Auditory cortex is implicated in tinnitus distress: a voxel-based morphometry study

Neuroimaging studies of tinnitus suggest the involvement of wide-spread neural networks for perceptual, attentional, memory, and emotional processes encompassing auditory, frontal, parietal, and limbic areas. Despite sparse findings for tinnitus duration and laterality, tinnitus distress has been shown to be related to changes in non-auditory cortical areas. The aim of this study was to correlate tinnitus characteristics with grey matter volume in two large samples of tinnitus patients. High-resolution brain images were obtained using a 1.5 T magnetic resonance imaging scanner and analysed by means of voxel-based morphometry. In sample one (n = 257), tinnitus distress correlated negatively with grey matter volume in bilateral auditory areas including the Heschl's gyrus and insula, that is, the higher the tinnitus distress the lower the grey matter volume. The effects of this correlation were small, but stable after correction for potential confounders such as age, gender, and audiometric parameters. This negative correlation was replicated in a second independent sample (n = 78). Our results support the notion that the role of the auditory cortex in tinnitus is not restricted to perceptual aspects. The distress observed was dependent on grey matter alterations in the auditory cortex, which could reflect reverberations between perceptual and distress networks.