Systematic review of sound stimulation to elicit tinnitus residual inhibition

Abstract

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.

Keywords: Acoustic stimulation; Residual inhibition; Systematic review; Tinnitus.