Outcome of language therapy in bimodal-fit children versus unilateral cochlear implant children in bilateral sensorineural hearing impairment: a case-control study

Abstract
Background
Treating hearing-impaired children aims not only to improve their hearing but also to enhance language acquisition capability. In our community, the CI usually performed on one side because of financial issues at least for a period of time. Consequently, the brain may neglect the unfitted ear. Contralateral hearing aid is an alternative solution when bilateral CI is unavailable. Our purpose is to evaluate the language outcome in bimodal-fit children who using cochlear implant (CI) and contralateral hearing aid (HA) compared to children using unilateral cochlear implant only.

Results
In this case-control study, 15 children who are using binaural-bimodal stimulation by unilateral CI and contralateral HA and 15 children using monaural cochlear implant received auditory training and language therapy. All participants have been assigned randomly from the Phoniatrics and Audiology clinics. Filtering of patients was made to get the two groups matched regarding age, sex, family motivation, age of implantation, and age of hearing impairment. Evaluation and language therapy were performed in the Phoniatrics clinic. Language progress in each group was compared over different time-points. Also, it was compared between the two groups in each time-point. Both groups revealed significant language improvement over time with intensive auditory training and language therapy. In addition, the bimodal-fit children showed better language and speech outcomes than the unilateral CI children in receptive semantics, expressive semantics, word class, mean length of utterance, and speech intelligibility. The differences were significant with P-values 0.047, 0.034, 0.03, 0.016, and 0.028, respectively, after 9 months of rehabilitation.

Conclusion
Bimodal-fit children showed better improvement in language than the unilateral CI group. The contralateral hearing aid may be complementary to the unilateral cochlear implant by covering wider speech frequency range. Also, it prevents auditory deprivation and enables binaural hearing with positive impact on language outcome.