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

OBJECTIVES: To determine the levels of endogenous alpha1-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, 8 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 muL perilymphatic fluids were collected by micropipette. alpha1-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+/-1.9x10(6) LFQ and 3.2+/-1.2x10(6) LFQ, respectively (mean+/-SD; p=0.38). Mean levels of alpha1-antitrypsin in the perilymph fluid within the moderate group was 3.64x10(6) +/-2.1x10(6) LFQ vs. 3.5x10(6) +/-1.2x10(6) in severe hearing loss (p=0.81) and 2.4x10(6) +/-1.1x10(6) LFQ in the profound hearings loss group (p=0.06). The difference in levels of AAT in samples from the severe hearings loss group versus the profound hearings loss group, reached statistical significance (p=0.04). CONCLUSION: Insufficiency in alpha1-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 alpha1-antitrypsin directly onto the site of cochlear injury deserves thorough investigation.