Historical Perspectives on the Etiology of Cerebral Palsy 233 Tonse N.K. Raju

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1 PERINATAL CAUSES OF CEREBRAL PALSY Preface Marcus C. Hermansen xv Historical Perspectives on the Etiology of Cerebral Palsy 233 Tonse N.K. Raju This essay presents the early history on the evolution of concepts about the etiology of cerebral palsy, especially the contributions of the early pioneers. Insight into how they derived their hypotheses, including the errors they made, can help one understand the complex processes of deciphering etiologic associations. The Descriptive Epidemiology of Cerebral Palsy 251 Nigel Paneth, Ting Hong, and Steven Korzeniewski The prevalence of cerebral palsy (CP) ranges from 1.5 to 2.5 per 1000 live births with little or no variation among western nations, although data from the Americas are sparse. Time trends in overall CP prevalence for the past 40 years are most notable for their stability, but a modest increase in prevalence probably occurred in the last decades of the twentieth century. European countries have pioneered the development of CP registries, and as a result, CP is a condition that is enumerated regularly in several parts of the world. The United States has no CP registries, although ongoing surveillance of CP, along with other developmental disabilities, is performed by the Centers for Disease Control and Prevention in metropolitan Atlanta. The Panorama of Cerebral Palsy After Very and Extremely Preterm Birth: Evidence and Challenges 269 Michael E. Msall During the past 2 decades, major advances in maternal-fetal medicine and neonatology have resulted in unprecedented survival of VOLUME 33 NUMBER 2 JUNE 2006 vii

2 very preterm (< 32 weeks) and extremely preterm (< 28 weeks) babies. Despites these advances in prenatal care, neurodevelopmental motor impairment remains a substantial sequela. This article describes the major progress and challenges in understanding pathways of preterm children who go on to have one of the cerebral palsy syndromes. The contributions of chronic lung disease, intraventricular hemorrhage, retinopathy of prematurity, and postnatal steroids are analyzed. Management can then be directed to limiting the comorbidities that are associated with threats to survival and to improving protection of central nervous system functions that are involved in moving, manipulative skills, feeding, communication, and learning. Cerebral Palsy and Intrauterine Growth 285 Stephen Jarvis, Svetlana V. Glinianaia, and Eve Blair When birth weight for gestation is used as a surrogate for intrauterine growth, the prevalence of cerebral palsy varies continuously in a reversed J shape, with steep increases in the risk for infants lighter and heavier than the optimum size. Patterns of size-at-birth specific risk for cerebral palsy differ between male and female infants, as do the patterns for more severe versus milder cases. Although these excess risks with abnormal size at birth imply antenatal precursors, it is not clear whether or how intrauterine growth is involved in any of the suspected causal pathways resulting in cerebral palsy. The implication for clinicians is that serial measures of in utero growth may provide an important indicator of fetal health. Risk of Cerebral Palsy in Multiple Pregnancies 301 Peter O.D. Pharoah Multiple compared with singleton gestations have a five- to tenfold increased risk of CP. The increased risk associated with MC placentation has been variously ascribed to transfer of thromboplastin or thromboemboli from the dead to the surviving fetus, exsanguination of the surviving fetus into the low pressure reservoir of the dead fetus, or hemodynamic instability with bidirectional shunting of blood between the two fetuses. An increased risk of CP in assisted reproductive technology gestations is to be expected because of the higher proportion of preterm births. The increase in risk of CP associated with monochorionic placentation will not be observed except for the minority of assisted reproductive technology gestations that undergo monozygotic splitting. Perinatal Infections and Cerebral Palsy 315 Marcus C. Hermansen and Mary Goetz Hermansen Infections of the mother, the intrauterine environment, the fetus, and the neonate can cause cerebral palsy through a variety of mechanisms. Each of these processes is reviewed. The recently viii

3 proposed theory of cytokine-induced white matter brain injury and the systemic inflammatory response syndrome with multiple organ dysfunction syndrome is critically evaluated. Intrapartum Asphyxia and Cerebral Palsy: Is There a Link? 335 Jeffrey M. Perlman Perinatal hypoxic-ischemic cerebral injury, secondary to interruption of placental blood flow that results in cerebral palsy (CP), is a rare event. The ability to link an intrapartum event to subsequent CP should include a history of a sentinel event during labor, followed by the delivery of a depressed acidemic infant, and the subsequent evolution of neonatal encephalopathy, systemic organ injury, and acute neuroimaging abnormalities. Perinatal Trauma and Cerebral Palsy 355 Michael J. Noetzel In this article perinatal trauma is restricted to injuries that are sustained by the infant during the labor and delivery primarily as a result of mechanical factors, with the understanding that even under optimal circumstances, the process of birth is traumatic. Mechanical insults to the perinatal brain may result in primarily a hypoxic or ischemic injury to the cerebral tissues; those conditions are not discussed in this article. Although there are multiple types of perinatal trauma, this article is restricted mainly to those types that impact upon the subsequent development of cerebral palsy, although when applicable, other adverse developmental outcomes are mentioned. Cerebral Palsy Secondary to Perinatal Ischemic Stroke 367 Adam Kirton and Gabrielle deveber Congenital hemiplegia is the most common form of cerebral palsy in children born at term, and stroke is the number one cause. Neonatal ischemic stroke includes perinatal arterial ischemic stroke, presumed pre- or perinatal stroke, and cerebral sinovenous thrombosis, all of which have emerged as important contributors to cerebral palsy. Of increasing interest is how the overlapping list of associations and risks for stroke and cerebral palsy relate to each other. Stroke-induced injury is focal, and the preservation of normal areas of brain may afford unique opportunities for plastic adaptation. The implications of this essential difference are stressed in a discussion of how the epidemiology, pathophysiology, diagnosis, and therapeutic advancements in perinatal stroke relate to the outcome of cerebral palsy. ix

4 Hyperbilirubinemia and Kernicterus 387 Steven M. Shapiro, Vinod K. Bhutani, and Lois Johnson This article describes new findings concerning the basic science of bilirubin neurotoxicity, new considerations of the definition of clinical kernicterus, and new and useful tools to diagnose kernicterus in older children, and discusses treatments for kernicterus beyond the newborn period and why proper diagnosis is important. Neurometabolic Diseases in the Newborn 411 James J. Filiano This article is designed to be a basic introduction to neurometabolic diseases (ie, inheritable inborn errors of metabolism, genetic disorders of developmental neural topography, and degenerative disorders of neural function) that present in the neonate. It is intended to assist those who provide primary care for newborns to help them recognize signs and symptoms that signify neurometabolic disease; to teach how and when to initiate a neurometabolic diagnostic sequence; and to help neurologists and pediatricians interface with geneticists and metabolists. This article is intended to inform general newborn care practitioners, not metabolists. Therefore, pathways and concepts are presented in a simplified manner for deliberate educational purposes. Cerebral Palsy due to Chromosomal Anomalies and Continuous Gene Syndromes 481 John H. Menkes and Laura Flores-Sarnat When cerebral palsy is defined as a disorder of movement and posture that is due to nonprogressive disturbances that occur in the developing fetal and infant brain, a significant proportion up to 10% is the consequence of chromosomal anomalies and continuous gene syndromes. Abnormalities of chromosomes are constitutional or acquired. Acquired chromosomal abnormalities develop postnatally, affect only one clone of cells, and are implicated in the evolution of neoplasia. Constitutional abnormalities develop during gametogenesis or early embryogenesis and affect a significant portion of the subject s cells. Placental Pathology and Cerebral Palsy 503 Raymond W. Redline Recent classification systems of cerebral palsy call for an assessment of the timing and etiology of brain injury. The placenta is an underused resource for addressing these important questions. An expert assessment of the placental pathology can provide temporally and mechanistically specific data not available from any other source. Key concepts for an understanding of the role of placental x

5 pathology are the sentinel lesion, the high prevalence of thromboinflammatory lesions affecting large fetal placental vessels, the significance of underlying placental reserve, and the realization that placental findings can serve as markers for processes occurring in the mother or fetus. Neuroimaging Evaluation of Cerebral Palsy 517 Robert A. Zimmerman and Larissa T. Bilaniuk MRI can demonstrate and differentiate the various insults and anomalies that can be responsible for cerebral palsy. Recent advances have resulted in techniques and sequences that allow prompt detection of cytotoxic edema and evaluation of brain perfusion. MRI precisely demonstrates the various patterns of injury, distinguishing insults owing to profound asphyxia, partial prolonged asphyxia, and mixed partial prolonged and profound asphyxia. Infants and children can be studied with MRI, and ultrafast MRI permits evaluation of the fetal central nervous system. In the fetus, the cause of ventriculomegaly can be determined, such as cerebrospinal fluid flow obstruction, brain malformation, or brain destruction with or without hemorrhage. Results from fetal MRI have led to better understanding of many brain abnormalities. Cerebral Palsy Life Expectancy 545 J.L. Hutton The life expectancy of people who have perinatally acquired cerebral palsy can be similar to that of the general population, or it can be reduced substantially. The most important factors that are associated with reduced survival are disabilities of motor, cognitive, or visual functions. Prematurity and low birth weight are associated with lower rates of disability, and better survival. A 2-year-old who has severe cerebral palsy has about a 40% chance of living to age 20, in contrast to a child who has mild cerebral palsy, for whom the chance is 99%. Cerebral palsy, respiratory diseases, epilepsy, and congenital malformation are the most commonly recorded causes of early death. Erratum 557 Index 559 xi