Some evidence for improvement in hearing after hyperbaric oxygen therapy for sudden idiopathic hearing loss

Bennett MH, Kertesz T, Perleth M, Yeung P, Lehm JP. Hyperbaric oxygen for idiopathic sudden sensorineural hearing loss and tinnitus. Cochrane Database of Systematic Reviews 2012, Issue 10. Art. No.: CD004739.

Contact address: Michael H Bennett, Department of Anaesthesia, Prince of Wales Hospital, Barker Street, Randwick, NSW, 2031, Australia.

Editorial group: Cochrane Ear, Nose and Throat Disorders Group.
Publication status and date: New search for studies and content updated (no change to conclusions), published in Issue 1, 2010.
Review content assessed as up-to-date: 19 July 2009.
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

This is an update of a Cochrane Review first published in The Cochrane Library in Issue 1, 2005 and previously updated in 2007.
Idiopathic sudden sensorineural hearing loss (ISSHL) is common and has a significant effect on quality of life. Hyperbaric oxygen therapy (HBOT) may improve oxygen supply to the inner ear and result in an improvement in hearing.

To assess the benefits and harms of HBOT for treating ISSHL and/or tinnitus.

Search strategy
We repeated the search in July 2009. Our search included the Cochrane Ear, Nose and Throat Disorders Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, CINAHL and the Database of Randomised Trials in Hyperbaric Medicine (DORCTHIM).

Selection criteria
Randomised studies comparing the effect on ISSHL and tinnitus of HBOT and alternative therapies.

Data collection and analysis
Three authors evaluated the quality of trials using the 'Risk of bias' tool and extracted data from the included trials.

Main results
Seven trials contributed to this review (392 participants).
Pooled data from two trials did not show any significant improvement in the chance of a 50% increase in hearing threshold on Pure Tone Average with HBOT (risk ratio (RR) with HBOT 1.53, 95% CI 0.85 to 2.78, P = 0.16), but did show a significantly increased chance of a 25% increase in PTA (RR 1.39, 95% CI 1.05 to 1.84, P = 0.02).
There was a 22% greater chance of improvement with HBOT, and the number needed to treat (NNT) to achieve one extra good outcome was five (95% CI 3 to 20).
There was also an absolute improvement in average pure tone audiometric threshold following HBOT (MD 15.6 dB greater with HBOT, 95% CI 1.5 to 29.8, P = 0.03). The significance of any improvement in tinnitus could not be assessed.

There were no significant improvements in hearing or tinnitus reported for chronic presentation (six months) of ISSHL and/or tinnitus.

Authors' conclusions
For people with acute ISSHL, the application of HBOT significantly improved hearing, but the clinical significance remains unclear. We could not assess the effect of HBOT on tinnitus by pooled analysis. In view of the modest number of patients, methodological shortcomings and poor reporting, this result should be interpreted cautiously. An appropriately powered trial 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 ISSHL or tinnitus and we do not recommend use of HBOT for this purpose.