 min (range 7-12 min) and in group B was 14±3 min (range 10-20 min) P = 0.008. Conclusion: the injection of methylene blue dye into the inferior thyroid artery or its branches is a feasible, effective, reliable way that can be used as a method for the identification of the RLN during thyroidectomy.