Jekaterina Byčkova, Eglė Gradauskienė, Eugenijus Lesinskas, Violeta Mikštienė, Algirdas Utkus
The present study aims are to clarify causes of congenital hearing loss in children who received cochlear implant (CI) and to evaluate the early outcomes after cochlear implantation. 46 children with congenital deafness who underwent cochlear implantation were assessed prior to and 12 months after activation of the CI. The average hearing threshold measured by auditory brainstem response (ABR) audiometry was 98,2 dB. The average age of diagnosis of hearing loss for all 46 children was 14,6 months. Molecular genetic testing was performed for 21 patients. 12 cases of genetic non-syndromic connexin mutation related deafness were identified and two syndromes – CHARGE and Jacobsen were diagnosed. Of the causes identified, a genetic mechanism was present in 30,4% of the cases, peripartal problems in 23,9%, congenital cytomegalovirus infection in 2,2%, postnatal infection 4,3%, and in 39,1% of the cases etiologic factor remained unknown. According to CT imaging findings, 3 children showed inner ear anomalies: 2 Mondini malformations and a narrow internal auditory canal, and one partial cochlear ossification. The majority of children (30; 65,2%) were implanted before 24 months of age. The average age at implantation was 25,4 months. Outcomes were measured using the Categories of Auditory Performance (CAP) score. For all children, the CAP score increased after implantation. After 12 months 28 (60,9%) children had a CAP score of 4 or 5 (discriminates speech sounds or understands common phrases without lipreading). This study demonstrates that the better auditory performance was achieved by children who were implanted at a younger age. So, since one third of the cases of congenital deafness is due to genetic factors, molecular genetic testing plays a central role in the evaluation of the etiology and should be extended. Hearing loss for most of the children was diagnosed late, thus it is necessary to introduce the universal newborn hearing screening in our country. Further studies to evaluate late outcomes as well as determine prognostic factors in our population of implanted children are needed.
Keyword(s): pediatric cochlear implantation; etiology; outcomes
Full Text: PDF