Prenatal and perinatal factors in the etiology of cerebral palsy

Declining diagnosis of birth asphyxia in California: 1991-2000

OBJECTIVE

Birth asphyxia is recognized as an important cause of neonatal morbidity and mortality. Whether advances in perinatal care have altered the incidence of birth asphyxia is unknown. We determined the incidence of birth asphyxia diagnoses made over a 10-year period in California.

METHODS

In a population-based retrospective cohort study of 5,364,663 live births, we determined the incidence and case fatality of birth asphyxia between 1991 and 2000. Using a statewide administrative hospital discharge database, we identified all newborn admissions that generated a diagnosis of birth asphyxia (International Classification of Diseases, Ninth Revision, Clinical Modification codes 768.5, 768.6, or 768.9) or a diagnosis that overlaps with birth asphyxia, such as congenital encephalopathy or fetal distress. We determined incidence and in-hospital case fatality rates adjusted for birth weight and demographic characteristics and stratified by associated perinatal complications.

RESULTS

The 24 330 newborns who received a diagnosis of birth asphyxia yielded a population incidence of 4.5 per 1000 live births. Black ethnicity (relative risk [RR]: 1.3; 95% confidence interval [CI]: 1.2-1.3), male gender (RR: 1.2; 95% CI: 1.1-1.2), and low socioeconomic status (RR: 1.2; 95% CI: 1.1-1.2) all were associated with increased risk. The diagnosis of birth asphyxia decreased by 91% from 14.8 to 1.3 per 1000 live births during the study years. This decrease could not be explained by an increased diagnosis of overlapping conditions. Overall case fatality was 4%, and the majority of deaths in infants >2000 g occurred in the presence of congenital anomalies, cord abnormalities, or maternal hemorrhage. In newborns <2000 g, case fatality was highest in the presence of chorioamnionitis (48%).

CONCLUSION

The diagnosis of birth asphyxia has decreased dramatically in recent years. The factors that are responsible for this decline are unclear and deserve additional investigation.

Neuropsychiatric syndromes in adults with intellectual disability: issues in assessment and treatment

The purpose of this article is to present a survey of important neuropsychiatric issues and recent findings regarding the evaluation and treatment of neuropsychiatric symptoms and syndromes in patients with intellectual disability (ID). The cause of ID, environmental or genetic, can be determined in few patients. Etiology is idiopathic in most patients. ID and psychiatric illness are not mutually exclusive; individuals with ID have increased rates of psychiatric illness. Although recognition of significant axis I psychopathology is important, not all challenging behaviors in persons with ID will have a clear axis I diagnosis. Psychologic, behavioral, and environmental treatments are appropriate measures, but pharmacotherapy often is needed. Our experience has shown us that the more severe, disruptive, and dangerous the behavior, the stronger the indication for empirical drug treatment trials. Community-based models of support with neuropsychiatric intervention can be a potent therapeutic combination in the management of challenging behaviors in individuals with ID.

Primary nonmedically indicated cesarean section ("section on request"): evidence based or modern vogue?

Cesarean section, initially described as an emergency operative procedure for delivering moribund parturients, is now advocated by many as a routine technique with major advantages over vagi-nal delivery. In fact, it has been suggested that labor and vaginal delivery are no longer the desired consequence of pregnancy, a conclusion that reflects perceived medical advantages and patient and physician convenience. This article systematically reviews the various medical implications to the mother and infant of this procedure in the hope of facilitating a more rational approach to this spreading and controversial phenomenon.

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.

The "Bermuda triangle" of neonatal neurology: cerebral palsy, neonatal encephalopathy, and intrapartum asphyxia

The terms "cerebral palsy," "neonatal encephalopathy," and "intrapartum asphyxia" are frequently used in pediatric neurology. This article presents concise, verifiable definitions for each of these entities based on our current understanding and formulates the nature of the interrelationships between them. The aim is to provide a level of clarity that will enhance diagnostic and pathogenetic precision and minimize conceptual misunderstanding. This should aid future therapeutic and research efforts in this important area.

Infection as a cause of preterm birth

In summary, there is little question that intrauterine and some extrauterine infections play important roles in the etiology of early, spontaneous, preterm labor and PROM. Disappointing are the mixed results from various treatment attempts, usually with antibiotics, to reduce the preterm birth rate. Clearly, a better understanding of the pathways leading from infection to preterm birth will be necessary to develop effective interventions to reduce infection-related preterm delivery. Research must also address the question of individual susceptibility to infections and the influence of other exposures that may moderate the association between infection and preterm birth.

Etiology of cerebral palsy

Cerebral palsy has a complex and multifactorial etiology. Approximately 5%-10% of cases can be ascribed to perinatal hypoxia, but the vast majority of cases are caused by the interplay of several risk factors and antenatal, perinatal, and neonatal events. The strongest risk factors include prematurity and low birth weight. The prevalence of cerebral palsy has remained constant despite improvements in obstetric and neonatal care. For a long time, the only causal factors explored to account for risk for cerebral palsy were complications of labor and delivery. As other periods have been investigated, new associations have come to light. The current understanding of contributors to the risk for cerebral palsy is still incomplete. Multiple causes may interact by way of excitotoxic, oxidative, or other converging pathophysiologic pathways. A single factor, unless present to an overwhelming degree, often may be insufficient to produce cerebral damage, whereas two or three interacting pathogenic assaults may overwhelm natural defenses and produce irreversible brain injury. The low prevalence of cerebral palsy makes the formal testing of preventative strategies difficult. There is a need for such strategies to be carefully assessed in well designed, multicenter, randomized, controlled trials before becoming part of clinical practice, however, so that the balance between harm and benefit is known in advance.

The epidemiology and causes of cerebral palsy

Cerebral palsy is the commonest physical disability in childhood, occurring in 2.0 to 2.5 per 1000 live births. Although the total number of children with cerebral palsy has remained stable or increased slightly since 1970, there has been a consistent rise in the proportion of cerebral palsy associated with preterm and very preterm births. Known causes of cerebral palsy--whether prenatal, perinatal or postnatal--must be distinguished from risk factors or associations. Much is known about such risk factors which, alone or in combination, may indirectly result in cerebral palsy. Causes and risk factors implicated in cerebral palsy are discussed in detail, together with directions for future research.

Etiologic yield of cerebral palsy: a contemporary case series

Cerebral palsy is an established symptom complex that results from heterogeneous etiologies. Our understanding of the relative contribution of underlying etiologies to the occurrence of cerebral palsy is largely derived from studies lacking systematic neurologic evaluation or the application of contemporary imaging modalities. Throughout a 10-year inclusive period, the case records of all consecutive patients diagnosed with cerebral palsy in a single pediatric neurology practice were reviewed with reference to clinical features and diagnostic yield. A total of 217 cases of cerebral palsy were identified (129 male, 88 female): 77 (35.5%) spastic quadriplegic, 68 (31.3%) spastic hemiplegic, 39 (18%) spastic diplegic, five (2.7%) spastic monoplegic, 12 (5.5%) mixed, 12 (5.5%) ataxic-hypotonic, two (0.9%) dyskinetic, two (0.9%) Worster-Drought syndrome. Overall etiologic yield was 82.0%, varying according to type of cerebral palsy: 50% dyskinetic, 59% diplegia, 80% monoplegia, 80.9% hemiplegia, 90.9% quadriplegia, 91.7% ataxic hypotonia, and 100% mixed/Woster-Drought. The top five etiologic entities identified were periventricular leukomalacia, 24.9%; intrapartum asphyxia, 21.7%; cerebral dysgenesis, 17.1%; intracranial hemorrhage, 12.9%; and vascular, 9.7%. Although a single etiology was apparent in 144 (66.4%) of the cases, multiple etiologies were believed to be contributory in 34 (15.6%) of the cases. The etiologic profile varied according to such features as the type of cerebral palsy, gestational age, and the source (high-risk neonatal population or not) of the patients. Features of the child's cerebral palsy, such as microcephaly, neonatal difficulties, prior or coexisting epilepsy, and high-risk source, were found to be predictive of eventual etiologic yield. This contemporary evaluation of cerebral palsy etiologic yield suggests that it is much higher than previously reported and varies, depending on key clinical features.

Trends in the prevalence of cerebral palsy in a population-based study

OBJECTIVE

To determine trends in the prevalence of congenital cerebral palsy (CP) over a 16-year period for 1-year survivors using a large, population-based surveillance program.

METHODS

We determined birth weight-specific trends in the prevalence of CP in live birth and 1-year survivor cohorts of children in a 5-county metropolitan Atlanta area for the periods from 1975-1977, 1981-1985, and 1986-1991. We ascertained children with CP in metropolitan Atlanta by record review as part of an ongoing developmental disability surveillance program conducted by the Centers for Disease Control and Prevention and the Georgia Department of Human Resources. A total of 110, 262, and 443 cases of congenital CP were identified for the birth years 1975-1977, 1981-1985, and 1986-1991, respectively. Data were analyzed by birth weight, race, subtypes of CP, and whether the CP existed as an isolated disability or was accompanied by another disability.

RESULTS

There was a modest increase in the overall prevalence of congenital CP from 1.7 to 2.0 per 1000 1-year survivors during the period from 1975-1991. This trend was primarily attributable to a slight increase in CP in infants of normal birth weight--CP rates in moderately low and very low birth weight infants did not show consistent trends. There was an increase in the proportion of children who had CP and no other disabilities that was most apparent in infants of normal birth weight from 17% in 1975-1977 to 39% in 1986-1991. For children weighing <1500 g, the proportion of children with spastic diplegic CP increased over time (7% of cases in 1975-1977, 36% in 1985-1988, and 32% in 1986-1991).

CONCLUSIONS

In the only ongoing population-based study of CP in the United States, there has been a modest increase in the prevalence of CP in 1-year survivors born from 1975-1991. This increase however was seen only in infant survivors of normal birth weight. No change was seen in the trends in CP prevalence in low birth weight and very low birth weight infant based on infant survivors.

Therapies administered to mothers at risk for preterm birth and neurodevelopmental outcome in their infants

A decrease in the rate of preterm births and the prevention of prematurity-associated neurodevelopmental morbidity are critical for the reduction of neurodevelopmental disability. Efforts to reduce the overall preterm delivery rate have been unsuccessful. Although progress has been achieved in the prevention of short-term neonatal morbidity over the past several decades, the majority of the improvements have resulted from improved neonatal care. Whether obstetric interventions can improve neurodevelopmental outcome is unknown. The ability to adequately assess obstetric interventions is hampered by the limited number of interventional studies that included long-term outcome assessment. Thus, it is incumbent upon ongoing and future interventional studies to consider long-term outcome assessment as a critical component of the overall evaluation of efficacy of obstetric therapies.

Perinatal exposure to infection and risk of childhood leukemia

BACKGROUND

A population-based case-control study was conducted to investigate the association between childhood leukemia and infectious exposures during pregnancy and early neonatal period.

PROCEDURE

Children born and diagnosed with leukemia between 1973 and 1989 in Sweden (578 lymphatic, 74 myeloid) were selected as cases. One control was randomly selected for each case and individually matched by sex, month, and year of birth. Children with Down's syndrome were excluded. Exposure data were blindly abstracted from antenatal, obstetric, and other standardized medical records. Odds ratios (OR) and 95% confidence intervals (CI) were calculated by conditional logistic regression.

RESULTS

A history of maternal infection was not significantly associated with childhood leukemia, OR = 1.25 (95% CI 0.95-1.65). Maternal lower genital tract infection significantly increased the risk of childhood leukemia, OR = 1.78 (95% CI 1.17-2.72), and especially for children over 4 years of age at diagnosis, OR = 2.01 (95% CI 1.12-3.80). Neonatal infection was not associated with the risk of leukemia. The results remained unaltered after adjustment for potential confounders, and separate analyses for myeloid and lymphoid leukemia.

CONCLUSIONS

We could document an association between exposure to maternal lower genital tract infection in utero, and a subsequent risk for childhood leukemia, which indicate the importance of an early exposure.

Antenatal and intrapartum antecedents of cerebral palsy: a case-control study

AIM

To identify antenatal and intrapartum factors contributing to the aetiology of cerebral palsy (CP).

METHODS

A case-control study using moderate/severe cases of cerebral palsy identified from the Victorian Cerebral Palsy Register and two controls per case identified through the Victorian Perinatal Data Collection Unit.

RESULTS

A number of previously identified risk factors for CP were confirmed in our data. New observations were (in specific sub-groups): protective effects of mother's negative Rhesus status, cigarette smoking at the first visit and episiotomy and an increased risk of CP associated with an abnormal antenatal cardiotocograph.

CONCLUSIONS

Although the result of the deliberate investigation of specific aspects of the antenatal and intrapartum period identified from a pilot study, our new findings must be interpreted with caution as they were not all based on specific a priori hypotheses, although some had been examined by other investigators. We would encourage their evaluation in other data sets.

Neuropathology associated with stillbirth

Neuropathologic findings in stillbirths oftentimes provide insight into the specific mechanisms leading to death. Examination of the brains of stillborn infants may also identify pathophysiologic processes that result in prenatal brain injury in liveborn as well as stillborn infants and that lead to neurologic disorders in liveborn infants, such as cerebral palsy or the sudden infant death syndrome (SIDS). A variety of abnormalities are found in the brains of stillborns, the most common including cerebral white matter necrosis (periventricular leukomalacia) or gliosis, germinal matrix or intraventricular hemorrhage, cerebral infarcts, pontosubicular necrosis, and spinal cord or brainstem necrosis. The 2 major hypotheses that have been proposed for the pathophysiology of cerebral white matter injury in the perinatal period are hypoxia/ischemia and infection/cytokines as the basis for injury. The fetal brain may be selectively vulnerable to various insults at specific stages of development.

Cerebral palsy births in eastern Denmark, 1987--90: implications for neonatal care

The Cerebral Palsy Register in eastern Denmark has collected cases using a uniform data sampling procedure since birth year 1979. We have investigated changes in the rate of cerebral palsy, related to gestational age, mortality and perinatal risk factors in children born 1983--90. The total cerebral palsy birth prevalence decreased from 3.0 in the birth year period 1983--86 to 2.4 per 1000 live births (P < 0.01) in 1987--90, owing to a decrease among all preterm infants (29--19 per 1000, P < 0.001). The perinatal and early neonatal mortality in preterm infants was unchanged from 1983--86 to 1987--90. The rate of cerebral palsy in term infants was 1.5 per 1000 in all birth-year periods from 1979--90. Among the cerebral palsy infants, the proportion of very preterm babies treated with mechanical ventilation in the neonatal period decreased from 95% in 1983--86 to 61% in 1987--90 (P < 0.001), while the group treated with CPAP among the moderately preterm babies increased from 61% to 78% (P < 0.05). The significant decline in cerebral palsy rate in preterm infants born 1987--90 may be due to a change in treatment at the neonatal intensive care units using less mechanical ventilation, a hypothesis which needs further investigation.

Congenital abnormalities among children with cerebral palsy: More evidence for prenatal antecedents

OBJECTIVES

To investigate the association between cerebral palsy (CP) and congenital abnormalities among children with very low, low, and normal birth weight.

STUDY DESIGN

A population-based, case-control study among the cohort of 155,636 live births delivered between 1983 and 1985 in 4 California counties. Children with moderate or severe congenital CP (n = 192) diagnosed by age 3 were identified from 2 California State service agencies, and 551 control children were randomly sampled from birth certificate files. Information on congenital abnormalities diagnosed by the age of 1 year was obtained from the California Birth Defects Monitoring Program registry. Odds ratios (OR) and 95% CIs were calculated to estimate risk for CP associated with congenital abnormalities.

RESULTS

Among singletons, congenital abnormalities were present in 33 (19.2%) children with CP and 21 (4.3%) control children (OR = 5.2, 95% CI 2.8-9.7). For each birth weight group, the percent of children with congenital abnormalities among children with CP exceeded that among control children. Structural abnormalities of the central nervous system were more common among children with CP (OR = 16.2, 95% CI 5.8-49.3) than control children. In contrast, the percent of children with non-central nervous system abnormalities only was similar between case patients and control subjects.

CONCLUSION

These findings provide further evidence that factors operating in the prenatal period contribute significantly to the etiology of CP.

Cognitive and neuropsychological functioning in children with cerebral palsy

This article reviews the extant literature on intellectual functioning in different subtypes of cerebral palsy. Following a definition of the characteristics of each of three major cerebral palsy groups, typical neurologic and magnetic resonance imaging findings are reported. More recent studies that examine the intellectual and neuropsychological functioning of children within these classification groups are also reviewed. This review concludes that there remains a significant lack of precise information about the impact of cerebral palsy on the intellectual, motor, and neuropsychological functioning of children and that neuropsychological assessment can provide the necessary tools for such studies.

Umbilical vein white blood cell count as a marker of acidemia in term neonates

OBJECTIVE

White blood cells are mobilized under both hypoxic and infectious conditions. Intrauterine hypoxia is linked to increased risk of cerebral palsy and is potentiated by the presence of infection. We hypothesized that umbilical vein white blood cell elevation in term neonates is associated with intrauterine acidemia.

METHODS

We prospectively evaluated all liveborn neonates delivered at our institution for a 6-month period. Umbilical arterial blood was analyzed for pH and blood gas and venous blood for hematologic indices. Medical records of cases greater than or equal to 37 weeks' gestation were reviewed for correlative data. Student's t-test was used to determine difference of means and Chi-square test for goodness of fit. Pearson coefficients of correlation were applied where appropriate.

RESULTS

A total of 1,948 liveborn, term neonates were delivered during the study period; 1,561 cases had white blood cell analysis and arterial blood gas data available. Acidemic cases had higher white blood cell (15.0 vs. 12.4 cells x 10(3)/mm3, P < 0.001), lymphocyte (4.43 vs. 3.59 cells X 10(3)/mm3, P < 0.0001), and neutrophil counts (9.08 vs. 7.71 cells x 10(3)/mm3, P < 0.01). As umbilical artery pH decreased, white blood cells became more prevalent. Likewise, as base deficit deepened, white blood cell counts increased.

CONCLUSIONS

This study demonstrates an association between deepening acidemia and increasing white blood cell, lymphocyte, and neutrophil counts. Although statistically different, mean white blood cell counts for acidemic and nonacidemic cases are fairly close, limiting the clinical applicability in determining whether pathology is present in an individual case.

Perinatal infection is an important risk factor for cerebral palsy in very-low-birthweight infants

Sixty-nine very-low-birthweight infants out of a population of 923 had cerebral palsy (CP) at an 18-month follow-up. Thirty-nine of these had cranial ultrasound abnormalities in the neonatal period and 30 had normal cranial ultrasounds. The distribution of subtypes of CP differed markedly between the two groups, with hemiplegia predominating in those with abnormal cranial ultrasounds and diplegia in those with normal cranial ultrasounds. Regardless of ultrasound appearance, the relative risk of CP increased approximately fourfold with a neonatal history of sepsis.

Can neurological injury be timed?

Our knowledge about the cause of cerebral palsy continues to expand and prenatal events are thought to play an important role. This article reviews laboratory tests, imaging studies and pathologic findings that have been used to identify the timing of neurological injury. Limitations exist for all modalities, however, imaging studies, electroencephalograms and pathologic examination provide the most useful information. Improvements in our ability to time neurological injury will better direct our efforts to prevent cerebral palsy.

Antecedents of cerebral palsy in very low-birth weight infants

Research from the last two decades provides directions for efforts to prevent CP in VLBW infants. The pathogenesis of CP seems to involve factors operating both during pregnancy and in the neonatal period. The most important prenatal factor appears to be intrauterine infection. Perinatal infection and other risk factors, such as the death of a co-twin, placental abruption, and cerebral ischemia, could trigger a cytokine cascade resulting in damage to the developing brain. The low frequency of intrauterine infection in mothers with preeclampsia might explain the apparent protective effect of this disorder. If the brain damage attributed to intrauterine infection and other risk factors involves cytokines as intermediates, then blockade of the proinflammatory cascade or promotion of endogenous inhibitors might prevent CP. Other potentially preventive strategies include corticosteroids given to mothers (but not those given to neonates) and thyroid hormone.

Fetal heart rate observations in the brain-damaged infant

The objective of this study was to describe the fetal heart rate patterns and underlying pathophysiologic changes in the brain-damaged fetus. Fetuses with brain damage from hypoxic ischemic encephalopathy do not manifest uniform fetal heart rate patterns. However, these fetuses do show distinct fetal heart rate patterns that permit categorization based on their admission heart rate, subsequent changes in their baseline rate; and neonatal findings. Based on the observations of infants brain damaged in utero because of hypoxic ischemic encephalopathy, the intrapartum fetal management will depend on the admission fetal heart rate pattern, and the subsequent changes in the baseline rate.

Other factors/conditions associated with cerebral palsy

The cause for most cases of cerebral palsy is unknown. There are however, risk factors that have been associated with this chronic neuromuscular disease. The objective of this article is to review the maternal and fetal conditions (other than asphyxia and infection) strongly associated with increased rate of cerebral palsy. What remains to be elucidated is whether or not these associations are causative.

Photon migration through fetal head in utero using continuous wave, near-infrared spectroscopy: development and evaluation of experimental and numerical models

In this work experimental tissue phantoms and numerical models were developed to estimate photon migration through the fetal head in utero. The tissue phantoms incorporate a fetal head within an amniotic fluid sac surrounded by a maternal tissue layer. A continuous wave, dual-wavelength (lambda = 760 and 850 nm) spectrometer was employed to make near-infrared measurements on the tissue phantoms for various source-detector separations, fetal-head positions, and fetal-head optical properties. In addition, numerical simulations of photon propagation were performed with finite-difference algorithms that provide solutions to the equation of radiative transfer as well as the diffusion equation. The simulations were compared with measurements on tissue phantoms to determine the best numerical model to describe photon migration through the fetal head in utero. Evaluation of the results indicates that tissue phantoms in which the contact between fetal head and uterine wall is uniform best simulates the fetal head in utero for near-term pregnancies. Furthermore, we found that maximum sensitivity to the head can be achieved if the source of the probe is positioned directly above the fetal head. By optimizing the source-detector separation, the signal originating from photons that have traveled through the fetal head can drastically be increased.

Photon migration through fetal head in utero using continuous wave, near infrared spectroscopy: clinical and experimental model studies

Near infrared (NIR) measurements were made from the maternal abdomen (clinical studies) and laboratory tissue phantoms (experimental studies) to gain insight into photon migration through the fetal head in utero. Specifically, a continuous wave spectrometer was modified and employed to make NIR measurements at 760 and 850 nm, at a large (10 cm) and small (2.5/4 cm) source-detector separation, simultaneously, on the maternal abdomen, directly above the fetal head. A total of 19 patients were evaluated, whose average gestational age and fetal head depth, were 37 weeks +/- 3 and 2.25 cm +/- 0.7, respectively. At the large source-detector separation, the photons are expected to migrate through both the underlying maternal and fetal tissues before being detected at the surface, while at the short source-detector separation, the photons are expected to migrate primarily through the superficial maternal tissues before being detected. Second, similar NIR measurements were made on laboratory tissue phantoms, with variable optical properties and physical geometries. The variable optical properties were obtained using different concentrations of India ink and Intralipid in water, while the variable physical geometries were realized by employing glass containers of different shapes and sizes. Third, the NIR measurements, which were made on the laboratory tissue phantoms, were compared to the NIR measurements made on the maternal abdomen to determine which tissue phantom best simulates the photon migration path through the fetal head in utero. The results of the comparison were used to provide insight into the optical properties and physical geometry of the maternal and fetal tissues in the photon migration path.

Antepartum, transabdominal near infrared spectroscopy: feasibility of measuring photon migration through the fetal head in utero

OBJECTIVE

We report the feasibility of measuring photon migration through the fetal head in utero using antepartum, transabdominal, near infrared (NIR) spectroscopy.

METHODS

We developed a continuous wave (CW) spectrometer that incorporates a halogen light source, silicon photodetectors, and a differential processing circuit for antepartum, transabdominal, NIR spectroscopy. By placement of the light source and photodetector on the midline of the maternal abdomen above the fetal head at a separation (approximately 10 cm) large enough for the light to propagate through maternal and fetal tissues via multiple scattering events before being detected at the surface and the use of filtered illumination and detection at wavelengths (760 nm, 850 nm), which coincide with the absorption bands of oxygenated and deoxygenated hemoglobin in the NIR window, we performed studies to evaluate whether antepartum, transabdominal NIR spectroscopy can measure photon migration through the fetal head in utero.

RESULTS

The results demonstrate that the CW spectrometer we developed can be employed to make NIR measurements from the maternal abdomen at a 10 cm source-detector separation, with an excellent signal-to-noise ratio. Furthermore, a variety of antepartum, transabdominal NIR measurements that we performed on patients undergoing a routine nonstress test demonstrate the feasibility of measuring photon migration through the fetal head in utero.

CONCLUSIONS

Preliminary assessment of transabdominal NIR spectroscopy suggests that this technique can enable photon migration through the fetal head in utero. This is an important step towards the development of this technique for measuring and quantifying fetal cerebral blood oxygenation in utero.

Antenatal and perinatal antecedents of moderate and severe spastic cerebral palsy

Routinely collected perinatal morbidity data were abstracted for 204 cases of moderate and severe spastic cerebral palsy and 816 matched controls. Separate analyses were conducted for cases with birth-weight > or = 2,500 g and birth-weight < 2,500 g. The presence of a congenital abnormality was an important risk factor for cerebral palsy in both groups and further analyses were conducted after dividing the groups according to presence or absence of a congenital abnormality. In the < 2,500 g group, resuscitation needed was clearly identified as a risk factor for cerebral palsy in the group with no congenital abnormalities (adjusted OR=3.4; 95% CI=1.6-7.5) while in the group with congenital abnormalities, none of the risk factors were clearly associated with an increased risk of cerebral palsy. Among the cases with birth-weight > or = 2,500 g, intrauterine hypoxia/birth asphyxia was clearly associated with an increased risk of cerebral palsy (adjusted OR=18.1; 95% CI=1.8-186) in the group with no congenital abnormalities while in the group with congenital abnormalities, none of the factors were clearly associated with an increased risk of cerebral palsy.

Short interpregnancy interval and the risk of disabling cerebral palsy in a low birth weight population

OBJECTIVE

The objective of this study was to investigate the relation of short interpregnancy interval and cerebral palsy (CP) in a low birth weight population in whom neonatal brain injury was systematically ascertained in the newborn period.

STUDY DESIGN

We used data from a prospective cohort study of 1105 infants born < or = 2000 gm, designed to study the cause and consequences of neonatal brain injury. Of the 777 children with data on brain injury and CP, 382 were born to multiparous women, and 375 had information available to calculate interpregnancy interval, defined as the number of days from the end of the last pregnancy to conception of the index pregnancy.

RESULTS

In the presence of the strong explanatory power of neonatal brain injury, short interpregnancy interval maintains an independent risk for disabling CP.

CONCLUSION

In this cohort of low birth weight infants, short interpregnancy interval appears to represent a significant risk for the development of disabling CP.

Risk factors for cerebral palsy

Cerebral palsy is a major cause of crippling in children, but it's etiology is poorly understood. This case control study was done to assess some of the identified risk factors for cerebral palsy, 125 cerebral palsy cases selected from hospital clinic and 125 age and sex matched neighbourhood controls, all aged less than 5 years and residing in Delhi (India) were studied. Information regarding antenatal, natal and postnatal period was collected by mother's interview, and wherever available, from hospital records with the study subjects. Most common type of cerebral palsy was spastic (88%). Quadriplegia was the commonest topographical subtype (86.4%). Birth asphyxia was found to be present in only 25.6% of cases. The commonest risk factor amongst cases was low birth weight (28.8%). The multivariate odds ratios (confidence limits) for the risk factors found to be significantly associated with cerebral palsy were 36.1 (7.76-160) for birth asphyxia, 13.8 (4.95-38.3) for low birth weight, 37.4 (4.47-313) for neonatal convulsion, 23 (4.7-112) for neonatal jaundice, 14.4 (3.69-56.4) for neonatal infection, 24.9 (2.78-223) for instrument assisted delivery and 15.4 (1.57-152) for antepartum hemorrhage. Precipitate labour, caesarean section, twins, toxemia, breech delivery and head injury were not found to be significantly associated with cerebral palsy. Thus birth asphyxia, low birth weight, neonatal convulsions, neonatal jaundice, neonatal infection, instrument assisted delivery and antepartum hemorrhage are significant risk factors for cerebral palsy.

Assessment of gestational age using birth certificate data compared with medical record data

We assessed the extent to which use of medical record data might improve gestational age estimates compared with reliance on the birth certificate alone. Using population-based data from four northern Californian counties, we constructed an algorithm to select the best gestational age estimate from antenatal assessments recorded in medical records. A total of 172 singletons with moderate or severe congenital cerebral palsy from the California Cerebral Palsy Project were compared with 472 randomly selected controls with regard to discrepancies between the algorithm-derived estimated gestational age (bestgest) and an estimate based solely on the last menstrual period as recorded on birth certificates. Agreement between bestgest and birth certificate estimated gestational age was exact or within one week for at least 60% of both cases and controls in each of the three birthweight strata. In general, the greater the birthweight of the babies, the better the agreement. The mean number of weeks of overestimation by the birth certificate was 0.7 weeks for cases and 1.1 weeks for controls in the lowest birthweight group (< 1500 g). When compared with bestgest, clinical examination of the infant also tended to overestimate gestational age. In the < 1500 g birthweight group, cases were twice as likely as controls to have a bestgest of 'low certainty,' but antenatal estimates of 'high certainty' were obtained for at least a third of very low birthweight babies born during the mid-1980s. More widespread use of early ultrasound in more recent birth cohorts may result in a greater proportion of accurate antenatal estimates. When a distinction between immaturity and intrauterine growth retardation is important to the understanding of the aetiology of the outcome under investigation, the use of antenatal estimates from medical records may substantially improve the certainty of the data.

The problem of low birthweight, the cost and possibilities of prevention

Low birthweight is costly to sufferers and to society. Primary prevention gives benefits exceeding costs, but many plans to prevent low birthweight, for example improvement in antenatal care, have failed because the intervention is too late. Preconception care is generally necessary. Poor maternal nutrition and infection are the major causes of low birthweight.

Cerebral palsy, perinatal depression and low ponderal index

To determine whether asymmetric growth restriction, abnormally lean body morphology, is associated with cerebral palsy (CP) in infants born with perinatal depression, perinatally depressed Collaborative Perinatal Project infants were assessed. Rates of ponderal index less than 5% for gestational age and race (low PI), a marker for asymmetric growth, were compared in infants either neurologically normal or having CP at 7 years of age. Low PI was associated with CP in infants with Apgar scores of 0 to 3 at 10, 15 or 20 minutes in both of these groups, after exclusion of small-for-gestational-age infants, and was a significant individual correlate of cerebral palsy with multiple logistic regression. The attributable risk of cerebral palsy related to low Pl was 12.4%.

Uncertain value of electronic fetal monitoring in predicting cerebral palsy

BACKGROUND

Electronic monitoring of the fetal heart rate is commonly performed, in part to detect hypoxia during delivery that may result in brain injury. It is not know whether specific abnormalities on electronic fetal monitoring are related to the risk of cerebral palsy.

METHODS

Among 155,636 children born from 1983 through 1985 in four California counties, we identified singleton infants with birth weights of at least 2500 g who survived to three years of age and had moderate or severe cerebral palsy. The children with cerebral palsy were compared with randomly selected control children with respect to characteristics noted in the birth records.

RESULTS

Seventy-eight of 95 children with cerebral palsy and 300 of 378 controls underwent intrapartum fetal monitoring. Characteristics found to be associated with an increased risk of cerebral palsy were multiple late decelerations in the heart rate, commonly defined as slowing of the heart rate well after the onset of uterine contractions (odds ratio, 3.9; 95 percent confidence interval, 1.7 to 9.3), and decreased beat-to-beat variability of the heart rate (odds ratio, 2.7; 95 percent confidence interval, 1.1 to 5.8); there was no association between the highest or lowest fetal heart rate recorded for each child and the risk of cerebral palsy. Even after adjustment for other risk factors, the association of abnormalities on fetal monitoring with an increased risk of cerebral palsy persisted (adjusted odds ratio, 2.7; 95 percent confidence interval, 1.4 to 5.4). The 21 children with cerebral palsy who had multiple late decelerations or decreased variability in heart rate on fetal monitoring represented only 0.19 percent of singleton infants with birth weights of 2500 g or more who had these fetal-monitoring findings, for a false positive rate of 99.8 percent.

CONCLUSIONS

Specific abnormal findings on electronic monitoring of the fetal heart rate were associated with an increased risk of cerebral palsy. However, the false positive rate was extremely high. Since cesarean section is often performed when such abnormalities are noted and is associated with risk to the mother, our findings arouse concern that, if these indications were widely used, many cesarean sections would be performed without benefit and with the potential for harm.

Risk factors for cerebral palsy: a case-control study in Greece

The purpose of this study was to investigate the relation between a series of maternal, antenatal, perinatal, socioeconomic and environmental variables and the occurrence of cerebral palsy (CP) in a setting different from those in which previous analytic epidemiologic studies had been undertaken. The study was of case-control design and included 103 children with cerebral palsy born between 1984 and 1988 and residents of the Greater Athens area at any time during 1991 and 1992. Controls were chosen among the neighbors of the index case or were healthy siblings of children with neurological diseases other than CP seen by the same neurologists as the children with CP; a total of 254 control children were eventually included. Statistical analysis was done by modeling the data through unconditional logistic regression. Statistically significant (p < 0.05) risk factors of potential causal importance were: twin membership (OR = 10.2), gestational age (OR = 0.5 per 4 weeks), birth weight conditional on gestational age (OR = 0.9 per 100 g), congenital malformations (OR = 7.5), unhealthy placenta (OR = 6.6), placenta previa (6 cases, no controls), abnormal amniotic fluid (OR = 3.6), head circumference more than 36 cm (OR = 9.0), general anesthesia during labor (OR = 4.3), forceps delivery (OR = 6.8), and birth trauma (OR = 11.5). Among children with no identifiable prenatal risk factors there was no excess prevalence of one or more perinatal risk factors in CP cases compared to controls, which implies that the latter factors impart their effect through interactions with co-existing prenatal or other risk factors.

Case-control study of antenatal and intrapartum risk factors for cerebral palsy in very preterm singleton babies

The increase in survival of very preterm babies during the 1980s was accompanied by a sharp increase in the rate of cerebral palsy in this group. The relation between antenatal and intrapartum factors and cerebral palsy in such babies has not been well defined. To identify adverse and protective antenatal and intrapartum factors we undertook a case-control study of 59 very preterm babies who developed cerebral palsy, identified from a population-based register, and 234 randomly selected controls. The frequency of cerebral palsy decreased with increasing gestational age and birthweight. Antenatal complications occurred in 215 (73%) of the women with preterm deliveries. Factors associated with an increased risk of cerebral palsy after adjustment for gestational age were chorioamnionitis (odds ratio 4.2 [95% CI 1.4-12.0]) prolonged rupture of membranes (2.3 [1.2-4.2]), and maternal infection (2.3 [1.2-4..5]). Pre-eclampsia was associated with a reduced risk of cerebral palsy (0.4 [0.2-0.9]), as was delivery without labour (0.3 [0.2-0.7]). There was no increased risk of cerebral palsy with intrauterine growth retardation (1.0 [0.9-1.1]). The effect of rigorous management of adverse antenatal factors on the frequency of cerebral palsy in very preterm babies should be tested in randomised controlled trials.

Geburtsasphyxie als Ursache kindlicher Hirnschäden?

The prevalence of cerebral palsy (CP) has increased over the last 15 years in most countries. This is explained by an improved survival of very low birth weight prematures. In term infants birth asphyxia is of minor significance as a cause for CP. In only 10% of all CP cases following delivery at term, birth asphyxia must be discussed as a possible cause. In premature deliveries events during the perinatal period are of greater significance for the later development of a CP. Only severe forms of oxygen deficit, leading to tissue damage in the brain and other organs with clinical symptoms during the first days of life, are of significance for the long term prognosis. Even in the presence of severe birth asphyxia the causal relationship with a psychomotor handicap is not proven, since brain damage may have developed during pregnancy before the onset of labour and may be the cause of birth asphyxia. Brain damage and birth asphyxia may be the result of a common pathology of pregnancy.

Prevention by magnesium of excitotoxic neuronal death in the developing brain: an animal model for clinical intervention studies

Excitotoxic disturbances during brain development were studied in the mouse using intracerebral injections of ibotenate, a glutamatergic agonist of the N-methyl-D-aspartate (NMDA) complex receptor, to analyse the protective effect of a systemic bolus of MgSO4, a non-competitive antagonist of the NMDA ionophore-complex receptor. MgSO4 did not prevent microgyia, induced by ibotenate when injected at P0 immediately after the post-migratory settlement of layer V, but did prevent ulegyrias, porencephalic cysts, and other cortical and cortical-subcortical hypoxic-like lesions arising after completion of the neocortical cyto-architectonic development at P5. Protection was optimal in 80 per cent of mice at 600mg/kg, with no mortality due to MgSO4; thereafter mortality increased with dosage. The protective effect appears after the developmental acquisition of two properties of the excitotoxic cascade, namely the coupling of the massive calcium influx with NMDA-receptor overstimulation and the predominance of magnesium-obliterable calcium channels. This animal model supports the clinical intervention studies with magnesium in hypoxias/perfusion failures and has implications for their design. If maturation of the excitotoxic cascade follows the same sequence in humans, protection is probably low before 26 weeks of gestational age.

Clinical aspects of perinatal hypoxic-ischemic brain injury

Perinatal hypoxic-ischemic cerebral injury is a significant cause of neurological morbidity and mortality in childhood. It is often difficult to determine the precise timing of such injury. Data from epidemiological and neuropathological studies have identified several maternal and fetal risk factors that seem to be associated with suspected prenatal brain injury. Hypoxic-ischemic cerebral injury that originates earlier in gestation may result in few, if any, clinical abnormalities during the newborn period. Clinical abnormalities may also be difficult to recognize in the premature newborn, and greater reliance must be placed on other adjunctive investigations, eg, neuroimaging. In contrast, term infants who sustain acute, intrapartum hypoxic-ischemic insult of sufficient magnitude to result in long-term sequelae invariably show recognizable encephalopathy during the newborn period. A combination of clinical data and adjunctive investigations during the neonatal period is a powerful predictive tool for long-term outcome.

[Handicaps and the perinatal period. II. Perinatal pathology and severe deficiencies]

BACKGROUND

In the last two decades, the infant mortality rate has dramatically declined. But improved management of newborns may induce an increased prevalence of neurodevelopmental handicaps. The aim of this paper is to estimate the rate of major disabilities and their relationships to perinatal events.

POPULATION AND METHODS

Three hundred and sixteen children born in 1984 and registered by the "Commission Départementale de l'Education Spéciale" (CDES) were included in the study. Among these, 97 had either cerebral palsy, blindness, deafness, or mental retardation. These 97 children were compared to 602 school age controls using a multivariate analysis (logistic regression).

RESULTS

The rate of major disabilities among the 6-year old children is 3.4/1000. It was 5/1000 in 1972 and 4.3/1000 in 1976. This frequency is higher in the children who were preterm (odds ratio--OR = 4.8), small for gestational age (OR = 3.3) or suffered from perinatal asphyxia (OR = 32.8). These three factors accounted for 37.4% of major disabilities.

CONCLUSION

This study emphasizes the relationships between perinatal events and some major handicaps but also shows that antenatal factors may be involved in neurodevelopmental problems.

Fine motor deficit: an etiologically distinct entity

The prevalence of risk and adverse factors associated with fine motor disorder (n = 35) were compared with gross motor deficit (n = 158), global developmental delay (n = 336), and combined fine and gross motor deficit among 1,241 children up to 3 years of age identified in the Haifa health district. A significantly increased preponderance of males was observed among the study group as compared to the group with gross motor deficit. Intranatal problems were significantly increased among children with fine motor deficits as compared to those with gross motor deficits as were minor physical anomalies, seizures, and behavioral deficits. Less significant differences were observed between the study group and children with global developmental delay or fine and gross motor deficit. The different risk factor profiles indicated that the children with fine motor deficits constituted an etiologically distinct group highly associated with early antepartum, possibly genetic, origins.

Case-control study of intrapartum care, cerebral palsy, and perinatal death

OBJECTIVE

To investigate the relation between suboptimal intrapartum obstetric care and cerebral palsy or death.

DESIGN

Case-control study.

SETTING

Oxford Regional Health Authority.

SUBJECTS

141 babies who subsequently developed cerebral palsy and 62 who died intrapartum or neonatally, 1984-7. All subjects were born at term of singleton pregnancies and had no congenital anomaly. Two controls, matched for place and time of birth, were selected for each index case.

MAIN OUTCOME MEASURES

Adverse antenatal factors and suboptimal intrapartum care (by using predefined criteria).

RESULTS

Failure to respond to signs of severe fetal distress was more common in cases of cerebral palsy (odds ratio 4.5; 95% confidence interval 2.4 to 8.4) and in cases of death (26.1; 6.2 to 109.7) than among controls. This association persisted even after adjustment for increased incidence of a complicated obstetric history in cases of cerebral palsy. Neonatal encephalopathy is regarded as the best clinical indicator of birth asphyxia; only two thirds (23/33) of the children with cerebral palsy in whom there had been a suboptimal response to fetal distress, however, had evidence of neonatal encephalopathy; these 23 formed 6.8% of all children with cerebral palsy born to residents of the region in the four years studied.

CONCLUSION

There is an association between quality of intrapartum care and death. The findings also suggest an association between suboptimal care and cerebral palsy, but this seems to have a role in only a small proportion of all cases of cerebral palsy. The contribution of adverse antenatal factors in the origin of cerebral palsy needs further study.

Clinical associations of prenatal ischaemic white matter injury

Neuropathological examinations were carried out at necropsy on 274 cases of intrauterine death or neonatal death at or before three days after birth. Fifty six (20.4%) subjects had evidence of prenatal ischaemic brain damage. On review of the maternal case notes to ascertain antenatal clinical associations there was an increased incidence of intrauterine growth retardation, either based on birth weight for gestational age (odds ratio (OR) 2.0; 95% confidence interval (CI) 1.1 to 3.7) or diagnosed antenatally (OR 2.7; 95% CI 1.3 to 5.6). Oligohydramnios was also more common (OR 2.9; 95% CI 1.2 to 7.0). The association of intrauterine growth retardation and white matter damage remained after excluding fetuses with a major congenital anomaly (OR 2.4; 95% CI 1.1 to 5.1). The findings suggest that chronic intrauterine hypoxia may be associated with damage to cerebral white matter among fetuses and infants who die. The relation between ischaemic white matter damage and cerebral palsy among survivors remains speculative.

Acid-base status at birth and subsequent neurosensory impairment in surviving 500 to 1000 gm infants

OBJECTIVE

The purpose of this study was to assess, in infants born weighing < or = 1000 gm, if umbilical cord blood acid-base measures at birth are associated with an additional increase in neurosensory impairment.

STUDY DESIGN

Of 289 surviving infants with a birth weight of 500 to 1000 gm born from 1979 to 1989, 219 had umbilical cord acid-base status measured at birth and were followed prospectively for > or = 1 year. Measures of neurologic impairment used in this study included mental retardation, cerebral palsy, and major neurosensory impairment.

RESULTS

Gestational age was inversely associated with all neurosensory impairments and was a better predictor of subsequent impairment in this population than was birth weight. Very low umbilical cord pH values were also significantly related to adverse outcomes. There was also an inverse relationship between cord blood bicarbonate levels and major neurosensory impairment. The highly significant relationship between cord blood bicarbonate and pH values and the development of neurosensory impairments persisted in spite of adjustment for gestational age, birth weight, plurality, use of general anesthesia, maternal race, and presence of hypertension.

CONCLUSION

An adverse acid-base status at birth is additive to the effect of gestational age in predicting neurosensory impairment in infants weighing < or = 1000 gm.

Prevalence of cerebral palsy among ten-year-old children in metropolitan Atlanta, 1985 through 1987

The Metropolitan Atlanta Developmental Disabilities Study was a population-based study (1985 through 1987) to determine the prevalence of five developmental disabilities among 10-year-old children. The disabilities included cerebral palsy, mental retardation, visual impairment, hearing impairment, and epilepsy. The prevalence of cerebral palsy (CP) and a description of the children with CP are reported here. Using a record review approach, we identified 204 10-year-old children with CP (resulting in a prevalence of 2.3 per 1000). The rate of CP was significantly higher among boys (prevalence odds ratio = 1.5; 95% confidence interval = 1.1, 2.0), and the rate was also higher among black children than white children (prevalence odds ratio = 1.3; 95% confidence interval = 1.0, 1.7). Thirty-three of the children (16%) acquired CP postnatally; these children were more likely to be black or male. The gender and racial differences found for acquired CP were greater than those for congenital CP. Approximately 75% of the children had one of the other four disabilities studied; 65% of the children were mentally retarded, 46% had epilepsy, and 15% had a sensory impairment. Our multiple-source method of identifying children with CP gave us a population-based sample from which to determine the prevalence of the condition and to study factors that are associated with CP.