Diffusion Tensor Imaging is More Sensitive than Conventional Magnetic Resonance Imaging in Demonstrating White Matter Abnormalities in Susac's Syndrome

© 2009 Nova Science Publishers, Inc. Objective: Susac's syndrome is characterized by the triad of hearing loss, branch retinal artery occlusions, and encephalopathy with predominantly cognitive and psychiatric symptoms. Focal ischemic lesions in the corpus callosum detectable by conventional magnetic resonance imaging (MRI) are a characteristic feature of Susac's syndrome. They do not, however, fully explain the type and severity of the neuropsychological deficits. In this study, we tested the hypothesis that widespread tissue damage of otherwise normal-appearing white matter (NAWM) can be detected in Susac's syndrome when using diffusion tensor imaging (DTI). Methods: Three-dimensional fractional anisotropy (FA) maps were calculated from DTI data of five patients with Susac's syndrome and a group of 63 matched healthy controls. Results: Voxel-based statistics of spatially normalized FA maps revealed highly significant widespread impairment of fiber integrity in all patients. Lesions were particularly located in the genu of the corpus callosum and in the frontotemporal connecting fascicles. Patients showed specifically reduced mean FA values in the region of interest outlining the genu. This was true even if the genu was not focally affected on conventional MRI. Interpretation: We conclude that DTI is much more sensitive than conventional MRI in demonstrating WM abnormalities in Susac's syndrome. FA reductions in NAWM of the genu of the corpus callosum seem to be disease-specific. Psychiatric symptoms and cognitive deficits of these patients are most likely caused by the disruption of the anatomical connectivity of the frontal lobes.

ISBN:978-1-60741-034-8

Publication year:2009