Event related potentials (ERPs) to assess the tinnitus complaint during drug treatment

Abstract

Introduction: Previous studies have shown that the attention given to tinnitus can be a determinant of tinnitus severity. Some of these studies have shown changes in the amplitude and/or latency parameters of the event-related auditory potentials (ERPs). One of the tools previously employed to investigate an individual's attention is the Event Related Potential (ERP), which reflects the amount of attention from the patient to the provided auditory stimuli.

Objective: To verify if the use of central and peripheral drugs tested for the treatment of tinnitus present changes in the measurable parameters of event-related potentials when compared to Tinnitus Handicap Inventory (THI) and Visual Analogue Scale (VAS).

Method: Eighty-eight tinnitus patients were randomly sorted into two drug groups: (1) drugs with a central action mechanism and (2) drug with peripheral action mechanism. Their effects upon the negative aspects caused by tinnitus symptoms were evaluated by the ERPs during three periods: Premedication (T1), at Termination of the drug treatment (T2), and following the Washout period (T3), and then compared with the results from the THI questionnaire and VAS.

Results: ERP waves in both groups did not demonstrate significant differences during the three evaluated periods (P=0.53), despite the significant improvement seen through the evaluation by the THI questionnaire and VAS for tinnitus annoyance and intensity (P<0.0001).

Conclusion: The use of ERPs with patients of chronic tinnitus who have been submitted to treatment using drugs having actions on both the CNS and peripheral auditory system did not present changes in either latency or amplitude of the waves throughout the treatment when compared to the THI questionnaire and VAS. The ERPs cannot be considered as criterion to evaluate the evolution of drug treatment in patients complaining of tinnitus. The statistically significant reduction in THI and VAS scores among all drugs used occurred with dopamine antagonists. Considering the possible antipsychotic effects, we can conclude that the concomitance of a variety of psychopathological conditions such as obsessive-compulsive disorder may be associated with tinnitus in some patients and may be responsible for the severity of the symptom.

Keywords: Auditory evoked potentials; Drug treatment for tinnitus; Event related potentials; Long latency potentials; P300; Tinnitus.