The importance of preoperative laryngoscopy in patients undergoing thyroidectomy: voice, vocal cord function, and the preoperative detection of invasive thyroid malignancy.

BACKGROUND: Vocal cord paralysis is associated with extrathyroidal invasive malignancy. This study was performed to analyze the presentation of patients with invasive thyroid malignancy and to determine the preoperative symptomatic and radiographic correlates of vocal cord paralysis.
METHODS: In a group of 365 consecutive patients undergoing thyroidectomy, the group of 21 patients with invasive thyroid malignancy was compared with the 344 patients who had benign thyroid disease or noninvasive cancers.
RESULTS: Preoperative recurrent laryngeal nerve paralysis was a robust marker for invasive thyroid malignancy, being present in 70% of patients with invasive disease and only 0.3% of patients with noninvasive disease. Vocal cord paralysis was associated with voice change in only one third of patients. Preoperative computed tomography was read as positive for vocal cord paralysis in only 25% of patients.
CONCLUSIONS: Laryngoscopic examination is essential for the detection of vocal cord paralysis preoperatively. Symptomatic voice assessment and radiographic evaluation are insufficient. Preoperative vocal cord paralysis tracts with invasive disease and facilitates preoperative recognition of disease extent, allowing for appropriate operative planning and central neck clearance at first operation. Because of the prevalence (approximately 6% in our study) of invasive thyroid disease, the importance of preoperative diagnosis of invasive disease in operative planning and patient counseling, and the importance of vocal cord functional analysis in recurrent laryngeal nerve management algorithms for nerves found infiltrated at operation, and laryngoscopic examination is recommended for all patients undergoing thyroid operation.