Auditory Related Resting State fMRI Functional Connectivity in Tinnitus Patients: Tinnitus Diagnosis Performance

The purpose of the present study was to investigate functional connectivity in tinnitus patients with and without hearing loss, and design the tinnitus diagnosis performance by resting state functional magnetic resonance imaging (rs-fMRI).

Nineteen volunteers with normal hearing without tinnitus, 18 tinnitus patients with hearing loss, and 11 tinnitus patients without hearing loss were enrolled in this study. The subjects were evaluated with rs-fMRI, and region of interests (ROIs) based correlation analyses were performed using the CONN toolbox version 16 and SPM version 8. The correlation coefficients from individual level results were converted into beta values.

With a beta threshold of more than 0.2, 91% of all possible connections between auditory-related ROIs (Heschl's gyrus, planum temporale, planum polare, operculum, insular cortex, superior temporal gyrus) in the control group remained intact, whereas 83 and 66% of such connections were present in the hearing loss and the normal-hearing tinnitus group. However, between non-auditory-related ROIs, the rates of intact connections at a beta threshold of more than 0.2 were 17% in the control group, and 16 and 15% in the tinnitus groups. When resting state fMRI positive is defined as less than 9% of all possible connections between auditory-related ROIs with a beta threshold of more than 0.7, the sensitivity and specificity of tinnitus diagnosis is 86 and 74%, respectively.

The associations between auditory-related networks are weakened in tinnitus patients, even if they have normal hearing. It is possible that rs-fMRI can be a tool for objective examination of tinnitus, by focusing the auditory-related areas.