Intraoperative neuromonitoring in thyroidectomy: the learning curve

Abstract

AIM: To evaluate the learning curve in the use of intraoperative neuromonitoring of recurrent laryngeal nerve and vagus in thyroid surgery.

MATERIALS OF THE STUDY: We analyzed 140 pts treated consecutively for thyroid disease. All the patients were neuromonitored with Intraoperative neuromonitoring of recurrent laryngeal nerve and vagus. We divided these patients in 7 groups to collect the adverse events during our learning curve.

RESULTS: We monitored consecutively 271 nerves. The incidence of transient paralysis was 0.73%.No significant differences were recorded in the groups about the calceium values,the mean operative time. Sensitivity was 100%, specificity 99%, Predictive positive value was 33%, negative predictive value was 100%.

DISCUSSION: The recurrent laryngeal nerve injury is the most frequent adverse event in thyroid surgery. The causes of the lesion are different. The introduction of non-invasive monitoring devices that define the standard of IONM in thyroidectomy is increasing in the last period. In our study we performed the neuromonitoring in four times finding several benefits: avoid damage from excessive traction of the thyroid; early identification of RLN extra-laryngeal branches; identification and preservation of the parathyroid glands.

CONCLUSION: The use of neuromonitoring in course of thyroidectomy helps the surgeon to early localization, identification, visualization and dissection of the RLN. It is important highlight that for the surgeon, especially the less experienced, the opportunity to immediately verify the absence of nerve structures and the presence of lesions is very important especially in education and research. We confirm that real learning curve requires at least 60 consecutive cases as reported by others in literature.