正常新生儿ABR的表现形式及建立正常参考值的可行性探讨

Wave Features of Auditory Brainstem Response in Normal Newborns and the Feasibility to Set up Newborns ABR Normative Data

目的探讨正常新生儿听性脑干反应(auditory brainstemresponse,ABR)的表现形式及建立新生儿ABR正常参考值的可行性。方法对20例(40耳)足月产且通过瞬态诱发耳声发射筛查的3～5天龄新生儿进行听性脑干反应测试,观察其反应阈、潜伏期、波间期及波形随着刺激强度降低的几种表现形式,并与耳科正常青年人50例相关数据进行比较。结果正常新生儿ABR反应阈为33.67±6.25dB nHL,80dB nHL刺激时,波I、III、V潜伏期分别为1.91±0.16、4.85±0.28、6.98±0.28ms,I-V波间期为5.05±0.25ms,III-V波间期为2.17±0.21ms,I-III波间期为2.90±0.22ms。其反应阈高于正常青年人,各波潜伏期及波间期较正常青年人延长,V/I振幅比0.55±0.27,低于正常青年人。两组上述各观察值差异有统计学意义。阈强度时,波I、III、V同时可见者占40%,仅可见波V者占25%,仅可见波III者占32.5%,仅可见波I者占2.5%。单耳波III或波I最后消失者,均为右耳。结论相同天龄的新生儿听觉系统的成熟程度存在较大的个体差异,分别表现为波V、波III或波I最后消失,或在阈强度时,同时可见波I、波III及波V;同一个体左右侧发育程度亦不同步,因而难以在某一个年龄点上建立正常参考值。

Objective To investigate the morphology of auditory brainstem response（ABR） of normal newborns and the establishment of the newborns ABR normative data. Methods Tested were 20 cases of normal newborns aged 3-5 days in ABR thresholds, latencies, inter--peak lateneies and the changes caused by the decreased stimulus intensity. The data were compared to that of their counterparts of 50 cases of normal young adults. Results The thresholds of newborn ABR were 33.67± 6.25 dB nHL when the stimulus was 80 dB nHL click; the latencies of wave I,III and V were 1.91±0.16 ms,4.85±0.28 ms,6.98±0.28 ms, respectively; the inter--peak latencies of I--V, III--V and I--III were 5.05±0.25 ms,2.17±0.21 ms and 2.90±0.22 ms respectively. The ABR thresh- olds of newborns were elevated from that of adults while all the latencies and inter--peak latencies of newborn were longer than that of adults. The amplitude ratio of wave V/I was 0.55±0.27, substantially lower than that of adults. The data between newborns and adults showed statistically significant differences. When the stimulus intensity reached at thresholds, wave I,III and V were noticeable in 40% of all ears tested while wave V in 25% of all, wave III in 32.5% , and wave I in 2.5% . If wave III or wave I were noticeable at threshold intensity for one ear, it seemed that they all appeared on the right side. Oonctusion The maturity of the central auditory system seems to have great individual differences among newborns even at the same age in different mature level, ABR remained wave I, wave III, wave V and wave I＋III＋ V at the threshold intensity respectively. The inter--ear differences were noted between the left and right ear of the same individual, implying that the two ears have different mature levels. This has made it difficult to establish reliable normative data for all newborns.