Relationship between vestibular syndrome and autoimmune thyroiditis

Dear Editor,

For years, autoimmune hypothyroidism has been associated with the development of other diseases, demonstrating the possible role that antithyroid antibodies could play at the systemic level. Some of these diseases are coeliac disease, type 1 diabetes mellitus, pernicious anaemia, multiple sclerosis, vitiligo, dermatitis herpetiformis and chronic urticaria.¹ There are also studies that show the association between autoimmune thyroid disease and vestibular dysfunction (Ménière's disease, benign positional paroxysmal vertigo, etc.), although to date they are scarce, with discordant results, and they do not clarify the role of antithyroid antibodies in the pathogenesis of vestibular dysfunction.^2–4 The objective of this work is to assess the relationship between peripheral vestibular syndrome and autoimmune thyroiditis.

For this, an observational, descriptive, retrospective, cross-sectional epidemiological study was carried out between 1 November 2017 and 31 October 2018, at the Hospital Universitario Los Arcos del Mar Menor, in Murcia. The study analysed 52 patients who presented positive antiperoxidase and antithyroglobulin antibodies, or pathological data suggestive of lymphocytic thyroiditis after biopsy or surgical excision of the gland due to symptomatic multinodular goitre or suspicious thyroid nodules. In all of them, the history or presence of vertiginous symptoms was investigated, that is, the sensation that you or everything around you is spinning or moving, associated or not with nausea and vomiting, in the last year. Those excluded were patients with a history of previous otological problems or surgery, vascular or neurological disorders that could simulate vestibular symptoms (stroke, transient ischaemic attack, multiple sclerosis, etc.) and consumption of drugs that could have vestibular alterations as a secondary effect. Quantitative plasma levels of the hormones free T4 and TSH and antithyroid antibodies were determined by electrochemiluminescence immunoassay (ECLEIA). And for the data analysis, the statistical software IBM SPSS Statistics 24® was used.

Of the 52 patients included in the study, 19 presented clinical criteria compatible with vestibular dysfunction (36.5%), of whom 15 were women and four were men, with a mean age of 56.5 years. Patients with vestibular symptoms had significantly higher levels of TSH (18 ± 33.9 IU/ml) and lower levels of plasma T4 (0.95 ± 0.37 ng/dl) compared to those who did not, with p values of 0.039 and 0.04, respectively. No statistically significant relationship was found between the levels of antithyroid antibodies and the presence or absence of vestibular symptoms. However, 45% and 57% of patients with levels of antiperoxidase and antithyroglobulin antibodies greater than 700 IU/ml, respectively, had symptoms of dizziness. Of the 18 patients (34.6%) who underwent total thyroidectomy, all presented pathological characteristics indicative of lymphocytic thyroiditis. However, 22.2% of them had data suggesting multinodular goitre and 39% papillary thyroid cancer. Ten of the thyroidectomised patients also presented with a vertiginous syndrome and 70% of them reported clear clinical improvement after surgery.

Despite the limited sample size, our results show an increased prevalence of hypothyroidism in patients with vestibular dysfunction, compared to the general population (15-20%),⁵ and better control of vertigo after thyroidectomy, which could be explained by the role played by thyroid autoimmunity in these patients. To date, the role of thyroid surgery in vestibular control in patients with autoimmune thyroiditis has not been described in the literature. That is why we believe it is necessary to propose new care protocols that include the study of thyroid function in patients who consult for vertigo, and also to highlight the anamnesis regarding the presence of symptoms compatible with peripheral vestibular disease in patients with autoimmune thyroiditis as well as the continuation or resolution of the vertiginous symptoms after thyroidectomy. With this, we could contribute to an early diagnosis of both diseases and it would give us the opportunity to carry out large-scale prospective randomised studies to clarify the involvement of antithyroid antibodies in vestibular disorders and the role of thyroid surgery in the treatment of severe vestibular dysfunction secondary to thyroid autoimmunity.

Conflicts of interest

The authors declare that they have no conflicts of interest.