Intraoperative monitoring of recurrent laryngeal nerve function

Intraoperative recurrent laryngeal nerve identification is sometimes difficult in reoperative cervical dissection or operation for inflammatory thyroid disorders. Three modalities have been described to intraoperatively assess nerve function: vocal cord visualization with fiberoptic bronchoscopy or direct laryngoscopy, electromyelographic surveillance of arytenoid muscle function, and cord function assessment with an electromyelogram-electrode endotracheal tube. Our study focused on patients requiring cervical dissection for thyroid or parathyroid disease in which intraoperative recurrent laryngeal nerve function was monitored by nerve stimulation with a concentric bipolar probe. Impulses were tracked via a specialized electrode-bearing endotracheal tube with signal transduction to a recording monitor. No operative nerve injuries occurred in the patients of our study group. This surveillance technique's several advantages include use of standard intubation techniques with no increase in operative time, nerve stimulation tracings that are quantifiable and reproducible with production of a permanent record, and less subjectivity due to observer variability. We believe these factors make the electromyelogram-electrode endotracheal tube approach to intraoperative recurrent laryngeal nerve assessment the optimal technique.