Long-term follow-up of oral language development in children with permanent bilateral hearing loss

Abstract

Objective: The aim of this study was to assess the oral language development of children with permanent bilateral hearing loss without additional disabilities longitudinally (5 time points t1-t5). Method: The present follow-up study evaluated both receptive and expressive language developmental quotients (DQ; desired value 1.0) with standardised developmental scales and receptive and expressive vocabulary size with standardised tests (results in T-scores; m=50, SD=10). Mean follow-up duration was 38.1 (SD 4.8) months. Sample: A cohort of n=18 sensorineural hearing-impaired children was recruited from the German Gottinger Hor-Sprachregister. Mean diagnosis age was 21.4 (SD 16.6) months and mean age of amplification with hearing aids was 21.7 (SD 16.5) months. Results: The mean DQs slowly increased from t1 to t4 (DQ receptive 0.37/0.48/0.55/0.56; DQ expressive: 0.51/0.51/0.55/0.55) and remained norm deviant. The diagnosis age of hearing loss and both the developmental quotients for receptive (-0.41/-0.42/-0.53; p < 0.05/-0.80; p < 0.01) and expressive language (-0.77; p < 0.01/-0.55; p < 0.05/-0.66; p < 0.01/-0.79; p < 0.01) were significantly correlated. The mean receptive vocabulary size apparently increased and came up to the lower norm range (29.6-34.2-43.8), however the mean expressive vocabulary remained far below the norm (26.8-29.8). Children with a hearing loss from 71-90 dB scored on average mostly higher than children with a loss > 90dB who all had received a cochlear-implant up to t3. Children who were identified as hearing-impaired before the age of 18 months exhibited on average generally greater DQs. Conclusion: The individual best available amplification of hearing loss did not compulsively cause an age-adequate spoken language development, at least not in case of a hearing loss > 40dB. So a newborn hearing screening must be the first step in identification, intervention and habilitation of an infant with hearing loss. Use of a cochlear implant seemed to have a great impact on the oral language development of children with a bilateral loss > 90 dB.