Endogenous α1-antitrypsin levels in the perilymphatic fluid correlates with severity of hearing loss

Objectives: To determine the levels of endogenous α1-antitrypsin in the perilymph of patients undergoing cochlear implant (CI), and its reverse association with the severity of hearing loss. Study Design: Retrospective study. Setting: Tertiary care university hospital. Participants: The study includes 38 patients undergoing CI surgery, 11 patients diagnosed with congenital deafness and 27 non-congenital deafness, eight patients diagnosed with moderate hearing loss (N = 8; PTA = 70 dB), severe hearing loss (N = 11; PTA 70-90 dB) and profound hearing loss (N = 19; PTA > 90 dB). Main outcome and measure: 1 to 12 μL perilymphatic fluids were collected by micropipette. α1-antitrypsin levels were determined, and current and historic audiological parameters were obtained. Results: The congenital and non-congenital group exhibited AAT concentrations of 2.5 ± 1.9 × 10⁶ LFQ and 3.2 ± 1.2 × 10⁶ LFQ, respectively (mean ± SD; P =.38). Mean levels of α1-antitrypsin in the perilymph fluid within the moderate group was 3.64 × 10⁶ ± 2.1 × 10⁶ LFQ vs 3.5 × 10⁶ ± 1.2 × 10⁶ in severe hearing loss (P =.81) and 2.4 × 10⁶ ± 1.1 × 10⁶ LFQ in the profound hearings loss group (P =.06). The difference in levels of AAT in samples from the severe hearings loss group vs the profound hearings loss group reached statistical significance (P =.04). Conclusion: Insufficiency in α1-antitrypsin levels in the perilymph fluid of the inner ear appears to display a relationship with the severity of hearing loss. The prospect of introducing clinical-grade plasma-purified α1-antitrypsin directly onto the site of cochlear injury deserves thorough investigation.