Hyperbaric oxygen therapy in the treatment of sudden sensorineural hearing loss: a retrospective analysis of outcomes

Objective: To analyse predictive factors affecting outcome after treatment with hyperbaric oxygen (HBOT) in patients with idiopathic sudden sensorineural hearing loss (ISSHL). Methods: This is a retrospective audit of outcome in 77 consecutive patients referred for consideration of HBOT for ISSHL for either adjunctive treatment or after failure of steroid therapy. The hearing measured from the pre- and post-HBOT pure-tone audiogram (PTA(4)) at four frequencies; 500 Hz, 1 kHz, 2 kHz and 4 kHz, was averaged and compared. The PTA(4) score was classified into three groups: complete improvement (<= 25 dB residual hearing loss); moderate improvement (11-50 dB gain) and no improvement (<= 11dB gain). Data were also analysed using mean residual loss on completion as the outcome measure. Results: Seventy-six patients underwent 1,029 HBOT sessions. Twenty five of 78 ears (33%) had complete resolution of deafness after HBOT. A further 31 (40%) had a significant improvement in PTA(4). Delay (> 28 days) and older age were associated with worse outcomes in PTA(4) improvement. Those with less severe hearing loss and short delay (< 15 days) had the best outcome (mean residual loss 28 dB). Eight of nine patients who were delayed > 28 days had no improvement in PTA(4). Conclusions: Fifty-six of 76 (74%) patients had complete (25) or moderate (31) improvement in hearing loss after HBOT. Short delay to HBOT, a severer degree of hearing loss and younger age were the best predictive factors of improved PTA(4). Outcome was poor if treatment was delayed over 28 days. Well-designed randomised controlled trials are needed to clarify the role of HBOT and steroids.