Statе of bioelectric activity of the brain in persons who received acoustic trauma in area of combat actions with a different stage of disorders in the auditory system
Authors: Shidlovskaya Tetiana , Shidlovskaya Tamara , Kozak Nikolay , Petruk Lyubov 
Published: January 2020

Topicality: Providing medical care to patients with combat acoustic trauma remains a topical issue of military medicine. There are works in the literature that show changes in the central nervous system under the influence of intense noise and at acoustic trauma, however, only in individual studies this objective assessment of the functional state of the central nervous system in patients with sensorineural hearing loss is shown as well as the promising use of them.
Aim: is to determine the most significant indicators of bioelectric activity of the brain according to the EEG in terms of prediction of the course and ways of co-rejection of sensorineural hearing disorders in persons who have received an acute trauma in the area of fighting.
Materials and methods: A group of servicemen with acoustic trauma was examined with the most characteristic, typical forms of audiometric curves – with a downward, precipitous type of the curve, which were divided into three groups depending on the degree of severity of sensorineural deafness. Group 1 – patients with initial non-expressed violations of the function of sound perception in the basal part of the cochlea, group 2 – with a more significant SDP accompanied by violations of speech and supra-vocal audiometry, the 3 groups included patients with severe violations of auditory function, lesions of the mediobasal part of the cochlea, often – with a "break" of perception of tones in the conventional range. A total of 205 patients with acoustic trauma were examined. As a control group, 15 healthy normal people were examined.
The EEG study was carried out using the computer electroencephalometry of the firm "DX-System" (Ukraine) according to the generally accepted methodology according to the scheme of electrodes "10-20"
Results: In qualitative analysis of electroencephalograms, servicemen with combat acoustic trauma revealed deviations from the norm in the functional state of the central nervous system, expressed in varying degrees, with the most characteristic decreasing of the bioelectric activity of the brain, irritative changes, disorganization and desynchronization of rhythms, more often in the temporal and frontal leads. The most significant changes were in patients with more severe hearing impairment (group 3). These changes indicate signs of severe cortex irritation and deep brain structures in servicemen with acoustic trauma from the combat zone.
The analysis of EEG quantitative indicators showed that changes in the bioelectric activity of the cerebral brain in patients with acoustic trauma were manifested by deformation of the basic rhythm with modulation and weakened response to functional loads, especially in the anterior leads. Patients had the significantly (P<0,05) decreased percentage of alfa rhythm in the normal picture of the EEG and the increased representation of beta and delta rhythm, both in the background recording and in the functional loading of photostimulations and hyperventilation . The most significant (P<0,05) changes in bioelectric activity, in comparison with the control group, were observed in individuals 2 and, personally, in 3 groups, with more significant violations of auditory function.
We also conducted a comparative analysis of EEG quantitative indicators among the study groups. The results of the research indicate a reliable (P<0,05) difference in the indices in the groups, from the first to the third group there was an increase in the representation of delta, theta and beta rhythm, most in the forward projections, and the decrease in the proportion of alpha rhythm. Moreover, these tendencies were maintained both during the background recording and at the functional loads.
Conclusions: Thus, the servicemen with an acoustic trauma revealed objective signs of functional disorders in the cortical and deep structures of the brain. As the auditory function decreases in patients with acoustic trauma and redistribution of the main EEG rhythms in the direction of the growth of manifestations of slow-wave activity on a disorganized background occurs, especially in the frontal and temporal infections. In the subjects we surveyed with severe violations of auditory function, there are significantly more significant changes in the central nervous system than in patients with an initial SDE, which should be taken into account when carrying out treatment and preventive measures aimed at rehabilitation of the victims of combat operations with acoustic trauma.