[Ultrastructure of the mucous membrane of the human newborn vocal folds]

The life-cycle and restoration of the human vocal fold

Objective

To better understand the challenges of designing therapies to treat damaged vocal fold lamina propria, it is essential to understand the biophysical and pathophysiological mechanisms involved in vocal fold development, maintenance, injury, and aging. This review critically analyses these points to try and direct future efforts and new strategies toward science-based solutions.

Data Sources & Review Methods

MEDLINE, Ovid Embase, and Wed of Science databases were used to identify relevant literature. A scoping review was performed following the preferred reporting items for systematic reviews and meta-analyses extension for scoping reviews checklist.

Results

The layered arrangement of the vocal fold, develops during early childhood and is maintained during adulthood unless injury occurs. The stellate cells of the macular flava are likely to be important in this process. The capacity for vocal fold regeneration and growth is lost during adulthood and repair results in the deposition of fibrous tissue from resident fibroblasts. With advancing age, viscoelastic tissue declines, possibly due to cell senescence. Strategies aimed at replacing fibrous tissue within the vocal folds must either stimulate resident cells or implant new cells to secrete healthy extracellular protein. Injection of basic fibroblast growth factor is the most widely reported therapy that aims to achieve this.

Conclusions

The pathways involved in vocal fold development, maintenance and aging are incompletely understood. Improved understanding has the potential to identify new treatment targets that could potentially overcome loss of vocal fold vibratory tissue.

Normative vocal acoustic parameters for preschool and elementary school Egyptian children

BACKGROUND

A reliable acoustic analysis necessitates the availability of standard normative values at different ages. Normative values of vocal acoustic parameters are readily available for the adult population but not much data are available for the pediatric population.

OBJECTIVES

Providing a database for the normative vocal acoustic parameters in preschool and elementary school Egyptian children to lay out an objective model for the diagnosis and optimal treatment of childhood voice disorders.

METHODS

A total of 237 Egyptian children between the ages of 4 and 9 years from both genders were enrolled in the study. A Computer-assisted acoustic vocal analysis was done for all children.

RESULTS

Fundamental frequency values differed significantly according to gender with higher measures in girls. Mean values of the fundamental frequency were 258.57 Hz ± 39.69, jitter percentage 0.85% ± 0.67, shimmer percentage 1.59% ± 1.03, fundamental tremors 1.64HZ ± 0.421, maximum phonation time 4.81sec. ± 1.73 and harmonic/noise ratio were 15.34 dB ± 10.65. A decline of measures of the fundamental frequency and jitter percentage with increasing age and an increase of values of harmonic/noise ratio and shimmer percentage in children residing in rural areas are observed.

CONCLUSION

This study provides an insight into the normative values of vocal acoustic parameters in preschool and elementary school Egyptian children. Comparable to other studies, both fundamental frequency and jitter percentage values show a decline with increasing age. Also, fundamental frequency values differ significantly among genders. The difference in socioeconomic environment seems to influence some of the vocal acoustic parameters in children.

Vitamin A-Storing Stellate Cells in the Human Newborn Vocal Fold

Objectives:

Vocal fold stellate cells (VFSCs) in the newborn vocal fold were examined and compared with VFSCs in the adult vocal fold.

Methods:

Light and electron microscopic investigation of VFSCs was carried out on 5 human newborn larynges.

Results:

The VFSCs were distributed in human newborn maculae flavae. They were stellate or oval in shape, and possessed cytoplasmic processes. The VFSCs in some cells formed a gap junction with each other. A few lipid droplets were present in the cytoplasm, but they were much fewer than those of an adult. The nucleus-cytoplasm ratio was high, and the intracellular organelles were not very well developed. Free ribosomes were well developed in the cytoplasm. The VFSCs in some cells showed strong cytoplasm staining with periodic acid-Schiff stain and type III collagen. There were vesicles along the periphery of the cytoplasm of the VFSCs, and newly released amorphous materials were seen, but fewer were observed on the cell surface. The newborn VFSCs had started to synthesize extracellular matrices such as collagenous fibers, reticular fibers, elastic fibers, and glycosaminoglycan.

Conclusions:

The VFSCs in the newborn maculae flavae were immature, but had already started the synthesis of extracellular matrices essential for the viscoelastic properties of the vocal fold mucosa.

Expression and Distribution of CD44 and Hyaluronic Acid in Human Vocal Fold Mucosa

Objectives:

Expression of CD44 (a cell surface receptor for hyaluronic acid) and the distribution of hyaluronic acid were examined in the human vocal fold mucosa.

Methods:

Light microscopic investigation was carried out on 10 normal larynges of newborn, infant, younger adult, and older adults with Alcian blue staining, a hyaluronidase digestion study, and immunohistochemistry for CD44.

Results:

Before the appearance of hyaluronic acid in the newborn vocal fold mucosa, CD44 was expressed on the stellate cells in the macula flava and on the fibroblasts in Reinke's space. During infancy, hyaluronic acid appeared and was distributed in the vocal fold mucosa. Many more stellate cells in the macula flava showed CD44 expression, and a large amount of hyaluronic acid was present around the infant stellate cells; however, the fibroblasts in Reinke's space expressed little CD44. During adulthood, hyaluronic acid was distributed in the vocal fold mucosa. Almost all of the stellate cells in the macula flava showed CD44 expression, and much hyaluronic acid existed around the stellate cells in the adult macula flava. However, fibroblasts in the adult Reinke's space expressed little CD44, and hyaluronic acid density in that space was lower than that in the macula flava.

Conclusions:

Stellate cells in the macula flava and CD44 cooperatively play important roles in maintaining hyaluronic acid in the human vocal fold mucosa as a vibrating tissue.

Medical and surgical treatment of pediatric dysphonia

The production of sound for communication is the last of the prime functions of the larynx, yet it is its most salient feature. Pediatric dysphonia may be caused by a variety of general causes. These causes may be classified as infectious, anatomic, congenital, inflammatory, neoplastic, neurologic, and iatrogenic. When a child presents with hoarseness, a complete assessment is necessary. Fine points during the history and physical may help distinguish between those pathologic conditions found in these general categories.