Auditory Cortex Maturation and Language Development in Children with Hearing Loss and Additional Disabilities

Abstract

A significant portion of hearing-impaired children have additional disabilities, but data about the maturation of their auditory cortex are scarce. In these children, behavioral tests are often unreliable, and objective tests are needed for diagnostics and follow-up. This study aimed to explore auditory cortical maturation and language development, and the usability of an objective electroencephalogram-based biomarker in children with multiple disabilities. In 65 hearing aid and cochlear implant users (36 females; 36 with multiple disabilities; 44.3 ± 18.5 months of age, mean ± SD), auditory processing was examined using the P1 cortical auditory evoked response biomarker, and language development with the Preschool Language Scales 5th edition (PLS-5). During the study, all of the children received intensive extra language therapy for six months. No significant differences were found between the groups in P1 latency development, the proportion of abnormal P1 latencies, or the number of children whose P1 latencies changed from abnormal to normal during the study. The PLS-5 total language scores, auditory comprehension scores, or expressive communication scores did not differ between groups either. The P1 latencies showed meaningful negative correlations with the language scores. The results suggest that auditory cortex development is similar in hearing-impaired children with/without additional disabilities, and the P1 biomarker is a feasible tool to evaluate central auditory maturation in children with multiple disabilities.

Keywords: CAEP; EEG; P1 biomarker; auditory; cortical; disability; electroencephalogram; evoked potential; hearing loss; language.

Figure 1

Individual CAEP P1 latency trajectories in children with complete datasets. Straight arrow lines show the improvement of the individual latencies from baseline (20 children with isolated hearing loss and 17 children with multiple disabilities) to follow-up (22 children with isolated hearing loss and 22 children with multiple disabilities): solid lines depict children with isolated hearing loss, and dashed colored lines depict children with multiple disabilities. Different disabilities are shown with different colors. Confidence intervals for age-matched normative values are indicated by the light gray areas. CMV = cytomegalovirus.

Figure 2

Average age-normalized CAEP P1 latencies at baseline and follow-up (mean ± SEM, in ms). Negative values indicate the raw P1 latencies within normal limits in comparison to age-matched normal hearing peers, and positive values indicate abnormally long P1 latencies. At baseline, 21 children with isolated hearing loss and 18 children with multiple disabilities had identifiable P1 responses; at follow-up, the numbers were 22 and 23, respectively.

Figure 3

Individual PLS-5 score trajectories in children with complete datasets. Arrow lines demonstrate the improvements in individual age equivalent scores from baseline to follow-up (23 children with isolated hearing loss and 22 children with multiple disabilities): solid lines depict children with isolated hearing loss, and dashed colored lines depict children with multiple disabilities. Different disabilities are shown with different colors. The linear gray lines show the normal development trajectories. CMV = cytomegalovirus.

Figure 4

Age-equivalent language outcomes (mean ± SEM, in ms). Greater values indicate a higher age equivalent language age in months. There were 29 children with isolated hearing loss who completed PLS-5 language testing, while 36 children with multiple disabilities completed PLS-5 language testing. At follow-up, 28 children with isolated hearing loss completed language testing, and 33 children with multiple disabilities completed language testing.