婴幼儿听神经病

Investigation of clinical features of auditory neuropathy in infants

目的对12名婴幼儿听神经病患者进行临床资料和听力学特征的讨论,了解婴幼儿听神经病的临床听力学特点。方法对我院门诊2004年-2006年确诊的婴幼儿听神经病12例进行临床资料分析。(1)听力学检查:视觉强化测听(VRA)、声导抗测试、畸变产物耳声发射(DPOAE)、瞬态诱发性耳声发射(TEOAE)、听性脑干反应(ABR)、听性稳态反应(ASSR)、40Hz听觉相关电位(40HzAERP);(2)辅助检查:颞骨CT扫描及血液维生素B12、叶酸及同型半胱氨酸含量测定。结果发病年龄为0-2岁,其中1岁以内发病者8例,占66.7%。进行视觉强化测听的8例(15耳)中重度至极重度聋12耳(占80%),听力图为上升型3耳(占20%),下降型4耳(占26.7%),平坦型8耳(占53.3%)。10例(20耳)完成声导抗测试,鼓室曲线图为As型或C型者12耳(占60%),20耳同侧及对侧镫骨肌反射均未引出反应。10例(19耳)行DPOAE检查,8耳各频率均检出反应,8耳在低频、3耳在低频和高频有个别频率未引出反应;另2例(4耳)行TEOAE检查,3耳各频率均引出反应,1耳低频和高频各有一频率未引出;对侧白噪声抑制效应均消失。12例(23耳)中,10例(19耳)ABR各波均未引出,2例(4耳)可见I波。ASSR阈值比主观听阈低的占76.9%,且两者之间无明显相关性。40HzAERP检出率为100%,阈值比主观听阈高的占66.7%,且两者之间无明显相关性;6例CT扫描,5例未见异常,1例示双侧中耳乳突炎及双侧上颌窦、筛窦炎;8例生化检查者中5例叶酸含量升高,3例同型半胱氨酸降低。结论婴幼儿听神经病有一定的特殊性:听力损失程度较重,易合并中耳疾病而混淆诊断。耳声发射正常、ABR和镫骨肌反射引不出及影像学检查不支持蜗后占位性病变等是诊断婴幼儿听神经病的主要标准,ASSR和40 Hz AERP可以辅助诊断。新生儿听力筛查时OAE应与快速ABR联合使用,以提高检出率。

Objective To analyse the clinical data and audiological characteristics of 12 infants with auditory neuropathy（AN） for gaining a better understanding of the clinical features of auditory neuropathy in infants. Methods The clinical methods used in this study were as follows： （1） audiological examination, including visual reinforcement audiometry （VRA）, acoustic immitance testing, distortion product otoacoustic emission （DPOAE）, transient evoked otoacoustic emission （TEOAE）, auditory brainstem response （ABR）, 40 Hz auditory event related potential （40 Hz-AERP）, and auditory steady state response （ASSR）; （2） auxiliary examination, including high-resolution computed tomography（CT） scan of the temporal bone, assay for vitamin B12, vitamin M and homocysteic acid. Results The onset age of the 12 infants ranged between 0- 2 yr and 8 of whom it was lower than lyr. Among the 8 patients （15 ears） who underwent VRA testing most （80%） showed severe to profownd deafness. Ten patients （20 ears） underwent acoustic immitance measurements, and the acoustic stapedial reflex was absent in all ears. All the patients had a normal DPOAE or TEOAE, but the ABR was absent or only wave I was present. In addition, the ASSR thresholds were lower, while the 40Hz-AERP thresholds were higher in most infants than subjective hearing threshold. Conclusion The audiological characteristics of auditory neuropathy in infants are different from those in adults and children. The diagnosis of auditory neuropathy in infants is documented by normal DPOAE, absent ABR, and no evidence of retrocochlear lesions in imaging examination. The ASSR and 40Hz-AERP would assist diagnosis. Therefore, OAE should be combined with automated ABR to more effectively diagnose auditory neuropathy in infants.