• M H Bennett, T Kertesz, and P Yeung.
• Diving and Hyperbaric Medicine, Prince of Wales Hospital, Barker St., Randwick, NSW, Australia, 2031. m.bennett@unsw.edu.au
• Cochrane Db Syst Rev. 2005 Jan 25 (1): CD004739.

BackgroundIdiopathic sudden sensorineural hearing loss (ISSHL) with or without tinnitus is common and presents a health problem with significant effect on quality of life. Hyperbaric oxygen therapy (HBOT) may improve oxygen supply to the inner ear and thereby result in an improvement in hearing and/or a reduction in the intensity of tinnitus.ObjectivesTo assess the benefits and harms of HBOT for treating ISSHL and tinnitus.Search StrategyWe searched the Cochrane ENT Specialist Register (June 2004), CENTRAL (The Cochrane Library Issue 3, 2004), MEDLINE (1966 to 2004), EMBASE (1974 to 2004), CINAHL (1982 to 2004), DORCTHIM (1996 to 2004), and reference lists of articles. Researchers in the field were contacted.Selection CriteriaRandomised studies comparing the effect on ISSHL and/or tinnitus of therapeutic regimens which include HBOT with those that exclude HBOT.Data Collection And AnalysisThree reviewers independently evaluated the quality of the relevant trials using the validated Jadad 1996 Oxford-Scale and extracted the data from the included trials.Main ResultsFive trials contributed to this review (254 subjects, 133 receiving HBOT and 120 control). Pooled data from two trials involving 114 patients (45% of the total) suggested there was a trend towards, but no significant increase in, the chance of a 50% increase in hearing threshold on Pure Tone Average (PTA) over four frequencies when HBOT was used (relative risk (RR) for good outcome with HBOT 1.53, 95% confidence interval (CI) 0.85 to 2.78, P = 0.16). The chance of achieving a 25% increase with HBOT was, however, statistically significant (RR 1.39, 95% CI 1.05 to 1.84, P = 0.02). Fifty-six per cent of the control subjects achieved this outcome versus 78% of the HBOT subjects, with the number-needed-to-treat (NNT) to achieve one extra good outcome being 5 (95% CI 3 to 20). A single trial involving 50 subjects (20% of the total) also suggested a significant improvement in the mean PTA threshold expressed as a percentage of baseline (61% improvement with HBOT, 24% with control, WMD 37%, 95% CI 22% to 53%). The effect of HBOT in tinnitus could not be assessed due to poor reporting. There were no significant improvements in hearing or tinnitus reported in the single study to examine the effect of HBOT on a chronic presentation (six months) of ISSHL and/or tinnitus.Authors' ConclusionsFor people with early presentation of ISSHL, the application of HBOT significantly improved hearing loss, but the clinical significance of the level of improvement is not clear. We could not assess the effect of HBOT on tinnitus by pooled analysis. The routine application of HBOT to these patients cannot be justified from this review. In view of the modest number of patients, methodological shortcomings and poor reporting, this result should be interpreted cautiously, and an appropriately powered trial of high methodological rigour is justified to define those patients (if any) who can be expected to derive most benefit from HBOT. There is no evidence of a beneficial effect of HBOT on chronic presentation of ISSHL and/or tinnitus.

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