Electrocochleography (ECochG) has evolved as an important tool in the diagnosis/assessment/monitoring of Ménière's disease/endolymphatic hydrops (MD/ELH). This manuscript provides an update on the use of ECochG for these purposes. The material presented includes descriptions of the components of the electrocochleogram; ECochG recording approaches and parameters; how to prepare for an exam, including subject/patient considerations; construction and placement of a tympanic membrane recording electrode; and interpretation the electrocochleogram. Various approaches aimed at improving ECochG's sensitivity and specificity to MD/ELH also are described. These approaches go beyond simple measurement of the now-conventional summating potential (SP)/action potential (AP) magnitude ratio to include the SP magnitude to tonebursts, the SP/AP area ratio, and the AP latency difference to clicks of opposing polarity.

Conventional analysis of the click-evoked electrocochleogram includes measurement of the amplitudes of the cochlear summating potential (SP) and auditory nerve action potential (AP) to derive the SP/AP amplitude ratio. It is now well documented that an amplitude ratio where SP is elevated relative to AP may be a positive finding for endolymphatic hydrops in patients suspected of having Ménière's disease (MD). However, the incidence of an elevated SP/AP amplitude ratio in the general MD population is only approximately 60%. This relatively low value necessitates efforts to improve the diagnostic sensitivity of electrocochleography (ECochG) for MD. A review of early and more recent literature in this area indicates that consideration of both the amplitude and duration of ECochG components may help to achieve this goal. The present study combined these features to measure the "area" of the SP-AP complex in normal and MD populations. A software routine was used to measure the amplitude x duration area of the SP-AP complex in (a) normally hearing adults with normal SP/AP amplitude ratios (Group 1), (b) confirmed MD patients with elevated SP/AP amplitude ratios (Group 2), and (c) probable MD patients with normal SP/AP amplitude ratios (Group 3). Ninety percent of the confirmed MD patients in Group 2 displayed elevated SP/AP area ratios relative to the normative value established from Group 1. In addition, almost half of the probable MD patients from Group 3 displayed elevated area ratios. These findings indicate that measurement of the SP/AP area ratio holds promise for improving the sensitivity of ECochG in the diagnosis of MD.

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Research related to expanding and improving the clinical use of electrocochleography (ECochG) has been ongoing for 25 yr at the University of Kansas Medical Center. This article presents highlights of findings from our laboratory during this period that have contributed to current ECochG recording approaches and clinical applications. A review of new data related to improving the sensitivity of ECochG in the diagnosis of Ménière's disease, the use of an ear canal recording approach for improving auditory brain stem response testing in newborns, and technical aspects related to recording the cochlear microphonic in newborns also will be presented.

The SP/AP area curve ratio significantly improves ECochG diagnostic sensitivity in possible MD. This ECochG refinement will allow earlier intervention to preserve inner ear function in MD.