高危晚期早产儿脑损伤病因学及其磁共振发现

目的 探讨以弥散加权成像(DWI)结合常规磁共振成像(T1WI-T2WI)诊断的高危晚期早产儿脑损伤的相关危险因素及临床特点,并分析不同时间MRI序列的信号特点及DWI的早期诊断价值。方法 首先对符合纳入标准的649例晚期早产儿的MRI片重新阅片，按照脑损伤评估标准得出诊断，其次收集相关的临床资料，分析不同类型脑损伤的危险因素和临床特点，并对其中271例确诊脑白质损伤（CWMD）的MRI序列进行分析，探讨不同类型CWMD的信号特点、损伤部位及结局。结果 ①晚期早产儿发生脑损伤332例（51.2%），其中CWMD 271例（41.8%），以局灶性CWMD为主（62.7％，170例）；颅内出血112例（17.3%），主要为蛛网膜下腔出血55.4%（62/112）。②非出血性脑损伤的危险因素是男性（OR=1.510，95％CI：1.067～2.136，P=0.020）、阴道分娩（OR=2.367，95％CI：0.251～22.294 ，P=0.000）、早发型败血症（OR=2.194，95％CI：1.159～4.155，P=0.016）及抢救复苏史（OR=3.784，95％CI：1.908～7.506，P=0.000）。出血性脑损伤的危险因素是阴道分娩（OR=7.195，95％CI：4.249～12.184 ，P=0.000）和早发型败血症（OR=2.692，95％CI：1.185～6.117，P=0.018）。低钙血症（OR=2.593，95％CI：1.343～5.005，P=0.005）、晚发型败血症（OR=1.533，95％CI：1.012～2.323，P=0.044）和抽搐（OR=4.006，95％CI：1.790～8.970，P=0.001）是非出血性脑损伤组的主要临床特点。出血性脑损伤组主要表现为高血糖和抽搐。③局灶性CWMD 65.3％仅累及一处损伤，主要集中在侧脑室后脚（53.5%），有97.1%病灶消失或病灶范围减少；广泛性CWMD 79.2%累及胼胝体和内囊；弥漫性CWMD 50％合并灰质损伤，全部发生软化。④生后2周内，DWI具有较高的敏感性，98.0%表现为高信号，T1WI信号无变化或稍高信号，伴或不伴T2WI低信号。局灶性CWMD DWI高信号持续时间长达3周以上，弥漫性CWMD DWI高信号持续时间2周以内。结论 晚期早产儿仍然容易受产前产时因素影响而发生不同类型的脑损伤。对有高危因素，或早期出现临床表现或电解质紊乱的患儿应选择生后2周内（1周内最佳）进行DWI和常规MRI检查，以早期发现病变。局灶性CWMD预后较好，合并有灰质损伤或弥漫性CWMD预后极差，需要动态随访，并进行早期康复训练。

The etiology and MRI findings of the late high-risk preterm brain injury diagnosed by DWI combined with conventional MRI

Objective To investigate the risk factors and clinical features of the late high-risk preterm brain injury diagnosed by DWI combined with conventional MRI. To analyze the dynamic MRI signal characteristics and the diagnostic value of DWI at the early time. Methods A total of 649 late preterm infants met the inclusion criteria, their MRI images were reanalyzed and the related clinical data were collected. The risk factors and clinical features of different types of brain injury were analyzed, the MRI signal characteristics, injury location and the ending of different types of CWMD were investigated. Results ①In the 332 late preterm infants with brain injury (51.2%), 271 cases(41.8%) showed white matter damage, in which the focal cerebral white matter damage was the main type. In the 112 (17.3%) intracranial hemorrhage cases, 62 cases (55.4%) showed subarachnoid hemorrhage. ②The male(OR=1.510, 95％CI：1.067-2.136, P=0.020), vaginal delivery(OR=2.367, 95％CI：0.251~22.294, P=0.000), early onset of sepsis(OR=2.194, 95％CI：1.159-4.155, P=0.016) and asphyxiation rescues(OR=3.784, 95％CI：1.908-7.506, P=0.000) were the risk factors of non hemorrhagic cerebral injury. The risk factors of hemorrhagic cerebral injury were vaginal delivery (OR=7.195, 95％CI：4.249-12.184, P=0.000) and early onset of sepsis (OR=2.692, 95％CI：1.185-6.117, P=0.018). The preterm infants with non hemorrhagic cerebral injury were characterized by hypocalcaemia（OR=2.593，95％CI：1.343-5.005，P=0.005）, late onset of sepsis（OR=1.533，95％CI：1.012-2.323，P=0.044）and seizures（OR=4.006，95％CI：1.790-8.970，P=0.001）. The preterm infants with hemorrhagic cerebral injury were characterized by seizures and hyperglycemia. ②There were different injury locations and endings in differten types of CWMD. Focal CWMD was often involved one site of damage only (65.3%), mainly concentrated in the lateral ventricle posterior (53.5%). 97.1% of focal CWMD were characterized by disappearing or decreasing of the lesion range. Widespread CWMD was often involved corpus callosum and internal capsule (79.2%), and diffuse CWMD was often combined with gray matter injury, accounting for 50%, and all developed into PVL. ④Within the first two weeks of white matter damage, DWI had high sensitivity and 98% were characterized by high signal. T1WI also showed normal or slightly high signals, with or without low signals on T2WI. High signal on DWI of focal CWMD could last for more than 3 weeks, but diffuse CWMD had short duration (within 2 weeks). Conclusion Late preterm infants are still vulnerable to perinatal factors and suffer from different types of brain damage. MRI and DWI should be done for the high-risk late preterm infants within 2 weeks after birth, in order to detect the damage as early as possible. The prognosis of focal CWMD is good. However, the infants with diffuse CWMD have poor prognosis, and need to be followed up and receive early suitable recovery as soon as possible.