Use of fNIRS for Improved Prognosis for Cochlear Implant Candidates

Background

The large variability in speech understanding by adult cochlear implant (CI) users remains a challenge in spite of technical advances. Only around 10% of this variability can be explained by subject factors such as duration of deafness. Recent brain imaging research suggests that plastic changes in the cortex due to auditory deprivation may play a crucial role in CI outcomes.

Objective

This study used functional near-infrared spectroscopy (fNIRS) in a longitudinal study in adult CI candidates to determine how brain plastic changes due to periods of deafness and due to re-activation of the auditory pathways after implantation influence speech understanding outcomes.

Methods

15 adult CI candidates were imaged before implantation and at 1, 3, and 12 months post-implantation while listening to speech, or speech-reading. Speech perception tests were carried out at the same times and a cognitive assessment performed.

Results

Preliminary results indicate that the degree of cross-modal activation of the auditory cortex by visual stimuli, and how it changes over time after implant, might be clinically useful to aid prognosis before implantation and to understand the reasons for poor recovery rate of speech understanding post-implantation.

Conclusions

fNIRS can reveal significant changes in the function of the language-associated networks in the cortex, and these changes influence the ability to adapt to CI stimulation after implantation.

Acknowledgements

The study was supported by the Garnett Passe and Rodney Williams Memorial Foundation. The Bionics Institute acknowledges the support it receives from the Victorian Government through its Operational Infrastructure Support Program.