Electrocochleography in Individuals with Auditory Dys-Synchrony

Abstract

Auditory neuropathy is characterized by the absence or severe impairment of auditory brainstem responses with the preservation of otoacoustic emissions and/or cochlear microphonics. In the present study extratympanic electrocochleography was recorded in individuals with auditory dys-synchrony and those with normal hearing. Cochlear rnicrophonics was present in all the individuals in both groups. Amplitude of the cochlear microphonics was significantly higher in individuals with auditory neuropathy/dys-synchrony subjects when compared to normal hearing individuals Latency of the cochlear microphonics was also significantly prolonged in individuals with auditory neuropathyldys-synchrony. Further, for the normal hearing individuals the amplitude of the cochlear microphonics was enhanced when noise was presented in the contralateral ear whereas in individuals with auditory neuropathy/dys-synchrony there was no difference in the amplitude across the two conditions. Presentation of contralateral noise did not affect the latencies in both the groups. Summatillg potential was absent in 40% of normal hearing individuals and action potential was present in all the individuals with normal hearing, whereas both the potentials were absent in all the subjects with auditory neuropathy/dys-synchrony. There was a significant reduction in the amplitude of summating potential s and action potentials in individuals with normal hearing when it was recorded in the presence of noise.