RESUMO
OBJECTIVE: To investigate whether distortion product otoacoustic emissions (DPOAEs) can be a prognostic indicator of hearing outcomes in patients with idiopathic sudden sensorineural hearing loss (ISSNHL). METHODS: Seventy-eight consecutive patients with ISSNHL were enrolled. DPOAEs were measured at the first hospital visit. Two primary pure tones with a frequency ratio (f2/f1) of 1.2 were used at non-equal sound pressure levels (L1/L2=80/70dB SPL). The DPOAE amplitude was measured at the 11 frequencies of 2f1-f2 with f2 varying from 593 to 6031Hz. All the patients received steroid administration in combination with hyperbaric oxygen (HBO) therapy. Hearing recovery was evaluated by the improvement in hearing compared to the unaffected contralateral ear. Correlations between the hearing improvement rate and five potential prognostic factors (the DPOAE amplitude, patient's age, days from onset to the start of treatment, initial hearing level, and presence of vertigo) were examined by simple and multiple regression analyses. RESULTS: The net DPOAE amplitude in patients with hearing improvement rate ≥50% was significantly larger than that with hearing improvement rate <50% at f2 frequencies of 3031 and 4812Hz (unpaired Student's t-test, p<0.05). A simple regression analysis showed that the hearing improvement rate significantly correlated with the net DPOAE amplitude at f2 frequencies of 3031 and 4812Hz, but not with that at the other f2 frequencies tested. The correlation coefficients were 0.528 and 0.522 for 3031 and 4812Hz, respectively, with p values <1×10(-6). In a multiple regression analysis, the partial correlation coefficients of the net DPOAE amplitude were 0.308 and 0.246 with p values of 0.008 and 0.036 for 3031 and 4812Hz, respectively. CONCLUSION: The significant correlation between hearing recovery and DPOAEs measured before treatment indicates that DPOAEs are a potentially useful means of predicting hearing prognosis in ISSNHL.