The development of auditory perception in children after auditory brainstem implantation

Abstract

Auditory brainstem implants (ABIs) can provide useful auditory perception and language development in deaf children who are not able to use a cochlear implant (CI). We prospectively followed up a consecutive group of 64 deaf children up to 12 years following ABI surgery. The etiology of deafness in these children was: cochlear nerve aplasia in 49, auditory neuropathy in 1, cochlear malformations in 8, bilateral cochlear postmeningitic ossification in 3, neurofibromatosis type 2 in 2, and bilateral cochlear fractures due to a head injury in 1. Thirty-five children had other congenital nonauditory disabilities. Twenty-two children had previous CIs with no benefit. Fifty-eight children were fitted with the Cochlear 24 ABI device and 6 with the MedEl ABI device, and all children followed the same rehabilitation program. Auditory perceptual abilities were evaluated on the Categories of Auditory Performance (CAP) scale. No child was lost to follow-up, and there were no exclusions from the study. All children showed significant improvement in auditory perception with implant experience. Seven children (11%) were able to achieve the highest score on the CAP test; they were able to converse on the telephone within 3 years of implantation. Twenty children (31.3%) achieved open set speech recognition (CAP score of 5 or greater) and 30 (46.9%) achieved a CAP level of 4 or greater. Of the 29 children without nonauditory disabilities, 18 (62%) achieved a CAP score of 5 or greater with the ABI. All children showed continued improvements in auditory skills over time. The long-term results of ABI surgery reveal significant auditory benefit in most children, and open set auditory recognition in many.

Figure 1

Median pediatric ABI scores on the CAP test over time. Results are grouped by the highest score ultimately achieved for categories 4–7.

Figure 2

Best ABI CAP scores as a function of the age at implantation. Open symbols represent children with additional disabilities. Filled symbols indicate children with no additional disabilities. Only the 53 children who had the ABI at least 3 years and were under 10 years of age at the time of implantation are included.

Figure 3

Median pediatric ABI CAP scores over time grouped according to other disorders. Children with no other disorders only had cochlea or cochlear nerve pathologies. Other disorders include a variety of congenital disorders listed in Table 1. The numbers of children at each follow up year for the two groups are as follows. For the group “No Other Disorders”: 29, 29, 26, 23, 17, 14, 11, 9, 5, 4, 2 for years 0–10, respectively, and for the group “Other Disorders”: 35, 35, 30, 30, 26, 21, 17, 13, 10, 10, 8 for years 0–10, respectively.

Figure 4

Median pediatric ABI scores on the CAP test over time grouped by primary diagnosis. The numbers in parenthesis after each category indicates the number of children in that category at 1 year post implant. Numbers of children in each category diminish with years. Actual numbers at each year are found in Table 1. The dashed line reproduces CAP scores over time from 53 children with a CI from Archbold et al., 1995.