Auditory Brainstem Responses in Neonatal Period
Part I. Studies on Maturational Changes in ABR of the Neonates
1983 Volume 35 Issue 3 Pages 517-527
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1983 Volume 35 Issue 3 Pages 517-527
Auditory brainstem response was first described by Jewett and Sohmer in 1970, as the early 10 msec duration of component of auditory evoked potential, which was recorded from scalp electrodes. ABR changes in its wave components with the development of brainstem. ABR is consisted of seven components and wave V is shown to be the most detectable one in human neonates.
Recently, ABR has been used as the tool for clinical assessment of neurological diseases and auditory function in adults and children. For the purpose of establishing the normal value of ABR wave components in neonatal period at our institute, ABR was recorded in 65 normal newborns without any neurological, respiratory and other abnormalities, in age from 28 to 45weeks of gestation. The mean and standard deviations were calcurated in each gestational age, and various changes were observed as following.
1) In full term neonates, the latencies of ABR wave components when measured with a stimulus of 85 dB, and 4000 Hz were as follows; Wave I: 1.98±0.08 msec, Wave 4.94±0.39 msec, Wave V: 7.04±0.47 msec, and I - V interval: 5.05±0.38 m sec.
2) The wave V latency decreases 0.26 msec a week with according to development.
3) The latency is influenced by various click. For example, the wave V latency prolonged with decreasing stimulus tone intensity and also decreased with increasing stim u lus tone cycles. There was significant difference in the wave V latency between 6000 Hz and 2 0 00Hz. (P<0.001)
4) There was also significant difference in latencies to each wave got from AFD and SFD with similar body weight. This result suggests that, ABR may be of use for the assessm e nt of gestational age.
5) There are no significant difference between ABR patterns of full term neonates and the premature neonates at the time of 40 weeks in gestational age.
6) It is necessary to establish the normal values of ABR in each institution for assessment of abnormality in ABR, because each ABR-device may depict different wave patterns.
