BRAIN-STEM AUDITORY-EVOKED RESPONSE IN RELATION TO NEONATAL GLUCOSE-METABOLISM

Imprecise control of glucose homeostasis is a hallmark of neonatal glu cose metabolism. A relatively wide range of glucose concentrations is considered 'euglycemic' (2.22-6.94 mmol/l, 40-125 mg/dl) in the neonat al period. We investigated the effects of a wide range of glucose conc entrations on brain stem conduction time (BCT) I-V interpeak latency o r prolonged wave V latency, Neonates were assessed by brain stem audit ory-evoked response followed immediately by heelstick sampling to dete rmine the blood glucose concentration. Twenty-seven appropriate for ge stational age (AGA) term neonates (birth weight 3,245 +/- 766 g, mean +/- SD; gestational age 39 +/- 2 weeks) were studied 3.1. +/- 3.7 days after birth. Twenty-three AGA preterm neonates (birth weight 2,175 +/ - 477 g; gestational age 35 +/- 1 weeks) were studied 6.0 +/- 7.2 days after birth. Brain stem conduction time wave I-V interpeak latency an d wave V latency were determined in two trials using a Grason-Stadler ABR screener at a 60-decibel stimulation level in the right ear. Neona tes were studied between 33 and 40 weeks gestational age, Although the blood glucose concentration ranged from 1,38 to 6.83 mmol/l(25-123 mg /dl), there was no correlation between either brain stem conduction ti me wave I-V interpeak latency or wave V latency and blood glucose conc entration. We conclude that alterations in glucose concentration withi n the generally accepted neonatal euglycemic range do not effect the f unctional status of the brain stem auditory pathway. We suggest that t he data can be interpreted to affirm that tighter clinical control of glucose homeostasis is probably not required in the neonatal period.