Asymmetric sensorineural hearing impairment in the adult population

Abstract

The relevance of the problem of a sensorineural hearing loss (ASNL) arises from the necessity of the special approaches to the diagnostics of this condition, the complications accompanying this pathology, and the difficulties encountered in the implementation of the methods designed for hearing rehabilitation of such patients. The objective of the present study was to estimate the prevalence of ASHL among the adult population. The sensorineural impairment of hearing was diagnosed in a total of 2456 (72%) examined patients presenting with hearing loss. To determine the presence of asymmetry of sensorineural hearing loss, we employed three counting techniques allowing (1) to calculate the difference between the average hearing thresholds at four frequencies within the range from 0.5 to 4 kHz (the difference was found to be 15 dB or more in 17% of the patients), (2) to calculate the difference between the degrees of hearing loss in the right and left ears (the difference was documented in 47% of the patients), (3) to calculate the difference between the hearing thresholds at least at a single frequency within the range from 0.125 to 8 kHz (he difference was found to be 15 dB or more in 71% of the patients). When using the third method to characterize asymmetry of hearing impairment, it was identified in most patients (53%) at one or two frequencies. Moreover, there was a large number of the patients (13%) with asymmetry apparent over the entire frequency range. A high degree of threshold asymmetry (in excess of 40 dB) was more often noted in the mid-frequency range. In the majority of the patients, the asymmetry manifested itself as the different degree of bilateral sensorineural hearing impairment (51%) or unilateral sensorineural hearing loss with the normal hearing ability preserved in the contralateral ear (35%). The results of the present study give evidence of the necessity of developing a reliable method for the identification of clinically significant ACNL.