A retrospective evaluation of the etiology of unilateral vocal fold paralysis over the last 25 years.

Previous studies have shown that the etiology of laryngeal paralysis has changed over the last decades, with an increase in the incidence of cases attributable to thyroid surgery. The aim of this study was to evaluate longitudinal changes in the etiology of unilateral vocal fold paralysis (UVFP) in a single institution over the last 25 years. This retrospective study analyzed the etiology of UVFP between 1990 and 2015 by comparing a cohort of patients treated in 1990-1992 with a cohort treated in 2013-2015. The final analysis was based on data concerning 356 patients (38.8 % males; mean age 55.3 ± 20.4 years): 113 in the 1990-1992 cohort, and 243 in the 2013-2015 cohort. The main cause of UVFP in the population as a whole was thyroidectomy (41.3 %), followed by an idiopathic origin (25.3 %) and thoracic surgery (12.1 %); this was confirmed in both intra-group analyses. There was a statistically significant association between etiology and the sub-group periods: the prevalence of post-thyroidectomy UVFP was highly significantly lower in the 2013-2015 cohort (35.4 vs 54.0 %), and the prevalence of idiopathic cases was higher (28.4 vs 18.6 %). Etiology significantly related to gender in both cohorts (p value ≤0.001). In the 2013-2015 cohort, there was also a statistically significant relationship between etiology and age classes (p value 0.017), and the left side was more frequently affected than the right (67.1 vs 32.9 %). Our findings document changes in the etiological pattern of UVFP over the last 25 years, with a considerable decrease in post-thyroidectomy UVFP, and a growing predominance of idiopathic and post-thoracic surgery UVFP.