Proper pre-operative hearing aid fitting and cochlear implant: language and cognitive outcomes

Background Proper and consistent hearing aid (HA) fitting before cochlear implant (CI) surgery provides auditory stimulation with preservation of central auditory pathway activation that supports the post-implant auditory rehabilitation. The duration of HA use before CI may significantly influence auditory and speech outcomes following implantation. Objective The main aim of this study is to evaluate the effect of the HA use duration before cochlear implantation (CI) on the postoperative auditory processing, cognitive functions and language development outcomes in children. Methods This study included a control group (20 normal-hearing children) and a study group (46 children fitted with unilateral CI). According to the duration of HA use prior to CI, the study group was classified into two subgroups: subgroup 1 (HAD1) included 21 children with HAs use duration of one year or less, while subgroup 2 (HAD2) included 25 children with HAs use duration of more than one year. The evaluation test battery included history, otoscopic examination, basic audiological evaluation, mismatch negativity, cortical auditory evoked potentials, and the Arabic version of the Montreal Cognitive Assessment (MoCA) scale. Results There was a significant reduction in speech discrimination score (SD%) in both HAD1 and HAD2 subgroups when compared to controls, with no significant difference between the two subgroups. MMN latency was significantly prolonged in the HAD1 subgroup compared with both HAD2 and controls. For CAEPs, both P1 and N1 latencies were significantly delayed in HAD1 and HAD2 subgroups compared with controls with no significant difference between the two subgroups. P2 latency was significantly prolonged only in HAD1 compared with controls. MoCA scores were significantly lower in both HA subgroups compared with controls. Conclusion The outcomes of CI are shaped by multiple factors. Although the early and consistent auditory stimulation through HA prior to CI plays a critical role in shaping both auditory and cognitive outcomes in children with hearing loss.