Introduction:
The aim of this prospective randomized clinical trial was to compare the therapeutic efficacy of steroid treatment (systemic and intratympanic) versus combined administration of steroids and hyperbaric oxygen therapy (HBOT) as initial treatment in cases of idiopathic sudden sensorineural hearing loss (ISSNHL).

Material and methods:
102 patients with up to a 10-day history of ISSNHL were randomized into two groups and followed prospectively. Group A (52 patients) received prednisolone intravenously followed by methylprednisolone orally and 3 courses of intratympanic injections with dexamethasone, whereas Group B (50 patients) were administered a combination of the aforementioned treatment together with 10 sessions of HBOT. The patients were followed-up with audiograms and pure-tone averages (PTAs) were measured. Hearing change was evaluated by comparing pre- and posttreatment PTAs.

Results:
The final mean hearing gain was 21.0 for Group A and 31.1 dB HL for Group B. The 10.1 dB HL difference in favor of Group B was statistically significant (p=0.004). However, when recovery was assessed in terms of Siegel’s criteria, no statistically significant difference could be demonstrated. Patients younger than 45 years old achieved better hearing outcomes, and treatment was more effective at low frequencies (0.25 and 0.5 kHz). Combined HBOT and steroid treatment seems to provide greater hearing benefit for patients with severe hearing loss (initial PTA >70 dB HL).

Conclusions:
Early application of HBOT combined with systemic and intratympanic steroid administration significantly improved hearing outcomes with an absolute gain in PTA audiometric threshold of 10.1 dB (95% CI 1.5–29.8, p=0.004). Therefore, adding HBOT along with steroids as initial treatment in ISSNHL is recommended. Younger patients with severe hearing loss can be expected to derive most benefit.