Abstract

Relevance: The frequency of acute trauma in connection with full-scale war is increasing, which makes it important to study the auditory disorders caused by it. Subjective audiometry remains the most accessible and sufficiently informative method of studying auditory function. Subjective audiometry data of affected with acute trauma in the combat zone have certain features that should be taken into account when diagnosing hearing disorders in this contingent.

Aim: to provide a quantitative description of subjective audiometry indicators in persons who received acoustic trauma in the area of ​​hostilities with varying degrees of auditory function impairment.

Materials and methods: The subjective audiometry data of 152 servicemen with the most common descending forms of audiometric curves were analysed and divided into 3 groups taking into account the degree of auditory impairment: 1^st and 2^nd group include 65 persons and 3^rd – 22 people. The control group consisted of 15 healthy, normal-hearing people. The audiometric study was performed in a soundproof chamber, where the background noise level did not exceed 30 dB, with the help of a clinical audiometer AC-40 from the company “Interacoustics” (Denmark).

Results and discussion: According to the data of subjective audiometry, the most significant reliable (P<0.01) increase in hearing sensitivity thresholds relative to the norm in the soldiers with acute trauma on the tonal threshold audiometric curve was observed in the region of 4, 6 and 8 kHz of the conventional, and at all frequencies of the studied high-frequency (9-16) kHz ranges. Frequently the a “break” in perception both in the conventional and, especially, in the extended frequency range was observed.

Comparatively to the control, the tonal threshold audiometry data of the conventional (0.125-8 kHz) frequency range of 1-3 examined groups revealed a significant difference in the indicators of hearing thresholds for tones at all frequencies of the conventional range (with the exception of the frequency of 0.125 kHz for 1^st group) and the studied extended range: 9-16 kHz. At the same time, the indicators of tone threshold audiometry in individuals from group 3 both in the conventional and in the extended frequency ranges were significantly different not only from those in the control group at all studied frequencies, but also from the those ​​in groups 1 and 2. A significant difference was found in the tone threshold audiometry indicators between groups 1 and 2, starting from 2 kHz. Thus, at a frequency of 4 kHz, the indicators of hearing thresholds for groups 1, 2 and 3 were 26,72±1.89; 45.43±1.82 and 55.83±3.96 dB; in the area of ​​6 kHz – 38.72±2.52; 56.88±1.96 and 64.82±3.86 dB; at a frequency of 8 kHz – 41.52±2.36; 55.43±2.82 and 69.82±4.32 dB, respectively.

In 18,7% of cases in our examined patients from group 2 and 35,9% from group 3 were a slow increase in the intelligibility of the speech test when the sound pressure level increased. In a significant part of the examinees with combat acute trauma, the presence of discomfort and a decrease in DT according to Lüscher in the area of ​​2 and especially 4 kHz were observed, which indicates damage of the receptor part of the auditory analyser in such patients. Most of these signs were observed in patients from the 3 group. Thus, in group 1, signs of damage of the receptor parts of the auditory analyser occurred in 46,3%, in groups 2 and 3 – in 100% of cases.

Thus, violations on the tonal audiometric curves in patients with acoustic trauma received in the combat zone are mainly of a descending, often abrupt type with damage of the basal and mediobasal parts of the cochlea with the most significant increase of the hearing thresholds to tones in region of (4-8) kHz. The level of the hearing thresholds to the tones of this area has the greatest diagnostic and prognostic value in combat acoustic trauma. It is also important to consider indicators of speech intelligibility, the presence of discomfort and the value of DT according to the Lüscher method, especially at frequency 4 kHz.

Conclusions: According to the data of subjective audiometry in servicemen with acute trauma examined by us, the most significant (P<0.01) increase relative to the norm in hearing sensitivity thresholds on the tonal threshold audiometric curve was observed in the region of 4, 6 and 8 kHz of the conventional, and on all at the frequencies of the investigated high-frequency (9-16) kHz ranges. Hearing impairment in patients with combat trauma is accompanied by impaired perception of the speech test, slowed growth of its intelligibility, discomfort phenomena, relatively reduced or low DT according to Lüscher, especially in the 4 kHz region, which indicates damage of the receptor part of the auditory analyzer in such patients. The level of the hearing thresholds for the tones of the area (4-8) kHz has the greatest diagnostic and prognostic value in combat acute trauma. It is also important to consider indicators of speech intelligibility, the presence of discomfort and the value of DT according to the Lüscher method, especially at frequency 4 kHz.

Keywords: auditory analyzer, sensorineural deafness, acoustic trauma, subjective audiometry, tonal audiometry.