[Review of the evaluation criteria for low tone sudden deafness]

Low tone sudden deafness (LTSD) has the three following features; obscure origin, acute or sudden onset and sensorineural hearing loss limited to low frequencies without vertigo. Twenty LTSD patients with total hearing levels at low frequencies (125 Hz, 250 Hz, 500 Hz) from 70 dB to 95 dB (Group A) and 19 LTSD patients (typical LTSD) with levels above 100 dB (Group B) were studied. All patients visited our department within one week after onset. All presented over the past 3 years and were followed up for two years or more after initial examination. The clinical parameters such as incidence, subjective symptoms, the configuration of the audiogram and the prognoses of patients in the two groups were investigated comparatively. The following results were obtained. (1) Patients in their twenties were more frequently affected in group A, but patients aged 20 to 50 were equally affected in group B. (2) Females were more frequently affected in both groups, remarkably so in group B. (3) Hearing disorders frequently occurred after an upper respiratory tract infection and stress in both groups. (4) Fullness of the ear, tinnitus and hearing disturbance were common chief complaint and subjective symptoms in both groups. (5) The configuration of the audiogram seemed to be variable within each group and between the two groups. (6) The ratios of recurrent type to monoattack type were almost the same and the patients had good prognoses in both groups. From the results mentioned above, both groups were considered to belong to the same category of LTSD.(ABSTRACT TRUNCATED AT 250 WORDS)