Objective analysis of swallowing and functional voice outcomes after thyroidectomy: A prospective cohort study

Abstract

Impairment in voice and swallowing functions are common after thyroidectomy. We aimed to evaluate the objective functional voice and swallowing outcomes in a series of patients undergoing thyroidectomy. A total of 43 consenting patients who underwent thyroidectomy were prospectively recruited. Subjective evaluation of swallowing was assessed with 'Swallowing Impairment Score' and 'MD Anderson Dysphagia Inventory'. Fiberoptic endoscopic evaluation of swallowing (FEES) was applied for objective evaluation. Also, functional oral intake scale (FOIS) and functional outcome swallowing scale (FOSS) were used for swallowing assessment. Voice evaluation was assessed with videostrobolaryngoscopy (VSL) and 'The Multi-Dimensional Voice Program (MDVP)' was used for capturing and analyzing the voice samples. All evaluations were performed preoperatively and on 1st day, 2nd week and 6th months postoperatively. This study is registered with ClinicalTrials.gov, number NCT03436186. According to the objective analyses there was no difference between pre- and post-operative scores for the intake of fluid and thickened liquid food. There was a significant difference regarding light and moderate residual accumulation in solid food intake (p=0.013). FOSS showed no difference, but FOIS revealed specific functional limitation (p=0.034). Subjective data showed no correlation with objective findings (p>0.05). Regarding voice evaluation, a significant increase was observed in standard deviation of average fundamental frequency and degree of subharmonics (p<0.01). Even in the absence of recurrent laryngeal nerve injury, subjective and objective swallowing and voice alterations do occur after thyroidectomy.