Routine Preoperative Laryngoscopy for Thyroid Surgery Is Not Necessary Without Risk Factors

Abstract

Background: Routine pre-operative vocal cord (VC) assessment with laryngoscopy in patients undergoing thyroidectomy allows clear documentation of baseline VC function, aids in surgical planning in patients with palsies, and facilitates interpretation of intraoperative neuromonitoring (IONM) findings. We aimed to determine the incidence of pre-operative vocal cord palsy (VCP); to evaluate the associated risk factors for pre-operative VCP; and to calculate the cost-savings potential of implementing a selective approach. Methods: Patients with a pre-thyroidectomy VC assessment by fiberoptic laryngoscopy were retrospectively recruited from the Monash University Endocrine Surgery Unit (MUESU) database from 2000 to 2018. Cases with pre-operative VCP were reviewed for potential contributing factors and compared to a non-palsy cohort. Results: Of the 5 987 patients who had pre-operative laryngoscopy, VCP was documented in 41 (0.68 %) patients. Four clinical parameters were found to be potential indicators of VCP including: age (p < 0.001), nodule ≥ 3.5 cm recorded on ultrasound imaging (p = 0.01), presence of voice symptoms (p < 0.001), and previous neck surgery (p < 0.001). Malignant cytology (p = 0.5) and exposure to head and neck irradiation were not different between the groups. Utilizing these risk factors, 2 354 (39 %) patients had at least one feature that may raise suspicion for pre-operative VCP. By performing pre-operative laryngoscopy only on this subset of patients, the potential cost savings exceeds $400 Australian Dollars per patient. Conclusion: Using this large dataset, we have established that a VCP is rare in the absence of a large nodule, hoarseness or previous neck surgery. Therefore, in the era of IONM, we support a selective approach to pre-operative laryngoscopy using the aforementioned criteria.