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

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).

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.

A cohort of n=18 sensorineural hearing-impaired children was recruited from the German Göttinger Hör-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.

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 > 90 dB 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.

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 > 40 dB. 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.