Vocal Improvement After Voice Therapy in Unilateral Vocal Fold Paralysis

Unilateral vocal fold paralysis (UVFP) is associated with changes in acoustic and aerodynamic voice measurements and can have a significant impact on a patient's quality of life. Few objective data regarding the efficacy of voice therapy for UVFP exist. The aim of this study was to retrospectively analyze voice modifications in a group of patients with UVFP before and after voice therapy. Forty patients with UVFP of different etiology were included in the study. Each subject had voice therapy with an experienced speech/language pathologist twice a week; the mean number of sessions was 12.6. A multidimensional assessment protocol was used; it included videoendoscopy, the maximum phonation time (MPT), the GIRBAS scale, spectrograms and a perturbation analysis, and the Voice Handicap Index (VHI). Pre- and posttreatment data were compared by means of the Wilcoxon and Student's t tests. A complete glottal closure was seen in 8 patients before voice therapy and in 14 afterward. Mean MPT increased significantly. In the perceptual assessment, the difference was significant for five out of six parameters. A significant improvement was found on spectrographic analysis; as for perturbation analysis, the differences in jitter, shimmer, and noise-to-harmonic ratio values were significant. VHI values showed a clear and significant improvement. A significant improvement of voice quality and quality of life after voice therapy is an often reached and reasonable goal in patients with UVFP.     

Objective Voice Quality Analysis Before and After Onset of Unilateral Vocal Fold Paralysis

This study was designed to investigate objective voice quality measurements in unilateral vocal fold paralysis (UVFP) by eliminating intersubject variability. To our knowledge this is the first report objectively analyzing paralytic dysphonia as compared to the same voice before onset of UVFP. The voices of two male subjects were prospectively recorded before and after the onset of iatrogenic UVFP (thoracic surgery).The following acoustic measurements of the vowel /a/ were performed using the CSL and MDVP (Kay Elemetrics): jitter, shimmer, harmonics-to-noise ratio, cepstral peak prominence, the relative energy levels of the first harmonic, the first formant and the third formant, the spectral slope in the low-frequency zone (0-1 kHz and 0-2 kHz), and the relative level of energy above 6 kHz. Distribution of spectral energy was analyzed from a long-term average spectrum of 40 seconds of text. Laryngeal aerodynamic measurements were obtained for one patient before and after onset of paralysis using the Aerophone II (Kay Elemetrics). Pitch and amplitude perturbation increased secondary to UVFP, while the harmonics-to-noise ratio and the cepstral peak prominence decreased. A relative increase in the mid-frequency and high-frequency ranges and a decrease in the low-frequency spectral slope were observed. Mean airflow rate and intraoral pressure increased, and glottal resistance and vocal efficiency decreased secondary to UVFP. The findings of this self-paired study confirm some but not all the results of previous studies. Measures involving the fundamental and the formants did not corroborate previous findings. Further investigation with vocal tract modeling is warranted.