title: Left hemisphere fractional anisotropy increase in noise-induced tinnitus: a diffusion tensor imaging (DTI) study of white matter tracts in the brain.
abstract: Diffusion tensor imaging (DTI) is a contemporary neuroimaging modality used to study connectivity patterns and microstructure of white matter tracts in the brain. The use of DTI in the study of tinnitus is a relatively unexplored methodology with no studies focusing specifically on tinnitus induced by noise exposure. In this investigation, participants were two groups of adults matched for etiology, age, and degree of peripheral hearing loss, but differed by the presence or absence (+/-) of tinnitus. It is assumed that matching individuals on the basis of peripheral hearing loss, allows for differentiating changes in white matter microstructure due to hearing loss from changes due to the effects of chronic tinnitus. Alterations in white matter tracts, using the fractional anisotropy (FA) metric, which measures directional diffusion of water, were quantified using tract-based spatial statistics (TBSS) with additional details provided by in vivo probabilistic tractography. Our results indicate that 10 voxel clusters differentiated the two groups, including 9 with higher FA in the group with tinnitus. A decrease in FA was found for a single cluster in the group with tinnitus. However, seven of the 9 clusters with higher FA were in left hemisphere thalamic, frontal, and parietal white matter. These foci were localized to the anterior thalamic radiations and the inferior and superior longitudinal fasciculi. The two right-sided clusters with increased FA were located in the inferior fronto-occipital fasciculus and superior longitudinal fasciculus. The only decrease in FA for the tinnitus-positive group was found in the superior longitudinal fasciculus of the left parietal lobe.
authors.affiliation: Center for Neurological Studies, Novi, MI, USA.
authors.forename: Randall R
authors.initials: RR
authors.lastname: Benson
authors.affiliation: Department of Radiology, Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Ramtilak
authors.initials: R
authors.lastname: Gattu
authors.affiliation: Department of Communication Sciences & Disorders, Wayne State University, 207 Rackham, 60 Farnsworth, Detroit, MI 48202, USA. Electronic address: cacacea@wayne.edu.
authors.forename: Anthony T
authors.initials: AT
authors.lastname: Cacace
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016880:Anisotropy; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold; D016022:Case-Control Studies; D054022:Cerebrum / Q000473:pathology* / Q000503:physiopathology; D002908:Chronic Disease; D056324:Diffusion Tensor Imaging; D006317:Hearing Loss, Noise-Induced / Q000473:pathology / Q000503:physiopathology; D006319:Hearing Loss, Sensorineural / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D008875:Middle Aged; D011237:Predictive Value of Tests; D012720:Severity of Illness Index; D014012:Tinnitus / Q000473:pathology* / Q000503:physiopathology; D055815:Young Adult