Cortical habituation deficit in tinnitus sufferers: contingent negative variation as an indicator of duration of the disease.

Cortical attention and habituation parameters are altered in patients suffering from tinnitus. The aim of the study was to quantify cortical attention and habituation parameters in tinnitus patients by recording the contingent negative variation (CNV) response and to correlate amplitudes of different CNV parameters with duration of disease. Twenty patients suffering from tinnitus (median: 44 years) and twenty age- and sex-matched healthy controls (median: 41 years) were tested by a CNV paradigm. We recorded overall CNV, initial CNV, and terminal CNV and calculated habituation slopes. All CNV parameters were Spearman-correlated with individual duration of disease. Highly significant between groups differences emerged in total (tinnitus: -8.4 uV vs. controls: -3.8 uV), initial (-11.2 vs. -6.0 uV), and terminal CNV (-11.9 vs. -6.5 uV) demonstrating higher negative amplitudes in tinnitus patients. Habituation differed in total and terminal CNV, indicating missing habituation in tinnitus patients. Overall CNV (ϱ = -.365) and initial CNV (ϱ = -.529) showed a medium Spearman correlation with duration of disease. We conclude that the correlation between duration of tinnitus and the initial CNV amplitudes indicates an altered state of cortical excitability that can also be observed in more negative CNV-amplitudes in tinnitus patients. We assume that this state indicates a chronicity process in tinnitus disease.