Real-time monitoring of the recurrent laryngeal nerve: An observational clinical trial

Background A variety of tools has been developed to identify nerve structures and to lower the risk of nerval injury during thyroid surgery. These tools are usually based on intermittent electrophysiological tracing of the nerves, but its use is still associated with permanent recurrent laryngeal nerve (RLN) injury. We are now presenting the results of the implementation of a novel real-time nerve monitoring system, based on a new vagal nerve cuff electrode. Methods Nineteen consecutive patients scheduled for thyroid surgery (17 with benign, 2 with malignant disease), were enrolled in this observational trial. The flexible cuff electrode was implanted during each operation and atraumatically surrounded the vagal nerve. The evoked potentials were sensed by standard thyroid electrodes. Electrical stimulation and recording were achieved through a multichannel electromyography (EMG) system. The signal analysis was performed in real-time by specially designed software. Results The cuff electrode did not cause any complications during or after the surgery. In all patients, stable and reproducible signals were easily evoked. The mean time required to place the electrode was 6.5 min. The mean overall vagal nerve stimulation time was 65 min. No permanent RLN lesions were detected in any patient. One patient with a postoperative bleeding from a strap muscle vein required a wound revision, which was performed without nerve monitoring. This patient experienced a temporary partial impairment of the left vocal cord. No hypoparathyroidism was observed in any patient postoperatively. Conclusions The presented technique of real-time continuous RLN monitoring by stimulation of the vagal nerve is feasible, safe, reproducible, and easy to perform. In addition, this new system is compatible with existing equipment and can be used as an add-on with conventional nerve monitoring devices during thyroid surgery.