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 ( < .05). There was significant reduction in thyroarytenid muscle thickness ( < .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.