Abstract
Background
This is an update of a Cochrane Review first published in The Cochrane Library in Issue 1, 2005 and previously updated in 2007 and 2009.
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.
Objectives
To assess the benefits and harms of HBOT for treating ISSHL and/or tinnitus.
Search methods
We searched the Cochrane Ear, Nose and Throat Disorders Group Trials Register; the Cochrane Central Register of Controlled Trials (CENTRAL); PubMed; EMBASE; Database of Randomised Trials in Hyperbaric Medicine (DORCTHIM); CINAHL; Web of Science; BIOSIS Previews; Cambridge Scientific Abstracts; ICTRP and additional sources for published and unpublished trials. The date of the most recent search was 2 May 2012, following previous searches in 2009, 2007 and 2004.
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). The studies were small and of generally poor quality. 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% confidence interval (CI) 0.85 to 2.78, P = 0.16), but did show a significantly increased chance of a 25% increase in pure-tone average (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 5 (95% CI 3 to 20). There was also an absolute improvement in average pure-tone audiometric threshold following HBOT (mean difference (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 the use of HBOT for this purpose.
Plain language summary
Hyperbaric oxygen for sudden hearing loss and tinnitus (ringing in the ears) of unknown cause
Idiopathic sudden sensorineural hearing loss (ISSHL) is common and often results in permanent hearing loss. It therefore has a high impact on the well-being of those affected. Tinnitus (abnormal persistent noises or ringing in the ear) is similarly common and often accompanies the hearing loss. Although the cause of these complaints is not clear, they may be related to a lack of oxygen secondary to a vascular problem not yet identified. Hyperbaric oxygen therapy (HBOT) involves breathing pure oxygen in a specially designed chamber and it is sometimes used as a treatment to increase the supply of oxygen to the ear and brain in an attempt to reduce the severity of hearing loss and tinnitus.
We found some evidence from seven small trials of generally poor quality, that hearing may be improved in people with ISSHL and possibly that tinnitus may also be improved. This may only be true if HBOT is used within two weeks of the onset of problems and there is no evidence that HBOT can help people who have been deaf for some months. Further research is needed.
