HBO2 for subjective tinnitus has never been objectified, yet it is still advocated by many institutions. We analyzed the therapeutic effect of HBO2 treatment in the context of accompanying factors, especially focusing on the patients' attitude towards HBO2 prior to therapy.
Methods: 360 patients suffering from tinnitus were investigated in this study. They were randomized into 2 hyperbaric treatment protocols, one at 2.2, the other at 2.5 bar, 60 min bottom time each. All patients were asked to fill in a questionnaire (social and medical history, tinnitus characteristics, pre-HBO2 duration oftinnitus, prior therapy, pre-treatment expectation, accompanying symptoms) immediately before and one month after HBO2 treatment. The subjective impact of tinnitus on daily life was assessed using a score from 1 to 10 prior to HBO2 and one month after the treatment.
Results: 12 patients (3.3%) experienced complete remission of tinnitus, in 122 (33.9%) the intensity lessened, and 44 (12.2%) had a subjectively agreeable change of noise characteristics. 157 (43.6%) stated no change and 25 (6.9%) experienced deterioration. There was no statistically significant difference between the two hyperbaric protocols (p > 0.05). Out of 68 patients with positive expectation towards HBO2 therapy 60.3% stated that the tinnitus had improved whereas out of the patients who underwent therapy with indifferent (N = 271) or negative expectations (N = 21) only 47.2% and 19%, respectively, reported an improvement. The influence of both positive and negative anticipation on the outcome was statistically significant (p < 0.05).
Conclusion: The therapeutic effects of HBO2 on subjective tinnitus might be greatly due to psychological mechanisms triggered by the attitude of the patient towards HBO2 therapy prior to the treatment.