Does neural activity in the auditory cortex predict speech recognition with CI?

Introduction In this study, we showed an asymmetry of glucose metabolism in the primary auditory cortex (PrimAudCx) in patients with asymmetric hearing impairment using ¹⁸F]FDG-PET. However, this asymmetry decreased with increasing duration of deafness. The reduced asymmetry could result from cross-modal plasticity. Hence, our question is: Can neuronal activity in PrimAudCx be used as a predictor for speech recognition with cochlear implant (CI)?

Methods Seven patients received an [¹⁸F]FDG-PET examination prior to CI surgery. The asymmetry of glucose metabolism in PrimAudCx was quantified by region of interest analysis (25 %  hottest voxels) and expressed as an asymmetry index (AI; relative difference of both sides with respect to the mean value). Correlations were established between speech recognition with CI at 6 months after initial adjustment of CI and asymmetry in PrimAudCx as well as deafness duration.

Results The asymmetry in PrimAudCx showed a significant positive correlation with speech recognition with CI (R² = 0.68, p = 0.022). With an asymmetry index of = 3.5 % , speech recognition with CI of = 50 %  in OLSA in quiet and = 70 %  numerical understanding (65 dB SPL). Speech recognition with CI did not correlate significantly with deafness duration (p = 0.06).

Conclusions The neural activity, especially the asymmetry between ipsi- and contralateral PrimAudCx, could serve as a predictor for speech recognition with CI in asymmetrically hearing-impaired patients. The asymmetry of neuronal activity may predict speech recognition better than deafness duration based on the 7 investigated subjects. Studies with a larger number of subjects are necessary to confirm our hypothesis.

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Publication History

Article published online:
13 May 2021