Mechanical Parameters Based on High-Speed Videoendoscopy of the Vocal Folds in Patients With Ectodermal Dysplasia.

OBJECTIVE: Patients suffering from ectodermal dysplasia (ED), which is an inherited disorder in the development of the ectodermal structures, have a significantly reduced expression of teeth, hair, sweat glands, and salivary glands in the respiratory tract including the larynx. Previous studies within the framework of the present project showed a significantly reduced saliva production and an impairment of the acoustic outcome in ED patients compared to the control group. However, until now, no statistically significant difference between EDs and controls could be found regarding vocal fold dynamics in the high-speed videoendoscopy (HSV) recordings using representative parameters on closure, symmetry, and periodicity. The aim of this study is to examine the role of tissue characteristics by means of objective mechanical parameters derived from HSV recordings. METHODS: This study includes 28 ED patients and 42 controls (no ED, healthy voice). The vocal fold oscillations were recorded by high-speed videoendoscopy (HSV@4kHz). Based on the dynamical measures of the glottal area waveform (GAW), objective glottal dynamic parameters associated with tissue properties like flexibility and stiffness were computed. RESULTS: The present evaluation displays a significant difference between male ED patients and male controls concerning the HSV-based mechanical parameters indicating reduced stiffness and increased deformability for the vocal folds of male ED patients. In contrast to strongly amplitude-dependent parameters, the primarily velocity-based parameters showed no statistically significant deviation. CONCLUSIONS: The presented data provides the first promising indication toward the underlying causes on the laryngeal level leading to the voice conspicuities in ED patients. The significant difference concerning the mechanical parameters suggests a different composition of the extracellular matrix of the tissue of the vocal folds of ED patients compared to controls.