围产期缺氧对早产儿脑干功能的影响

The effect of perinatal hypoxia on brainstem function in preterm infants

目的用最大长度序列（MLS）脑干听觉诱发电位技术检测有围产期缺氧早产儿生后早期的脑干功能,研究不同程度缺氧对脑干功能的影响,并比较MLS脑干听觉诱发电位是否较常规法对异常的检出具有优越性。方法胎龄29-33^＋6周的早产儿,重度缺氧组51例,轻度缺氧组36例,对照组为相对正常早产儿41例。MLS脑干诱发电位的声刺激速率为91、227和455次/秒,选常规法21次/秒作为对照,观察指标为Ⅰ、Ⅲ、Ⅴ波潜伏期和振幅,Ⅰ-Ⅲ、Ⅲ-Ⅴ、Ⅰ-Ⅴ峰间期。结果随着缺氧程度加重,缺氧组早产儿V波潜伏期、Ⅲ-Ⅴ和Ⅰ-Ⅴ峰间期较正常对照组逐渐延长,V波振幅逐渐降低;通过MLS提高刺激速率后,缺氧早产儿Ⅲ波的潜伏期、Ⅰ-Ⅲ峰间期也表现出明显延长,Ⅲ波振幅也逐渐降低,并且随刺激速率逐渐增高,统计学差异逐渐明显。轻度缺氧组常规21次/秒时各参数与正常早产儿组无明显差异,但在MLS227及455次/秒时,Ⅲ、Ⅴ波潜伏期,各个峰间期也显示出延长[455次/秒时,轻度缺氧组Ⅲ波潜伏期为（6.55±0.53）ms,Ⅴ波潜伏期为（10.13±0.86）ms,Ⅰ-Ⅲ峰间期为（3.60±0.34）ms,Ⅲ-Ⅴ峰间期为（3.58±0.57）ms,Ⅰ-Ⅴ峰间期为（7.18±0.73）ms],同时部分振幅降低;重度缺氧组与轻度缺氧组的差异主要为Ⅴ波潜伏期、Ⅲ-Ⅴ和Ⅰ-Ⅴ峰间期延长及Ⅴ波振幅降低,而与正常早产儿组比较不仅上述差异更加显著,同时Ⅲ波的潜伏期及振幅、Ⅰ-Ⅲ峰间期也都显示出异常[455次/秒时,重度缺氧组Ⅴ波潜伏期为（10.57±0.93）ms,Ⅲ-Ⅴ峰间期为（3.93±0.53）ms,Ⅰ-Ⅴ峰间期为（7.60±0.73）ms,Ⅴ波振幅为（0.02±0.02）μV]。结论围产期缺氧会对早产儿生后早期的脑干功能造成损伤,且随缺氧程度加重诱发电位的变化也更加明显。MLS脑干听觉诱发电位通过提高刺激速率,加大神经元负荷,对脑损伤有更高的诊断价值。

Purpose To explore the brainstem auditory function in preterm infants with perinatal hypoxia,maximum length sequence brainstem auditory evoked potential （MLS BAEP） was recorded to study whether different level of hypoxia would exert different effect on brainstem function and if MLS BAEP was better for early detection of brain damage than the conventional BAEP. Methods There were 51 preterm babies in severe hypoxia group and 36 in mild hypoxia. The control group included 41 normal preterm infants. Their gestational age all ranged from 29 weeks to 33 weeks^＋6 weeks. The recording of MLS and conventional BAEP were performed on the 3rd-7th day after birth. 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. Results In preterm babies who had more severe hypoxia,their wave Ⅴ latency, Ⅲ-Ⅴ and Ⅰ - Ⅴ interpeak intervals increased while wave Ⅴamplitude decreased more obviously. It became more significant at higher click rates and at the same time wave Ⅲlatency and Ⅰ -Ⅲ interval also increased while wave Ⅲ amplitude decreased. There was no difference in all variables between mild hypoxia group and normal control one at conventional 21/s,while at 227/s and 455/s of MLS BAEP,wave Ⅲand V latencies, all interpeak intervals increased and some amplitudes reduced in mild hypoxia group [At455/s, Ill latency was （6.55 ± 0.53）ms, V latency was （10.13 -＋ 0.86）ms, Ⅰ -Ⅲ interval was （3.60 ± 0.34）ms, Ⅲ-Ⅴ interval was （3.58 ± 0.57）ms, I -V interval was （7.18 ±0.73）ms in mild hypoxia group3. Comparing variables in severe hypoxia group with those in mild one, the main differences were the increase of wave Ⅴ latency, Ⅲ-Ⅴ and Ⅰ -Ⅴ intervals and the decrease of wave Ⅴ amplitude,which became more significant when comparing with those in normal preterm group [At 455/s, Ⅴ latency was （10.57 ± 0.93）ms,Ⅲ-Ⅴ interval was （3.93 ± 0.53）ms, Ⅰ -Ⅴ interval was （7.60 ± 0.73）ms, Ⅴ amplitude was （0.02± 0.02）μv in severe hypoxia group] ,and at the same time the latency and amplitude of wave Ⅲ and Ⅰ -Ⅲ interval all became abnormal. Conclusions Perinatal hypoxia can injure the brainstem auditory function. Severe hypoxia causes severer abnormality in BAEP. MLS BAEP is a better method to reflect the abnormality of brainstem injury than conventional BAEP by increasing click rate.