Marion Smits PhD, Presenter: Nothing to Disclose

Dirk De Ridder, Abstract Co-Author: Nothing to Disclose

Silvia Kovacs, Abstract Co-Author: Nothing to Disclose

Ronald R Peeters PhD, Abstract Co-Author: Nothing to Disclose

Paul Van Hecke, Abstract Co-Author: Nothing to Disclose

Stefan Sunaert MD, PhD, Abstract Co-Author: Nothing to Disclose

Melcher et al. (J Neurophysiol 2000;83:1058-72) described that in patients with lateralized tinnitus fMRI signal change was less in the contralateral inferior colliculus (IC). In their study only 4 patients had lateralized tinnitus, all right sided, and the auditory cortices (AC) were not assessed.We performed fMRI of the entire auditory pathway, including the IC and the AC, in 43 patients with refractory, non-pulsatile tinnitus to assess lateralization of fMRI activation.

50 subjects (43 patients, 7 healthy volunteers) were scanned on a 3T MR scanner. A 3D T1w image covering the whole brain (matrix 256*256; TE/TR 4.6/9.7 ms; SENSE reduction factor (rf) 3) was acquired for anatomical reference. A T2*w EPI silent gap sequence was used during the stimulation paradigm (TE/TR/AT 33/5000/3000 ms; SENSE rf 2.5; 32 4.0 mm slices; scanned matrix 80). The stimulation paradigm was a block design of 12 epochs in which music was presented binaurally through headphones, which was switched on and off for periods of 50 seconds. Subjects underwent 1-2 sessions each. Data were analysed using SPM2 software and preprocessed with realignment, coregistration, normalisation and smoothing. Single subject and group statistical parametric maps were calculated. Group effects were analysed using(multiple) ANOVA with laterality, loudness and frequency of tinnitus as covariates. Healthy volunteers served as a control group.

Tinnitus was lateralized in 32 patients (74%, 13 right and 19 left sided). Significant signal change (corrected pSignal change was symmetrical in healthy volunteers. In patients with lateralized tinnitus, signal change was significantly less on the side contralateral to the side of tinnitus.

Our paradigm adequately visualized the auditory pathways in tinnitus patients. In lateralized tinnitus signal change is less on the contralateral side, which may be explained by a higher neural activity during rest or by a lower neural activity during stimulation on the affected side.

Smits, M, De Ridder, D, Kovacs, S, Peeters, R, Van Hecke, P, Sunaert, S, Lateralization of Signal Change in the Auditory Pathway in Patients with Lateralized Tinnitus Studied with Functional Magnetic Resonance Imaging (fMRI).  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4404254.html