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

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.

Retrospective study.

Tertiary care university hospital.

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).

1 to 12 μL perilymphatic fluids were collected by micropipette. α1-antitrypsin levels were determined, and current and historic audiological parameters were obtained.

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).

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.