Causes of bilateral sensorineural hearing loss in 838 patients according to degree of progression of hearing loss.

Purpose: This study aimed to investigate the etiology of hearing loss (HL) based on the rate of its progression. Material and methods: Pure tone audiometry was conducted on 42,744 tests (9,269 cases) at Shinshu University Hospital between 2012 and 2022. Cases with unilateral HL, conductive HL, postoperative ear issues, functional hearing loss, and those with bilateral scaling-out at initial examination or lacking detailed data were excluded. A retrospective review was performed on 838 cases followed for over 5 years. Hearing progression was categorized as "Stable" (0-1 dB HL/year), "Slow progression" (1-3 dB HL/year), and "Fast progression" (>3 dB HL/year). Causes were classified as genetic, middle ear disease, Meniere's disease-related, other known causes, and unknown etiology. Results: Of the 838 cases, 302 were classified as "Stable", 402 as "Slow progression", and 134 as "Fast progression". Across all groups, unknown etiology was the predominant cause of HL, followed by genetic factors in Stable and Slow progression groups, and others in the Fast progression group. Regarding genetic etiology, the GJB2 and STRC genes were most prevalent in the Stable group, while genes such as SLC26A4 and CDH23 were identified across all groups. Conclusions: Regardless of progression rate, over half of bilateral HL cases had an unknown etiology. Genes such as GJB2 and STRC were identified to exhibit stable hearing, consistent with our findings. This study suggests that genes responsible for progressive HL manifest in an intermittent, rather than continuous, manner, highlighting the clinical utility of genetic testing, particularly in cases lacking long-term follow-up data. [ABSTRACT FROM AUTHOR]