Intraoperative Neuromonitoring of the Recurrent Laryngeal Nerve Versus Neurostimulation

Anatomic and functional preservation of the recurrent laryngeal nerve is a key element of thyroid surgery. Surgical exposure and visual identification of the nerve during thyroid surgery has been shown to provide the best rates of normal postoperative vocal fold function. Nevertheless, identification of the nerve sometimes can be difficult in patients who are heavily scarred or who have undergone previous surgery. Moreover, an anatomical intact nerve does not always correlate with normal vocal fold function. So it is mandatory to identify the nerve and to establish its function. Two techniques are described to facilitate identification of the nerve and to test its function. One is the neurostimulation with laryngeal palpation which is an intermittent monitoring techniques that permits to evaluate the contraction of cricoarytenoid muscle (laryngeal twitch ) after stimulation of RLN or vagal nerve with an electric stimulator probe. More recently some authors have suggested a continuous intraoperative neuromonitoring which provide audio and visual feed back when the nerve is electrically or mechanically stimulated during thyroidectomy. However controversy remains as to whether intraoperative neuromonitoring confers any significant benefit in injury prevention of recurrent laryngeal nerve.