Conclusion: Various changes were observed in the cupula, including shrinkage and enlarged volume, following the disruption of the membranous labyrinth. Cupular change after membranous labyrinth disruption may be a pathology of vestibular disorders.
Objectives: To observe the morphological changes of the cupula after disruption of the membranous labyrinth and to compare the cupular changes with changes in the compound action potential (CAP) of the ampullary nerve.
Methods: A labyrinthine injury model was created by puncturing the membranous labyrinth of bullfrogs. The cupula was observed from 3 to 17 days after the membrane puncture. The CAP in response to mechanical endolymphatic flow was recorded from the ampullary nerve. The correlation between cupular change and CAP positivity was evaluated using the authors' scale.
Results: Various kinds of cupular changes including shrinkage were observed. Cupular change was more severe after a longer survival period. Large or elongated volume of the cupula was also observed, which was not observed in our previous study using gentamicin. The CAP could be recorded even when the cupular change was severe.