Continuous Intraoperative Neuromonitoring in Thyroid Surgery

Abstract

Intermittent intraoperative neuromonitoring (I-IONM) has been introduced to thyroid surgery during the past two decades. The neuromonitoring devices (hardware and software) were significantly improved with the development of the second and third device generations. Needle electrodes, which were widely used 10 years ago, are almost completely substituted by less invasive, optimized endotracheal tube electrodes that ensure signal stability. In addition, recommendations of surgical societies for the standardized application of IONM have been established and incorporated into guidelines. However, due to the already very low frequency of (permanent) recurrent laryngeal nerve (RLN) paralysis following primary thyroid resections, a significant benefit of IONM compared to the "gold standard" of visual identification of the RLN alone has not been demonstrated so far. Moreover, the idea to enable surgeons to recognize impending nerve damage during (not after) dissection cannot be implemented with I-IONM techniques. The main benefit of I-IONM, therefore, remains the possible change of resection strategy in case of a "loss of signal (LOS)" after resection of one thyroid lobe in patients with planned bilateral resection. The recent introduction of continuous neuromonitoring (C-IONM) represents a significant step forward, potentially enabling the surgeon to react before irreversible damage to the RLN occurs. Preliminary data are supporting this methodological advantage.