Identification of external branch of superior laryngeal nerve during thyroid surgery: a prospective study

Background: Identification of external branch of superior laryngeal nerve (EBSLN) according to Cernea et al classification and to describe a surgical technique of superior pole dissection to preserve EBSLN during thyroid surgeries. Methods: The study was done over 2 years period in a tertiary care hospital. 105 nerves were studied among the 90 patients who underwent thyroid surgeries. Avascular dissection over the JOLL’S triangle was carried out and identified EBSLN were classified according to Cernea et al classification. Individual ligation of superior pole vessels was carried out after identifying the nerve. Outcome was studied relating the identified nerve with sides of thyroidectomy performed, size of thyroid gland and nerves at risk according to Cernea et al classification. Results: Of the 105 nerves studied, in 81.90% of patients the nerve was identified. There were 34.88% of Type 1 nerves, 52.33% of Type 2A nerve and 12.79% of Type 2B nerves identified. Less number of nerves could be identified on the left side. Type 2B nerves were more common on left side inspite of less number of dissections carried out on left. Type 2 variation was more common in large goiters. Conclusions: Careful dissection should be done in superior pole in avascular cricothyroid space, with lateralization of superior pole and individual identification of superior pole vessels once the nerve is identified. Identification of the nerve is mandatory in all patients who undergo thyroid surgery for optimal functions of the larynx. These results showed a better identification of nerves by proper surgical techniques without use of any sophisticated equipments.