MATERIALS AND METHODS: A retrospective repeated crosssectional study was conducted by recruiting patients with cochlear implants presenting to the Dr. Cipto Mangunkusumo National General Hospital, Jakarta, Indonesia between 2017 and 2021. Basal (b1, b2) and apical (a1, a2) electrodes, representing the outermost and innermost parts of the cochlear implant electrodes, were measured at switch on and at 1 year post-implantation.
RESULTS: A total of 123 patients, with a total of 123 cochlear implant samples, were included in the analysis. We found a substantial change in electrical impedance between switch on and follow-up periods, where the impedance levels of basal electrodes decreased (b1: mean difference (MD) -1.13 [95% confidence interval (CI): -1.71, -0.54], p<0.001; b2: MD -0.60 [95%CI: -1.17, -0.03], p=0.041) and those of apical electrodes increased (a1: MD 0.48 [95%CI: -0.28, 0.99], p=0.064; a2: MD 0.67 [95%CI: 0.12, 1.22], p=0.017). We also found that the choice of surgical approaches for implant insertion may affect the electrode impedance. Cochleostomy approach resulted in a higher impedance than round window in basal (b1) and apical (a2) electrodes both at switch on and follow-up (b1 at switch on and at follow-up: p=0.019 and p=0.004; a2 at follow-up: p=0.012). Extended round window approach also resulted in a higher impedance than round window in basal (b1) and apical (a2) electrodes at follow-up (p=0.013 and p=0.003, respectively).
CONCLUSION: Electrical impedance of cochlear implant electrodes may change over time, highlighting the importance of regular impedance assessments for cochlear implant users to ensure optimal device function. The round window approach resulted in better initial and long-term impedance levels compared to cochleostomy, and better long-term impedance levels than extended round window. Extended round window approach also gives better impedance level than cochleostomy. Further research should investigate the potential interplay between surgical approach and other factors that may impact impedance levels to confirm our findings.
MATERIALS AND METHODS: cCMV-infected neonates aged ≤3 weeks old were recruited and underwent clinical and laboratory tests to detect viremia and symptomatic infection, hearing examinations at three and six months of age, and radiological imaging of brain auditory pathways using diffusion tensor imaging.
RESULTS: From 26 eligible infants (52 ears), we detected symptomatic infection in nine (34.6%), viremia in 14 (14/25; 56.0%) and sensorineural hearing loss (SNHL) in 14 infants (53.8%). We observed 40 ears (76.9%) with unstable hearing thresholds, 17 (42.5%) of which fluctuated. Hearing fluctuation and progressivity were more common in symptomatic infection (66.7% vs. 14.7%, p<0.001; and 38.9% vs. 2.9%, p=0.002; respectively). A substantial proportion of ears had reduced fractional anisotropy (FA) in the medial geniculate body (59.1%), superior olivary nucleus (45.5%), trapezoid body (40.9%), auditory radiation (36.4%) and inferior colliculus (31.8%). Symptomatic infection was associated with an increased FA in the medial geniculate body (mean difference, MD: 0.12; 95% Confidence Intervals, 95%CI: 0.03, 0.22) and viremia in the inferior colliculus (MD: 0.09; 95%CI: 0.02, 0.16). An FA in the inferior colliculus of ≥0.404 had a sensitivity and specificity of 68.8% and 83.3% in predicting viremia (area under the curve 0.823; 95%CI: 0.633, 1.000, p=0.022).
CONCLUSION: SNHL along with its fluctuation and progression are common in cCMV-infected infants. cCMV infection may induce structural changes in the central auditory pathway.