Efficacy of speech language therapy intervention in unilateral vocal fold paralysis - a systematic review and a meta-analysis of visual-perceptual outcome measures

Objective: Unilateral vocal folds paralysis is a disorder that affects a patient's quality-of-life by disturbing their phonation, breathing, and swallowing activities. This systematic review aimed to estimate the efficacy of voice treatment on the vocal fold motility in adult patients with unilateral vocal folds paralysis. Methods: PubMed, CINAHL, CENTRAL, and Web of Science were searched for retrospective and prospective cohort, case-control, and cross-sectional with comparative studies with adults that were published between 1 January 2008 to 31 December 2018. After applying the inclusion and exclusion criteria a total of 10 studies containing morpho-functional evaluation results were included in the analysis. Pooled data analysis of the motility of the vocal folds before and after voice therapy allowed inferring about the efficacy of voice therapy intervention in patients with unilateral vocal folds paralysis. A random-effect model was used to estimate the effect size. Publication bias was considered. Results: The pooled data analysis of the visual-perceptual measures revealed that vocal fold motility improved in 72% (95% CI: 64.0-80.0) of all patients after the therapeutic interventions. The inconsistency index (I-2 = 18.35%) of the studies included in this meta-analysis revealed an extremely low heterogeneity. Funnel plot and Cochran's Q test showed no publication bias. The systematic review was limited to only English language articles. Conclusion: This meta-analysis supports the evidence that voice therapy intervention can have a positive effect on the vocal fold motility, that is, they can improve the glottal gap closure, irrespective of the exercises and techniques used.