[Cerebral palsy--perinatal aspects]

Cerebral palsy is a group of non-progressive but often changing motor impairment syndromes resulting from lesions or anomalies occurring in the early stages of fetal development and childhood. This condition is responsible for significant emotional, financial and social difficulties for the patient and the family, and professionals providing specific care for these people. This review describes the incidence, risk factors and the etiopathogenesis of this condition. A lot of evidences of the relations between intrauterine infection, prematurity, prenosenost, intrapartalna asphyxia, multiple pregnancy and assisted reproductive techniques are decribed. In the review is has been demonstrated the most important aspects of perinatal cerebral palsy.

Neonatal management and long-term sequelae

Intrauterine or fetal growth restriction is best defined by using customised birth weight percentiles based upon the growth potential for an individual infant. Growth restriction in utero may be classified as asymmetric or symmetric depending upon the duration of the process. Asymmetric growth restriction is caused by placental insufficiency, maternal hypertensive conditions, long-standing maternal diabetes, smoking, living at altitude or multiple gestation. Symmetric growth restriction may be due to congenital infections, chromosomal or other abnormalities, fetal alcohol syndrome, low socioeconomic status or be constitutional. The underlying cause of growth restriction often predicts the potential adverse effects on the foetus and newborn and later effects in childhood and adulthood. With placental insufficiency, there may be chronic or acute on chronic fetal hypoxia with birth asphyxia and hypothermia, neonatal hypoglycaemia, polycythaemia and coagulopathy. Management is directed at prevention or early treatment of these conditions. In contrast, symmetrically growth-restricted infants should be examined carefully to look for congenital infections and malformations that may need specific interventions. Infants with constitutional short stature generally do not need any specific management. Feeding of growth-restricted infants is important to overcome deficiencies incurred in utero. Most infants show catch-up growth although about 10% do not. Those with excessive catch-up growth may be at greatest risk of developing insulin resistance in adulthood leading to diabetes, obesity and heart disease. The so-called fetal origins of disease may actually have a postnatal onset related more to excessive weight gain in infancy. There is still controversy over the indications for growth hormone treatment in growth-restricted infants who remain of short stature in early childhood. Intrauterine growth restriction is also associated with a five- to seven-fold increased risk of cerebral palsy probably due to chronic placental insufficiency.

Infant neurodevelopment following fetal growth restriction: relationship with antepartum surveillance parameters

OBJECTIVES

To evaluate the relationship between fetal Doppler parameters, biophysical profile score (BPP) and neurodevelopmental delay at 2 years of corrected age in infants who had been growth-restricted in utero.

METHODS

This was a prospective observational study including 113 pregnancies complicated by intrauterine growth restriction (IUGR) (abdominal circumference<5th percentile and elevated umbilical artery (UA) pulsatility index). The relationships of UA, middle cerebral artery and ductus venosus (DV) Doppler features, BPP, birth acidemia (artery pH<7.0+/or base deficit>12), gestational age at delivery, birth weight and neonatal morbidity (i.e. bronchopulmonary dysplasia, >Grade 2 intraventricular hemorrhage, or necrotizing enterocolitis) with a 2-year neurodevelopmental delay were evaluated. Best Beginnings Developmental Screen, Bayley Scale of Infant Development II (BSID) and Clinical Adaptive/Clinical Linguistic Auditory Milestone Stage were used. BSID<70, cerebral palsy, abnormal tone, hearing loss and/or blindness defined neurodevelopmental delay.

RESULTS

Seventy-two of the 113 pregnancies completed assessment; there were 10 stillbirths, 19 neonatal deaths, three infant deaths and nine pregnancies with no follow-up. Twenty fetuses (27.8%) had UA reversed end-diastolic velocity (REDV), 34 (47.2%) abnormal DV Doppler features and 31 (43.1%) an abnormal BPP. Median gestational age at delivery and birth weight were 30.4 weeks and 933 g, respectively. Twelve infants had acidemia and 28 neonatal morbidity. There were 38 (52.8%) infants with neurodevelopmental delay, including 37 (51.4%) with abnormal tone, 20 (27.8%) with speech delay, 23 (31.9%) with an abnormal neurological examination, eight (11.1%) with a hearing deficit and six (8.3%) with cerebral palsy. Gestational age at delivery was associated with cerebral palsy (r2=0.52, P<0.0001; 92% sensitivity and 83% specificity for delivery at <27 weeks). UA-REDV was associated with global delay (r2=0.31, P=0.006) and birth weight with neurodevelopmental delay (r2=0.54, P<0.0001; 82% sensitivity and 64% specificity for BW<922 g).

CONCLUSIONS

Although UA-REDV is an independent contributor to poor neurodevelopment in IUGR no such effect could be demonstrated for abnormal venous Doppler findings or BPP. Gestational age and birth weight remain the predominant factors for poor neurodevelopment in growth-restricted infants.

Secondary cytomegalovirus infection can cause severe fetal sequelae despite maternal preconceptional immunity

OBJECTIVES

To describe our experience in cases with sonographic signs of fetal infection and with maternal serological 'immunity' to cytomegalovirus (CMV) infection.

METHODS

This was a bicenter study of six pregnant women referred for evaluation of suspected fetal infection. All cases had confirmed maternal serology for past exposure to CMV but no evidence of recent secondary CMV infection. All underwent sonographic evaluation as well as complete investigation for CMV infection.

RESULTS

The mean age of the women was 29 (range, 23-35) years and the mean gestational age at diagnosis was 23.5 weeks (range, 20-31) weeks. Sonographic findings included microcephaly, ventriculomegaly, periventricular calcifications and cystic lesions, echogenic bowel, hydrops and hepatosplenomegaly. Amniocentesis was performed in all cases for fetal karyotyping and viral assessment, and all were found by polymerase chain reaction to be positive for CMV infection. Four pregnancies were terminated following the parents' request. One pregnancy continued until intrauterine fetal death occurred 2 weeks after diagnosis. Postmortem was denied in all cases but one. One infant was delivered with evidence of severe cerebral palsy.

CONCLUSION

In the presence of sonographic findings suggestive of fetal CMV infection, prompt investigation of amniotic fluid should follow even if maternal serology does not support recent maternal seroconversion.

Prevalence and pathogenesis of congenital anomalies in cerebral palsy

BACKGROUND

It has been hypothesised that cerebral palsy (CP) and other congenital anomalies are attributable to feto-fetal transfusion problems in a monochorionic multiple gestation. Thus more than one organ could be compromised leading to the coexistence of two or more anomalies in a fetus. Such anomalies in a singleton birth may be attributable to early demise of the co-conceptus as a vanishing twin.

AIM

To determine whether the coexistence of congenital anomalies and CP is greater than a chance finding by comparing the prevalence of congenital anomalies in children with CP with that in the general population of children.

METHODS

A population-based register of children with CP born in 1966-1991 in the counties of Merseyside and Cheshire, UK, comprised the index population. Coexisting congenital anomalies were recorded. For comparison the population prevalence of congenital anomalies was obtained from eight congenital malformation registers in the UK.

RESULTS

Children with CP were found to have highly significant increases in risk for microcephaly, isolated hydrocephaly, congenital anomalies of the eye, congenital cardiac anomalies, cleft lip and/or palate and congenital dislocation of the hips and talipes (p<0.001) and atresias of the oesophagus (p<0.001) and intestines (p<0.01). The relative risks ranged from 3.1 (95% CI 1.9 to 4.8; p<0.001) for congenital malformations of the cardiac septa to 116.09 (95% CI 84.0 to 162.3; p<0.001) for microcephaly.

CONCLUSIONS

Congenital anomalies in children with CP are found much more frequently than expected by chance. A common pathogenic mechanism may account for the coexistence of disparate congenital anomalies. A hypothesis is proposed for such a common pathogenic mechanism.

Cerebral palsy and fetal inflammatory response syndrome: a review

Cerebral palsy (CP) is the most common cause of severe physical disability in childhood. The precise etiological factor for the development of the majority of cases of CP has not been identified, however, prematurity is considered to be the leading identifiable risk factor. During the last decade, intrauterine infection/inflammation has been identified as the most common cause of preterm delivery and neonatal complications. When microorganisms or their products gain access to the fetus they stimulate the production of cytokines and a systemic response termed FIRS (Fetal Inflammatory Response Syndrome). Subsequently, FIRS was implicated as a cause of fetal or neonatal injury that leads to CP and chronic lung disease. Several authors found an increase in the risk for CP in infants born to mothers with clinical chorioamnionitis, especially in preterm neonates. A relationship between CP and intra-amniotic inflammation was demonstrated, intrauterine infection may lead to activation of the cytokine network which in turn can cause white matter brain damage and preterm delivery, as well as the future development of CP. This white matter insult is identified clinically as periventricular leucomalacia (PVL) which is associated with the subsequent development of impaired neurological outcomes of variable severity including CP.

Postnatal laboratory timers of antenatal hypoxemic-ischemic brain damage

OBJECTIVE

Markers were sought to identify the antenatal starting times and rates at which brain damage advanced in children with hypoxemic-ischemic cerebral palsy.

STUDY DESIGN

Fetal bradycardia's onset marked the damage's start. Using this baseline, the following were tested as additional timers of the damage's onset: serial blood counts of neonates' normoblasts, platelets, lymphocytes,differences at birth between base excess values in umbilical arterial and venous bloods,brain damage patterns.

RESULTS

Each timer had a broad antenatal time frame within which it could identify specific damage starting times. The broad time frames are as follows: Blood lymphocyte counts: 0.45 to 13.8 hours before birth, blood normoblast counts: 0.45 to 55.0 hours before birth, blood platelet counts: 0.5 to >72 hours before birth. Brain damage patterns: 0.4 to >0.7 hour before birth. Hyperventilating and hyperoxygenating neonates greatly accelerated the damage's advance.

CONCLUSIONS

Commonly obtained laboratory values and brain images can identify when such brain damage began and the rate at which it advanced.

Brain damage in preterm infants: etiological pathways

Preterm newborns represent a high-risk population for brain damage, primarily affecting the white matter, and for related neurodevelopmental disabilities. Determinants of brain damage have been extensively investigated, but there are still many controversies on how these factors can influence the developing brain and provoke damage. The concept of etiological pathway, instead of a single determinant, appears to better explain pathogenetic mechanisms: the brain damage may represent the final outcome of exposure to several combinations of risk factors in the same pathway or in different pathways and can change according to the gestational age. The aim of this article is to review the current knowledge on the pathogenesis of brain damage in preterm infants, within the frame of two main theoretical models, the ischemic and the inflammatory pathway. The relationship between the two pathways and the contribution of genetic susceptibility to ischemic and/or inflammatory insult, in modulating the extent and severity of brain damage, is also discussed.

The causal pathway model and cerebral palsy

This article reviews possible prenatal, perinatal, and postnatal causes of cerebral palsy. The interactive effects of various causes are evaluated. Groups of intervention strategies are then presented based on the causal pathway model.

Antenatal risk factors for cerebral palsy

Two of every 1000 live-born children develop cerebral palsy (CP). The aetiology of CP is often unclear and because CP is a symptom complex rather than a disease, clinically defined at 4-5 years of age, it is not surprising that there are considerable problems associated with epidemiological studies of its aetiology. The only reason for the CP concept is that it emanates from an insult to a growing, developing brain and a dynamic clinical picture from static pathology. Evidence suggests that 70-80% of CP cases are due to prenatal factors and that birth asphyxia plays a relatively minor role (<10%). Some antenatal risk factors are repeatedly observed to be related to CP: low gestational age, male gender, multiple gestation, intrauterine viral infections and maternal thyroid abnormalities. Recently, intrauterine infection/inflammation with a maternal response (consisting of chorioamnionitis) and a fetal inflammatory response (consisting of funicitis or elevated interleukin-6 in fetal plasma) has been found to be related to white matter injury and CP. Some risk factors are associated with CP at all gestational ages whereas others mostly affect term or preterm infants, e.g. intrauterine growth restriction seems to be a risk factor in term infants. There also seems to be an association between autoimmune and coagulation disorders and CP.

Intrauterine infection and the development of cerebral palsy

Cerebral palsy is a serious motor disorder that appears in early life. The expectation that improved obstetrical and neonatal care would decrease the rate of this condition has not been realised. Recent evidence indicates that white matter brain lesions, often termed periventricular leukomalacia (PVL), are the most important identifiable risk factors for the development of cerebral palsy. The hypothesis under examination is that inflammatory cytokines released during the course of intrauterine infection play a central role in the genesis of preterm parturition, fetal PVL, and cerebral palsy. We examined the relationship between umbilical cord plasma concentrations of cytokines at birth and the occurrence of PVL in preterm gestation and demonstrated that umbilical cord plasma concentrations of interleukin (IL)-6 was a significant independent predictor of PVL-associated lesions. We also demonstrated that preterm neonates born to mothers with elevated amniotic fluid concentrations of pro-inflammatory cytokines were at increased risk for the subsequent development of PVL and cerebral palsy. Histological chorioamnionitis and congenital neonatal infection-related morbidity were more common in neonates with PVL than those without PVL in this study. We have also been able to induce PVL-like brain white matter lesions in the fetal rabbit after experimental ascending intrauterine infection. In support of this hypothesis, we were able to demonstrate overexpression of tumour necrosis factor-alpha and IL-6 in histological sections of neonatal brains with PVL. Moreover, the presence of funisitis, a histological counterpart of the fetal inflammatory response syndrome, and elevated concentrations of amniotic fluid IL-6 and IL-8 were strong and independent risk factors for the subsequent development of cerebral palsy at the age of 3 years in our recent study. Therefore, clinical and experimental data provide strong support for the hypothesis. There are significant implications of our findings. First, cytokine determinations in amniotic fluid provide information about the risk of PVL and cerebral palsy before birth. Second, the process responsible for some cases of PVL and cerebral palsy begins during intrauterine life, implying that effective strategies for the prevention of cerebral palsy associated with PVL must begin in utero.

Fetal or infant death in twin pregnancy: neurodevelopmental consequence for the survivor

AIM

To determine the neurodevelopmental morbidity in the surviving twin after fetal or infant death of the co-twin.

METHODS

Twin pregnancies with an antepartum or infant death delivered between 1981 and 1992 were identified from the Northern Perinatal Mortality Survey. Information on the neurodevelopmental morbidity of infant survivors of a deceased co-twin was obtained by a questionnaire sent to the community paediatrician or general practitioner.

RESULTS

A total of 111 children who survived infancy after the fetal death of the co-twin (group 1) and 142 from liveborn twin pairs in which one twin died in infancy (group 2) were traced. Responses were received from 97 (87%) and 130 (92%) respectively. In group 1, the cerebral palsy prevalence was 93 (95% confidence interval (CI) 43 to 169) per 1000 infant survivors; it was more common in like-sex pairs (8/70) with a prevalence of 114 (95% CI 51 to 213) compared with 45 (95% CI 1 to 228) per 1000 infant survivors in unlike-sex pairs (1/22). The overall prevalence of neurodevelopmental morbidity (including developmental delay) was 175 (95% CI 106 to 266) per 1000. In group 2, the cerebral palsy prevalence was 154 (95% CI 84 to 223) per 1000 infant survivors in like-sex (16/104) and 77 (95% CI 9 to 251) in unlike-sex (2/26) survivors; the overall prevalence of neurodevelopmental morbidity was 246 (95% CI 172 to 320) per 1000.

CONCLUSIONS

The risk of cerebral palsy is increased in the surviving twin after a fetal or infant co-twin death compared with the general twin population. Like-sex twins are at greater risk than unlike-sex. The probable cause, in addition to the consequences of prematurity, is twin-twin transfusion problems associated with monochorionicity.

Neonatal risk factors for cerebral palsy in very preterm babies: case-control study

OBJECTIVE

To identify neonatal risk factors for cerebral palsy among very preterm babies and in particular the associations independent of the coexistence of antenatal and intrapartum factors.

DESIGN

Case-control study.

SETTING

Oxford health region.

SUBJECTS

Singleton babies born between 1984 and 1990 at less than 32 weeks' gestation who survived to discharge from hospital: 59 with cerebral palsy and 234 randomly selected controls without cerebral palsy.

MAIN OUTCOME MEASURES

Adverse neonatal factors expressed as odds ratios and 95% confidence intervals.

RESULTS

Factors associated with an increased risk of cerebral palsy after adjustment for gestational age and the presence of previously identified antenatal and intrapartum risk factors were patent ductus arteriosus (odds ratio 2.3; 95% confidence interval 1.2 to 4.5), hypotension (2.3; 1.3 to 4.7), blood transfusion (4.8; 2.5 to 9.3), prolonged ventilation (4.8; 2.5 to 9.0), pneumothorax (3.5; 1.6 to 7.6), sepsis (3.6; 1.8 to 7.4), hyponatraemia (7.9; 2.1 to 29.6) and total parenteral nutrition (5.5; 2.8 to 10.5). Seizures were associated with an increased risk of cerebral palsy (10.0; 4.1 to 24.7), as were parenchymal damage (32; 12.4 to 84.4) and appreciable ventricular dilatation (5.4; 3.0 to 9.8) detected by cerebral ultrasound.

CONCLUSION

A reduction in the rate of cerebral palsy in very preterm babies requires an integrated approach to management throughout the antenatal, intrapartum, and neonatal periods.

The undesirable consequences of controlling for birth weight in perinatal epidemiological studies

OBJECTIVE

To compare the effects of controlling for birth weight with those of controlling for gestational age at delivery in perinatal epidemiological studies using two examples.

SETTING

Western Australia.

SUBJECTS

Population data: all white births born at 20-46 weeks of gestation in Western Australia during 1985-91 inclusive (n = 147564). Example 1: All Western Australian births from 1980-89 born either at 33-36 weeks inclusive (n = 13607), or born with a birth weight of 2050-2900 g (n = 34107). Example 2: 160 singleton cases of spastic cerebral palsy born to white mothers in Western Australia from 1975-80 and whose gestational age was known, compared with (a) 480 controls individually matched for gender and birth weight and (b) singletons with known gestational age liveborn to white mothers in Western Australia from 1980-81, or 1979-82 if < 30 weeks' gestational age at birth (n = 32031).

MEASUREMENTS AND MAIN RESULTS

The risks of cerebral palsy associated with two separate exposures in groups defined by birth weight were compared with those in groups defined by gestational age. The origin of the differences are explained using total population data. The estimates of risk differ when exposure and outcome are both associated with appropriateness of fetal growth. The difference varied with gestational age, being greatest in the moderately preterm (33-36 weeks' gestation).

CONCLUSION

Epidemiological studies in which appropriateness of fetal growth is an important variable should be based on gestational age at birth rather than birth weight, whatever the neonatal size or maturity.

[Cerebral palsy in the light of old and new research results--in what direction does the pendulum swing?]

Cerebral palsy is reviewed from Little's first description of spastic diplegia in 1843 to the results of the most recent studies. One central question concerns whether prenatal or perinatal causes are the most important for the development of cerebral palsy. Current research indicates that conditions prior to and during pregnancy probably play a more important role than earlier thought. For years it has been the belief that cerebral palsy is caused by mismanagement in the perinatal period. At the same time, it has been suggested that improved perinatal care would reduce the incidence of cerebral palsy. This has not been the case, and many studies indicate that, despite proper perinatal care, the incidence of cerebral palsy is increasing. Much research remains to be done to obtain an overall picture of the etiology of cerebral palsy before we can establish measures to prevent this complex and serious condition.

Family patterns of gestational age at delivery and growth in utero in moderate and severe cerebral palsy

The relation of familial factors to the aetiology of cerebral palsy was assessed in a case-control study of all moderate and severe cases born in Western Australia between 1980 and 1986. The data did not suggest recurrence of cerebral palsy, congenital malformations or reproductive loss in cerebral palsy families. Preterm and small-for-gestational-age birth recurred within both case and control families. Cases and controls did not differ significantly from their siblings in measures of intra-uterine growth, but (with the exception of controls unmatched for both birthweight and gestational age) were born significantly earlier than their siblings. A family history of preterm or small-for-gestational-age birth was found to affect the risk of cerebral palsy by influencing the risk of preterm birth or growth retardation in the index pregnancy.

Hypoxic-hemodynamic pathogenesis of brain lesions in the newborn

For more than a century two opposing views on the pathogenetic mechanisms and the timing of the origin of cerebral palsy (CP) have prevailed: the idea first formulated by Little attributing CP to "difficult deliveries" has been opposed by the view by Freud recognizing fetal influences, and the issue seems to be unsettled. The present review seeks to bridge the gap by recognizing that late prenatal or perinatal hypoxic-hemodynamic insult is a dominating final common path in the pathogenesis of static encephalopathies during development, in particular in premature infants. In turn, however, such lesions are determined by early genetic and environmental influences. The pathogenesis of static encephalopathy should therefore be seen as a chain of events, with its origin before gestation.

Perinatal observations in forty-eight neurologically impaired term infants

OBJECTIVE

Our goal was to review the perinatal characteristics of 48 singleton term infants with central nervous system neurologic impairment.

STUDY DESIGN

Medical records were retrospectively reviewed for maternal characteristics, prenatal and intrapartum care patterns, neonatal course, and long-term outcome. Those patients without evidence of an obvious acute asphyxial event, traumatic delivery, or preterm birth were excluded. The study population was then subclassified according to the admission fetal heart rate pattern.

RESULTS

Of these 48 term infants the admission fetal heart rate pattern was nonreactive in 33 (69%) and reactive in 15 (31%). Maternal characteristics, prenatal care, and long-term outcome were statistically similar between the two groups. However, the nonreactive group exhibited significantly more characteristics consistent with a prior asphyxial event: thick "old" meconium, "fixed" nonreactive baseline fetal heart rate, meconium-stained skin, and meconium aspiration syndrome. In contrast, in the reactive group a fetal heart rate pattern developed that was consistent with Hon's theory for intrapartum asphyxia and manifested by a prolonged tachycardia in association with persistent nonreactivity, diminished fetal heart rate variability, and fetal heart rate decelerations.

CONCLUSIONS

Among fetuses later found to be neurologically impaired, a persistent nonreactive fetal heart rate tracing obtained from admission to delivery appears to be evidence of prior neurologic injury.

A fetal type of Minamata disease. An autopsy case report with special reference to the nervous system

Our knowledge concerning the pathology of fetal cases of human Minamata disease (methylmercury poisoning) is relatively limited. We report here a case with description of the distribution of mercury in the systemic organs, and the ultrastructural changes of the nervous system after a survival of 29 yr. The patient was a female born in 1957, with a body wt of 3000 g, who died in 1987. She carried a diagnosis of cerebral palsy, and had a convulsion at age 3 yr. Mercury levels in her mother's hair were 101 micrograms/g at the time of examination in 1959. At autopsy, the body measured 43 cm and weighed 23 kg. The brain weighed 920 g and showed marked cerebral atrophy, mild neuronal loss in the calcarine, postcentral and precentral cortices, cerebellar atrophy, and segmental demyelination of peripheral nerves. Mercury granules were present in the brain, kidney, and liver. Ultrastructural examination of the calcarine, post- and precentral cortices, and cerebellar cortices, showed severe atrophy of nerve cells, with a decrease in rough ER and an increase in nuclear chromatin and preservation of mitochondria. Autophagosomes were increased in number. In addition, high electron density, globular and dense bodies, measuring 0.3-1.8 microns in diameter, were found, surrounded by limited membrane, within both cerebral and cerebellar neurons. In the cellebellum, synapses were well-preserved.

Destructive brain lesions of presumed fetal onset: antepartum causes of cerebral palsy

Antepartum events have been associated with fetal brain injury and may contribute to later neurological sequelae. However, children with these injuries may be asymptomatic or exhibit few clinical signs during the neonatal period. Six neonates are presented with destructive brain lesions of fetal onset based on radiological and neurophysiological studies at birth. No intrapartum difficulties were noted in any of the cases. Two maternal histories were significant for either placental bleeding or toxemia during the second or third trimesters of pregnancy. Fetal porencephaly from presumed intraventricular hemorrhage was documented by serial abdominal sonography for these two children. No causes could be assigned for the remaining four patients with destructive brain lesions. All six children had normal results on neurological examinations at birth, although four neonates later presented with isolated seizures at 8 to 30 hours of life which resolved after administration of anti-epileptic medication. In all cases initial neonatal electroencephalographic records showed abnormalities consisting of major background asymmetries or seizures. Initial documentation of cerebral lesions was made by fetal sonography (two patients) and computed tomography scan (four patients) during the initial 30 hours of life, timing the lesions to the antepartum period. Cerebral palsy has been documented in all children; one child had resolution of her deficits by 6 months of age. Better surveillance of events during the antepartum period may help identify specific pathophysiological conditions that contribute to cerebral palsy. Neurophysiological and imaging studies should be used during the immediate new-born period for neonates believed to have cerebral lesions based on maternal sonography or isolated seizures.

Prenatal and perinatal factors in the etiology of cerebral palsy

Among 19,044 children born to mothers with monitored pregnancies and followed medically for at least 5 years, 41 (0.2%) had cerebral palsy that was not the result of a progressive disease or of a neural tube defect. All children without cerebral palsy were entered as controls subjects in the analysis. Significant prenatal or gestational predictors of cerebral palsy were a severe or nonsevere birth defect other than cerebral palsy or its sequelae, low birth weight, low placental weight, abnormal fetal position, and premature separation of the placenta. Maternal antecedents of cerebral palsy were unusually long or unusually short intervals between pregnancies and unusually long menstrual cycles. Perinatal risk factors were delayed crying as a measure of birth asphyxia and abnormal delivery. Children who had seizures within 48 hours of birth were at high risk for the development of cerebral palsy. Seventy-eight percent of children with cerebral palsy did not have birth asphyxia, and the 22% who did had other prenatal risk factors that may have compromised their recovery.

The causes of cerebral palsy. A contemporary perspective

In a retrospective review of cases, the causes of cerebral palsy in 142 children living in the northwestern United States and born after Jan 1, 1970, were prenatal in 50% of the cases, similar to findings recently reported from Sweden. The causes were perinatal in 33%, postnatal in 10%, and mixed in 7%. Epidemiologic studies from the 1950s report the origins of cerebral palsy to be mostly perinatal. The discrepancy is explained largely by differences in interpretation of medical findings prompted by recent advances in knowledge of fetal development and implications of obstetric and neonatal events. Cerebral palsy was considered medically preventable in 6% of full-term perinatal cases, possibly medically preventable in another 4%, and socially preventable in 4% of posttraumatic and 22% of preterm cases. Research in prenatal development, improvements in health education, and expansion of clinical genetic services are suggested as the most promising avenues toward prevention of cerebral palsy.