Background: The increasing use of intraoperative neuromonitoring (IONM) in thyroid surgery has revealed the need to develop new strategies for cases in which a loss of signal (LOS) occurs on the first side of a planned total thyroidectomy.
Objectives: This study reviews the experience of the authors in using IONM for planned total thyroidectomy after LOS on the first thyroid lobe. The aims were to estimate the incidence of LOS on the first side of resection and to compare intraoperative strategies applied after this event.
Materials and methods: Intermittent IONM was performed with stimulation of both the vagal nerve and the recurrent laryngeal nerve (RLN) (V1, R1, R2, V2). Patients underwent pre- and postoperative laryngoscopy. Before surgery, patients were informed that staged thyroidectomy might be required.
Results: This study analyzed 803 consecutive thyroid procedures. Of these, V2 LOS (<100 mcV) occurred after first lobe exeresis in 23 (2.8%) procedures. The surgical procedure was stopped in 20 cases (ie, staged thyroidectomy was performed). In three cases with malignancy and severe comorbidity (ASA score 3-4), total bilateral thyroidectomy was performed as planned. No cases of bilateral RLN palsy occurred. Postoperative laryngoscopy confirmed RLN palsy in 21 of the 23 cases. All true positive patients received speech therapy. Patients who had false positive LOS (n = 2) or malignancy (n = 8) and patients who were symptomatic (n = 7) received completion thyroidectomy within 6 months. One patient received radioactive iodine therapy for hyperthyroidism. Two patients received follow up.
Conclusions: Neuromonitoring changes the surgical decision-making process in a multidisciplinary manner. A shared decision-making process involving the patient, anesthesiologist, and endocrinologist is suggested. In the case of intraoperative LOS on the first-operated side in a planned total thyroidectomy, the thyroid surgeon essentially has three options for surgery on the contralateral side: 1) Perform staged thyroidectomy. This option is recommended in bilateral goiter, Graves' disease, or low-risk thyroid carcinoma (differentiated or medullary thyroid carcinoma). The aim is to avoid bilateral vocal cord palsy. Two-stage completion surgery is delayed until recovery of ipsilateral nerve function. 2) Perform subtotal resection on the contralateral side ventrally to the RLN plane at a safe distance from the nerve. The aim is to avoid further disease recurrence and revision surgery. 3) Perform total thyroidectomy as planned for advanced thyroid carcinoma (including undifferentiated thyroid carcinoma). The aim is to improve disease control through radioactive iodine therapy, radiation therapy, or target therapy immediately after surgery.
Level of evidence: 4.
Keywords: Thyroid surgery; loss of signal; nerve injury; recurrent laryngeal nerve; staged thyroidectomy.