Limbic-Auditory Interactions of Tinnitus: An Evaluation Using Diffusion Tensor Imaging.
OBJECTIVE
Tinnitus is defined as an imaginary subjective perception in the absence of an external sound. Convergent evidence proposes that tinnitus perception includes auditory, attentional and emotional components. The aim of this study was to investigate the thalamic, auditory and limbic interactions associated with tinnitus-related distress by Diffusion Tensor Imaging (DTI).


METHODS
A total of 36 tinnitus patients, 20 healthy controls underwent an audiological examination, as well as a magnetic resonance imaging protocol including structural and DTI sequences. All participants completed the Tinnitus Handicap Inventory (THI) and Visual Analog Scales (VAS) related with tinnitus. The fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were obtained for the auditory cortex (AC), inferior colliculus (IC), lateral lemniscus (LL), medial geniculate body (MGB), thalamic reticular nucleus (TRN), amygdala (AMG), hippocampus (HIP), parahippocampus (PHIP) and prefrontal cortex (PFC).


RESULTS
In tinnitus patients the FA values of IC, MGB, TRN, AMG, HIP decreased and the ADC values of IC, MGB, TRN, AMG, PHIP increased significantly. The contralateral IC-LL and bilateral MGB FA values correlated negatively with hearing loss. A negative relation was found between the AMG-HIP FA values and THI and VAS scores. Bilateral ADC values of PHIP and PFC significantly correlated with the attention deficiency-VAS scores.


CONCLUSIONS
In conclusion, this is the first DTI study to investigate the grey matter structures related to tinnitus perception and the significant correlation of FA and ADC with clinical parameters suggests that DTI can provide helpful information for tinnitus. Magnifying the microstructures in DTI can help evaluate the three faces of tinnitus nature: hearing, emotion and attention.
Department of Radiology, Neuroradiology Section, Ondokuz Mayıs University, 55139, Kurupelit/Samsun, Turkey. hpgunbey@hotmail.com.
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Gunbey
Department of Otorhinolaryngology, Ondokuz Mayıs University, Samsun, Turkey.
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Gunbey
Department of Radiology, Neuroradiology Section, Ondokuz Mayıs University, 55139, Kurupelit/Samsun, Turkey.
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Aslan
Department of Radiology, Adıyaman University, Adıyaman, Turkey.
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Bulut
Department of Otorhinolaryngology, Samsun Research and Training Hospital, Samsun, Turkey.
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Unal
Department of Radiology, Neuroradiology Section, Ondokuz Mayıs University, 55139, Kurupelit/Samsun, Turkey.
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Incesu
D001303:Auditory Cortex / Q000000981:diagnostic imaging* / Q000473:pathology; D001306:Auditory Pathways / Q000000981:diagnostic imaging* / Q000473:pathology; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D066128:Gray Matter / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D008032:Limbic System / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D013788:Thalamus / Q000000981:diagnostic imaging* / Q000473:pathology; D014012:Tinnitus / Q000000981:diagnostic imaging* / Q000473:pathology
DTI; MRI; Tinnitus