Central Processing in Tinnitus: fMRI Study Outlining Patterns of Activation Using an Auditory Discrimination Task in Normal Versus Tinnitus Patients

Abstract

Objective: Elucidate brain activity differences between patients with tinnitus and controls.

Study design: Cross-sectional cohort study.

Setting: Outpatient Otolaryngology clinic.

Patients: Three cohorts; 8 controls, 12 with subjective idiopathic tinnitus (tinnitus without hearing loss), and 12 with both tinnitus and hearing loss.

Intervention: An auditory oddball identification task was performed in fMRI scanner.

Main outcome measures: Task performance and Tinnitus Handicap Inventory (THI) scores were recorded. Brain activation maps were generated comparing deviant and standard tones as well as at rest. One-way and two-way T-contrasts were generated in addition to multiple regression modeling which identified significant brain regions predicting tinnitus, disease severity, duration, and task performance.

Results: Task performance worsened in tinnitus patients with increased auditory workload, in terms of additional hearing loss. THI score and grade correlated with false alarms. The limbic system, heschel's gyrus, angular gyrus and cerebellum have a significant effect on both brain behavior in patients with tinnitus, and predictability of tinnitus and its behavioral implications.

Conclusion: Increased auditory workload resulted in poorer task performance. Moreover, it is possible to predict auditory task performance in patients with tinnitus by looking at the activity of specific regions of interest. Heschl's gyrus, angular gyrus, cerebellar, and limbic system activity are important contributors to neurological activity associated with tinnitus. Finally, predictive modeling may influence further research surrounding tinnitus treatment.