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

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 Meniere's disease. Objective. Assessment of cochlear function during induction of a destructive acute endolymphatic hydrops. Materials and methods. During repetitive microinjections of 0.5 mu l of artificial endolymph at a rate of 50 nl/s the 2f(1) - f(2) and f(2) - f(1) cochlear microphonics distortion products (CMDP) and 2f(1) - f(2) distortion products otoacoustic emissions (DPOAE) were recorded in the guinea pig. Results. A 'catastrophe' occurred in the inner ear when 2.5 - 3.5 mu l 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 2f(1) - f(2) DPOAE amplitude. The 2f(1) - f(2) and f(2) - f(1) CMDP amplitude increased during each injection prior to the rupture. After the rupture the f(2) - f(1) CMDP amplitude decreased during each injection, possibly due to a shift of the cochlear transducer operating point position.