Dottorato in TECNOLOGIE AVANZATE IN CHIRURGIA

Titolo della tesi: INTRAOPERATIVE NEURO-MONITORING VERSUS OPTICAL MAGNIFICATION IN THE PREVENTION OF RECURRENT LARYNGEAL NERVE INJURY IN THYROID SURGERY: A PROSPECTIVE RANDOMIZED STUDY

ABSTRACT Background: Different technological innovations have been introduced in thyroid surgery over the last 50 years with the aim to guarantee major accuracy and decrease the risk of severe complications, such as permanent hypoparathyroidism and laryngeal nerve paralysis. Intraoperative nerve monitoring (IONM) of the recurrent laryngeal nerve (RLN) facilitate dissection, detect any type of nerve injury and predict the postoperative and functional nerve status. On the other hand, a microsurgical approach in thyroid surgery by using optical magnification is stated to increase the surgeon’s precision and RLNs could be identified with major accuracy. Among the literature, we found a wide series of systematic reviews and meta-analyses of studies comparing IONM versus direct visual RLN identification alone with controversial results. The aim of our study is to compare the technique of identification, preparation and dissection of the RLN in the course of total thyroidectomy with the aid of IONM against the use of optical magnification devices alone. Materials and Methods: In our prospective randomized longitudinal study, 100 patients undergoing total thyroidectomy between October 2018 and February 2020, were included in a cohort study e divided in two groups of 50 patients. The first group had surgery with the use of IONM (group IONM) and the second group with magnification binocular loupes (OM group). The influence of IONM and OM on the incidence of RLN paralysis and other surgical outcomes was analyzed, comparing the two groups and using multivariable regression analysis. Results: We performed 100 total thyroidectomies divided in two groups of 50 patients which were homogeneous in distribution of age, sex and type of thyroid disease at the admission. In the first group (IONM Group), the use of IONM was associated with a significant statistical difference regarding RLN paralysis rate of 4% versus 0% in the optical magnification group (OM Group). We reported also, statistically significant difference, in favor of the OM Group, in the operation time (mean 80,9 vs 105,37 min) and length of hospital staying (mean 2,04 vs 5,09 days). No statistically significant differences in the presence of hyperfunction or thyroiditis was shown. Regarding the histological report, surprisingly, the data on the presence of occult carcinomas in the two groups were relevant (37.5% in the OM Group and 25.53% in the IONM Group). Conclusion: To the best of our knowledge, this is the first study in the literature that directly compares the use of IONM with optical magnification alone in the prevention of RLN injuries. The IONM technique alone cannot be considered a substitute for the accurate visualization and identification of RLN, but it can add greater confidence to the surgeon, especially if less experienced. From our experience it emerges that both methods can be considered a standard in the future, at least in highly specialized endocrine-surgical centers. In addition, associating IONM with the use of magnification loupes and microsurgery technique we expect to find better outcomes. Further clinical studies, with a larger cohort of patients, are necessary to validate our results.