International Session 44　　Tinnitus

Introduction : Postoperative vocal fold(VF)scarring remains a major challenge after laser cordectomy.Pirfenidone (PFD)is an antifibrotic agent, but its role in preventing VF scarring is unclear.We aimed to evaluate safety and preventive effect of PFD injection in a canine model.Methods : For toxicity assessment, saline or PFD(0． 5-10.0 mg/mL)was injected into bilateral VFs of three dogs, with histologic evaluation at 2 weeks.For efficacy testing, three dogs received unilateral VF injection with saline, 1． 0, or 2． 5 mg/mL PFD followed by laser cordectomy.Laryngoscopic evaluation was performed at 4 and 8 weeks.Vibratory function assessment with high-speed imaging, histologic and immunohistochemical analyses for collagen type I(COL1)and α-smooth muscle actin(α-SMA)were assessed at 8 weeks.Results : VFs injected with 2． 5 mg/ mL PFD showed complete epithelial healing, whereas higher concentrations caused epithelial detachment.PFD-treated VFs demonstrated improved mucosal wave amplitude, reduced fibrosis, and lower COL1 and α-SMA expression compared with controls.Conclusion : PFD injection may safely attenuate postoperative VF scarring after laser cordectomy.