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Functional MR spectroscopy of the auditory cortex in healthy subjects and patients with sudden hearing loss
T L Richards1, G A Gates, J C Gardner
1Department of Radiology, University of Washington, Seattle 98195, USA.
Purpose:
To use MR spectroscopy to study the biochemical changes produced by auditory stimuli in patients with sudden sensorineural hearing loss and to compare these findings with the biochemical changes seen in healthy volunteers.
Methods:
Single-voxel MR spectroscopy was used to study biochemical changes in the auditory cortex in 11 control subjects and 19 patients with sudden sensorineural hearing loss. MR spectroscopic signals were measured during three different sound conditions (scanner noise, music, and sirens).
Results:
A lower MR spectroscopic lactate signal was observed in control subjects during the music stimulus than during the other sound conditions. This music-induced lactate change was not observed in patients with hearing loss. The other proton metabolites (choline, creatine, N-acetylaspartate [NAA]) remained stable during the different auditory stimuli. However, the NAA/creatine ratio was higher in the auditory cortex of patients than in the control subjects, and was not dependent on the sound condition.
Conclusion:
The detection of stimulus-induced and stable biochemical MR spectroscopic changes in patients with hearing loss may be useful in assessing disease activity.