Pharyngeal Motility Before and After Thyroarytenoid Muscle Botulinum Toxin Injection

Botulinum toxin type A (BTA) injection in intrinsic laryngeal musculature may result in dysphagia and consequent loss of quality of life (QOL) in a percentage of patients. This study aims to evaluate pharyngeal motility as a putative cause for this change in swallow quality in light of high-resolution manometry (HRM). Twenty patients (95% females, median age 66 years) underwent high-resolution manometry before and after BTA injection. Dysphagia was evaluated based on a QOL dedicated questionnaire (SWAL-QOL) before and after BTA injection. Pharyngeal motility at the topography of the vellum, epiglottis, and upper esophageal sphincter (UES) were recorded. Eleven (55%) subjects had worsened QOL after BTA injection. In patients with worsened QOL, UES extension decreased (p = 0.005), UES residual pressure increased (p = 0.02), UES basal pressure decreased (p = 0.04), and velopharynx contraction duration decreased (p = 0.04). UES residual pressure increased (p = 0.01), velopharynx peak pressure (p = 0.04) and upstroke (p = 0.007) decreased in patients with maintained QOL. There was no difference between groups when comparing pre-injection values. UES extension (p = 0.01) and UES maximum relaxation time (p = 0.03) was lower in the group with worsened QOL after BTA as compared to no change in QOL. Pharyngeal motility as measured by HRM was not a predictor for post procedure dysphagia and the changes in motility after BTA injection does not seem to be a strong contributor to dysphagia.