Rupture of Reissner's membrane during acute endolymphatic hydrops in the guinea pig: a model for Ménière's disease?

Abstract

Conclusion. The changes in cochlear function during a destructive acute endolymphatic hydrops were relatively small. This might be consistent with the hypothesis that an endolymphatic hydrops is a marker of disordered inner ear homeostasis rather than the cause of the clinical symptoms of Ménière's disease. Objective. Assessment of cochlear function during induction of a destructive acute endolymphatic hydrops. Materials and methods. During repetitive microinjections of 0.5 µl of artificial endolymph at a rate of 50 nl/s the 2f1−f2 and f2−f1 cochlear microphonics distortion products (CMDP) and 2f1−f2 distortion products otoacoustic emissions (DPOAE) were recorded in the guinea pig. Results. A ‘catastrophe’ occurred in the inner ear when 2.5–3.5 µl of artificial endolymph was injected. A rupture of Reissner's membrane was then found, most often in the apical turn of the cochlea. This rupture had only minor effects on the endocochlear potential, whereas it caused a marked decrease in 2f1−f2 DPOAE amplitude. The 2f1−f2 and f2−f1 CMDP amplitude increased during each injection prior to the rupture. After the rupture the f2−f1 CMDP amplitude decreased during each injection, possibly due to a shift of the cochlear transducer operating point position.