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

Abstract

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. 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 min. Larynges were harvested after 42 days. High-speed video (> 10 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. Compared to injury-only VFs, implant-treated VFs demonstrated significantly reduced normal force and stiffness (5.28 ± 0.77 mN vs. 2.34 ± 0.66 mN, p < 0.0001; 17.74 ± 2.45 mN/mm vs. 6.80 ± 1.32 mN/mm, p < 0.0001), and increased displacement at 1.96 mN (0.14 ± 0.02 mm vs. 0.29 ± 0.05 mm, p < 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. 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.