Developmental changes of contralateral brainstem auditory evoked potentials: evaluation of brainstem maturation

Bilateral recordings of brainstem auditory evoked potentials obtained on monaural stimulation were studied in 147 normal subjects, aged 0 days to 21 years. We analyzed contralateral (opposite side to stimulation) wave forms in particular. The latencies of the contralateral wave II′ and III′ complex were shorter than those of ipsilateral wave III. The latencies of wave V on the ipsilateral side were shorter than those on the contralateral side. The contralateral wave II′ and III′ complex tended to separate into two divided peaks with age and could be classified into three types, i.e. a single slow peaked wave, a trapezium-like broad peaked wave and a double peaked wave. We called these wave forms the infantile, transient and adult types, respectively. The infantile type was seen in subjects aged under 14 months, the transient type between 1 month and 15 years, and the adult type over 13 months. Analysis of the contralateral wave forms of brainstem auditory evoked potentials may be useful for evaluation of functional maturation of the brainstem.