Abstract

OBJECTIVE: The purpose was to evaluate brain plasticity that contributes to speech performance after cochlear implantation (CI) in postlingual elderly (>60 years) patients.

MATERIALS and METHODS: Fifteen elderly postlingual deaf patients who underwent preoperative brain fluorodeoxyglucose positron emission tomography (FDG-PET) and were followed-up for more than 1 year after CI were included. The mean age of these patients was 64.6 years (range, 60–80 years). Based on their sentence score at 1 year after CI surgery, the patients were classified into two groups: poor performers (CID score of <80) and good performers (CID score of ≥80). The duration of deafness, age at operation, preoperative residual hearing, and preoperative brain metabolism were analyzed. SPM5 software was used for FDG-PET image preprocessing and statistical analysis.

RESULTS: Neither deafness duration nor preoperative residual hearing was associated with speech performance. The age at operation had little association with speech performance. Deaf patients whose brain metabolism was higher in frontotemporal regions became good CI users but those with higher metabolism in visual association areas became poor CI users. No significant cortical area of higher metabolism was associated with the duration of deafness.

CONCLUSION: Overactivation in the visual processing pathway correlated with a poor CI outcome at 1 year. Deaf patients who are going to be poorer performers with CI devices maintain visual information processing during preoperative silent resting periods.