State Institution "Institute оf Otolaryngology named after Prof. O. S. Kolomiychenko of the National Academy of Medical Sciences of Ukraine", Kyiv
Introduction. While being on duty military personnel can be exposed to powerful sounds, which are often accompanied by a shock wave due to use of various types of weapons, causing acoustic and barotraumatic damages in the auditory system of occupational pathology.
The aim of the study was to determine changes in the central parts of the acoustic analyzer, according to the examination of the longlatent auditory evoked potentials (LLAEP) in the military personnel, who received acoustic traumas in the zone of antiterroristic operations (ATO).
Materials and methods. We studied the function of the central parts of the acoustic analyzer in the military personnel with acoustic trauma, suffered in the ATO zone. The main group consisted of 50 military persons with acoustic trauma of the most common type of audiometric curves and the degree of severity of sensorineural hearing loss with an asymmetric impairment of the auditory function and the downward type of the audiometric tonal curve. The control group was presented by15 healthy individuals, who had no contact with sounds of high intensity. There were examined 65 individuals in total. The registration of longlatency (cortical) auditory evoked potentials was performed, using generally accepted methods with the analyzing system "Eclipse" of the company "Interacoustics" (Denmark). In the analysis of the obtained curves the clearness of the response, the shape of the curve, latent periods of peaks (LPP) of waves P1, N1, P2 and N2 LLAEP were taken into account. Results. When studying the central parts of the auditory system in military persons with acoustic trauma, according to the data of registration of the auditory evoked potentials, we have detected disorders in the cortical part of the auditory analyzer by the LLEAP in all (100 %) surveyed and in 84 % of cases in the brainstem structures, according to the SLEAP. Consequently, the irregularities in the central parts of the acoustic analyzer were found in all surveyed servicemen with acoustic trauma, who took part in ATO. Such changes were rapidly evolved and covered cortical and the subcortical and brainstem structures of various degree. We have detected the authentical increasing the average meanings of the LPP components P2 and N2 LLEAP in patients, in comparison with the control group. So, LPP component P2 in the military personnel with acoustic trauma made (189,6 ± 2,4) ms, whereas the meanings in the control group were (175,9 ± 2,6) ms (t = 3.87; P < 0,05 ), and N2 (302,2 ± 3,8) ms at a rate (251,4 ± 3,1) ms (t = 10,36; P < 0,0 1).
Conclusions. The application of objective methods in the examinations of the auditory system, in particular, LLEAP, is of great significance in terms of topical diagnostics, solving expert questions, identification and objectification of the severity of an illness in the military personnel with acoustic trauma, who took in ATO as well as for preventive and therapeutic measures.
According to the data of LLEAP in military personnel with acoustic trauma, who were in the zone of ATO, there have been found disorders in cortical and subcortical structures of the auditory analyzer, as evidenced by authentical elongation of LPP component P2 and N2 LLEAP up to (189,6 ± 2,4)ms and (302,2 ± 3,8) ms, respectively. The obtained data suggest an important role of the state of the cortical parts of the auditory analyzer in the development of sensorineural disorders with acoustic trauma, received in real combat conditions.
Key words: sensorineural hearing loss, acoustic trauma, acoustic analyzer, auditory evoked potentials