It is known that vascular factor is one of the main factors of occurrence and development of SHL of any etiology. Our previous studies have shown that this statement is also true in relation to sensorineural disorders that occur in acoustic trauma. With acoustic trauma, both peripheral and central – the brainstem and cortical departments of the auditory analyzer suffer. At the same time, in terms of clarifying the topic of the lesion of the auditory system, the temporal characteristics of the SLAEP are very informative, which allow to identify violations in the brainstem structures of the auditory analyzer, including those in the early stages. On the other hand, it is known that the correlation analysis of the results of instrumental studies is very important in relation to the characteristics of the relationship between certain indicators that characterize the relevant processes.
The purpose of the study is to determine the correlation coefficients between the temporal indices of SLAEP and
quantitative values of rheoencephalography data to clarify the relationship (correlation) between the state of the brains-
tem structures of the auditory analyzer and cerebral blood circulation in the carotid and vertebrobasilar systems in pa-
tients with acoustic trauma.
Materials and methods: to achieve this aim, we examined 71 patients with acoustic trauma at the age of 19-50 years, with predominantly bilateral asymmetric sensorineural disorders, a descending type of audiometric curve, a moderate degree of decrease in auditory function, the most pronounced significant (P<0.01) increase in hearing thresholds to tones 4, 6 and 8 kHz on the tonal threshold audiometric curve.
Cerebral blood flow in patients with acoustic trauma was studied by rheoencephalography using a computer rheograph of the company «DX-systems» (Ukraine) according to the generally accepted method. Registration of shortlatency auditory evoked potentials (SLAEP) was carried out using the analyzing system «Eclipse» of the company «Interacoustics» (Denmark), according to the generally accepted method.
To identify the correlation between the brainstem structures of the auditory analyzer and cerebral circulation in the vertebrobasilar and carotid systems, we took into account the correlation coefficients (r) and their errors (mr) between the main indicators REG in the carotid and vertebrobasilar systems, as well as the most informative time indicators SLEP patients with acoustic trauma.
Results and discussion: We carried out a correlation analysis between the values of LPP V wave of SLAEP and MPI (I-V) SLAEP, as well as the values of DCI, DSI and Pi in the carotid and vertebrobasilar systems in servicemen with combat acoustic trauma. The determination of such a connection is important because the severity of the lesion of the auditory system and the prognosis of the effectiveness of therapeutic measures in acoustic trauma largely depends on the presence and severity of dysfunction in the brainstem structures of the auditory analyzer. The obtained data confirm the influence of the state of cerebral circulation on the development of functional disorders of the cerebrospinal structures of the brain and the auditory analyzer in acoustic trauma.
There is a direct correlation in the development of such disorders with changes of the tone of cerebral vessels, but especially - violations of venous outflow. According to our data, in the carotid system, there is a weak direct correlation between the value of DCI, reflecting the tone of cerebral vessels, and LPP V wave of SLAEP (r=0.309; mr=0.063), as well as MPI I-V SLEP (r=0.322; mr=0.042). A weak direct correlation was also found between these indicators in the vertebralbasilar system, where the corresponding correlation coefficients were r=0.385, and mr=0.061, and r=0.348, and mr=0.036.
Between LPP V - SLAEP and DSI, which characterizes venous outflow, in the carotid system, r was 0.458 and mr=0.057, and for MPI I-V SLEP the coefficient was (r=0.463; mr=0.049). A direct correlation between these indicators was found in the vertebral-basilar system (the corresponding values were: r=0.516, mr=0.021 and r=0.523, mr=0.022).
Conclusion: Correlation analysis showed the presence of a relationship between the state of cerebral circulation according to REG in carotid, and, especially, in the vertebrobasilar systems and temporal indices of SLAEP in patients with acoustic trauma obtained in real combat conditions.
In patients with acoustic trauma, a significant inverse correlation was found between the temporal indices of SLAEP and the values of Ri according to REG data characterizing the state of pulse blood filling in the vertebrobasilar pool. Thus, a significant inverse correlation (r=-0,527, mr=0,068) is observed between the values Ri and the duration of the inter-peak interval I-V SLAEP, for the duration of the LPP V wave r was -0,512, and mr=0,026.
Only weak direct correlation in both carotid and vertebral-basilar systems was found with DCI indicators reflecting the state of cerebral vascular tone in the studied temporal characteristics of SLAEP. This may be due to the risk of changes in the tone of cerebral vessels (the tendency to both increase and decrease) in this contingent of patients.
With the value of DSI, which characterizes venous outflow, there is a direct correlation with both LPP V wave and MPI I-V SLAEP in both systems of cerebral blood supply. In the carotid system between LPP V SLAEP and DSI, r was equal to 0.458, and mr=0.057, and between MPI I-V SLAEP and the value of DSI was (r=0.463; mr=0.049), in the vertebrobasilar system, the corresponding values were r=0.516, mr=0.021 and r= 0.523, mr=0.022.
