Respiratory Pressure and Sustained Performance Across Etiologic Categories of Voice Disorders: A Pilot Study

To determine whether a data-driven composite factor reflecting respiratory pressure-generating capacity and sustained pressure performance differs across etiologic categories of voice disorders and to examine its associations with maximum phonation time (MPT) and cepstral measures of phonatory stability.

Prospective observational study.

Forty-three patients with voice disorders underwent voice and respiratory function assessments. Respiratory variables, including percent vital capacity (%VC), forced expiratory volume in one second to forced vital capacity ratio (FEV₁/FVC), maximum inspiratory pressure (PImax), maximum expiratory pressure (PEmax), and inspiratory and expiratory Mean Sustained Pressure Index (MSPI), were analyzed using principal component analysis (PCA) to derive a Respiratory Muscle Performance Factor (RMPF), a composite factor reflecting maximal pressure-generating capacity and sustained pressure performance. Differences in RMPF across etiologic categories (organic, neurological, and functional voice disorders) were examined using analysis of covariance (ANCOVA) controlling for age and sex. Associations between RMPF and phonatory measures, including MPT and cepstral peak prominence (CPP) derived from sustained vowels and connected speech, were analyzed using Spearman's rank correlation coefficients within each etiologic category.

RMPF differed significantly across diagnostic categories (P = 0.004), with the organic voice disorder group demonstrating significantly higher values than the functional voice disorder group. No significant effects of age or sex were observed. In the organic and neurological voice disorder groups, RMPF showed significant positive correlations with MPT. In contrast, in the functional voice disorder group, RMPF showed a significant positive correlation with CPP derived from the connected-speech sentence "waɾanojanenoieda." No significant associations were observed between RMPF and the remaining cepstral measures.

Respiratory muscle performance differs across etiologic categories of voice disorders and demonstrates diagnosis-specific associations with phonatory measures. Functional voice disorders were characterized by an association between respiratory function and connected-speech phonatory stability, whereas organic and neurological voice disorders demonstrated associations with phonatory duration. These findings suggest that disease-specific respiratory-phonatory interactions may contribute to differences in voice production and phonatory performance across voice disorder populations.