gms | German Medical Science

To investigate the correlation between intra-operative Neural Response Imaging (NRI) recordings and Most Comfortable levels (M levels) in paediatric users.

10 subjects, implanted with a CII Bionic Ear^® or a HiRes 90K^TM, participated in the study. NRI responses- generated as a result of the electrical stimulation of the cochlea through the cochlear implant- were measured intra-operatively at apical, medial and basal locations within the cochlea. Stimulating electrodes were 3, 9 and 15 and recording electrodes were 1, 7, and 13 respectively. In case of insertion depth, non-auditory stimulation, electrode impedance or integrity issues, the nearest appropriate electrode was used. Behavioral M levels were measured at first fitting and at the following post-first fitting intervals: 3 months, 6 months, and 12 months. M levels were measured by using the default automatic settings of the SoundWave^® fittting software- fully sequential, 16 channels, narrowest possible pulse width. Correlation between NRI responses and M levels was examined; both initial fitting levels and more stable program levels reached after 6 months of implant use were considered for the correlation.

Findings about the correlation between NRI thresholds and behavioral M levels will be presented. Preliminary results show that intra-operative tNRI is 83% of first fitting M levels and 61% of stable M levels.

Results show that NRI is a useful and practical objective tool: it can be used for paediatric fitting if it is difficult to obtain user feedback and the recordings can be easily performed intra-operatively during the flap closure without lengthening the operating time.