Relationship between the degree of endolymphatic hydrops and electrocochleography

The purpose of this study was to evaluate the relationship between the endolymphatic space image obtained using magnetic resonance imaging (MRI) and the results of electrocochleography. Electrocochleography recordings were obtained from 25 ears of 24 patients, who underwent MRI 1 day after the intratympanic injection of gadolinium diethylenetriamine pentaacetic acid bismethylamide. The average summating potential to action potential (SP/AP) ratio in patients with significant endolymphatic hydrops in the cochlea was 54 ± 17%. However, in some patients who had significant endolymphatic hydrops in the cochlea, the SP/AP ratio was not enlarged. This may imply that elevation of the SP/AP ratio is related to not only the degree of endolymphatic hydrops but also to the persistence of hydrops.