ISSN:1080-4013    

DOI:10.1002/(SICI)1098-2779(1997)3:1<1::AID-MRDD1>3.0.CO;2-W

出版商:John Wiley&Sons, Inc.    

年代:1997

数据来源: WILEY

摘要:

AbstractBrain injury in the premature infant is an extremely important problem, in part because of the large absolute number of infants affected yearly. The two principal brain lesions that underlie the neurologic manifestations subsequently observed in premature infants are periventricular hemorrhagic infarction and periventricular leukomalacia. This article emphasizes the neurology, neuropathology, and pathogenesis of these two lesions. Recent work suggests that the ultimate goal, prevention of the lesions, is potentially achievable. Periventricular hemorrhagic infarction may be preventable by prevention of germinal matrix‐intraventricular hemorrhage, and periventricular leukomalacia may be preventable by detection of impaired cerebrovascular autoregulation, prevention of impaired cerebral blood flow, and interruption of the cascade to oligodendroglial cell death by such agents as free radical scavengers. MRDD Research Reviews 3:3–12, 1997. © 1997 Wiley‐Lis

ISSN:1080-4013    

DOI:10.1002/(SICI)1098-2779(1997)3:1<3::AID-MRDD2>3.0.CO;2-U

出版商:John Wiley&Sons, Inc.    

年代:1997

数据来源: WILEY

摘要:

AbstractTo examine the potential contribution of epidemiologic research to the identification of perinatal brain damage as a “cause” of developmental disabilities, the authors review definitions and methods used in this field. The current literature provides considerably different estimates of the population prevalence of mental retardation (3–40 per thousand), cerebral palsy (1.2–2.6 per thousand), and learning disabilities (33–65 per thousand). Furthermore, the presumable proportion of disabilities caused in the perinatal period also differs with the population under investigation, age at examination, and exposure and outcome definition. Approximately 8–43% of cerebral palsy and 10–25% of mental retardation may be associated with variables describing perinatal morbidity usually interpreted as indicators of brain damage. The authors discuss the recent literature on the association of developmental disabilities and proxy variables, e.g., abnormal neuroimaging results, so‐called asphyxia, abnormal fetal heart rate patterns or thyroxine levels, and severity of illness scores. Exact definitions of exposure and outcome, a proper study design, and agreement of findings from multiple studies are needed before associations between perinatal brain damage and developmental disabilities should be accepted as causal. MRDD Research Reviews 3:13–21, 1997. © 19

ISSN:1080-4013    

DOI:10.1002/(SICI)1098-2779(1997)3:1<13::AID-MRDD3>3.0.CO;2-Y

出版商:John Wiley&Sons, Inc.    

年代:1997

数据来源: WILEY

摘要:

AbstractRecent epidemiologic data demonstrate that prenatal factors play a major role in the genesis of brain injury in childhood, e.g., cerebral palsy and mental retardation. Nevertheless, there is extensive experimental, clinical, and neuroimaging data that show that acute, intrapartum hypoxic‐ischemic insult is an important factor in the genesis of irreversible brain injury, especially in term newborns. The precise timing of onset of hypoxic‐ischemic cerebral injury in premature newborns may be more difficult to establish, and postnatal complications (e.g., intraventricular hemorrhage, posthemorrhagic hydrocephalus) undoubtedly play a major role. When the potential deleterious consequences of severe, intrapartum asphyxia are minimized, there is a risk that important opportunities for prevention of newborn cerebral injury may be missed. In this context, new techniques may permit rapid, in vivo delineation of the critical processes involved in newborn hypoxic‐ischemic brain injury that are key factors for the development of effective preventive and interventional strategies. MRDD Research Reviews 3:22–27, 1997. © 1997 Wiley

ISSN:1080-4013    

DOI:10.1002/(SICI)1098-2779(1997)3:1<22::AID-MRDD4>3.0.CO;2-Z

出版商:John Wiley&Sons, Inc.    

年代:1997

数据来源: WILEY

摘要:

AbstractNeuroimaging has considerable potential for assessing the severity of brain damage in neonates who have suffered hypoxic‐ischemic brain injury. This article reviews the recent literature concerning the concepts of perinatal hypoxic‐ischemic brain injury as they relate to patterns of brain injury and thus to neuroimaging. In addition, the temporal changes of brain injury—as detected by transfontanel sonography, x‐ray computed tomography, and magnetic resonance imaging—are discussed. The discussions of these modalities include new techniques such as Doppler sonography, quantitative sonographic feature analysis, diffusion magnetic resonance imaging, and perfusion magnetic resonance imaging. Finally and where applicable, the prognostic implications of the imaging findings are discussed. MRDD Research Reviews 3:28–41, 1997. © 1997 Wil

ISSN:1080-4013    

DOI:10.1002/(SICI)1098-2779(1997)3:1<28::AID-MRDD5>3.0.CO;2-T

出版商:John Wiley&Sons, Inc.    

年代:1997

数据来源: WILEY

摘要:

AbstractMagnetic resonance spectroscopy (MRS) and near‐infrared spectroscopy (NIRS) are capable of providing detailed information on cerebral oxidative metabolism in infants who have been resuscitated following an acute asphyxial episode. In severely affected infants studied by phosphorus and proton MRS, a consistent observation has been the development of deranged cerebral energy metabolism 12–48 hours after resuscitation, despite the maintenance of cardiovascular and respiratory homeostasis. Follow‐up studies have indicated that the development of delayed energy failure is closely associated with the development of microcephaly and an adverse neurodevelopmental outcome. This pathophysiologic sequence has been modelled in newborn animals, allowing the mechanisms of delayed energy failure to be elucidated and cerebroprotective treatments to be tested. New developments in MRS and magnetic resonance imaging will enable quantitative and highly localised information on cerebral metabolism to be obtained in asphyxiated infants, increasing the accuracy of early clinical assessment. Significant cerebral vasodilatation and vasoparalysis of the cerebral circulation have been observed by NIRS in asphyxiated infants following resuscitation, but the prognostic value of this observation remains uncertain. Technical advances in NIRS are likely to improve the reproducibility and accuracy of the technique, allowing the assessment of regional cerebral haemodynamics and metabolism at the bedside. MRDD Research Reviews 3:42–48, 1997. © 1997 Wiley

ISSN:1080-4013    

DOI:10.1002/(SICI)1098-2779(1997)3:1<42::AID-MRDD6>3.0.CO;2-Z

出版商:John Wiley&Sons, Inc.    

年代:1997

数据来源: WILEY

摘要:

AbstractThe remarkable advances in survival of infants with congenital heart disease who undergo cardiac surgery are due in large part to techniques that require periods of markedly decreased or arrested circulation. An obvious prerequisite has been the development of techniques that protect critical organ systems, particularly the nervous system, during the often prolonged periods of attenuated oxygen delivery. Despite the manifest success of current neuroprotective strategies, a substantial postoperative neurologic morbidity persists in these infants. The planned periods of hypoperfusion provide a unique clinical opportunity for the prospective, in vivo study of cerebral responses to hypoxic‐ischemic stress. Furthermore, the potential for pretreatment intervention is likely to make this an active setting for the clinical trial of future neuroprotective strategies. This article will evaluate the strengths and limitations of this clinical model, with particular reference to the mechanisms of hypoxia‐ischemia and potential interventions. MRDD Research Reviews 3:49–58, 1997. © 1997 Wiley‐L

ISSN:1080-4013    

DOI:10.1002/(SICI)1098-2779(1997)3:1<49::AID-MRDD7>3.0.CO;2-S

出版商:John Wiley&Sons, Inc.    

年代:1997

数据来源: WILEY

摘要:

AbstractThe failure of modern fetal monitoring techniques to measure either oxygenation or perfusion within the fetal brain may underlie their poor specificity in the detection of intrapartum hypoxia‐ischaemia. We have adapted the technique of near‐infrared spectroscopy (NIRS) to obtain continuous, quantified measurements of changes in human fetal cerebral oxygenation and blood volume during labour. More than 140 fetuses have been studied at University College London for periods ranging from 10 to 765 minutes. Reciprocal changes in the cerebral concentrations of oxyhemoglobin and deoxyhemoglobin, indicating changing cerebral haemoglobin saturation, have been observed during uterine hyperstimulation with oxytocin, administration of maternal oxygen, changing maternal posture, and late fetal heart rate decelerations. Uterine contraction frequency greater than 1 every 2 minutes was associated with a fall in fetal cerebral oxygenation. A method for quantifying the oxygen saturation of hemoglobin derived from all vascular compartments (SmcO2) is described. There was a significant positive correlation between SmcO2and umbilical artery pH. Conversely, the base deficit of blood from the umbilical artery showed a negative correlation with SmcO2.Changes in optical pathlength due to probe movement during uterine contractions are a potential source of error in the measurements. Preliminary data obtained using intensity modulated optical spectrometry, a technique that continuously measures optical pathlength, suggest that the maximum contribution of movement artifact to observed changes in chromophore concentration is 12%.These preliminary data demonstrate that NIRS is capable of measuring fetal cerebral oxygenation and blood volume during labour. However, because none of the fetuses in this study was born with evidence of intrapartum hypoxia‐ischaemia, we cannot comment on the value of NIRS as a means of intrapartum surveillance. Further developments, including the routine use of IMOS and rigorous testing by randomized trials, will be required before this question is answered. MRDD Research Reviews 3:59–68, 1997. © 1997 Wiley

ISSN:1080-4013    

DOI:10.1002/(SICI)1098-2779(1997)3:1<59::AID-MRDD8>3.0.CO;2-S

出版商:John Wiley&Sons, Inc.    

年代:1997

数据来源: WILEY

摘要:

AbstractThis review describes the manner in which glucose or carbon dioxide protects the perinatal brain from hypoxic‐ischemic damage. MRDD Research Reviews 3:69–75, 1997. © 1997 Wiley‐Lis

ISSN:1080-4013    

DOI:10.1002/(SICI)1098-2779(1997)3:1<69::AID-MRDD9>3.0.CO;2-S

出版商:John Wiley&Sons, Inc.    

年代:1997

数据来源: WILEY

摘要:

AbstractCell death caused by hypoxia‐ischemia appears to be due to multiple mechanisms causing lysis of cells, both by osmotic rupture and by calcium‐dependent activation of degradative processes, as well as apoptosis. In the case of osmotic and calcium‐dependent lysis, the triggering stimulus seems to be abnormal accumulation of glutamate in the extracellular space. In the case of apoptotic death, the triggering stimulus is unclear. Because activation of one or more death programs does not necessarily commit a cell to die, a therapeutic window exists in which it should be possible to intervene to prevent progression to cell death in many cells that are affected by an hypoxic‐ischemic episode. Several therapeutic approaches have emerged targeting various steps in the process set in motion by abnormal glutamate accumulation. In addition, other approaches need to be developed to block apoptotic cell death. The most efficacious forms of therapy will probably be those that are effective against all types of cell death triggered by hypoxia‐ischemia. This may be accomplished either by the use of multiple agents or by intervention targeting processes or intermediates shared by multiple mechanisms of cell death. MRDD Research Reviews 3:76–84, 1997. © 1997 Wil

ISSN:1080-4013    

DOI:10.1002/(SICI)1098-2779(1997)3:1<76::AID-MRDD10>3.0.CO;2-O

出版商:John Wiley&Sons, Inc.    

年代:1997

数据来源: WILEY