Voxel‐Based Morphometry and Subfield Volumetry Analysis Reveal Limbic System Involvement in Tinnitus.

Background and Purpose: Tinnitus is a condition in which individuals perceive sounds, such as ringing or buzzing, without any external source. Although the exact cause is not fully understood, recent studies have indicated the involvement of nonauditory brain structures, including the limbic system. We aimed to compare the volumes of specific brain structures between patients with tinnitus and controls. Methods: Voxel‐based morphometry and subfield volumetry were applied to analyze the brain structures of 53 patients with tinnitus and 52 age‐ and sex‐matched controls. The volumes of the amygdala, hippocampus, and thalamus were measured and compared between the groups. Results: Patients with tinnitus had larger volumes in the whole amygdala, basal nucleus, right lateral nucleus, and left paralaminar nucleus compared with controls. In addition, the subiculum head, left fimbria, and left presubiculum head in the hippocampus were larger in patients with tinnitus. No differences were found in the total thalamic volume or thalamic subnuclei between groups. The gray matter volumes in the thalamus, amygdala, and hippocampus were significantly high in the tinnitus group. The cortical thicknesses of both of the marginal branches of the cingulate sulcus, the left superior parietal lobule, and the left subparietal sulcus were also high in the tinnitus group. Conclusions: These findings indicate the involvement of the limbic system in tinnitus, and enhance our understanding of the condition. The subfield volumetry technique used in this study may aid in identifying the structural differences associated with specific neurological and psychiatric conditions. [ABSTRACT FROM AUTHOR]