Author(s)
Phillip Chung, BS
Elizabeth Bartlett, PhD
Suzan Parhizgar, MD
Megan Kuhlmey, AuD
Francesca Zanderigo, PhD
Akiva Mintz, MD, PhD
Hae-Ok Ana Kim, MD
Affiliation(s)
Columbia University;
Abstract:
Objective: To understand the neurobiological mechanisms responsible for hearing restoration in individuals with single-sided deafness (SSD) after cochlear implantation (CI).
Study Design: Observational longitudinal study.
Setting: Academic hospital.
Patients: Two adult patients with single-sided deafness who underwent cochlear implantation.
Interventions: Cochlear implantation.
Main Outcome Measures: The main outcome measure of this study is the change in neural activation patterns in individuals with SSD after receiving CI. To assess these changes, the study analyzed 18F-FDG-PET neuroimaging data acquired both before CI and six months after CI activation. 18F-FDG radioactivity measured 30 minutes after tracer injection was used as a proxy of neural activity. The comparative analysis of these images was carried out using statistical parametric mapping (SPM). Voxel-based paired t-test statistics, conducted across the whole brain, compared the intensities in pre-CI and post-CI images. The intensity of each image was normalized by the image’s global mean intensity. Regions with a p-value (family-wise error corrected) of less than 0.05 and a size threshold of at least 10 voxels were considered statistically significant.
Results: The results of the study indicate a statistically significant increase in neural activation in the anterior region of the superior temporal gyrus (ipsilateral to the side of hearing loss) after CI in individuals with SSD. This region of increased activation was found to have a size of 13 voxels and a p-value of 0.042. These findings were further validated by examining the patients' auditory function tests and cochlear implant usage data, which revealed significant improvements in auditory function post-implantation and substantial usage of the cochlear implant. This strengthened the inference that the heightened activation was attributable to the cochlear implant.
Conclusions: PET CT may be a novel method of examining cortical changes after CI. SSD provides a useful model to examine hemispheric differences. In this preliminary study in two patients, we observed increased neural activation within the anterior region of the superior temporal gyrus, ipsilateral to the side of hearing loss. This region plays a crucial role in auditory processing, language comprehension, and speech perception, making it a significant contributor to the neurobiological mechanisms underlying hearing restoration in SSD patients following CI.
Professional Practice Gap & Educational Need: The neurobiological mechanisms underlying hearing restoration after CI in SSD patients are poorly understood.
Learning Objective: To identify changes in neural activity following CI in individuals with SSD.
Desired Result: The study's desired results include enhancing physicians' understanding of the neurobiological mechanisms underlying hearing restoration in SSD patients following CI, which may help in understanding variations in CI outcomes among different individuals.
Level of Evidence – V
Indicate IRB or IACUC: Columbia University, IRB-AAAU0501