The Utility of Evaluating True Vocal Fold Motion Before Thyroid Surgery

Abstract

The objective of this study was to evaluate the utility of screening laryngoscopic examination in evaluating vocal fold (VF) mobility before thyroid surgery. The authors conducted a retrospective chart review of 340 patients who have undergone thyroid surgery from January 1998 to June 2005 and had preoperative laryngoscopy by mirror, fiberoptic, or videostroboscopic examination. Reports of preoperative voice change or complaint and reports of preoperative VF examination, including the method of examination, were recorded. For patients with VF motion impairment, reports of the intraoperative condition of the recurrent laryngeal nerve (RLN), preoperative diagnosis based on fine needle aspiration, and final postoperative histopathologic examination results were recorded. Twenty-two patients were found to have preoperative VF motion impairment, of which seven (32%) patients were asymptomatic with no detectable subjective or objective voice problems. This differs significantly from the hypothesis that patients with VF motion impairment are always symptomatic (P=.009). Using voice symptoms as a screening test to predict VF motion impairment in 340 patients reveals that the sensitivity was 68%, specificity was 91%, positive predictive value (PPV) was 31%, and negative predictive value (NPV) was 98%. Among the 22 patients with preoperative VF motion impairment, five (72%) of the seven asymptomatic patients had benign, slowly progressive disease on their final histopathology reports. Six of these asymptomatic patients had their preoperative VF evaluation by fiberoptic examination, whereas one patient had indirect mirror laryngoscopy. Of 22 patients with preoperative VF motion impairment, five (22.5%) patients had abnormal VF mobility contralateral to the thyroid lesion on their preoperative evaluation, and only two of them had nerve injury reported after a previous thyroid surgery. This result differs significantly from the hypothesis that impaired mobility is ipsilateral to the side of the lesion (P=.05). Patients without voice complaints can have VF motion impairment. Patients can also have VF motion impairment contralateral to the thyroid lesion. Preoperative VF examination helps counsel patients appropriately about the risks of surgery and helps outline a plan for the extent of surgery while minimizing the medicolegal ramifications of iatrogenic RLN injury.