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Effect of perilymphatic air perfusion on cochlear potentials
T Kobayashi1, Z Itoh, T Sakurada
1Department of Otorhinolaryngology, Tohoku University School of Medicine, Sendai, Japan.
Acta Oto-Laryngologica
|September 1, 1990
Summary
Air in the inner ear (pneumolabyrinth) causes hearing loss by disrupting cochlear potentials, not strial dysfunction. This study investigated the mechanism of reversible hearing loss from air intrusion into the perilymphatic space.
Area of Science:
- Otoacoustic Emissions
- Auditory Neurophysiology
Background:
- Perilymphatic fistula can cause acute profound hearing loss.
- The mechanism of reversible hearing loss in perilymphatic fistula is debated.
- Pneumolabyrinth (air in the inner ear) is a proposed cause of hearing loss.
Purpose of the Study:
- To examine the mechanism of hearing loss associated with pneumolabyrinth.
- To investigate the effect of air perfusion in the perilymphatic space on cochlear potentials.
Main Methods:
- Perfusion of the guinea pig cochlea's perilymphatic space with air.
- Recording of cochlear microphonics (CM), compound action potential (AP), and endocochlear dc potential (EP).
Main Results:
- Air perfusion caused immediate, drastic decreases in CM and AP.
- EP remained largely unaffected during the initial 20 minutes of air perfusion.
- EP decline was observed only after 30 minutes of air perfusion in half the ears.
Conclusions:
- The endocochlear potential exhibits significant resistance to air in the scala tympani.
- Initial hearing loss in pneumolabyrinth is likely due to impaired CM and AP generation, not strial dysfunction.