Prediction of speech intelligibility after cochlear implantation: Effect of cortical plasticity and cognitive abilities

• Applicant: Professorin Dr. Pascale Sandmann
• Subject Area: Otolaryngology, Phoniatrics and Audiology
• Term: from 2018 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 415896102

• Final Report Year: 2025

Final Report Abstract

There is a large variability in terms of speech recognition ability with a cochlear implant (CI). It can be assumed that this variability is related to cortical reorganization, i.e. changes in cortical activation. Therefore, a principal aim of this research project was to use electroencephalography (EEG) to show which cortical changes take place before and after implantation and how cortical reorganization affects speech understanding with CI. A further aim of this research project was to investigate whether the variability in speech recognition ability with a CI can be better explained if – in addition to previously identified demographic, audiologic and implantspecific factors – cognitive and electrophysiological measurement parameters are also included. We conducted a prospective longitudinal study with postlingually deafened patients who were tested once before and twice after implantation (five weeks, six months). A group of patients with normal hearing served as a control group. In addition to audiometric and standardized cognitive tests, the participants performed a recognition task with two-syllable words (auditory, visual, audio-visual) and a categorization task with faces. The participants focused their attention on either the visual or auditory signals. The evaluation of the EEG data included the analysis of evoked potentials as well as topographical analyses, time-frequency analyses, source analyses and connectivity analyses. The results showed deprivation-related changes in the cortical processing of static and articulating faces in the CI patients even before implantation, which largely persisted after six months of CI experience. There were also remarkable group differences with regard to auditory and audio-visual stimulus conditions after six months, although an approximation to the activation pattern of normal-hearing listeners took place during the first months of CI experience. In addition to visually dominated audio-visual speech processing, CI patients showed a positive correlation between the (generally reduced) visual cortical response (P1 amplitude) and auditory CI speech recognition ability. The computation of statistical models and cross-validation procedures showed that the variance of CI speech recognition ability can be better explained if – in addition to previously identified factors (“age at implantation”, “duration of hearing loss”, “hearing threshold” and “hearing aid use”) – the parameters “lip-reading ability” and “verbal learning and memorization ability” are included into the models. Overall, the prospective longitudinal study could be carried out successfully. The research project resulted in clinically relevant findings with regard to cortical plasticity and its connection the speech recognition ability with a CI. The findings of this project have been published in several scientific articles and they also provide an important foundation for future studies.

Publications

• Electrophysiological differences and similarities in audiovisual speech processing in CI users with unilateral and bilateral hearing loss. Current Research in Neurobiology, 3, 100059.
  Layer, Natalie; Weglage, Anna; Müller, Verena; Meister, Hartmut; Lang-Roth, Ruth; Walger, Martin; Murray, Micah M. & Sandmann, Pascale
  
• Side-of-Implantation Effect on Functional Asymmetry in the Auditory Cortex of Single-Sided Deaf Cochlear-Implant Users. Brain Topography, 35(4), 431-452.
  Weglage, Anna; Müller, Verena; Layer, Natalie; Abdel-Latif, Khaled H. A.; Lang-Roth, Ruth; Walger, Martin & Sandmann, Pascale
  
• The timecourse of multisensory speech processing in unilaterally stimulated cochlear implant users revealed by ERPs. NeuroImage: Clinical, 34, 102982.
  Layer, Natalie; Weglage, Anna; Müller, Verena; Meister, Hartmut; Lang-Roth, Ruth; Walger, Martin; Murray, Micah M. & Sandmann, Pascale
  
• Visual ERPs to face onset predict the speech recognition ability after cochlear implantation. International Conference of Cognitive Neuroscience, Mai 2022, Helsinki, Finnland
  Weglage, A., Layer, N., Müller, V., Walger, M., Lang-Roth, R. & Sandmann, P.
  
• The time course of auditory and audio-visual speech processing in cochlear-implant users revealed by cortical evoked potentials. International Evoked Response Audiometry Study Group, September 2023, Köln, Deutschland
  Sandmann P., Layer N., Weglage A., Meister H., Lang-Roth R., Walger M. & Müller V.
  
• Changes in visually and auditory attended audiovisual speech processing in cochlear implant users: A longitudinal ERP study. Hearing Research, 447, 109023.
  Weglage, Anna; Layer, Natalie; Meister, Hartmut; Müller, Verena; Lang-Roth, Ruth; Walger, Martin & Sandmann, Pascale
  
• Der Einfluss von Aufmerksamkeit auf visuell evozierte Potenziale im Laufe der CI-Versorgung. Jahrestagung der Deutschen Gesellschaft für Audiologie, März 2024, Aalen, Deutschland
  Weglage A., Layer N., Radecke, J.-O., Müller V., Walger M., Lang-Roth R., Meister H. & Sandmann P.
  
• Specific effects of auditory deprivation and cochlear implantation on cortical auditory, visual and audio-visual speech processing: A prospective longitudinal EEG study. World Congress of Audiology, September 2024, Paris, Frankreich
  Sandmann P., Müller V., Meister H., Lang-Roth R., Walger M. & Weglage A.
  
• Verändert sich nach der CI-Versorgung die cross-modale Modulation von kortikalen Antworten? Jahrestagung der Deutschen Gesellschaft für Audiologie, März 2025, Göttingen, Deutschland
  Sandmann P., Wächtler M., Müller V., Walger M., Lang-Roth R. & Weglage A.
  
• Vorhersage des Versorgungsergebnisses mit Cochlea-Implantat. Jahrestagung der Deutschen Gesellschaft für Audiologie, März 2025, Göttingen, Deutschland.
  Weglage A., Heiden P. & Sandmann P.