Travelling wave velocity test and Ménière's disease revisited

Transtympanic Electrocochleography (TT-ECoG) and the glycerol test can aid in the diagnostic process of Ménière's disease (MD). Measurement of travelling wave velocity (TWV) has been proposed as an alternative to TT-ECoG to detect endolymphatic hydrops. We assessed the feasibility and obtained normative data of the TWV test in the diagnosis of MD, and compared the test results in MD patients with their symptoms and their TT-ECoG results. The TWV test records two runs of auditory brainstem responses to clicks that are ipsilaterally masked with two different high pass filtered noise bands. The resulting latency difference of peak V was used as a measure of the TWV. The 95% confidence interval of this latency difference was defined in a group of 28 normals. Subsequently, the test was performed in nine MD patients. After the TWV test, seven of these patients underwent a TT-ECoG. The symptoms of MD patients at the time of testing and their TT-ECoG results were compared with TWV test results. The 95% confidence interval of the latency difference of peak V in the control group was 0.190-0.668 ms. A latency difference <0.190 ms indicates an increase in TWV, and thus reflects a positive test. In nine MD patients, we found a clear correlation between the result of the TWV test and TT-ECoG. The TWV test result did not significantly correlate with a single symptom. Our findings suggest that the TWV test can be useful to detect endolymphatic hydrops, but further experiments with larger patient groups are needed to confirm the diagnostic value of the TWV test.