Central recruitment in individual with auditory neuropathy

Auditory neuropathy (AN) describes patients with dysfunction of the auditory nerve in the presence of preserved cochlear outer hair-cell receptor functions in presence of normal otoacoustic emissions and/or cochlear microphonics. In individuals with auditory neuropathy speech are disproportionate to their hearing sensitivity and reported to be dependent on cortical evoked potentials. In individuals with AN, who have normal cortical potentials have better speech identification scores when compared to those with abnormal cortical potentials reflect relation between the cortical potentials and the speech identification scores. One group comparison research design was used for present study. The purpose of the study was to compare shift in latency of LLR peaks at different sensation level in subjects with auditory neuropathy and age matched normal individuals. 6 subjects (11 ears) diagnosed as having auditory neuropathy and 6 subjects (12 ears) with normal hearing Sensitivity participated for the study. Pure tone audiometry, immittance, reflexometry and otoacoustic emissions were administered. ABR was recorded for all the subjects at a repetition rate of 11.1 at an intensity of 90 dB nHL. LLR was carried out at different intensity levels for/da/speech stimulus at an intensity of 90 dB nHL. Latency of N1 and P2 of LLR was calculated at different sensation levels for both the groups. Descriptive analysis was carried out to find out the mean and standard deviation for latency of N1 and P2 for both, AN and normal hearing group. There was delay in latency of N1 and P2 for individuals with auditory neuropathy.