Recovery Rates by Severity of Hearing Loss in Cases of Acute Low-Tone Sensorineural Hearing Loss

Acute low-tone sensorineural hearing loss (ALHL), first reported in 1988, is a disease characterized by hearing loss, tinnitus, and other auditory symptoms, and is recognized as an independent disease entity from sudden hearing loss. Although the severity of hearing loss was defined for the first time in 2015 by the “Research Group on Intractable Hearing Impairment” of the Ministry of Health, Labour and Welfare, few studies have examined the treatment outcomes by the severity of hearing loss. We determined the overall cure rate (cure/all cases) in 336 ALHL cases treated over an 11-year period from 2011 to 2021, and also the cure rates by the severity of the hearing loss and steroid use. The overall cure rate was 64.0%, 75.0% in cases with Grade 1 severity, 74.3% in cases with Grade 2 severity, 57.4% in cases with Grade 3 severity, and 34.7% in cases with Grade 4 severity. The cure rate in the Grade 3/Grade 4 cases was significantly lower than that in the Grade 1/Grade 2 cases. There was no significant difference in the cure rate by steroid use. It is well known that the cure rate of sudden hearing loss depends on the hearing level at the time of the initial diagnosis, and the cure rate of ALHL can also be predicted by the sum of the hearing levels of the three lowest frequencies at the time of the initial diagnosis. Although this study did not demonstrate the efficacy of steroid use, it is possible that the study design biased the sample population. ALHL is associated with a higher incidence of recurrence than sudden hearing loss, but steroids also have a variety of side effects. Therefore, the appropriateness of steroid use in the treatment of ALHL should be determined based on a comprehensive assessment of comorbidities, patient age, and disease severity.