Sixty-four human larynges ranging in age between 70 and 104 years were investigated histologically. The results were incorporated into our previous data for younger age groups. Discussion was focused on the mucosa around the vocal fold edge. The following tendencies were observed with ageing: (1) the membranous vocal fold shortens in males; (2) the mucosa thickens in females; (3) the cover of the vocal fold thickens in females; (4) edema develops in the superficial layer of the lamina propria in both sexes; (5) the intermediate layer of the lamina propria thins and its contour becomes deteriorated in males; (6) elastic fibers in the intermediate layer become less dense and atrophy in males; (7) the deep layer of the lamina propria thickens in males; (8) collagenous fibers in the deep layer become denser and fibrotic in males. The degree of these geriatric changes vary from individual to individual.

Asymmetry of the laryngeal framework was investigated with 50 excised human larynges, ten from newborns (five males, five females), 20 from adults in their 20s (ten males, ten females), and 20 from adults in their 50s (ten males, ten females). All adults were right-handed. The results are summarized as follows. 1) The laryngeal framework was asymmetric to a greater or lesser extent in all larynges. 2) The degree of asymmetry did not differ among different age groups or between sexes. 3) In newborns, there was no directional preponderance in asymmetry. 4) In older adults, there was a directional preponderance in asymmetry. The right thyroid lamina tended to tilt laterally whereas the left lamina showed a tendency to tilt medially. The right cricoarytenoid joint tended to be located slightly more laterally, posteriorly, and inferiorly than the left joint. The longitudinal axis of the thyroid cartilage was inclined to shift to the right posteriorly against the axis of the cricoid cartilage. The thyroid cartilage as a whole tended to tilt to the right against the cricoid cartilage. 5) There must be some compensatory mechanisms for the asymmetric framework to keep the vocal fold edges relatively symmetric.

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Vocal function following hemilaryngectomy was investigated in 54 cases in which a superiorly based sternohyoid muscle flap was used for glottic reconstruction. Four types of material were employed for covering the muscle flap: hypopharyngeal mucosa, lip mucosa, thyroid perichondrium, and island cervical skin flap. The vocal function varied greatly from individual to individual; however, the following tendencies were observed in many cases: 1) the glottis did not close completely; 2) supraglottic structures (false fold, arytenoid region, and epiglottis) were hyperfunctional and vibrated instead of or together with the unaffected vocal fold; 3) vibrations of the laryngeal structures were irregular; 4) maximum phonation time was short; 5) mean airflow rate was high; 6) fundamental frequency and intensity ranges of phonation were limited; 7) the voice was rough, breathy, and/or strained; and 8) cases with poor vocal function were most frequent in the skin flap group and least frequent in the lip mucosa group.

In order to determine factors that may contribute to deglutition problems following supraglottic horizontal laryngectomy or its modified techniques, clinical records of 38 patients were studied. Contribution of the following factors was investigated: age; sex; tumor classification; radical neck dissection; extent of and symmetry in removal of the aryepiglottic folds, arytenoid cartilages, and false folds; removal of the base of the tongue, hyoid bone, and a part of the vocal folds; extent of removal of the epiglottis and thyroid cartilage; cricopharyngeal myotomy; and some complications and concomitant diseases. The results suggest that removal of the arytenoid cartilage and asymmetrical removal of the false folds contribute to deglutition problems. We conclude that the standard supraglottic horizontal laryngectomy associated with surgical approximation of the larynx to the base of the tongue and cricopharyngeal myotomy does not usually cause serious deglutition problems. When the arytenoid cartilage is removed, reconstruction of the structure is required for the prevention of severe aspiration.