The effects of hypothyroidism on the ears of cats and squirrel monkeys: A pilot study

Abstract

Eleven animals (five cats and six squirrel monkeys) were studied before and after being rendered hypothyroid by, surgical excision or radioactive ablation of the thyroid gland. Blood chemistry studies, before ablation and after, proved the presence of hypothyroid state. Audiometric studies by the behaviorally trained avoidance technique and electronystagmograms indicated hypoactivity regarding hearing and labyrinthine function. In one cat given thyroid hormone to full compensation level, the high frequency hearing loss returned to normal. Studies of temporal bone specimens of the five cats: hypothyroid, thyroid compensated, and control, microscopically showed no morphological alterations. Presumably functional changes were due to biochemical involvement which failed to show as a morphological one.

Effect of Experimental Hypothyroidism on Hearing in Adult Guinea Pigs

“…However, Ritter (1967) failed to show a hearing loss in all but one of a group of 166 rats which could not be accounted for by otitis media. Withers (1972), using 4 conditioned cats, showed a hearing loss at 8 kHz but not at any other frequency.…”

Human temporal bone feedings in acquire hypothyroidism

“…In experimentally induced hypothyroidism in animals several pathoanatomical changes have been found in the cochlea, predominantly in the morphology of the outer hair cells, pillar cells, strial area, and basilar membrane (De Vos, 1963;Poulsen, 1966;Ritter, 1967;Schatzle and Haubrich, 1967;Kohonen et al, 1971;Withers et al, 1972;Meyerhoff, 1979;Anniko and Rosenkvist, 1982). In addition, deposition of acid glycosaminoglycans has been demonstrated in the cochlea in hypothyroid guinea pigs (Poulsen, 1966;Schatzle and Haubrich, 1967;Meyerhoff, 1979).…”

Avaliação audiológica em crianças com hipotireoidismo congênito

“…Estudos com animais revelam que os hormônios tireoidianos e seus receptores são essenciais na maturação da audição em ratos (Withers, 1972;Deol, 1976;Van Middlesworth, 1980;Uziel, 1981;Rusch et al, 1998;Guadano-Ferraz et al, 1999;Knipper et al, 2000), estando os receptores beta da tireóide situados na cóclea (Bradley, 1994) e em estruturas cerebrais que compõem as vias auditivas (Li, 1995). A ausência desses hormônios no período embrionário e nos primeiros meses de vida pós-natal estão relacionados a prejuízos na morfogênese e na inervação coclear (Uziel et al, 1985;Corey, 1994;Chan, 2000;Knipper et al, 2000).…”