Seminars in perinatology
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Seminars in perinatology · Dec 2004
ReviewEmerging concepts in periventricular white matter injury.
Approximately 10% of newborns are born prematurely. Of these children, more than 10% will sustain neurological injuries leading to significant learning disabilities, cerebral palsy, or mental retardation, with very low birth weight infants having an even higher incidence of brain injury. Whereas intraventricular hemorrhage was the most common form of serious neurological injury a decade ago, periventricular white matter injury (PWMI) is now the most common cause of brain injury in preterm infants. ⋯ Other potential mechanisms of injury include activation of microglia and axonal damage. Chemical mediators that may contribute to white matter injury include reactive oxygen (ROS) and nitrogen species (RNS), 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 evolve.
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Seminars in perinatology · Dec 2004
Review Comparative StudyImaging perinatal brain injury in premature infants.
The primary methods currently in use for imaging the infant brain are cranial ultrasound (CUS), computed tomography (CT) and magnetic resonance imaging (MRI). This review outlines the relative strengths and weaknesses of these modalities in relation to the premature infant, with specific focus on the correlations between imaging findings and neurodevelopmental outcome. Since MRI is undergoing rapid development at this time, the newer MRI methods of brain volume measurement and diffusion tensor imaging are reviewed in more detail. Current guidelines regarding the application of these neuroimaging methods to the premature infant are discussed.
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Perinatal brain injury in the term infant is a relatively uncommon event. The principal lesions are intracranial hemorrhage including subarachnoid, subdural, intraparenchymal, intraventricular, focal cerebral infarction and hypoxic ischemic cerebral injury secondary to intrapartum hypoxia-ischemia. Both intracranial hemorrhage and focal cerebral infarction are invariably identified at the time of clinical symptoms, ie, seizures or apnea. ⋯ Secondary or reperfusion injury is potentially amenable to neuroprotective strategies. Modest hypothermia is one such therapy that has been studied in high-risk newborn infants with some initial success. Future studies need to focus on additional neuroprotective strategies.
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Seminars in perinatology · Dec 2004
ReviewRegulating axon growth within the postnatal central nervous system.
As neuronal development enters its final stages, axonal growth is restricted. Recent work indicates that several myelin-derived proteins, Nogo, MAG and OMgp, play a critical role in restricting axonal growth in the mature central nervous system (CNS). ⋯ Reduced expression of these proteins caused by the developmental hypoxia, or direct blockade of the myelin inhibitor pathways in the adult CNS leads to axonal sprouting and the formation of new neuronal connections. The regulation of axonal growth, sprouting and connections in the postnatal brain by myelin proteins is an area of important investigation and potential therapeutic intervention.