Objective: To study the pathophysiological features of acute low-tone sensorineural hearing loss without vertigo (ALHL) and its correlation with Meniere's disease.
Design: Retrospective review of medical charts of patients with ALHL.
Setting: University hospital clinic.
Participants: Eighty consecutive patients with ALHL, including 45 patients whose conditions were followed up for more than 3 years (average, 5 years 2 months; range, 3 years 3 months to 8 years).
Outcome measures: Age and sex distributions and results of audiological and neuro-otological tests, initial outcome, recurrence rates, and differences between patients with and without recurrence.
Results: About 75% (62/80) of the patients were between the ages of 30 and 60 years and the female-male ratio was 2:6. Positive glycerol test results were found in 74% (26/35) of patients and abnormally increased negative summating potential/action potential ratio in 63% (50/80). No abnormalities were found on neuro-otological tests. Hearing loss improved within 3 months in 84% (67/80) of the patients. Of 45 patients followed up for more than 3 years, 28 (62%) showed no evidence of recurrence, 12 (27%) developed cochlear Meniere's disease, and five (11%) developed classic Meniere's disease. No significant differences were found at the first examination between patients with and without recurrence.
Conclusions: These results suggest that ALHL may be caused by endolymphatic hydrops confined to the cochlea and that ALHL does not always lead to cochlear or classic Meniere's disease.