Identifying non-otologic risk factors for tinnitus: A systematic review

The origin of tinnitus has been attributed to a peripheral auditory lesion, inducing bottom-up changes and resulting in the perception of a "phantom sound." However, non-auditory factors can co-exist as well, and can even lie at the origin of tinnitus development. An increasing body of literature focuses on psychological, (neuro)muscular, cardiovascular and many other influences and their respective associations with tinnitus prevalence.

The purpose of this study was to provide a comprehensive description of these non-otologic risk factors, and to summarise the evidence in literature about their link with tinnitus.

A narrative systematic review was conducted, following the Preferred Reporting Items for Systematic reviews and Meta-Analyses statement.

The MEDLINE, Embase and Web of Science databases were systematically searched for eligible articles, supplemented with manual search methods and grey literature search. Epidemiological studies reporting on the relationship between various non-otologic risk factors and tinnitus were included.

Quality assessment was performed using the Hoy & Brooks tool.

Fifty-five studies were included. Studies were of variable quality, with poor tinnitus definitions and evaluations or questionable sampling of the study population as main contributing factors for high risk of bias. Multiple associated factors have been identified, including cardiovascular, psychological, neurological, musculoskeletal and dietary factors.

The current literature review identified multiple risk factors that could be of significant importance for tinnitus development, maintenance or aggravation. While causality remains uncertain, this systematic elaboration of possible tinnitus comorbidities/risk factors can help provide direction for future research, and can direct clinicians to identify patients at risk and treat relevant symptoms accordingly.