Vol.101 No.12 contentsPRACTICA OTO-RHINO-LARYNGOLOGICA
Vol. 101 No. 12 December 2008
Distortion Product Otoacoustic Emissions and Hearing Outcomes
in Idiopathic Sudden Sensorineural Hearing Loss
Takanori Mori, Nobuaki Hiraki, Koichi Hashida,
Gunji Nagatani, Narihisa Ueda and Hideaki Suzuki
(University of Occupational and Environmental Health)
We investigated the clinical usefulness of distortion product otoacoustic emissions (DPOAEs) for the prediction of hearing outcomes in idiopathic sudden sensorineural hearing loss (ISSNHL).
Thirty-two patients with ISSNHL (time from the onset to the start of treatment ≦14 days) were enrolled in the study. They received steroid administration (400 mg/day of hydrocortisone sodium succinate followed by tapered doses) combined with hyperbaric oxygen therapy. DPOAEs (f2/f1＝1.2, L1＝80 dBSPL, L2＝70 dBSPL, geometric mean (GM) of f1 and f2＝531-5,500 Hz, every one-third octave) were measured before and after treatment. The degree of hearing recovery was classified into four categories (complete recovery, good recovery, satisfactory recovery, no change) according to the criteria of the Ad Hoc Committee of the Japanese Ministry of Health, Labour and Welfare.
The DPOAE output in the high-frequency range (GM of f1 and f2≧2,781 Hz) before treatment was higher in the complete recovery group than in the other three groups. The DPOAE output at 2,781 Hz and 4,375 Hz was significantly higher in the complete recovery than in the satisfactory recovery and no change groups (Student's t-test, p＜0.05). However, the improvement of the DPOAE output after treatment did not statistically differ at any frequency among the four groups.
These results indicate that the DPOAE output in the high-frequency range before treatment can be a prognostic indicator of hearing outcomes in patients with ISSNHL.
Key words :idiopathic sudden sensorineural hearing loss, distortion product otoacoustic emission, hearing outcome, steroid, hyperbaric oxygen therapy