Elevated Oxidative Stress and Impaired Antioxidant Defense in Idiopathic Sudden Sensorineural Hearing Loss: A Case–Control Study

Objective: Sudden sensorineural hearing loss (SSNHL) is an acute otologic emergency that can profoundly affect quality of life. Although various mechanisms, including viral, vascular, and immune-mediated pathways, have been proposed, most cases remain idiopathic. Oxidative stress has been suggested as a potential contributor by disrupting the balance between reactive oxygen species (ROS) and antioxidant defences within the cochlea. This study aimed to investigate serum oxidative stress markers and antioxidant enzyme activities in patients with idiopathic SSNHL compared with healthy controls.Materials and methods: This case–control study included 30 patients diagnosed with idiopathic SSNHL and 30 age- and sex-matched healthy volunteers. SSNHL was defined as a ≥30 dB loss over at least three contiguous frequencies within 72 hours, with secondary causes excluded. Blood samples were collected at presentation before treatment initiation. Serum malondialdehyde (MDA) levels and antioxidant parameters, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and reduced glutathione (GSH), were measured using commercial spectrophotometric assay kits. Between-group comparisons were performed using appropriate statistical tests.Results: Patients with SSNHL exhibited significantly elevated oxidative stress. Mean serum MDA levels were 1.66±0.29 μmol/L in the SSNHL group versus 0.69±0.09 μmol/L in controls (p<0.001). Antioxidant enzyme activities were markedly reduced in patients with SSNHL: SOD (1.63±0.73 vs. 6.85±0.85 U/mL), Gpx (0.06±0.04 vs. 0.21±0.006 U/mL), CAT (0.09±0.13 vs. 0.29±0.09 U/L), and GSH (2×10⁻⁵±1×10⁻⁵ vs. 1×10⁻⁴±5×10⁻⁶ U/L) were all significantly lower (p<0.001 for all comparisons).Conclusion: Idiopathic SSNHL is associated with heightened oxidative stress and a significant reduction in key antioxidant defences. These findings support the role of oxidative injury in SSNHL pathogenesis and suggest that therapies targeting redox imbalance, such as antioxidant adjunctive treatments, may offer potential benefits alongside standard management.