Diagnostische Methoden für potentielle cochleäre Synaptopathie bei Menschen

Introduction:
Patients in early age-related hearing loss (ARHL) often report difficulty with speech recognition in background noise despite normal pure-tone audiograms, possibly due to cochlear synaptopathy (CS). This study investigates whether reduced speech discrimination in background noise during early ARHL is associated with changes in stapedius reflexes and decreased extended high frequency thresholds (EHT).

Material and Methods:
Thirty-eight participants (mean age 26.2 ± 3.3 years) underwent physical examination, pure-tone audiometry from 0.125 to 16 kHz, stapedius reflex measurements, and speech recognition tasks in background noise at varying signal-to noise ratios (SNRs). Speech discrimination data were analyzed using sigmoidal fits to determine the slope and speech recognition threshold at 50% discrimination (SRT50), which were correlated with stapedius reflex thresholds and EHT.

Results:
The average SRT50 was -5.8 ± 1.1 dB SNR with a slope of 0.74 ± 0.149%/dB. Four ears performed significantly worse (SRT50 between -3.3 and -1.9 dB SNR). The average EHT was 10.45 ± 15.6 dB HL; 14 ears were worse than 20 dB HL. Stapedius reflex thresholds averaged 75.4–80.6 dB HL. Stapedius reflex thresholds at 0.5 kHz correlated with SRT50 (R = 0.27, p = 0.02), slope (R = -0.37, p = 0.001), and EHT (R = -0.29, p = 0.01).

Discussion:
These results support the hypothesis that reduced speech recognition linked to CS is accompanied by changes in stapedius reflexes. Additionally, EHT correlates with these findings, supporting ist use as an early indicator of CS.

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