ELECTRIC-RESPONSE AUDIOMETRY IN YOUNG-CHILDREN BEFORE COCHLEAR IMPLANTATION - A SHORT-LATENCY COMPONENT

Objective: Evaluation of a short latency component (SLC) observed in p rofoundly deaf young children during recordings of the auditory brain stem response (ABR) before cochlear implantation. Design: Seventy youn g children (ages 2 to 11 yr) were investigated as part of their routin e audiologic and diagnostic assessment before cochlear implantation. T he ABR was evoked using click stimuli and tone pips (500 Hz and 1 kHz) at intensity levels up to 105 dB nHL. The incidence of the SLC arisin g at a latency of 3 msec with high level click stimuli, in addition to residual ABR waves, was assessed. Results: An SLC was observed in a t otal of 18 of the 70 children investigated. It was present in 15 out o f 31 congenitally deaf children (48%) compared with only 2 out of 33 c hildren deafened after meningitis (6%). A chi-squared test employing a 2 x 2 contingency table shows that this dependency on etiology of dea fness is highly statistically significant p < 0.001). The presence of the SLC in the congenitally deaf children is related to age at the tim e of the Electric Response Audiometry test and is more likely to be ob served in the younger child (p < 0.01). Conclusions: Interpretation of the ABR in profoundly deaf children should take into consideration th e possible presence of the SLC. An evoked potential arising from stimu lation of the vestibular system, particularly the vestibular nuclei, i s proposed as a likely origin for this component. Damage to sensory ce lls in the vestibular portion of the labyrinth might explain why an SL C is seen rarely in cases of deafness after meningitis.