Diffusion tensor imaging of the subcortical auditory tract in subjects with long-term unilateral sensorineural hearing loss

Several indices including axial diffusivity (λ_II), radial diffusivity (λ_·), mean diffusivity, and fractional anisotropy (FA) along the auditory pathway were extracted from diffusion tensor magnetic resonance images in 19 patients with unilateral sensorineural hearing loss (SNHL). Two regions of interest were selected bilaterally for evaluation: the lateral lemniscus and inferior colliculus. A significant decrease was observed in FA on the contralateral side in patients with SNHL due to an increase in λ_II while λ_· remained unchanged. Although the orientation of neural fibers along the subcortical auditory pathway appeared to be intact, the reduction in FA and increase in λ_· on the contralateral side might be attributed to axonal loss and/or demyelination.