Structural Abnormalities of the Brain Detected by 7 Tesla MRI in Patients with Usher Syndrome

Purpose: To analyze the structural changes in the brain related to combined hearing and vision loss in patients with Usher syndrome (USH) obtained by 7 Tesla MRI. Methods: Twenty patients with a diagnosis of USH and fifteen normal age- and gender-matched subjects were included in this study. USH patients underwent ophthalmological examination. All subjects underwent 7 Tesla MRI of the brain in two sequences: 3D BRAVO T1-weighted and 3D MT-weighted SILENT sequence. Results: Mean values of LGN volumes (right 95.65 mm³, left 88.61 mm³) are significantly (p < 0.001) lower in the USH group than in the control group (right 126.64 mm³, left 120.37 mm³). The average volumes of the left cuneus (4102.85 mm³), right parsorbitalis (2133.95 mm³), and right rostralanteriorcingulate cortex (ACC) (1727.60 mm³) in the patient group are significantly (p = 0.03673, 0.02434, and 0.04204, respectively) lower than in the control group (4673.73 mm³, 2485.13 mm³, and 2060.00 mm³, respectively). Mean lengths of the left lingual cortex (1.99 mm) and right pericalcarine cortex (1.84 mm) in the patient group are significantly (p = 0.02449 and 0.03153, respectively) smaller than in the control group (2.09 mm and 2.0 mm, respectively). Average lengths of the right insula (2.74 mm) in the patient group are significantly (p = 0.00041) greater than in the control group (2.49 mm). Conclusions: Parts of the brain engaged in the visual processing as LGN, pericalcarine cortex, lingual gyrus, and cuneus, are decreased, as well as those involved in hearing and language processing, such as parsorbitalis and ACC. The insula, a higher-order brain area possessing a crucial role in olfactory processing, is increased in USH patients. Our findings enhance the understanding of structural brain abnormalities related to combined hearing and vision loss and suggest complex adaptive changes that should be considered in the development of new visual rehabilitation and restitution strategies in USH patients.