正常乳幼児における聴性脳幹反応の頭皮上電位分布の研究

抄録

The purpose of present study was to investigate the developmental change of the waveforms, the amplitude and the latency of auditory brainstem responses (ABRs) in infants, in comparison with those in adults. Experiments were performed on 27 infants (1 month to 4 years of age) without major perinatal complication, and 7 adults with normal hearing. The topography of ABRs to monaural and binaural stimulation were obtained from 16 scalp electrode locations designated by the international 10-20 system with the reference electrode on the seventh cervical vertebra (CVII). A potential map of each ABR component and a time-course potential map were two-dimensionally displayed using a computer. The results were as follows: 1) There was a trend for all peak latencies to decrease with age. This effect was particularly pronounced for the later ABR components. The latency of wave I reached that of the adults at 2 months of age, wave III, wave V and interpeak-latencies at 2 years of age. 2) The ABR waveforms obtained from the infants above 2 years of age were similar to those of the adults. The wave II and wave III components in infants under 1 year of age had a tendancy to fuse. A peculiar finding in infant ABRs was that a peak appeared between wave I and wave II, which was named wave Ix. The wave was evident in infants less than 6 months of age, and disappeared at more than 2 years of age. Its origin was assumed to be at the central site of the eighth cranial nerve since the potential map of the wave was similar to that of wave I. 3) The two-dimensional map patterns of each component in infant ABRs were similar to those of adults. This fact suggests that the origin of ABR and the orientation of physiological firing in infants are identical with those in adults.