Rationale for the tinnitus retraining therapy trial

Abstract

The Tinnitus Retraining Therapy Trial (TRTT) is a National Institutes of Health-sponsored, multi-centered, placebo-controlled, randomized trial evaluating the efficacy of tinnitus retraining therapy (TRT) and its component parts, directive counseling and sound therapy, as treatments for subjective debilitating tinnitus in the military. The TRTT will enroll 228 individuals at an allocation ratio of 1:1:1 to: (1) directive counseling and sound therapy using conventional sound generators; (2) directive counseling and placebo sound generators; or (3) standard of care as administered in the military. Study centers include a Study Chair's Office, a Data Coordinating Center, and six Military Clinical Centers with treatment and data collection standardized across all clinics. The primary outcome is change in Tinnitus Questionnaire (TQ) score assessed longitudinally at 3, 6, 12, and 18-month follow-up visits. Secondary outcomes include: Change in TQ sub-scales, Tinnitus Handicap Inventory, Tinnitus Functional Index, and TRT interview visual analog scale; audiometric and psychoacoustic measures; and change in quality of life. The TRTT will evaluate TRT efficacy by comparing TRT (directive counseling and conventional sound generators) with standard of care; directive counseling by comparing directive counseling plus placebo sound generators versus standard of care; and sound therapy by comparing conventional versus placebo sound generators. We hypothesize that full TRT will be more efficacious than standard of care, directive counseling and placebo sound generators more efficacious than standard of care, and conventional more efficacious than placebo sound generators in habituating the tinnitus awareness, annoyance, and impact on the study participant's life.

Figure 1

Neurophysiological model of tinnitus depicting detection of the neutral tinnitus signal and activation of subcortical structures that filter out the tinnitus signal generated at a peripheral source (cochlea). Other components of the model are not activated and, therefore, there is neither awareness nor annoyance in response to the tinnitus. This depiction of the model is representative of the vast majority of persons with tinnitus, who are neither bothered nor distressed by their tinnitus (After Jastreboff^[21])

Figure 2

Neurophysiological model of tinnitus depicting full activation, including activation of non-auditory limbic and autonomic nervous system structures that are responsible for the emotional and negative reactions to the tinnitus. This engagement of both conscious and subconscious neuronal circuitry gives rise to the awareness and annoyance associated with distressing tinnitus (After Jastreboff^[21])

Figure 3

Neurophysiological model of tinnitus depicting complete tinnitus retraining therapy-induced habituation of the emotional (H_E) and negative (H_R) reactions to the tinnitus and it perception (H_P). The resulting representation of the model, subsequent to the habituation, is the same as that shown in Figure 1 for individuals who are neither bothered nor distressed by their tinnitus (After Jastreboff^[21])