Stimulation electromyography as a method of intraoperative identification of the recurrent laryngeal nerve in thyroid surgery.

INTRODUCTION: The iatrogenic injury of the recurrent laryngeal nerve during thyroid surgery still represents a major problem because of the great physiologic and psychologic trauma to the patients. The incidence of this complication ranges between 1% and 15% depending on the thyroid pathology and type of surgery. AIM: To evaluate the potential of stimulation electromyography as a method of intraoperative prophylaxis of iatrogenic injuries of the recurrent laryngeal nerve. MATERIAL AND METHODS: Intraoperative monitoring of the recurrent laryngeal nerve based on stimulation electromyography, which was introduced in the Clinics of Surgery and Otorhinolaryngology at the Higher Medical Institute in Plovdiv, was applied in thyroid surgery using Neurosign 100 (Magstim Company Ltd., Wales, UK) apparatus. The study involved 5 experimental dogs and 73 recurrent laryngeal nerves in 47 patients treated in the clinics from November 1, 1999 to February 15, 2000. RESULTS: In all experimental animals and patients the electrical stimulation was successful triggering an "M" response of the laryngeal muscles (the vocal muscle). A stable contact was achieved between the recording (needle) electrodes and the vocal folds. None of the patients had signs of laryngeal palsy or complaints other from the usual in endotracheal intubation. CONCLUSION: The results suggest that the intraoperative stimulation electromyography of the recurrent laryngeal nerve is a safe and effective method for evaluation of the nerve integrity during and at the end of the operation.

Intraoperative identification of recurrent laryngeal nerves in thyroid surgery by electrical stimulation.

INTRODUCTION: Iatrogenic injury of the recurrent laryngeal nerve and its prevention is one of the controversial issues in thyroid surgery. The incidence of this operative complication ranges from 0.4% to 3.9%. PATIENTS AND METHODS: The authors analysed the results of the identification of 114 nerves in 60 patients who underwent thyroid surgery between July 9, 1999 and December 19, 2000 in the 3rd Surgical Clinic at the Department of Clinical Surgery and in the Department of Ear Nose and Throat Diseases of the Medical University in Plovdiv, Bulgaria. Nerve integrity monitor Neurosign 100 and specially designed EMG electrodes (Magstim Company Ltd., Wales, UK) were used. The patients were examined pre- and postoperatively for vocal cord paralysis by otolarygologist. RESULTS: In all patients electrical stimulation of the recurrent laryngeal nerve was successfully used for identification of the nerve and evaluation of its integrity during and at the end of the operation. No postoperative recurrent laryngeal nerve deficit was detected clinically. CONCLUSIONS: The results indicate that the identification of the recurrent laryngeal nerve by electromyography is a safe, effective and simple method for electrophysiologic monitoring during thyroid surgery. This method allows assessment of the neural integrity at the end of the procedure.