The dissertation is devoted to the study of early manifestations of sensorineural hearing loss in patients with autoimmune thyroiditis who don’t have a thyroid gland function disorders (euthyroid state).
Scientific work consists of clinical and experimental research. In experimental part euthyroid AIT in rats was simulated. Registration of otoacoustic emission and auditory brainstream responses was carried out after confirming the presence of AIT in rats. The data presented, on the 113th day of the experiment, indicate a lack of response from the external hair cells during DPOAE registration and an increase in the latency of I peak ABR`s wave. In the pathological study of the inner ear structures of rats, intense proliferation of fibroblasts with granuloma formation, inflammatory lymphohistiocytic infiltrates, dystrophic and necrotic changes in the epithelium, hair cells, partial loss of nerve cells in the spiral ganglion, sclerotic changes of the vascular stripe were found. When conducting the clinical part of the study, an increase in the frequency of dysfunction of the inner ear OHC in patients with euthyroid AIT (the percentage of right ear is 40.7% (p=0.011), on the left – 37.3% (p=0.023)), as opposed to indicators of the control group (13.8%). Analyzing statistically significant differences when registering the ABR, lengthening the of the first ABR`s peak latency to 2.05 (1.90; 2.30) ms in the main group compared with the control group (p≤0.05), the absence of an increase in inter-peak intervals I-III and IV indicates a lesion of the inner ear structures in AIT. It was determined that in patients with euthyroid AIT, the function of OHC during the registration of DPOAE at a frequency of 8000 Hz depends on the blood level of ATTP, ATTG and prestin protein. Dysfunction of OHC is determined at significantly higher levels of blood ATPO to 89.20 (29.20;165.30) IU/ml, ATTG to 290.00 (82.00;421.30) μMO/ml of prestin protein to 139,00 (114.20;289.45) pg/ml. It was revealed that in patients with euthyroid AIT with dysfunction of the OHC at a frequency of 5714 Hz, there are significant differences in the indicators of the immune system only in the level of IgA. In cases of dysfunctions of OHC at a frequency of 8000 Hz, there are more significative differences: T-lymphocyte content (75.90 (72.55;78.85)%), T-helper cells (50.40 (44.45;56, 65)%), IgA (3.43 (1.57;3.98) g/l), IgG (17.51 (11.04;18.80) g/l). In general, the worsening of OHC function in AIT patients is associated with an increase in blood levels of ATPO, ATTG, T-lymphocytes, T-helper cells, IgA, IgG and prestin protein in blood.
The main pathogenetic mechanism of the pathological process of euthyroid AIT is the predominance of the dysfunction of the immune system in the form of products of specific (immunoglobulins) and the level of T-link immunity. Status and regulation of thyroid function play a secondary role in the formation of the pathological process in these patients. The function of OHC at the frequency of 8000 Hz is significantly related to the autoimmune process (ATTG) and the synthesis of prestin, which is the leading mechanism in the pathogenesis of hearing impairment in euthyroid AIT.
