The condition of bioelectrical activity of the brain among the patients suffering diabetes mellitus type II with hearing impairment
Authors: Shidlovskaya Tetiana A. , Ovsyanik Kateryna V. , Navalkivska Nadiya Ya. 
Published: April 2021

Topicality: The sensorineural hearing loss (SNHL) is a polyetiological disease with a complex pathogenesis. Sensorineural hearing loss is also caused by metabolic disorders and system diseases, including diabetes mellitus (DM).Quite often at sensorineural hearing loss there are extraauralic manifestations of the central nervous system (CNS). On the other hand, with diabetes, there are also observed the affection of the nervous system both in the form of polyneuropathy and certain disorders of the CNS. Electroencephalography (EEG) is a reliable, universal, objective, non-invasive method of research the functional condition of the CNS.
Aim: to investigate changes in the condition of bioelectrical activity of the brain according to electroencephalography among patients with diabetes mellitus type II with impaired auditory function.
Materials and methods: 43 patients with diabetes mellitus type II were examined, who, according to subjective audiometry, revealed impairments of auditory function and 15 persons of the control group. The EEG research was performed using a computer electroencephalograph from the company “DX-System” (Ukraine) according to the generally accepted method.
Results and discussion: The qualitative analysis of EEG results among patients with diabetes revealed abnormalities in the functional condition of the CNS in the form of diffuse changes in bioelectrical activity of the brain, disorganization and desynchronization of basic rhythms, signs of irritation of brain structures, amplified by functional loads. Among the examined patients using background EEG we observed the expressed irritative changes, decrease in bioelectrical activity of a brain, desynchronization and disorganization of rhythms. Among many of them there were periodic sharp peaks and potentials, a tendency to accelerating the basic rhythm, and against this background, the increase in the content of slow waves (theta), mainly in the front leads. Moreover, the most pronounced changes in bioelectrical activity took place in the temporal and frontal leads. Thus, in patients with diabetes mellitus type II with SNHL disorganization and desynchronization of the EEG picture was detected in 34 patients (79.1 % cases). The expressed irritative changes were registered in 39 persons (90.6 % cases),
hypersynchronous bursts were detected in 15 patients (34.8%), sharp peaks and potentials were present in 21 person (48.8 %) Many patients had smoothed zonal differences – 25 persons (58.1%) and lack of reaction to eye opening – 15 patients (34.8%)The decrease of bioelectrical activity reached 86.0 % cases. The amplitude of the basic alpha rhythm of the EEG among the examined patients diabetes mellitus type II with SNHL is significantly (p<0.01) lower than the norm in the temporal, parietal and occipital leads, which was 31.8±2.5, 44.1±3.1 and 43.5±4.2 мkV, respectively. In a significant part of the examined patients (88.3 %) with hearing impairments on the background of diabetes mellitus type II, these manifestations were increasing by hyperventilation. Violations of bioelectrical activity of the brain in 97.6% of cases were symmetrical, which indicates diffuse cerebral changes in the functional condition of the CNS in this category of patients.
Irritations of the cortical structures of the brain were registered in all examined patients with diabetes mellitus type II. In many of these patients (97.6%) cortical irritation was combined with the involvement of deep brain structures. Thus, dysfunction of the diencephalic structures of the brain occurred in 48,8% of cases, diencephalic-stem – in 39,5%, mediobasal – in 9.3% cases. Only one patient had irritation of only the cortical structures.
So, among our examined patients with diabetes mellitus type II with impaired auditory function according to EEG there are pronounced violations of bioelectrical activity according to EEG, including changes in the cortical and deep - diencephalic and stem structures of the brain.
Conclusions:
1. The researches made by EEG method in patients with diabetes mellitus type II and SNHL objectively confirm the violation of the functional condition of the CNS among such patients.
2. In patients with diabetes mellitus type II and SNHL there are changes in bioelectrical activity mainly in the form of decreasing of bioelectrical activity of the brain (86,0%), expressed irritative changes (90.6%), irritation of deep structures of the brain (97,6), disorganization and desynchronization of the EEG picture (79.1% cases).
3. In patients with SNHL on the background of diabetes mellitus type II there is significantly (p<0.01) lower decreasing of amplitude of the alpha rhythm in comparison with the control values in temporal, parietal and occipital leads to 31.8±2.5, 44.1±3.1 and 43.5±4.2 mkV, respectively.