40 INTRAUTERINE VERSUS EXTRAUTERINE MATURATION OF AUDITORY EVOKED RESPONSES (BMC ARs)

Abstract

Brainstem (ABR), Middle Latency (MLR) and Cortical (ACR) Auditory Responses were studied in 65 healthy preterm and 25 healthy term infants at 40 weeks conceptional age (CA) and al 52 weeks CA in order to establish the differences between intrauterine and extrauterine maturation of BMC ARs. The latencies of the ipsilateral ABR components I, II, V and ihe contralateral ABR components He and Ve at 40 and 52 weeks CA showed no significant differences between preterm infants and term infants, although in preterm infants a consistent tendency towards longer latencies was found. The latency of MLR component P0 was significantly longer in preterm infants compared to term infants, whereas MLR component Na showed no significant latency differences. The most interesting findings are related to the latency differences of the ACR components between term infants and preterm infants. At 40 weeks CA the latencies of components Na, Nl and P2 were significantly shorter in preterm infants, whereas at 52 weeks CA these latencies were significantly longer in preterm infants. Further, it was notable that at 40 and 52 weeks CA there was a striking difference in ACR wave form between preterm infants and lerm infants. At 40 and 52 weeks CA in preterm infants ACR wave form showed a less mature than in term infants, whereas term infants show a more mature wave form.