ObjectiveTo analyze the therapeutic effect and prognostic factors of patients with idiopathic sudden sensorineural hearing loss (ISSNHL) treated with adjuvant hyperbaric oxygen therapy (HBOT).MethodsThe clinical data of 167 ISSNHL patients were retrospectively analyzed. The patients were diagnosed and hospitalized in the First Affiliated Hospital of University of South China from January 2012 to January 2017. The patients were divided into two groups (complete recovery group in 84 cases, and no recovery group in 83 cases) according to the hearing recovery. Univariate and multivariate analysis were performed to assess the factors associated with prognosis (gender, ear side, age, initial hearing threshold, presence of tinnitus and vertigo, hypertension, diabetes, onset of HBOT, number of HBOT, audiogram) between recovery group and no recovery group.ResultsThe overall recovery rate was 50.3%, the rate of complete recovery, marked recovery and recovery were 2.0%、21.4% and 12.2%, respectively. According to multivariate analysis, initial hearing threshold, absence of vertigo and onset of HBOT had significant influence on prognosis of ISSNHL.Conclusion20 sessions of HBOT may be enough to achieve the therapeutic effect of ISSNHL. Patients with lower initial hearing threshold, absence of vertigo and earlier HBOT onset have better prognosis.