Evaluation of low-frequency biasing as a diagnostic tool in Menière patients.

Although it is generally accepted that endolymphatic hydrops is the cause of complaints in patients suffering from Menière's disease, it has not been possible up to now to prove the presence of an endolymphatic hydrops in living humans. This study evaluated the psychophysical method introduced by Mrowinski et al. [Mrowinski D., Gerull G., Nubel K., Scholz G., 1995. Masking and pitch shift of tone bursts and clicks by low-frequency tones. Hear. Res. 85, 95-102; Mrowinski D., Scholz G., Krompass S., Nubel K., 1996. Diagnosis of endolymphatic hydrops by low-frequency masking. Audiol. Neurootol. 1, 125-134] to diagnose endolymphatic hydrops. These authors used low frequency biasing to differentiate between individuals with and individuals without Menière's disease. In the present study no statistically significant differences in masking parameters could be found between a large number (n=91) of ears with Menière's disease and ears (n=52) with comparable sensorineural hearing losses, but without symptoms of Menière's disease. Our results support the idea that results deviating from normal in low frequency biasing measurements are not due to endolymphatic hydrops itself, but to other pathological changes of the inner ear. An explanation could be that with increasing hearing loss the gain of the cochlear amplifier decreases, leading to smaller modulation depths.