Voice Outcomes and Reinjection Rates After Injection Laryngoplasty in Vocal Fold Paralysis Following Thyroidectomy...

Vocal fold paralysis is a clinically significant complication of both thyroidectomy and thoracic surgery, yet comparative data on injection laryngoplasty outcomes between the two etiologies are limited. We compared voice outcomes and reinjection patterns between these two populations.

We conducted a retrospective cohort study of 141 patients who underwent hyaluronic acid injection laryngoplasty for unilateral vocal fold paralysis at a single tertiary center between January 2011 and December 2024-76 with thyroidectomy-induced paralysis and 65 with thoracic surgery-induced paralysis. Acoustic, perceptual, and patient-reported voice outcomes were assessed before injection and at 1, 3, 6, and 12 months thereafter. Reinjection rates, time to reinjection, and predictors of reinjection were analyzed.

The thoracic surgery group had significantly worse baseline voice parameters than the thyroidectomy group, with higher jitter, shimmer, and noise-to-harmonic ratio and a shorter maximum phonation time. Both groups improved after injection laryngoplasty, but outcomes remained inferior in the thoracic surgery group throughout the 12-month follow-up. Reinjection was more frequent in the thoracic surgery group (30.8% vs 15.8%; P = 0.044), and among reinjected patients the interval between the first and second injection was markedly shorter in the thoracic surgery group (median 36 vs 142 days; P = 0.002). On multivariable analysis, initial mean flow rate was the only independent predictor of reinjection (adjusted odds ratio 1.26 per 100 mL/s increase; P = 0.044).

Vocal fold paralysis after thoracic surgery is characterized by more severe baseline impairment, less favorable long-term outcomes, and a higher and earlier need for reinjection than thyroidectomy-induced paralysis. Initial mean flow rate is an independent predictor of reinjection and may guide individualized management. These findings support early laryngological referral and proactive longitudinal monitoring in thoracic surgical practice.