Laryngeal Nerves Monitoring Versus Non-monitoring in Thyroid Surgery

Abstract

Background and objectives: Thyroid surgery is the most common cause of recurrent nerve (RLN) injury. Deliberate identification of the RLN minimizes the risk of injury. When the nerve is identified and dissected, the reported RLN injury rate during thyroidectomy is 0-2.1%. Continuous intra-operative nerve monitoring during surgery remains a controversial issue. The basic technique involves a skin surface electrode or muscle electrode used to make electromyography (EMG) recordings, which have an audible alarm to alert the surgeon if passive (e.g.stretch during traction) or active nerve stimulation has occurred. We aim to evaluate the use of intra-operative nerve monitoring (IONM) to preserve the laryngeal nerves that may be at risk for injury during thyroid surgery and show the merits of using electrophysiologic laryngeal nerve monitoring during thyroid surgery. Patients and methods: This study was conducted as a prospective study on 28 patients whom are thyroidectomy candidates; we elected 14 thyroidectomy candidates in whom we don’t use NIM during surgery (Control group_A). These patients were chosen to be evenly matched with another 14 thyroidectomy candidates to monitor the recurrent laryngeal (RLN) and external branch of superior laryngeal (EBSLN) throughout thyroidectomy procedures (NIM group_ B) to compare the laryngeal nerves risk of injury with and without the use of nerve monitor. Results: Four patients (2 patients in-group A and 2 patients in-group B) were dysphonic after operation. Laryngoscopy revealed unilateral recurrent laryngeal nerve palsy in all except one bilateral in group A. There were no significant differences in RLN paralysis, paresis, or total injury rates between both groups. The number of patients in the presented study was limited to draw a statistical conclusion for significance. Conclusions: The routine application of IONM cannot prevent or reduce recurrent laryngeal nerve injury. However the study signifies the trend towards the use of INOM in expectedly difficult cases and in revision surgery with distorted anatomical relationships and fibrous adhesions.