Digging into the Role of Inflammatory Biomarkers in Sudden Sensorineural Hearing Loss Diagnosis and Prognosis: A Systematic Review and Meta-Analysis

Abstract

Background and Objectives: Sudden Sensorineural Hearing Loss (SSNHL) is a quite common clinical finding in otolaryngology. Most cases are classified as idiopathic and there is a dearth of information on factors able to predict the response to treatment and hearing recovery. The main aim of this systematic review and meta-analysis was to assess and critically discuss the role of circulating inflammatory biomarkers in SSNHL. Materials and Methods: A search was conducted of the English literature published between 1 January 2009 and 7 July 2022 on Pubmed, Scopus, Web of Science, ScienceDirect, and Cochrane following PRISMA guidelines. Results: A total of 256 titles were retrieved from the search. After full-text screening and application of inclusion/exclusion criteria, 13 articles were included. Twelve out of thirteen studies reported significant differences in biomarkers values in SSNHL patients, of which Tumor Necrosis Factor alpha (TNF-α) and C-reactive Protein (CRP) were the most analyzed. Our meta-analysis for CRP’s mean values in SSNHL groups vs. controls showed significantly higher CRP levels with a pooled overall difference of 1.07; confidence interval (CI) at 95%: 0.03; 2.11. For TNF-α, discordant results were found: three studies showed significantly higher levels in SSNHL patients vs. controls, whereas other three investigations showed lower levels in the SSNHL groups (overall pooled difference 1.97; 95% CI: −0.90; 4.84). A high between-study heterogeneity was found. Conclusions: This systematic review pointed out that, although there exists a growing literature in the field of circulatory biomarkers identification in SSNHL, there is a high heterogeneity of results and low quality of evidence. CRP resulted to be higher in SSNHL patients than in controls, while TNF-α showed more heterogeneous behavior. The data reported herein needs to be confirmed in well-designed prospective multicenter randomized studies, with the objective of improving SSNHL treatment and outcome and thereby reducing the social burden of hearing loss.

Inflammatory markers and the risk of idiopathic sudden sensorineural hearing loss: A Mendelian randomization study

“…As an indicator of blood viscosity, fibrinogen is involved in various processes, such as platelet aggregation and activation of inflammation, suggesting a possible link between fibrinogen in serum and reduced blood flow in the cochlea (31). The results of this work are consistent with previous studies where a meta-analysis summarizing 13 years of English literature showed that CRP levels were higher in ISSHL patients than in the average population, while TNFα results were heterogeneous (11). Another meta-analysis found no difference in fibrinogen concentration between control and SSNHL patients (10).…”

“…However, these findings have been refuted in other studies (10). A recently published meta-analysis has not clarified their association with ISSHL (11). These contradictory results may result from potential confounders and reverse causality in traditional observational studies, so the causal relationship between them remains an open question.…”

Consideration of health inequity in systematic reviews and primary studies on risk factors for hearing loss

“…Of the 64 SRs included in Briscoe et al [35], 17 met the inclusion criteria for this secondary analysis (see Table 2) [38][39][40][41][42][43][44][45][46][47][48][49][50][51][52]. Of these, seven were published in 2021, and 10 were published in 2022.…”

“…Of the 17 included SRs, 10 considered physiological risk factors for hearing loss [38][39][40][41][42][43][44][45][46][47], four considered environmental risk factors [52][53][54], two considered demographic risk factors [49,50], and one considered behavioral risk factors [48]. Of the 251 primary studies, 248 were observational studies, and three were RCTs.…”

Comparison of Intratympanic Steroid and Hyperbaric Oxygen Salvage Therapy Hearing Outcomes in Idiopathic Sudden Sensorineural Hearing Loss: A Retrospective Study

“…Tinnitus and vertigo may be associated with SSNHL, which is usually unilateral (Schreiber et al 2010). The etiology of SSNHL remains unclear, despite many hypotheses regarding viral, circulatory, autoimmune, and metabolic disorders (Frosolini et al 2022) The incidence of SSNHL is estimated at 5 to 20 per 100,000 people yearly (Devantier et al 2022). Systemic steroids are the most commonly used first-line therapy for SSNHL, with hearing improvement rates cited at 61% of patients but with many studies questioning the efficacy of available treatment options (Wilson et al 1980).…”