Evoked and Spontaneous Otoacoustic Emissions in Acute Sensorineural Hearing Loss
| Project/Area Number |
04671036
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Otorhinolaryngology
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| Research Institution | NAGOYA UNIVERSITY |
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Principal Investigator |
HATTORI Taku Nagoya University School of Medicine, Associate Professor, 医学部, 講師 (10172933)
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| Co-Investigator(Kenkyū-buntansha) |
UEDA Hiromi Nagoya University School of Medicine, Associate Professor, 医学部, 講師 (20213358)
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| Project Period (FY) |
1992 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1993: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1992: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | Acute sensorineural hearing loss / Sudden deafness / Low tone sensorineural hearing loss / Evoked otoacoustic emission / EOAE / e-OAE |
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| Research Abstract |
Time course of 78 acute sensorineural hearing loss cases mainly on sudden deafness (SD) was evaluated by means of pure tone audiometry (PTA) and Evoked otoacoustic emissions (EOAEs). The minimum detectable levels (thresholds) of each components (fast and slow) of EOAEs showed improvement with or without correlation to the recovery of PTA levels. This difference seemed to come from the site, degree and combination of damaged cochlea partitions. In the full recovery group, the thresholds of EOAEs improved with good correlations to the recovery of PTA levels. In contrast, as the degree of PTA level improvement was decreased, changes of the thresholds of EOAEs lost good correlation in the prominent, partial recovery and no change groups. This result suggests that the main pathological change in the full recovery group of SD might be the metabolic damage of the inner ear which influences to the generator of EOAEs reversibly. Sometimes the thresholds of EOAEs in the healthy sides of SD cases showd unexpected changes suggesting the asymptomatic viral infection to the healthy side of the ear.
In acute low tone sensorineural hearing loss (ALTHL), in spite of the full or nearfull recovery of PTA levels in all cases, the thresholds of each components of EOAEs showd no remarkable change through the recovery course. Cochlea partitions Which are responsible for the ALTHL are revealed to be different the generator of EOAEs.
In animal experiment, the output of EOAEs showed reversible changes with administration of ototoxic drugs, suggesting that the affected site is metabolically dependent micromechanisms. In a preliminary study, EOAE power under 2 kHz in the FFT powergram was increased and above 4 kHz was decreased significantly after opening of auditory bulla. This result demonstrates that the consideration should be taken in the conditioned experiment.
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Report
(3 results)
Research Products
(9 results)
