Introduction: Idiopathic sudden sensorineural hearing loss (ISSHL) is hearing loss of unknown cause with greater than 30 dB loss over 72 hours or less across three consecutive frequencies. Hyperbaric oxygen therapy (HBOT) is a widely accepted treatment for this condition. HBOT protocols and outcomes measured vary between studies.
Methods: To update a systematic review with meta-analysis of relevant randomised trials to both quantify and estimate the quality of evidence to support or refute the use of HBOT for ISSHL. We followed the Cochrane Handbook for Systematic Reviews of Interventions methodology. We conducted a focussed search of the following databases - AMED, BIOSIS Previews, CENTRAL, CINAHL, Embase, Emcare, Global Health, Medline, Scopus and Web of Science. There were no language or publication status restrictions. The updated search covered 1 April 2012 to 22 February 2023. A total of 148 papers were found with 24 randomised and pseudo-randomised studies identified of which seven contributed to the final analysis. Studies using usual treatment (steroids) plus HBOT or no treatment plus HBOT were included. The ROBB 2 tool for risk of bias and the GRADE tool for certainty of evidence were utilised.
Results: Data pooling was hampered by variation in reporting of changes in pure tone average across these studies. Pooled analysis from five studies suggested the chance of improvement following HBOT and steroids was greater than after steroids alone (RR 1.6, 95% CI 1.3 to 2.0). Pooled data from four trials suggested a greater mean improvement following HBOT (mean difference 15.6 dB, 95% CI 1.5-29.8).
Conclusions: There is moderate evidence that HBOT improves hearing when applied up to 30 days after the onset of ISSHL. HBOT in combination with steroids (oral or intra-tympanic) can be justified as a routine treatment. Future trials should address optimal dose and timing of HBOT and ensure outcomes enable pooling of data in future reviews, as well as addressing some measure of the functional significance of any improvement.
Keywords: Deafness; Inner ear; Review article; Treatment.
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