Y Kaseki | PubMed Health

PubMed1991

Effects of persistent perilymph fistula on the inner ear.

To study the effects of a persistent perilymph fistula on the cochlea, a small cannula was inserted into the scala tympani of the basal turn of cochlea in guinea pigs. A month later, cochlear morphology and blood flow were studied using either histological evaluation or the microsphere surface preparation technique. Some animals showed no cochlear morphologic changes or no cochlear blood-flow reduction, even if tubal patency was maintained and perilymph leakage lasted for 1 month. This suggests that a prolonged perilymph fistula, per se, causes no permanent cochlear damage. However, in some animals, hair cell damage and cochlear blood-flow disorders were observed. These observations and the causes of hearing loss in clinical cases of perilymph fistula were studied.

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PubMed1990

Histological evaluation of cochlear blood flow using different fixation methods.

For an accurate histological evaluation of cochlear blood flow, it is essential to fix the cochlear vessels while maintaining their physiological state. In the present study, we administered 10% CO2 to guinea pigs and then used phase-contrast microscopy to determine how two different methods of fixation influenced the cochlear vasculature. The first method of fixation employed perilymphatic perfusion in vivo, while the second one involved fixation after decapitation. Decapitation caused significant changes in the vessels of the stria vascularis, including constriction and sludging. In contrast, no sludging occurred in the perilymphatic perfusion method and erythrocyte morphology was preserved. However, dilatation of the strial blood vessels occurred after the inhalation of 10% CO2 even in the decapitation method. The results demonstrate that particular attention must be paid to the fixation method used, especially when evaluating the blood flow of the stria vascularis.

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