Identification of early-stage Meniere's disease as a cause of unilateral tinnitus.

INTRODUCTION: Meniere's disease (MD) is characterized by episodic symptoms, including vertigo, hearing loss, and tinnitus.

OBJECTIVES: in this study, cases of unilateral tinnitus were investigated for MD.

METHOD: Twenty-two patients who presented with chronic unilateral tinnitus on puretone audiograms showing an average threshold better than 25 dB HL and thresholds in the lower frequencies worse than those in the higher frequencies by more than 10 dB were suspected to have early-stage MD and underwent electrocochleography (ECochG). Patients showing ECochG findings conclusive for MD were compared to a control group of patients presenting with chronic unilateral tinnitus on pure-tone audiograms showing an average threshold better than 25 dB and thresholds in the higher frequencies worse than those in the lower frequencies by more than 10 dB.

RESULTS: Eighteen of the 22 patients included in this study showed elevated summating potential amplitude to action potential amplitude ratios in ECochG (suggestive of endolymphatic hydrops due to MD) and were followed up for 2 months; 14 of them experienced at least two attacks of vertigo or unsteadiness. In contrast, only one patient in the control group reported two or more attacks of vertigo or unsteadiness in the 2 month observation period. The incidence of this finding in the two groups was significantly different.

CONCLUSION: Patients with early-stage MD can present with only unilateral tinnitus. Thus, the addition of "pure-tone audiograms showing lower-frequency thresholds worse than higher-frequency thresholds" to the probable MD category in the globally.agreed diagnostic criteria for MD, may be useful.