窒息早产儿最大长度序列脑干听觉诱发电位的变化及意义

目的 研究围产期窒息缺氧对早产儿脑干听觉功能的影响,分析能够早期反映脑干听觉功能变化的敏感指标以及最大长度序列脑干听觉诱发电位(maximum length sequence brainstem auditory evoked potential,MLS BAEP)是否较常规法对脑干听觉功能异常的检出具有优越性. 方法窒息早产儿组:胎龄29～33<'+6>"周有围产期窒息缺氧病史的早产儿51例.对照组:正常早产儿47例,正常足月儿38例.MLS BAEP检测时间分别为生后3～7 d、纠正胎龄37～42周、3个月.常规法声刺激速率为21次/s,MLS声刺激速率为91、227和455次/s,采用t检验比较组间Ⅰ、Ⅲ、Ⅴ波潜伏期和振幅,Ⅰ-Ⅲ、Ⅲ-Ⅴ、Ⅰ-Ⅴ峰间期的差异. 结果生后3～7 d,窒息早产儿较正常早产儿Ⅲ波、Ⅴ波潜伏期,Ⅰ-Ⅲ、Ⅲ-Ⅴ和Ⅰ-Ⅴ峰问期延长,Ⅴ波振幅降低(P<0.05).声刺激速率为455次/s时,窒息早产儿组Ⅲ波潜伏期为(6.64±0.58)ms,V波潜伏期为(10.57±0.93)ms Ⅰ-Ⅲ峰间期为(3.69±0.55)ms,Ⅲ-Ⅴ峰间期为(3.93±0.53)ms,Ⅰ-Ⅴ峰间期为(7.60±0.73)ms,明显低于正常早产儿.纠正胎龄足月时窒息早产儿组Ⅰ-Ⅲ峰间期已恢复正常,但Ⅴ波潜伏期、Ⅲ-Ⅴ和Ⅰ-Ⅴ峰间期仍相对延长且Ⅴ波振幅减低(P<0.01).在纠正年龄3个月时窒息早产儿组常规BAEP与足月儿组的差异已不明显,仅在较高声刺激速率时仍有部分参数异常. 结论围产期窒息缺氧可以对早产儿BAEP造成影响,但随早产儿生长发育有一定程度恢复.脑干听觉通路的近中枢部位对缺氧损伤易感,波形变化出现早,恢复慢.Ⅴ波潜伏期和振幅、Ⅲ-Ⅴ和Ⅰ-Ⅴ峰间期可作为判断早产儿缺氧损伤的早期敏感指标.MLS BAEP通过提高声刺激速率,可以提高诊断价值.

Development of maximum length sequence brainstem auditory evoked potential in preterm infants after perinatal asphyxia

Objective By detecting the effects of perinatal asphyxia on maximum length sequence brainstem auditory evoked potential (MLS BAEP) to find the sensitive variables which could reflect the changes of brainstem auditory function. Methods Asphyxia group included 51 preterm infants after perinatal asphyxia, whose gestational age was 29-33<'+> weeks. Control group included 47 normal preterm infants and 38 normal term infants. The recording of MLS and conventional BAEP were performed on 3-7 days after birth, 37-42 weeks and 3 months of corrected postconceptional age. MLS BAEP was recorded at 91/s, 227/s and 455/s, and the conventional BAEP was recorded at 21/s as control. Latencies and amplitudes of wave Ⅰ ,Ⅲ and Ⅴ and interpeak intervals of Ⅰ-Ⅲ, Ⅲ-Ⅴ and Ⅰ-Ⅴ were measured and compared by t-test. Results On 3-7 days after birth, wave Ⅲ and Ⅴlatencies, Ⅰ-Ⅲ, Ⅲ-Ⅴ and Ⅰ-Ⅴ intervals increased while wave Ⅴ amplitude decreased in asphyxia group comparing with normal preterm infants (P<0.05). In asphyxia group, Ⅲ latency was (6.645±0.58) ms, Ⅴ latency was (10.57±0.93) ms, Ⅰ-Ⅲ interval was (3.69±0.55) ms, Ⅲ-Ⅴ interval was (3.93±0.53) ms, Ⅰ-Ⅴ interval was (7.60±0.73) ms at 455/s, lower than normal preterm group. At term of postconceptional age, Ⅰ-Ⅲ interpeak interval had recovered while wave Ⅴ latency, Ⅲ-Ⅴand Ⅰ-Ⅴ interpeak intervals still increased and wave Ⅴ amplitude decreased in asphyxia group than those in normal term group (P<0.01). At 3 months of postconceptional age,no major difference was found between the asphyxia group and normal term group at conventional BAEP. Only several parameters were different between the two groups at higher click rate of MLS BAEP. Conclusions Perinatal asphyxia can damage the brainstem auditory pathway, but the auditory function of preterm infants can recover to some extent with their development. Central portion of the brainstem auditory pathway is more sensitive to hypoxic damage than peripheral portion, and its waveform changes occurs earlier and disappears later. Wave Ⅴ latency and amplitude, Ⅲ-Ⅴ and Ⅰ-Ⅴ interpeak intervals are sensitive variables to reflect the change of brainstem auditory function after hypoxic injury. MLS BAEP is a better method to reflect the neurophysiology and neuropathology of brainstem auditory pathway than conventional BAEP by increasing click rate.