Predictors of injection laryngoplasty volume for glottic insufficiency

Purpose: Volume injected for glottic insufficiency is paramount in achieving desired outcome. Factors that determine the required volume have not been thoroughly investigated and may correlate with outcome. The first objective of this investigation was to evaluate the association between injectable volume and various parameters, including lifestyle characteristics, pre-procedural factors, and voice measures, while the second aim assessed the correlation of volume to clinical outcomes in patients who underwent injection laryngoplasty.

Methods: For the first objective, a one-way ANOVA and univariate linear regression were used to analyze data from 124 patients (injected material, pre-operative diagnosis, previous voice therapy, age etc.). One-sample t-tests and Pearson correlational coefficients were employed for statistical analysis of aim 2 in a subgroup of 28 patients that had pre- and post-injection voice evaluations (e.g., acoustic and aerodynamic analysis, perceptual assessment, questionnaires).

Results: Average injection volume was 0.39 ± 0.062 mL (range: 0.1-1.6mL). No pre-procedural or lifestyle factor significantly affected injection volume (p > 0.05). There was no relationship between pre-procedural voice outcomes and injection volume (p > 0.05). Of the factors that were significantly improved post-injection laryngoplasty (GFI, VHI, and GRBAS), there were no significant correlations between the magnitude of improvement in these measures and injection volume (p > 0.05).

Conclusion: Injection volume does not appear to be affected by pre-procedural or lifestyle factors. In addition, injection volume does not significantly impact clinical outcomes assessed through voice analysis or patient-reported questionnaires. Our results underscore the complexity of factors at play in injection laryngoplasty for glottic insufficiency.