Structural Brain Changes in Tinnitus

TLDR

Tinnitus is a common, poorly understood disorder involving a phantom auditory sensation that persists after auditory nerve severing, with hypotheses implicating reorganization of tonotopic maps in the auditory cortex and limbic system participation. The study aimed to identify brain regions exhibiting structural changes in tinnitus patients. High‑resolution MRI and voxel‑based morphometry were used to compare tinnitus sufferers with healthy controls. Gray‑matter increases were observed only at the thalamic level, while decreases appeared in the subcallosal region including the nucleus accumbens, indicating reciprocal involvement of sensory and emotional areas in tinnitus generation.

Abstract

Tinnitus is a common but poorly understood disorder characterized by ringing or buzzing in the ear. Central mechanisms must play a crucial role in generating this auditory phantom sensation as it persists in most cases after severing the auditory nerve. One hypothesis states that tinnitus is caused by a reorganization of tonotopic maps in the auditory cortex, which leads to an overrepresentation of tinnitus frequencies. Moreover, the participation of the limbic system in generating tinnitus has been postulated. Here we aimed at identifying brain areas that display structural change in tinnitus. We compared tinnitus sufferers with healthy controls by using high-resolution magnetic resonance imaging and voxel-based morphometry. Within the auditory pathways, we found gray-matter increases only at the thalamic level. Outside the auditory system, gray-matter decrease was found in the subcallosal region including the nucleus accumbens. Our results suggest that reciprocal involvement of both sensory and emotional areas are essential in the generation of tinnitus.