Histopathological characteristics of larynx in hypothyroidism in an experimental rabbit model.

OBJECTIVE

Hypothyroidism has a significant effect on the patients' voices. This study evaluated the histopathological characteristics of larynx following hypothyroidism in an experimental rabbit model.

METHODS

Eleven male Dutch rabbits were included. Methimazole-induced hypothyroidism was done for nine rabbits. The remaining two rabbits were assigned as controls. Six weeks after starting methimazole, a histological examination was performed with parameters of inflammation, ulceration, hemorrhage, and thickness of epithelium, Reinke's space, vocal ligament, thyroarytenoid muscle, collagen deposition, and periodic acid-Schiff (PAS)-positive materials, as well as confirmation of hypothyroidism by T4 measurement.

RESULTS

Histologic examination showed a significant thickening of epithelium, Reinke's space, vocal ligament, and collagen PAS-positive materials deposition in hypothyroid rabbits (p < .05). There was significant reduction in thyroarytenid muscle thickness (p < .05). Inflammation, ulceration, and bleeding were not significantly different between hypothyroid and control rabbits' laryngeal specimens.

CONCLUSION

Hypothyroidism causes significant changes in the laryngeal tissues. Thickening of epithelium, Reinke's space, vocal ligament, collagen, PAS-positive materials, and reduced thickness of thyroarytenoid muscle are the major findings of this study.