Estimating eighth nerve survival by electrical stimulation.

L Smith; F B Simmons

doi:10.1177/000348948309200105

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Estimating eighth nerve survival by electrical stimulation.

L Smith·F B Simmons

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Abstract

Determining nerve survival is important in selecting patients for cochlear implants, and in predicting outcomes from such implants. In search of a possible method we deliberately destroyed nerve fibers (ganglion cells) in 17 cat cochleas to produce a range of degenerations. Months later, we electrically stimulated these ears (and seven controls) and recorded electrical ABR input-output functions. Cats with no surviving ganglion cells showed no ABR activity. Cats with 5%-10% surviving cells had ABRs which typically had normal thresholds but decreased input-output functions. The suprathreshold slopes of these input-output functions reliably predicted ganglion cell survival for all degrees of degeneration. Thus, perceptual (or electrical) threshold is a poor indicator of nerve survival. Loudness growth (or growth in the electrically-induced auditory brainstem response) is a good index of surviving ganglion cells.

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Animals Auditory Threshold Brain Stem Cats Cell Survival Cochlea Cochlear Nerve Evoked Potentials, Auditory Nerve Degeneration Nerve Fibers Spiral Ganglion Journal Article Research Support, U.S. Gov't, P.H.S.

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L Smith, F B Simmons. Estimating eighth nerve survival by electrical stimulation.. https://doi.org/10.1177/000348948309200105

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