The Role of Low Tone Average in the Diagnosis of Meniere's Disease
Dobbs, Alan K
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Meniere’s disease (MD) is a disease characterized by fluctuating hearing loss, bouts of vertigo, tinnitus, often accompanied by aural pressure. The American Academy of Otolaryngology and Head and Neck Surgery (AAO-HNS) has a set of subjective criteria, which must be met to meet the diagnosis of MD. Objective tests, such as electrocochleography (ECoG) exists to aid in the diagnosis; however the tests are not necessarily specific and in many cases require significant skill in performing, as well as interpreting, the results. Audiograms are performed routinely in evaluating a patient with suspected MD. Audiograms in MD patients, especially early in the disease, show a characteristic low-frequency loss. This study sought to explore the low-frequency loss as yet another aid in the correct diagnosis. The low-frequency loss was used to create two new measures: 1) Low tone average (LTA), which was an average of 250 Hz, 500 Hz, and 1000 Hz; and 2) Meniere’s Ratio (MR), which was a ratio of LTA to pure tone average. Ideally the LTA would include 125 Hz to emphasize the low-frequency loss: however, 125 Hz is not routinely tested and those frequencies were not available for this study. One hundred subjects were studied. All had audiograms and 47 had ECoG performed extratympanically. Results of the analysis performed showed that MR was most closely related to the gold standard, ECoG. There was a bias towards males noted in the testing. These findings suggest that the MR approach holds some promise that needs further evaluation regarding differential sensitivity given specific patient characteristics.