Tympanic electrocochleography: normal and abnormal patterns of response.

Electrocochleography has been widely used in human and animal studies of endolymphatic hydrops. A variety of response patterns have been reported in normal and hydropic ears. Recent clinical studies have focused almost exclusively on the amplitude ratio of the summating potential (SP) and action potential (AP) derived from alternating polarity click responses. In this report normal response patterns are described with a tympanic membrane electrode employing condensation, rarefaction and alternating polarity clicks and tone burst stimulation. A variety of response abnormalities are described in patients with suspected endolymphatic hydrops. The exclusive use of alternating polarity clicks is not adequate to reveal the nature of these abnormalities.