Impact of Pulmonary Function on Voice Outcomes After Injection Laryngoplasty for Unilateral Vocal Fold Paralysis

Pulmonary function is closely associated with voice quality especially in patients with voice disorder including unilateral vocal fold paralysis (UVFP). Injection laryngoplasty (IL) is the standard treatment for patients with UVFP. We investigated the subjective and objective voice outcomes according to pulmonary function test (PFT) before IL in patients with UVFP.

We retrospectively analyzed the patients who underwent IL for UVFP between 2004 and 2021 (N = 1201), and finally investigated 261 patients with PFT results before IL. The patients were classified into three groups according to results of PFT: normal (n = 189, 72%), mild (n = 40, 15%), and moderate (n = 32, 13%) obstructive pattern. Aspiration symptoms and subjective and objective voice parameters of voice handicap index (VHI), GRBAS score, maximal phonation time (MPT), Jitter, Shimmer, and noise to harmonic ratio (NHR) were compared between normal and abnormal (mild or moderate obstructive pattern) PFT groups.

Age (68.0 ± 9.1 and 61.2 ± 12.6, respectively) was significantly higher and males were more common (84.7% and 57.7%, respectively) in abnormal PFT than in normal PFT. Aspiration showed significant improvement in all groups. The subjective and objective voice parameters significantly improved after IL in normal and mild obstruction groups, but MPT, Shimmer, and VHI did not significantly improve in the moderate obstruction group. The improvement in VHI-30 after IL was significantly higher in the normal group (20.0 ± 29.5) than in the mild (10.3 ± 32.8) or moderate (9.9 ± 33.2) obstruction group (P = 0.035). Improved amounts of MPT, Jitter, Shimmer, and NHR were not significantly different among the groups, but improvement of VHI was smallest in the moderate obstructive pattern group.

Voice parameters showed significant improvement after IL in both normal and mild obstructive pattern groups, but MPT and VHI did not significantly improve in the moderate obstructive pattern group. In addition, patients with normal pulmonary function had marked improvement of subjective symptoms after IL in comparison with patients with abnormal pulmonary function.