Vestibular disorders in euthyroid patients with Hashimoto's thyroiditis: role of thyroid autoimmunity.

INTRODUCTION: A relationship between vestibular disorders and thyroid autoimmunity independently from thyroid function has been postulated. AIM: To shed more light on the actual relationship between vestibular lesions and Hashimoto's thyroiditis (HT) regardless of thyroid function. METHODS: Forty-seven patients with HT (89·4% F; aged 48·3 ± 12·7 years), 21 with multinodular goitre (MNG; 57·1% F; 54·1 ± 9·8 years) and 30 healthy volunteers (56·7% F; 50·7 ± 13·9 years) were enrolled. Inclusion criteria were the presence of normal thyroid function tests and no clinical history of vestibular dysfunction. Each subject was submitted to complete vestibular evaluation [Caloric Test, Vestibular evoked myogenic potentials (VEMPs), Head Shaking Test (HST)]. RESULTS: 52·2% of HT patients showed an alteration of VEMPs and 44·7% of caloric test (P < 0·0001 for both). None of the MNG patients showed any vestibular alteration, while one healthy control showed an altered caloric test. A correlation was found between vestibular alterations of HT patients and the degree of serum TPOAb level, not affected by age and serum TSH value. By logistic regression analysis, the absence of thyroid autoimmunity significantly reduced the risk of vestibular alterations: HR 0.19 (95%CI: 0·003-0.25, P = 0·0004) for caloric test; HR 0·07 (95%CI: 0·02-0·425, P < 0·0001) for VEMPs; and HR 0·22 (95%CI: 0·06-0·7, P = 0·01) for HST. CONCLUSION: In euthyroid HT patients, a significant relationship between subclinical vestibular damage and the degree of TPOAb titre was documented. This finding suggests that circulating antithyroid autoantibodies may represent a risk factor for developing vestibular dysfunction. An accurate vestibular evaluation of HT patients with or without symptoms is therefore warranted.