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- Engström, Elisabet, et al.
(author)
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Auditory event-related potentials and mismatch negativity in children with hearing loss using hearing aids or cochlear implants : A three-year follow-up study
- 2021
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In: International Journal of Pediatric Otorhinolaryngology. - : Elsevier. - 0165-5876 .- 1872-8464. ; 140
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Journal article (peer-reviewed)abstract
- Objectives: The primary aim was to examine how event-related potentials (ERPs) and mismatch negativity (MMN) change and develop over time among children with hearing loss (HL) using hearing aids (HAs) or cochlear implants (CIs). Children with normal hearing (NH) were tested as a reference group.Methods: This three-year follow-up study included 13 children with sensorineural HL (SNHL); 7 children using bilateral HAs and 6 children using CIs; and 10 children with NH as a reference group. ERPs were recorded at baseline and after three years. At time for the original study the children were approximately 5-8 years old and at the follow-up study 8-11 years old. ERP recordings and data processing were identical in both sessions. A standard stimulus alternated with five different deviants (gap, intensity, pitch, location and duration), presented in a pseudorandom sequence, thus following the multi-feature paradigm, Optimum-1. MMN was calculated from the average ERP of each deviant minus the standard stimuli. Repeated measures ANOVA was used for the statistical analyses and the results were based on samples within a specific time interval; 80-224 ms.Results: There was a statistically significant difference in the obligatory responses between the NH and HA groups at baseline, but this difference disappeared after three years in our follow-up study. The children with HA also showed a significant difference in mean ERP at baseline compared to follow-up, and significant differences between the deviants at follow-up but not at baseline. This suggests an improvement over time among the children with HAs. On the other hand, the children with CIs did not differ from the NH children at baseline, but after three years their mean ERP was significantly lower compared to both the children with HA and NH, indicating a reduced development of the central auditory system in this age span among the children with CIs. Regarding MMN, there was an interaction between the duration deviant and time for the children with HA, also indicating a possible improvement over time among the HA children.Conclusions: This three-year follow-up study shows neurophysiological differences between children with HL and children with NH. The results suggest a delay in the central auditory processing among the HA children compared to children with NH, but a possible catch-up, over time, and this potential may be worth to be utilized. Regarding the CI children, similar improvement in this age span is missing, meaning there are differences between the subgroups of children with HL, i.e. the children with HAs vs. CIs. The results highlight the importance of distinguishing between subgroups of children with HL in further research.
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| 2. |
- Jönsson, Göran, et al.
(author)
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Increased serum bactericidal activity of autologous serum in C2 deficiency after vaccination against Haemophilus influenzae type b, and further support for an MBL-dependent C2 bypass mechanism
- 2021
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In: Vaccine. - : Elsevier BV. - 0264-410X. ; 39:8, s. 1297-1302
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Journal article (peer-reviewed)abstract
- Deficiencies of C2 and other components of the classical pathway of complement are associated with increased risk of infections with encapsulated bacteria, such as Haemophilus (H.) influenzae. Defense against H. influenzae is dependent on specific antibodies and complement, which mediate serum bactericidal activity (SBA) and opsonization. Due to lack of normal classical and lectin complement pathway function in C2 deficiency (C2D), SBA would have to depend either on the alternative pathway or on C2 bypass mechanisms. Here we studied SBA against H. influenzae type b (Hib) before and after vaccination in a group of C2-deficient persons, as the bactericidal capacity of antibodies in autologous complement in relation to vaccination has not been investigated at group level in C2D. Sera from 22 persons with C2D and 26 healthy controls were available. Out of these, 18 persons with C2D and all controls had been vaccinated with Act-HIB®. SBA against Hib bacteria was analyzed with autologous serum as the only complement source. Antibodies to Hib capsular polysaccharide had been analyzed previously. Concentrations of mannose-binding lectin (MBL) and other complement components were measured in serum. SBA of both C2-deficient persons and controls was significantly more efficient after vaccination (p = 0.002 and p < 0.0001, respectively). After vaccination, all but two C2-deficient sera and one control serum showed sufficient SBA (<50% surviving bacteria). Before vaccination, SBA of C2-deficient sera was negatively correlated to serum concentrations of MBL (lower proportion of surviving bacteria with higher MBL concentration; r = −0.55, p = 0.008). After vaccination, SBA of C2-deficient sera was negatively correlated to serum concentrations of IgG Hib antibodies (r = −0.56, p = 0.01). In conclusion, SBA against Hib in autologous serum is increased after vaccination in persons with C2D. In unvaccinated C2-deficient persons SBA was correlated to MBL concentration, providing further support for an MBL-dependent C2 bypass mechanism operating in C2D.
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