lunes, 23 de septiembre de 2013

Acúfenos: Sección est"udios: "Cortical and subcortical fMRI of unilateral tinnitus."

Cortical and subcortical fMRI of unilateral tinnitus.
(Abstract of ARO Meeting Denver, Colorado)
Cris Lanting1,2, Emile de Kleine1,2, Hilke Bartels1, Dave Langers1,2, Pim van Dijk1,2
1Department of Otorhinolaryngology / Head and Neck Surgery, University Medical Center Groningen,
2Fac. of Medical Sciences, School of Behavioral and Cognitive Neurosciences, University of Groningen 

The current understanding of possible mechanisms of tinnitus generation is still poor. 

Our goal is to find a possible neural correlate of tinnitus, using fMRI.

In this work we used 10 patients (5 male) with unilateral tinnitus (5 left sided, 5 right sided) and 9 healthy subjects (4 male). 

Subjects had no or minor hearing deficits in both ears (max. 30 dB HL). 

Experiments were performed on a 3T Philips Intera scanner. 

41 coronal slices (2 mm) were acquired using a matrix of 128x128 voxels (1.75 x 1.75 mm2) using sparse sampling (TR=10 s). 

Stimuli consisted of right and left stimulation with levels of 40 and 70 dB (SPL) of rippled noise.

Data were realigned and normalized to a custom made template using SPM5. 

First level analysis was performed using multiple regression and regions of interest (ROI) of the auditory pathway were defi ned (cortex, MGB, IC, SOC and CN).

Percent signal changes were obtained for each condition for each region and symmetry indices were obtained. 

A second level analysis was performed using an ANOVA design to assess group differences and group-by-level interactions.

Results from the ROI analysis indicate that for the control group the cortex and inferior colliculus responded strongest to contralateral stimuli.

A difference was observed between the two tinnitus patient groups. 

The left sided tinnitus group showed a predominant response towards ipsilateral stimuli at the cortex while the right sided tinnitus group responded more like the control group.

A general trend of higher activation in the inferior colliculus as response to stimuli was observed in tinnitus patients compared to controls.

Our data suggest that there are differences in activation on cortex level and inferior colliculus level between the control group and the patient groups. 

Analysis of other nuclei will be performed. 

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