Recently, acute low-tone senseorineural hearing loss (ALHL) has become common, and its good prognosis is known well. On the other hand, several reports have suggested that ALHL is frequently associated with Meniere's disease. We retrospectively examined the clinical course of 357 cases that were diagnosed and treated as ALHL at our hospitals. Forty-four of these cases that showed high-tone hearing loss in association with age-related changes were classified as atypical cases. The clinical futures of 49 "poor prognosis cases", who experienced recurrent hearing loss and/or profound hearing loss, are reported. Eight of the 49 cases who experienced recurrences had progressive hearing loss upto middle or high tones. Seventeen cases complained of vertiginous sensation, and 8 of these cases experienced recurrent attacks of vertigo and were diagnosed as having Meniere's disease. The former seventeen cases accounted for 34.7% of the "poor prognosis cases", and the latter eight accounted for 16.3% of these cases. Our results suggest that the hearing loss is more frequently associated with Meniere's disease in cases who experience recurrent hearing loss. Thus, cases initially diagnosed as ALHL may include some cases of progressive hearing loss and Meniere's disease. Even in cases in which hearing improvement is obtained, careful clinical observation is necessary, especially in older patients with bilateral affliction and atypical presentation. ALHL has been generally considered to have a good prognosis, however our examination revealed a relatively high frequency of recurrences, progressive hearing loss and complication by vertigo. We recommend, based on this evidence, that careful explanation of this disease is necessary at time of initial informed consent.
