Role of visuo-auditory integration in speech comprehension in deaf subjects with cochlear implants

Sebastien Lagleyre, Service ORL, Hopital Purpan

Abstract
Because multisensory integration results in perceptual improvements by reducing ambiguity, we have investigated the role of visuo-auditory interactions in speech comprehension in deaf subjects that received a cochlear implantation (Nucleus). In a population of 56 cochlear implanted patients (CI) we performed a longitudinal post-implantation analyze of the performances in bisyllabic words recognition in three modalities : lipreading, speech and visuo-auditory. At time of implantation, patients show a greater word recognition using lipreading compared to control (36% vs 9%). In CI, lipreading performances remain important (37%) even 3 years after implantation. Cochlear implants generate a significant improvement in auditory speech recognition as expressed as an increase in performances from 45% at one month to 79% after one year, followed by a slight increase in the following years (85% at 3 years). Visuo-auditory stimulation is largely beneficent to speech recognition, the performances increasing to 85% at one month and reaching nearly 100% after one year. These results indicate that in CI the multisensory gain is maximum during the first months after implantation suggesting a functional reorganization of the neuronal network involved in speech comprehension during the corresponding period. Ongoing PET scan analysis will assess the nature of such cross-modal plasticity.

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