Inner ear pressure changes in normal guinea pigs induced by the Meniett 20

Abstract

Introduction. The objective was measurement of inner ear fluid pressure changes of normal guinea pigs induced by the Meniett 20 (Pascal Medical, Sweden), a possible therapeutic pressure generator to be used by patients with Meniere's disease. Methods. In seven guinea pigs, the tip of a micropipette was inserted into the inner ear via the round window membrane, reached by a retroauricular approach. A small hole was cut in the tympanic membrane and the bulla was closed again. Middle ear pressure was altered via the external meatus using a pressure generator (Meniett 20) which produced complex oscillatory pressure pulses. Inner ear pressure was simultaneously measured with a WPI micropressure system. Results. Middle ear pressure changes were transferred instantly to the inner ear of guinea pigs. Inner ear pressure declined while middle ear pressure kept relatively stable. An average undershoot of −1.0 cm water with respect to the steady state pressure was seen after application of a pressure pulse, which was released in a few seconds. There was no change in steady state inner ear pressure after a complete session. Conclusion. Complex oscillatory pressure pulses produced by the Meniett 20 applied to the middle ear of guinea pigs causes a transient reduction of inner ear fluid volume.