Human summating potential to tone bursts: observations on tympanic membrane versus promontory recordings in the same patients.

ABSTRACT

Electrocochleographic responses to tone bursts and clicks were recorded from the tympanic membranes (TMs) and promontories of six suspected Meniere's patients. Although the majority of ears had normal summating potentials (SPs), regardless of recording site and stimulus type, some displayed amplitude-enlarged SPs at both sites and to both types of stimuli. The following observations were made from these patients regarding the choice of recording approaches and stimuli for ECochG (1) Although SP amplitudes at the promontory were approximately four times larger than corresponding TM values, response "patterns" leading to diagnostic interpretation were the same at both sites; (2) the majority of patients who displayed enlarged SP amplitudes to tone bursts also had enlarged SPs to clicks; and (3) with tone-burst stimuli, the amplitude of the SP alone was sufficient for diagnostic interpretation of the ECochG waveform.