Value of the intraoperative neuromonitoring in surgery for thyroid cancer in identification and prognosis of function of the recurrent laryngeal nerves

INTRODUCTION: The aim of this study was both, to evaluate the usefulness of the method of neuromonitoring in intraoperative identification of the RLN and to estimate its value in the prognosis of postoperative RLN function in patients operated for TC. MATERIAL AND METHODS: Among 109 patients undergoing surgery for TC between 12/2004 and 12/2005 the neuromonitoring method was used in 69 (63.3%) individuals (including 5 operations of completion total thyroidectomy). A Neurosign 100 equipment with laryngeal electrodes was employed in identification and assessment of total number of 134 RLN. Intraoperative results were compared to the postoperative results of the ENT-specialist examination of vocal cords mobility in indirect laryngoscopy, in each patient. RESULTS: Transient vs. permanent, unilateral RLN palsy was noted in 3 vs. 2 patients (2.2% vs. 1.4% of nerves at risk). The method of neuromonitoring facilitated identification of 123 (91.8%) RLN being not helpful in 11 (8.2%) cases. However, neuromonitoring was helpful in identification of the RLN, the value of the method in prognosis of posteoperative function of the RLN was limited. Results of indirect neurostimulation were more accurate than direct neurostimulation and were more accurate in prognosis of late rather than early RLN function after surgery (sensitivity 98.3%; specificity 100%; positive predictive value 100%; negative predictive value 50%, accuracy 98.4%). CONCLUSIONS: Application of intraoperative neuromonitoring facilitates identification of the RLN during surgery for TC. However, the method is of limited value in prognosis of postoperative RLN dysfunction in cases of missing signal after nerve stimulation.