Evaluation of peripheral vestibular system in Hashimoto thyroiditis.

Background/Aim: Hashimoto thyroiditis (HT) is a common autoimmune thyroid disease that may have systemic effects on any organ, including the inner ear. Increased frequency of autoimmune thyroid disease in patients with Meniere's disease and benign paroxysmal positional vertigo (BPPV) has been found, and autoimmunity was implicated in the etiopathogenesis of both diseases. The aim of this study was to evaluate vestibular functions and the effect of levothyroxine (LT4) therapy in patients with Hashimoto's thyroiditis. Methods: The study included 61 men and women with HT diagnosis (group I: 31 patients who did not receive treatment; group II: 31 patients on LT4 treatment) and 30 healthy individuals (control group) between 18 and 60 years of age. Free T3, free T4, TSH, anti-TPO, and anti-Tg levels of all individuals were measured, and Cervical vestibular evoked myogenic potentials (cVEMPs), ocular vestibular evoked potentials (oVEMP), and video head impulse test (vHIT)tests were performed. Results: In the cVEMP results, a 20% VEMP wave was not obtained in the group with HT on LT4 treatment. However, no significant difference was found in the statistical results between the groups. There was no significant difference in vHIT and oVEMP tests between groups. Vestibular tests of patients with hypothyroidism (TSH >4.9) were compared with those of euthyroid patients. The altered frequency in the cervical VEMP test of the left ear was higher in hypothyroid patients (P=0.042). The oVEMP test results were similar for both ears in both groups. The groups were similar in terms of VOR gain in the vHIT test. Conclusion: In euthyroid HT patients, vestibular tests were normal. Progression of vestibular dysfunction might be induced by hypothyroidism rather than autoimmune thyroid diseases. [ABSTRACT FROM AUTHOR]