HASHIMOTO THYROIDITIS AND VESTIBULAR DYSFUNCTION.

OBJECTIVE: The aim of this review was to analyze the existing literature concerning the relationship between Hashimoto thyroiditis (HT) and vestibular dysfunction. METHODS: We used electronic databases (PubMed, EMBASE, Cochrane Library) to search and collect all published articles about the association between HT and vestibular disorders. RESULTS: Several observational and retrospective studies have postulated a relationship between thyroid autoimmunity and vestibular disorders. In most cases, an appropriate control group was lacking, and the impact of thyroid functional status could not precisely be established. In recent years, two well-designed prospective studies have provided convincing evidence that the association is not random. One article reported that patients with Ménière disease (MD) had a significantly higher prevalence of positive anti-thyroid autoantibody as compared to healthy controls. Moreover, more than half of MD patients had either positive anti-thyroid or non-organ-specific autoantibody titers, compared to less than 30% of both patients with unilateral vestibular paresis without cochlear involvement and healthy controls. Another study found that patients with benign paroxysmal positional vertigo (BPPV) had significantly higher serum thyroid-stimulating hormone and antithyroid autoantibody levels than healthy controls. Additionally, almost one-fifth of euthyroid patients with HT had signs of BPPV. CONCLUSION: The published results indicate that patients with MD or BPPV are potential candidates to also develop HT. Thus, in HT patients, the presence of even slight symptoms or signs potentially related to vestibular lesions should be carefully investigated. ABBREVIATIONS: AITD = autoimmune thyroid disease; BPPV = benign paroxysmal positional vertigo; EH = endolymphatic hydrops; HT = Hashimoto thyroiditis; L-T4 = L-thyroxine; MD = Ménière disease; PS = Pendred syndrome; Tg = thyroglobulin; TPO = thyroid peroxidase; TSH = thyroid-stimulating hormone.

The relationship between benign paroxysmal positional vertigo and thyroid autoimmunity.

CONCLUSION: Although there have been few studies concerning BPPV and thyroid autoimmunity and a positive relation was found between them, this study didn't find any relation between BPPV and thyroid autoimmunity. IT is thought that further large-scale studies must be done to clarify the relation. OBJECTIVES: Benign paroxysmal positional vertigo (BPPV) consists of ∼ 20% of vestibular disorders. Self-limited rotatory nystagmus with positional vertigo are the main findings of BPPV. Although canalolithiasis theory was confirmed by demonstrating freely floating debris in the endolymph of the posterior semicircular channel in following studies, currently, the etiology hasn't been explained totally. This study investigated the relation of BPPV and thyroid autoimmunity evaluated via measurement of serum thyroid autoantibodies. METHOD: Fifty patients (37 female, 13 male) with BPPV (BPPV group), 52 patients (40 female, 12 male) with non-BPPV vertigo (non-BPPV group) and 60 otherwise normal control (38 female, 22 male) samples were enrolled in the study. All samples of BPPV, non-BPPV groups and controls had undergone a cochleovestibular test following thorough ENT examination. After blood samples were drawn from each subject, thyroid-stimulating hormone (TSH), anti-thyroid peroxidase antibody (TPO-Ab) and anti-thyroglobulin antibody (TG-Ab) levels were measured accordingly. RESULTS: In the study, eight patients of the BPPV group (16%) had a high thyroid antibody level. In the non-BPPV group, six patients (11.5%) had elevated thyroid antibodies. In the control group, 15 patients (25%) had elevated thyroid antibodies. TSH values of all subjects were detected to be within normal range. No statistical difference was found between the groups with respect to TG-Ab and TPO-Ab values (p-values = 0.729 and 0.812, respectively).