Systematic review of sound stimulation to elicit tinnitus residual inhibition.

BACKGROUND: Residual Inhibition is considered as tinnitus alteration immediately after exposure to sound. Its clinical significance and correlation with the pathophysiology and treatment prognosis of tinnitus remain enigmatic. The objective of this review is to critically appraise scientific evidence regarding the residual inhibition prevalence and how it is correlated with different sound stimuli. METHODS: A systematic review of tinnitus Residual Inhibition (RI) studies was performed, focusing on prevalence, methods used, stimuli presented and responses obtained. A literature search (PubMed, Cochrane Central Register of Controlled Trials, Scopus, MEDLINE) was conducted. Seventeen studies involving 1066 patients fulfilled the inclusion criteria. Sound stimulation was performed using pure tones, customized sounds, narrow- and broadband noises, and modulated sounds. RESULTS: Sound stimuli exposure produced complete RI of tinnitus in 34.5% of patients (range 5.6-72%), with higher RI rates after stimulation with pure tones and narrowband noise centered to the tinnitus perceived pitch. RI duration tends to increase when stimuli duration increases. CONCLUSIONS: RI is frequent and can be induced by narrow-band noise (NBN), broadband noise (BBN), pure tones, customized sounds and modulated sounds. Adequate evidence to support the use of RI as a tool for tinnitus phenotyping or as a management option is pending. Further clinical research exploring the profile of patients with RI and its potential use as prognostic factor should be conducted.

Towards a unification of treatments and interventions for tinnitus patients: The EU research and innovation action UNITI.

Tinnitus is the perception of a phantom sound and the patient's reaction to it. Although much progress has been made, tinnitus remains a scientific and clinical enigma of high prevalence and high economic burden, with an estimated prevalence of 10%-20% among the adult population. The EU is funding a new collaborative project entitled "Unification of Treatments and Interventions for Tinnitus Patients" (UNITI, grant no. 848261) under its Horizon 2020 framework. The main goal of the UNITI project is to set the ground for a predictive computational model based on existing and longitudinal data attempting to address the question of which treatment or combination of treatments is optimal for a specific patient group based on certain parameters. Clinical, epidemiological, genetic and audiological data, including signals reflecting ear-brain communication, as well as patients' medical history, will be analyzed making use of existing databases. Predictive factors for different patient groups will be extracted and their prognostic relevance validated through a Randomized Clinical Trial (RCT) in which different patient groups will undergo a combination of tinnitus therapies targeting both auditory and central nervous systems. From a scientific point of view, the UNITI project can be summarized into the following research goals: (1) Analysis of existing data: Results of existing clinical studies will be analyzed to identify subgroups of patients with specific treatment responses and to identify systematic differences between the patient groups at the participating clinical centers. (2) Genetic and blood biomarker analysis: High throughput Whole Exome Sequencing (WES) will be performed in well-characterized chronic tinnitus cases, together with Proximity Extension Assays (PEA) for the identification of blood biomarkers for tinnitus. (3) RCT: A total of 500 patients will be recruited at five clinical centers across Europe comparing single treatments against combinational treatments. The four main treatments are Cognitive Behavioral Therapy (CBT), hearing aids, sound stimulation, and structured counseling. The consortium will also make use of e/m-health applications for the treatment and assessment of tinnitus. (4) Decision Support System: An innovative Decision Support System will be implemented, integrating all available parameters (epidemiological, clinical, audiometry, genetics, socioeconomic and medical history) to suggest specific examinations and the optimal intervention strategy based on the collected data. (5) Financial estimation analysis: A cost-effectiveness analysis for the respective interventions will be calculated to investigate the economic effects of the interventions based on quality-adjusted life years. In this paper, we will present the UNITI project, the scientific questions that it aims to address, the research consortium, and the organizational structure.