Correlation between the Cernea Classification of External Branch of Superior Laryngeal Nerve in Relation to the Ultrasound-based Volume of Thyroid Gland

INTRODUCTÍON: Goiter is a very common problem dealt with by surgeons. Surgical treatment of thyroid requires removal of a part (hemi) or whole of the gland (total thyroidectomy). The external branch of the superior laryngeal nerve (EBSLN) is an important but less researched structure to be preserved during surgery. Various studies have described the incidence of different types of EBSLN, but have not described regarding the relationship between the change in volume of the gland to the nerve. MATERIALS AND METHODS: A prospective analysis of 100 patients who underwent total thyroidectomy in our department was done. All patients underwent preoperative ultrasonography and the volume of the gland was calculated. Intraoperatively, the EBSLN was identified and preserved prior to ligating the superior thyroid vessels. The nerve was classified as per the Cernea classification. The gland was divided into high and low volume, taking 20 ml as the cutoff. The incidence of Type 2 nerve in a low-volume gland was compared with that of a high-volume gland. RESULTS: In 100 patients (200 nerves), 191 nerves were identified. The nerve was type 1 in 56/200 (28%), Type 2a in 116/200 (58%), and Type 2b in 19/200 (9%) patients. In large-volume glands, Type 2 nerve was more common (87%). CONCLUSION: Dissection of thyroid gland requires expertise to preserve the EBSLN. Large volume glands pose a more difficult challenge, as the gland is more closer to the nerve.