Can electrocochleography in Meniere's disease be noninvasive?

OBJECTIVES

To evaluate and compare the results of extratympanic and transtympanic electrocochleography (ECochg) in clinically diagnosed cases of Meniere's disease and controls.

DESIGN

Prospective study on 20 clinically diagnosed cases of Meniere's disease and 20 age- and sex-matched controls.

SETTING

Department of Otolaryngology, Head and Neck Surgery, Postgraduate Institute of Medical Education and Research, Chandigarh, India.

METHODS

Electrocochleography was performed by a transtympanic method using a stainless steel needle electrode kept on the promontory and by an extratympanic method whereby the needle electrode was inserted into bony canal skin.

MAIN OUTCOME MEASURES: The various parameters compared were summation potential latency and amplitude, action potential latency and amplitude, and ratio of summation to action potential amplitude (SP/AP).

RESULTS

A significant difference in summation to action potential amplitude ratio (SP/AP) between cases and controls was obtained by both methods. Using 0.29 as a cutoff for SP/AP, the transtympanic method yielded a sensitivity of 100% and a specificity of 90%, whereas the extratympanic method showed corresponding values of 90% and 80%, respectively.

CONCLUSION

Contrary to previous studies, extratympanic ECochg is shown to be an efficacious and a less invasive test as compared with the transtympanic method and can be easily performed in clinical practice.