Vocal Fold Scar Treatment via Controlled Dexamethasone Delivery With a Light-Activatable Implant.

Abstract

OBJECTIVE: Intralesional steroid injections for vocal fold (VF) scarring are rapidly cleared, limiting their effectiveness. This study evaluates the efficacy of a light-activatable dexamethasone implant compared to a single steroid injection for VF scar healing. METHODS: Ten rabbits underwent endoscopic VF injury and were treated with either a dexamethasone injection or a light-activatable implant; injured-only and no-injury VFs served as controls. On days 0 and 21, VF implants were irradiated with a near-infrared pulsed laser for 1&#x2009;min. Larynges were harvested after 42&#x2009;days. High-speed video (>&#x2009;10&#x2009;kHz) of excised larynges captured VF vibrations for kymographic analysis. Normal force, structural stiffness, and displacement were measured. Data were analyzed with appropriate statistical tests. RESULTS: Compared to injury-only VFs, implant-treated VFs demonstrated significantly reduced normal force and stiffness (5.28&#x2009;&#xb1;&#x2009;0.77&#x2009;mN vs. 2.34&#x2009;&#xb1;&#x2009;0.66&#x2009;mN, p&#x2009;<&#x2009;0.0001; 17.74&#x2009;&#xb1;&#x2009;2.45&#x2009;mN/mm vs. 6.80&#x2009;&#xb1;&#x2009;1.32&#x2009;mN/mm, p&#x2009;<&#x2009;0.0001), and increased displacement at 1.96&#x2009;mN (0.14&#x2009;&#xb1;&#x2009;0.02&#x2009;mm vs. 0.29&#x2009;&#xb1;&#x2009;0.05&#x2009;mm, p&#x2009;<&#x2009;0.0001) along the injury zone. Implant-treated VFs exhibited larger amplitude ratios and improved tissue architecture than untreated scars. No differences in quantitative measures were observed between implant-treated and injection-treated groups. CONCLUSION: A light-activatable dexamethasone implant improved VF biomechanics, vibratory behavior, and histological outcomes in a rabbit injury model comparable to a single steroid injection. This novel approach shows promise for delivering controlled, repeatable therapy to VF scars.