Back Stephen A
Department of Pediatrics, Oregon Health & Sciences University, Portland, Oregon, USA.
Ment Retard Dev Disabil Res Rev. 2006;12(2):129-40. doi: 10.1002/mrdd.20107.
Perinatal brain injury in survivors of premature birth has a unique and unexplained predilection for periventricular cerebral white matter. Periventricular white-matter injury (PWMI) is now the most common cause of brain injury in preterm infants and the leading cause of chronic neurological morbidity. The spectrum of chronic PWMI includes focal cystic necrotic lesions (periventricular leukomalacia; PVL) and diffuses myelination disturbances. Recent neuroimaging studies support that the incidence of PVL is declining, whereas focal or diffuse noncystic injury is emerging as the predominant lesion. Factors that predispose to PVL during prematurity include hypoxia, ischemia, and maternal-fetal infection. In a significant number of infants, PWMI appears to be initiated by perturbations in cerebral blood flow that reflect anatomic and physiological immaturity of the vasculature. Ischemic cerebral white matter is susceptible to pronounced free radical-mediated injury that particularly targets immature stages of the oligodendrocyte lineage. Emerging experimental data supports that pronounced ischemia in the periventricular white matter is necessary, but not sufficient to generate PWMI. The developmental predilection for PWMI to occur during prematurity appears to be related to both the timing of appearance and regional distribution of susceptible oligodendrocyte progenitors. Injury to oligodendrocyte progenitors may contribute to the pathogenesis of PWMI by disrupting the maturation of myelin-forming oligodendrocytes. Chemical mediators that may contribute to white-matter injury include reactive oxygen species glutamate, cytokines, and adenosine. As our understanding of the pathogenesis of PWMI improves, it is anticipated that new strategies for directly preventing brain injury in premature infants will develop.
早产幸存者的围产期脑损伤对脑室周围脑白质有一种独特且无法解释的偏好。脑室周围白质损伤（PWMI）现在是早产儿脑损伤最常见的原因，也是慢性神经疾病的主要原因。慢性PWMI的范围包括局灶性囊性坏死性病变（脑室周围白质软化；PVL）和弥漫性髓鞘形成障碍。最近的神经影像学研究表明，PVL的发病率正在下降，而局灶性或弥漫性非囊性损伤正成为主要病变。早产期间易患PVL的因素包括缺氧、缺血和母婴感染。在相当数量的婴儿中，PWMI似乎是由脑血流紊乱引发的，这反映了血管系统的解剖和生理不成熟。缺血性脑白质易受明显的自由基介导损伤，这种损伤特别针对少突胶质细胞谱系的未成熟阶段。新出现的实验数据表明，脑室周围白质的明显缺血是必要的，但不足以产生PWMI。早产期间PWMI发生的发育偏好似乎与易感少突胶质细胞祖细胞的出现时间和区域分布有关。少突胶质细胞祖细胞的损伤可能通过破坏形成髓鞘的少突胶质细胞的成熟而导致PWMI的发病机制。可能导致白质损伤的化学介质包括活性氧、谷氨酸、细胞因子和腺苷。随着我们对PWMI发病机制的理解不断提高，预计将开发出直接预防早产儿脑损伤的新策略。
