A Quantitative Electroencephalography Study on Cochlear Implant-Induced Cortical Changes in Single-Sided Deafness with Tinnitus

• Main Authors: Jae-Jin Song, Kyungsoo Kim, Woongsang Sunwoo, Griet Mertens, Paul Van de Heyning, Dirk De Ridder, Sven Vanneste, Sang-Youp Lee, Kyung-Joon Park, Hongsoo Choi, Ji-Woong Choi
• Format: Article
• Language: English
• Published: Frontiers Media S.A. 2017-05-01
• Series: Frontiers in Human Neuroscience
• Subjects: single side deafness; tinnitus; cochlear implantation; electroencephalography; dynamic peripheral reafferentation
• Online Access: http://journal.frontiersin.org/article/10.3389/fnhum.2017.00210/full

The mechanism of tinnitus suppression after cochlear implantation (CI) in single-sided deafness (SSD) is not fully understood. In this regard, by comparing pre- and post-CI quantitative electroencephalography (qEEG), we explored cortical changes relevant to tinnitus improvement. In SSD patients who underwent CI, qEEG data were collected: (1) before CI, (2) 6 months post-operatively with CI-on, and (3) 30 min after CI-off and source-localized cortical activity/functional connectivity analyses were performed. Compared to the pre-operative baseline, the CI-on condition demonstrated significantly decreased activity in the right auditory- and orbitofrontal cortices (OFC) for the delta frequency band as well as decreased connectivity between the auditory cortex/posterior cingulate cortex for the delta/beta2 bands. Meanwhile, compared to the CI-off condition, the CI-on condition displayed decreased activity in the right auditory cortices/OFC for the delta band, and in bilateral auditory cortices, left inferior frontal cortex/OFC for the gamma band. However, qEEG analyses showed no significant differences between the CI-off and baseline conditions. CI induced overall decreased cortical activity and functional connectivity. However, judging from no differences between the CI-off and baseline conditions, CI-induced cortical activity and functional connectivity changes are not by cortical plastic changes, but by dynamic peripheral reafferentation.