Ringing cochlear microphonic waveform ini auditory neuropathy subjects : characteristics and outcomes of cochlear implantation

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Impedance, neural response telemetry, and speech perception outcomes after reimplantation of cochlear implants in children

OBJECTIVE: To compare mean impedance levels, neural response telemetry (NRT), and auditory perception after initial and explant-reimplant pediatric cochlear implants. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral hospital and cochlear implant program. PATIENTS: Children 0 to 16 years inclusive who have undergone explant-reimplant of their cochlear implant. INTERVENTION: Impedance levels, NRT, and speech perception performance. MAIN OUTCOME MEASURES: Impedance, NRT, and auditory perception at switch on, 3 months, 12 months, 3 years, and 5 years after initial cochlear implant and reimplantation. RESULTS: The explant-reimplant group receiving Cochlear contour array had significantly (p < 0.001) raised impedance at switch on, 3 months, 12 months, and 3 years, compared with their initial implant. The explant-reimplant group receiving Cochlear straight array had marginally significant (p = 0.045) raised impedance at switch on, 3 months, 12 months, and 3 and 5 years. Infection was associated with greater increases in impedance in the reimplant Contour group. NRT was increased in the explant-reimplant group but not significantly (p = 0.06). Auditory perception returned to preexplant levels within 6 months in 61% of children. CONCLUSION: Impedance is higher after explant-reimplant and remains increased for years after explant-reimplant with Cochlear contour and to a lesser degree the straight array device.9 page(s

Frequency-specific electrocochleography indicates that presynaptic and postsynaptic mechanisms of auditory neuropathy exist

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Correlation between speech perception and electrically-evoked auditory potentials measured in subjects with Auditory Neuropathy after cochlear implantation

Cochlear implantation is considered an effective management option for children diagnosed with auditory neuropathy. It is assumed that this is because, in most cases of auditory neuropathy, the lesion is located at the inner hair cells or the primary afferent synapse, rather than the auditory nerve per se. Previous studies reporting benefit in cochlear implantation in this population of subjects have assessed benefit using behavioural measures such as speech perception tests. In this study, we have assessed the benefit of cochlear implantation in subjects with AN using objective assessments including electrically-evoked auditory brainstem responses (ABR) and cortical auditory evoked potentials (CAEP) and have correlated this with subjective assessments of speech perception. Correlations between objective and subjective assessments demonstrate that the role of electrical stimulation in providing benefit is not simple. We show that there is no correlation between the electrically-evoked ABR and the electrically-evoked CAEP waveforms. Nor is there a correlation between the objective tests and speech perception abilities.1 page(s