[Effects of a change in environmental pressure on spontaneous nystagmus in patients with cochleovestibular diseases].

Cochlear and vestibular effects of variation of middle ear pressure have been discussed for more than 50 years. In 1975, Densert reported on temporary improvement of hearing threshold in patients suffering from Ménière's disease after reduction of air pressure in a pressure chamber. One year later Ingelstedt observed reduction of spontaneous nystagmus under this condition. The transmission of relative overpressure from the middle ear to the labyrinth with consecutive decongestion of the hydropic endolymphatic system to the saccus was thought to be the cause of this phenomenon. Meanwhile a direct effect of labyrinthine pressure on the activity of the inner ear and labyrinth in healthy subjects and animals has been described. In order to gain further information on the phenomenon observed by Densert and Ingelstedt we performed investigations on patients suffering from several cochleovestibular diseases. Chamber pressure was altered and simultaneous electronystagmographic recording was performed. As a striking result, we observed a reduction of the pathological spontaneous nystagmus in a majority of patients with vestibular damage during and after the reduction of chamber pressure. Many of these subjects showed a partial restitution of nystagmus if the chamber pressure was increased again. This observation was made in patients with Méni ere's disease, vestibular neuritis and sudden hearing loss with vestibular involvement. Hence, we conclude that this phenomenon is not specific for Ménière's disease. A transmission of middle ear pressure to the labyrinth may be an explanation of our observations.