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The authors analyse their own and literature data on surgical treatment of Meniere's disease (MD) as intervention on the endolymphatic sac with assessment of various modifications by long-term results, on sympathetic intraaural and extraaural lesions. Surgical interventions on the endolymphatic sac are pathophysiologically validated. Insufficient knowledge on hydrodynamics in the internal ear labyrinth and the role of endolymphatic hydrops in MD pathogenesis hampers assessment and further development of surgical treatment of the disease. Future lines of the research in Meniere's disease and its treatment are outlined.

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The paper characterizes age-specific involution of the ENT tissues, acoustic and vestibular analyzers, hearing and equilibrium defects. Original investigations of the authors give wider possibilities of early detection of age-related failure of the internal ear functions. Relevant tests are proposed.

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Current views on neurosensory hypoacusis necessitate clear definitions and distinctions between acute and sudden hypoacusis as independent nosological entities of hearing defects. Sufficient data available make it possible to characterize the above forms clinically, etiologically and pathogenetically. Common views of many Russian ENT specialists on sudden and acute hypoacusis as the same entity complicate solving the problem of neurosensory hearing disorders. Orderly classification of acute and sudden hypoacusis variants and subgroups will encourage differentiated and sound approach to treatment of neurosensory hearing loss.

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To clarify the role of dynamic registration of acoustic impedance in early detection of hypoacusis in otosclerosis, the authors analyzed impedometry readings in subjects with unilateral otosclerosis. Special emphasis is laid on cases with minor audiogram bone-air intervals. Based on comparison of contra- and ipsilateral reflexes, registration of the acoustic reflex may provide early signs of otosclerosis.

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Comparative characteristics of acoustic impedance measured in 130 healthy children aged from 1 month to 16 years suggested possibility of the method usage as a screening test for latent disorders of the middle ear. The combination of the dynamic impedance metry with a functional test (mucosal anemization and inflation of the acoustic tube) significantly contributed to the diagnostic accuracy of the method.

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Results are presented of plotting a dimeric mathematical model of human internal ear cochlea with allowance for the dependence of the basilar membrane mass on the length of its region between the registered point and the labyrinth wall of the threshold window region. Investigations carried out on such a model by means of a computer permitted calculation of the location of the rounding curve maximum point of the displacement waves of the basilar membrane for the frequencies of 0.05-95 kHz included. An analysis of the rounding waves of the sonic and ultrasonic range showed that although above 20 kHz the curves maximum acquires slured contours, it is well enough pronounced up to 75 kHz. The results obtained suggest adequate effect of ultrasounds on the internal ear and analogy of mechanical reaction of human cochlea to sonic and ultrasonic stimulation.

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The hearing function in 32 patients with various forms of disseminated sclerosis was measured. Their hearing sensitivity, loudness and discrimination as well as spatial hearing and ability to localize sound sources were determined. In the absence of changes in hearing sensitivity, loudness and discrimination all the patients displayed marked disorders or complete loss of their capability to localize sound sources in the vertical plane but retained their capability to localize sound sources in the horizontal plane. Therefore, in contrast to the widely recognized concept that the hearing function in patients with disseminated sclerosis remains intact, spatial hearing impairment should be viewed as a pathognomonic symptom which is very important for diagnosing it at all stages of its development, including the earliest stages.

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Short-latency acoustic evoked potentials (SAEP) were recorded in 40 patients with vestibulocochlear neurinoma and 15 patients with unilateral cochlear hypoacusis. The results were compared with their psychophysical audiometric parameters. In the case of neurinoma, electric responses typically showed elongation of single waves and intervals between two peaks. In addition, they also displayed two other features. One of them was horizontal or ascending configuration of the curve reflecting the latency/intensity function. This indicates the absence of an electrophysiological equivalent of the phenomenon of loudness increment acceleration and, in more general terms, the stability of responses: lack of SAEP wave shortening and enhancement of acoustic stimulation level. The second feature was deterioration of the pattern and disintegration of individual complexes with a greater number of realizations. This can be attributed to the lability of nervous structures, in the case of neurinoma. This feature may also be responsible for the generally recognized concept that in neurinoma primary SAEP waves are not detectable when the routine method of recording responses to a large number of stimuli is used. These parameters are pathognomonic of neurinoma of the vestibulocochlear nerve and are never identified in the case of unilateral hypoacusis caused by cochlear lesions.

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Perfusion of the cochlear perilymphatic space was performed in guinea pigs with complete or partial removal of K+, Na+ or Ca++ from the solution. The most obvious changes of the endocochlear potential occurred in the deficiency of Na+ in the perilymph: i. e., after a short increase the potential steadily diminished in accordance with the degree of Na+ deficit in the perilymph. The deficit of K+ in the perilymph caused a lesser and reversible reduction of the potential. The absence of Ca++ in the perilymph did not affect the potential.

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A piesoelectric bony telephone for determining audible thresholds while sound is conducted through the bone over expanded frequency range of 0.25 kHz up to 20.0 kHz is described. Fundamental limitations of electromagnetic bony telephones preventing them from metering audible thresholds at the frequencies greater than 6 kHz have been revealed. Analysis of the piesoelectric transducer equivalent circuit has demonstrated on principle the possibility to measure audible thresholds with such a device over the expanded frequency range to 20 kHz. A model of piesoelectric bony telephone conforming the IEC recommendations is described and some experimental results obtained for the frequency range of 0.25 kHz to 20.0 kHz are presented.

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