FUNCTIONAL MAGNETIC RESONANCE IMAGING OF AUDITORY CORTEX IN PARTIAL DEAFNESS TREATMENT

Abstract

BackgroundRecently, there has been a surge of interest in neuroimaging techniques that might help to objectively evaluate the residual hearing abilities of patients with hearing abilities of patients considered for partial deafness treatment (PDT). Such an evaluation might allow a wider range of PD candidates to benefit from cochlear implantation (CI). Although existing studies suggest that functional magnetic resonance (fMRI) may help predict the benefits of CI for hearing-impaired patients, little is known about the activity of the primary auditory cortex in patients with partial deafness. This study is the first to apply fMRI to examine BOLD signal changes in the auditory cortex induced by chirp stimulation in patients with partial deafnessMaterial and MethodTen patients considered for partial deafness treatment with electro-acoustic stimulation (PDT-EAS) and 10 patients considered for electrical complement treatment (PDT-EC) according to Skarżyński’s categorization of partial deafness treatment (PDT) participated in the study. fMRI measurements were performed in a 3T Siemens Magnetom Trio scanner at the Bioimaging Research Center (BRC) of the Institute of Physiology and Pathology of Hearing in Kajetany, Poland. During the fMRI study, subjects were presented with a chirp of two different bandwidths: 50–950 Hz (middle frequency 500 Hz) and 3000–5000 Hz (middle frequency 4000 Hz) at 90 dB(C) via MRI-compatible earphones. A sparse paradigm was used and the data was analyzed using the SPM8 package (Statistical Parametric Mapping, http://www.fil.ion.ucl.ac.uk/spm/). Standard preprocessing was followed by a second-level analysis for contrast of low and high frequencies.ResultsAs expected, bilateral activation in the auditory cortex was observed in response to stimulation by 500 Hz chirps in PDT-EAS and PDT-EC candidates. Activation in response to 4000 Hz chirps were found only in the PDT-EAS group but less strongly than for 500 Hz chirps.ConclusionsfMRI can be used as an objective way of assessing residual hearing in the auditory cortex of patients with partial deafness.