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Electrocochleography with postural changes in perilymphatic fistula. Animal studies
1Department of Otolaryngology-Head and Neck Surgery, University of Iowa College of Medicine, Iowa City.
The Annals of Otology, Rhinology, and Laryngology
|June 1, 1994
Summary
Altering body position significantly affected electrocochleography in normal guinea pigs but not those with perilymphatic fistula. Fistula presence increased summating potential (SP) amplitude and SP/action potential (AP) ratio, regardless of position.
Area of Science:
- Otorhinolaryngology
- Neuroscience
- Physiology
Background:
- Perilymphatic fistula (PLF) can cause auditory symptoms.
- Electrocochleography (ECoG) measures inner ear electrical activity.
- The impact of body position on ECoG in PLF is not well understood.
Purpose of the Study:
- To investigate the effect of body position changes on ECoG findings.
- To compare these effects in normal and PLF guinea pig models.
- To determine if postural changes influence ECoG parameters in the presence of PLF.
Main Methods:
- Three groups of guinea pigs: normal controls, experimental PLF, and control PLF.
- ECoG recordings (SP and AP amplitude, AP threshold) using click and tone burst stimuli.
- Testing in different body positions (ventral down, ear up) and a static position control.
Main Results:
- Normal controls showed significant body position effects on the SP/AP amplitude ratio.
- PLF groups exhibited high variability in SP/AP ratio, masking positional effects.
- Both PLF groups had significantly larger SP/AP ratio and SP amplitude than normal controls.
- No significant changes in action potential threshold were observed across positions.
Conclusions:
- Body position influences ECoG in normal ears but not significantly in PLF ears due to high variability.
- PLF significantly elevates the SP/AP amplitude ratio and SP amplitude.
- ECoG may be a useful tool for diagnosing PLF, but positional testing requires careful interpretation.