Cepstral analysis in patients with a vocal fold motility impairment: advantages of the cepstrum over time-based acoustic analysis

Scaffold-Forming Collagen and Motor-Endplate Expressing Muscle Cells for Porcine Laryngoplasty

OBJECTIVE

Vocal fold paralysis impairs quality of life, and no curative injectable therapy exists. We evaluated injection of a novel in situ polymerizing (scaffold-forming) collagen in the presence and absence of muscle-derived motor-endplate expressing cells (MEEs) to promote medialization and recurrent laryngeal nerve (RLN) regeneration in a porcine model of unilateral vocal fold paralysis.

METHODS

Twelve Yucatan minipigs underwent right RLN transection. Autologous muscle progenitor cells were isolated from muscle biopsies, differentiated, and induced to MEEs. Three weeks after RLN injury, animals received injections of collagen, collagen containing MEEs, or saline into the paralyzed right vocal fold. Stimulated laryngeal electromyography and acoustic vocalization were used for function assessments. Larynges were harvested and underwent histologic, gene expression, and further quantitative analyses.

RESULTS

Injections were well-tolerated, with the collagen scaffold showing immunotolerance and collagen-encapsulated MEEs remaining viable. Collagen-treated paralyzed vocal folds showed increased laryngeal adductor muscle volumes relative to that of the uninjured side, with those receiving MEEs and collagen showing the highest volumes. Muscles injected with MEEs and collagen demonstrated increased expression of select neurotrophic (BDNF and NTN1), motor-endplate (DOK7, CHRNA1, and MUSK), and myogenic (MYOG and MYOD) related genes relative to saline controls.

CONCLUSION

In a porcine model of unilateral vocal fold paralysis, injection of in situ polymerizing collagen in the absence and presence of MEEs enhanced laryngeal adductor muscle volume, modulated expression of neurotrophic and myogenic factors, and avoided adverse material-mediated immune responses. Further study is needed to determine long-term functional outcomes with this novel therapeutic approach.

LEVEL OF EVIDENCE

NA Laryngoscope, 2024.

Effect of Smoking on Cepstral Parameters

Smoking exerts certain damage to the voice, which affects sound characteristics. This study explored the effects of smoking, smoking time, and smoking amount on cepstral parameters. We collected the acoustic signals of sustained vowels in 301 participants (135 smokers and 166 nonsmokers). The cepstral parameters, including cepstral peak prominence (CPP), CPP standard deviation (CPP SD), low to high-frequency spectral ratio (L/H), low to high-frequency spectral ratio standard deviation (L/H SD), and voice disorder cepstral/spectral index of dysphonia (CSID), of the sustained vowels were investigated through the analysis of dysphonia in speech and voice (ADSV) application. The effects of smoking on these parameters were explored. The influences of smoking time and smoking amount on cepstral parameters were also analyzed by multiple linear regression. The CPP and L/H values in the smoking group were lower than those in the nonsmoking group (CPP: P < 0.001, L/H: P = 0.033) and negatively correlated with smoking time (CPP: R2 = 0.3828, P < 0.0001; L/H: R2 = 0.02996, P = 0.0447) and smoking amount (CPP: R2 < 0.4526, P < 0.0001; L/H: R2 = 0.08823, P = 0.00005). The CPP SD, L/H SD, and CSID values in the smoking group were higher than those in the nonsmoking group (CPP SD: P = 0.006, L/H SD: P = 0.034, CSID: P < 0.001) and positively correlated with smoking time (CPP SD: R2 = 0.03648, P = 0.0265, L/H SD: R2 = 0.09121, P = 0.0004, CSID: R2 = 0.01247, P = 0.1972) and smoking amount (CPP SD: R2 = 0.05495, P = 0.0062, L/H SD: R2 = 0.1316, P < 0.0001, CSID: R2 = 0.03851, P = 0.0225). Compared with other cepstral parameters, smoking time and smoking volume had the greatest impact on CPP (smoking time: R2 = 0.385, smoking amount: R2 = 0.443). This study confirmed that smoking has a significant effect on cepstral parameters. Compared with the cepstral parameters of nonsmokers, an increase in smoking time and smoking volume increases the abnormality of the cepstral parameters of smokers.

Predicting Airflow from Measures Sensitive to Mid-cord Glottal Gap During the COVID-19 Pandemic

OBJECTIVES

To determine if trans-laryngeal airflow, important in assessing vocal function in paresis/paralysis and presbylarynges patients with mid-cord glottal gaps, could be predicted by other measures sensitive to mid-cord glottal gap size but with smaller risks of spreading COVID-19, and if any patient factors need consideration.

METHODS

Four populations were: unilateral vocal fold paresis/paralysis (UVFP, 148), aging and UVFP (UVFP plus aging, 22), bilateral vocal fold paresis/paralysis without airway obstruction (BVFP, 49), and presbylarynges (66). Five measures were selected from the initial clinic visit: mean airflow from repeated /pi/ syllables, longer of 2 /s/ and 2 /z/ productions, higher of 2 cepstral peak prominence smoothed for vowel /a/ (CPPSa), and Glottal Function Index (GFI). S/Z ratios were computed. Stepwise regression models used 3 measures and 5 patient factors (age, sex, etiology, diagnosis, and potentially impaired power source for voicing) to predict airflow.

RESULTS

Log-transformations were required to normalize distributions of airflow and S/Z ratio. The final model revealed age, sex, impaired power source, log-transformed S/Z ratio, and GFI predicted log-transformed airflow (R2 = .275, F[5,278] = 21.1; P < .001).

CONCLUSIONS

The amount of variance explained by the model was not high, suggesting adding other predictive variables to the model might increase the variance explained.