[Clinical study of acute low-tone sensorineural hearing loss].

Objective: To explore the etiology, clinical aspects, diagnosis and therapeutic strategies of acute low-tone sensorineural hearing loss (ALHL).
Methods: Thirty patients (31 ears) with ALHL were selected for this study. Detailed history collection, otological examination and systematic audiological evaluations were conducted. The hearing tests included pure tone audiometry, acoustic immittance, auditory brainstem response (ABR) and otoacoustic emissions (OAE). All cases received therapeutic trial of corticosteroid for 15 days with 6 to 14 months' following-up.
Results: ALHL mainly affected young people. Low-tone tinnitus, a sensation of ear fullness and hearing impairment were the frequent complains. Otological examinations showed normal results. Mild to moderate sensorineural hearing loss at low frequencies and type "A" tympanograms were found in all patients. Acoustic stapedial reflexes were elicited in 26 of 31 affected ears, and 14 of them had positive results on the Metz test. ABR responses were normal in all 20 tested ears. In 14 out of 20 ears, TEOAEs were absent and DPOAE grams at low frequencies (0.5, 0.75 kHz) were abnormal on the first visit. After steroid therapy, 24 ears demonstrated complete recovery, but 4 ears showed partial recovery and 3 ears unchanged. The total improvement rate was 90.3%.
Conclusions: ALHL patients are clinically characterized by low-tone tinnitus, aural fullness and hearing loss, which mainly involved unilateral ear. Audiological findings indicate a cochlear impairment, which only invades low frequency region. The basic pathological feature may be endolymphatic hydrops involves immune response. Conflicting data exist on whether ALHL is an independent disorder or a subtype of Meniere's disease. Ideal therapeutic strategy has not been established by now and corticosteroid is probably an effective agent.