A comparison of three methods of using transtympanic electrocochleography for the diagnosis of Meniere's disease: click summating potential measurements, tone burst summating potential amplitude measurements, and biasing of the summating potential using a low frequency tone.

CONCLUSION

Stimulus biasing modulated the amplitude of the tone burst evoked summating potential (SP) in ears affected by Meniere's disease less than in normal ears. A reduced SP bias ratio added diagnostic accuracy for the diagnosis of Meniere's disease.

OBJECTIVES

To evaluate the effect of stimulus biasing on the human tone burst SP, and to determine if stimulus biasing could contribute to the electrocochleography as a means of confirming the diagnosis of Meniere's disease.

PATIENTS AND METHODS

Patients referred for transtympanic electrocochleography (TT ECochG) were assessed prospectively on clinical grounds according to the AAO-HNS criteria and a scale devised by one of the authors. A Meniere's group of ears and a non-Meniere's group of ears was determined. The ears opposite a Meniere's ear were not included in the analysis. The ratio of the click SP amplitude and the action potential (AP) amplitude (SP/AP ratio), the tone burst SP amplitude at 500 Hz,1 kHz, 2 kHz and 8 kHz, and the effect of stimulus biasing on the tone burst SP were measured.

RESULTS

A unipolar stimulus biasing ratio established for the modulation of the 1 kHz tone burst SP separated the Meniere's ears from the non-Meniere's ears with a sensitivity of 85% at a specificity of 80.6% and the difference between groups reached statistical significance (p=0.016). The 1 kHz SP amplitude measurements and the stimulus biasing measurements were superior to the click SP/AP ratio for identifying the Meniere's group. A combination of 1 kHz SP amplitude measurements and SP bias ratio separated the Meniere's ears from the non-Meniere's ears with an accuracy of 85%.