Investigation of Optimal Trafermin Dosage and Pre‐Injection Factors in Vocal Fold Paralysis

ABSTRACT Objective Optimal trafermin dosages and outcome predictors for treating unilateral vocal fold paralysis (UVFP) remain unclear. We aimed to investigate the optimal trafermin dosage and pre‐injection factors contributing to voice improvement after intracordal trafermin injection (ITI) for UVFP. Methods Medical records of 198 patients diagnosed with UVFP who received ITI at the Tokyo Voice Center between 2012 and 2024 were retrospectively evaluated. To investigate the effect of ITI on voice improvement prior to trafermin injection, we assessed age, sex, causative diseases, and pre‐ and post‐injection maximum phonation time (MPT), pitch range (PR), mean flow rate (MFR), and voice handicap index (VHI). Patients were categorized by dosage: low (< 100 μg), normal (100 μg), and high (> 100 μg). The normal, low, and high groups comprised 152, 12, and 34 cases, respectively. Results Following ITI, improvements in the normal, low, and high dosage groups were as follows: MPT (s) (3.03, 3.13, 5.57), PR (ST) (6.82, 4.5, 8.74), MFR (mL/s) (191.28, 121.02, 409.63), and VHI (score) (21.75, 1.83, 33.45) (with data missing for MFR and VHI in eight and three cases, respectively). Analysis of variance revealed significant improvements in MPT, MFR, and VHI among groups. Dunnett's test showed significantly better outcomes in the high‐dosage group compared to normal. Covariance analysis identified pre‐injection values and comorbidities as significant predictors. Conclusion Higher trafermin dosage may provide greater and more sustained voice improvement in patients with UVFP. Identifying optimal candidates based on pre‐injection factors can allow for more personalized treatments. Level of Evidence 3.