Acute low-tone sensorineural hearing loss

Two-hundred forty-one patients with acute low-tone sensorineural hearing loss (ALSH) who consulted my clinic from 1987 to 1996 were retrospectively investigated. The results were as follows: (1) In 110 patients, the sum of hearing level in three low frequencies (125 Hz, 250Hz and 500Hz) was more than 100dB, and that in three high frequencies (2KHz, 4KHz and 8KHz) was less than 60dB. This audiological finding is a widely accepted criterion for the diagnosis of ALSH. One-hundred thirty-one patients did not fit this criterion. (2) The annual number of ALSH patients gradually increased during these ten years due to an increase in the number of female patients. (3) A high incidence of young females characterized these ALSH patients. (4) Of 162 patients, 64.8% and 17.9% showed complete and partial recovery of hearing, respectively. (5) The recovery rates were compared in two groups, one group consisted of patients whose sum of hearing level in the three lower frequencies was more than 100dB, and the other group was comprised of patients whose sum of hearing level in the same lower frequencies was less than 100 dB. There was no statistical difference in recovery rate between the two groups. (6) The frequency distribution of the mean of hearing level in the three lower frequencies was investigated. The mean and standard deviation was 39.1 +/- 11.8dB. By histogram, these results resembled a normal distribution. This suggests that these 241 patients has same disease entity. The pathophysiological condition of ALSH must not be various. Also, that ALSH has the peculiarity that an approximate 40 dB hearing loss may be a normal occurrence.