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correlate the alterations in the vocal folds of the elderly

population with the rest of the body’s epithelial covering,

Ximenes Filho et al

performed the simultaneous histomor-

phometric analysis of vocal folds and inguinal skin from 20

elderly cadavers (10 male and 10 female), finding similar

alterations in both locations such as lamina propria and

epithelial atrophy.

The immunohistochemical staining revealed that this net-

work is mainly formed by collagen I and III (

Table 1

;

Figures 3

and

) with a significant decreased in density of

elastin in the elderly larynx (

Table 1

;

Figure 7

). These

structural changes in the vocal fold cover are responsible

for the hardening of the vocal folds,

6,19,20

clinically mani-

fested by symptoms of hoarseness, vocal fatigue, and vocal

range restriction, having a direct impact on speech in higher

frequencies.

21,22

Keeping the proportion of elastic and collagen fibers in

the lamina propria of the larynx is important for this organ

to retain local resistance, provided by collagen fibers, and

distensibility, given by the elastic fibers. Studies of the

larynx in animals

and in humans

have confirmed the

role of collagen I in resistance and that of collagen III and

elastin in flexibility and elasticity. These parameters work

as a ‘‘balance,’’ whose equilibrium determines the relative

participation of the different vocal fold layers in phonation.

When collagen fibers start to predominate in the lamina pro-

pria, as seen in our study, the vocal folds become more

rigid, which negatively affects voice qualities.

According

to Ohno et al,

the collagen increase in the elderly larynx

affects the mucosal wave, resulting in decreases of phona-

tory intensity and fundamental frequency, especially in

women. The voice becomes failing and weak, a vocal pat-

tern known as phonasthenia.

In an attempt to better understand what causes the abnor-

mal production of collagen in the elderly larynx, Koszty

Hojna et al

studied the ultrastructure of vocal folds retrieved

at elderly autopsies or from total laryngectomies due to supra-

glottic larynx carcinomas, without damage to the actual vocal

folds. Using transmission electronic microscopy, the authors

observed the destruction of epithelial cells, a vacuolar degen-

eration of the cell’s cytoplasm, a considerable increase of col-

lagen fibers, a vacuolar degeneration of fibroblasts, an increase

of the endoplasmic reticulum, and an increase of blood vessels.

These authors suggest that the increase of collagen fibers is

connected to the cytoplasmatic alterations observed in fibro-

blasts. This possibility is insufficiently supported by the litera-

ture and therefore requires additional studies.

Although the mechanisms are not yet understood, the

elderly larynx fibroblasts produce collagen in an excessive

and irregular way, as well as a lower amount of hyaluronic

acid and elastic fibers. In a study of young and elderly rat

larynx fibroblast cultures, Hirano et al

observed in the latter

lower amounts of hyaluronic acid and higher concentrations

of collagen I. They observed the opposite when the fibro-

blasts were exposed to fibroblast growth factor, which was

thus considered by the authors a potential therapeutic tool for

Figure 3.

Vocal folds. (A) Control group: collagen I staining the basement membrane and the superficial layer. (B, C) Elderly groups: dense

collagen I staining the superficial and deep layers of the lamina propria. Immunohistochemical reaction, 20

Figure 4.

Vocal folds. (A) Control group: collagen III staining the basement membrane and the superficial layer. (B, C) Elderly groups: col-

lagen III staining the superficial (B) and deep layers (C) of the lamina propria. Immunohistochemical reaction, 20

Branco et al