Preserving vocal cord function: Continuous intraoperative vagus nerve monitoring in total thyroidectomy

Abstract

A 42-year-old female patient who underwent left hemithyroidectomy for a benign thyroid nodule, was referred for further management, as histology revealed a minimally invasive follicular carcinoma requiring completion thyroidectomy as recommended by Oncologists. She had developed unilateral vocal card palsy following the initial hemithyroidectomy. Pre operatively vocal cord function was evaluated by fibre optic laryngoscopy, which confirmed a left vocal cord palsy. During the completion thyroidectomy, continuous intraoperative nerve monitoring was done using an electrode attached to endotracheal tube. A delta electrode was attached to the Vagus nerve and continuous monitoring of the Vagus nerve was done while performing intermittent monitoring of the Recurrent Laryngeal nerve. Stimulation was performed using a current of 1–2 mA. According to the International Nerve monitoring Study Group (INMSG) guidelines initial amplitude value of at least 500 μV was considered as the normal value.According to INMSG guide lines, change of EMG signal curve amplitude below 100 μV was considered as loss of signal during the operation. Post-operative period of the patient was uneventful and the right vocal cord function was confirmed as normal by fibre optic endoscopic examination. Even though intraoperative nerve monitoring is a useful procedure for all the thyroidectomy surgeries it is documented to be more beneficial during revision surgeries, thyroid malignancies and pre-operative unilateral nerve palsy patients.