Treatment effectiveness for Vocal Cord Dysfunction in adults and adolescents: A systematic review

Objective: To determine whether treatment effectiveness can be established for a range of vocal cord dysfunction (VCD) interventions in adolescents and adults. Design: A systematic review of the literature and risk of bias appraisal was completed using the Joanna Briggs Institute Critical Appraisal Tools. Data were qualitatively synthesized in the broad intervention groups of glottic airway and respiratory retraining, pharmacological therapies, airway device therapies and psychological therapies. Data sources: Nine electronic databases, two clinical trial registries and the grey literature were searched from inception to September 2021 for articles on VCD interventions or equivalent terms. Eligibility criteria: Studies were included if they were randomized controlled trials, non-randomized controlled trials, quasi-experimental pre- and post-test studies and within-subject repeated measure designs, participants were 13 years or older, VCD was diagnosed using laryngoscopy or CT larynx, VCD intervention was provided and outcome measures reported on VCD symptoms. Results: The search yielded no randomized controlled trials. There were 17 quasi-experimental studies that met the eligibility criteria, and these studies reported on glottic airway and respiratory retraining, botulinum toxin injections, inspiratory muscle strength training and amitriptyline; all were associated with VCD symptom reduction. In addition, 2 within-subject repeated measure studies reported inspiratory muscle strength training and respiratory retraining to be effective in reducing symptoms in participants with exertional VCD. The included studies were reported in full-text publications (11) and conference proceedings (8). There was a high risk of bias and low quality of evidence across all intervention areas. Conclusion: Glottic airway and respiratory retraining, botulinum toxin injections, low-dose amitriptyline and inspiratory muscle strength training devices have been associated with symptom reduction in adults and adolescents with vocal cord dysfunction. Limited objective data exist to support the effectiveness of these interventions, and robust controlled trials are needed in this area. Systematic Review Registration: CRD42018092274 (PROSPERO).