Different cohort, disparate results: Selection bias is a key factor in autopsy cohorts

INTRODUCTION

Research-oriented autopsy cohorts provide critical insights into dementia pathobiology. However, different studies sometimes report disparate findings, partially because each study has its own recruitment biases. We hypothesized that a straightforward metric, related to the percentage of research volunteers cognitively normal at recruitment, would predict other inter-cohort differences.

METHODS

The National Alzheimer's Coordinating Center (NACC) provided data on N = 7178 autopsied participants from 28 individual research centers. Research cohorts were grouped based on the proportion of participants with normal cognition at initial clinical visit.

RESULTS

Cohorts with more participants who were cognitively normal at recruitment contained more individuals who were older, female, had lower frequencies of apolipoprotein E ε4, Lewy body disease, and frontotemporal dementia, but higher rates of cerebrovascular disease. Alzheimer's disease (AD) pathology was little different between groups.

DISCUSSION

The percentage of participants recruited while cognitively normal predicted differences in findings in autopsy research cohorts. Most differences were in non-AD pathologies.

HIGHLIGHTS

Systematic differences exist between autopsy cohorts that serve dementia research. We propose a metric to use for gauging a research-oriented autopsy cohort. It is essential to consider the characteristics of autopsy cohorts.

Placental contribution to neonatal encephalopathy

Placental assessment, although currently underused, can inform our understanding of the etiology and timing of Neonatal Encephalopathy (NE). We review our current understanding of the links between placental dysfunction and NE and how this information may inform clinical decisions, now and in the future, emphasizing the four major placental lesions associated with NE. In addition, we discuss maternal and fetal factors that are hypothesized to contribute to specific placental pathologies, especially innate or acquired thrombophilias. We outline the importance of assessing placenta across trimesters and after delivery. As this field continues to evolve, currently available placental histopathological examination methods may need to be combined with advanced prenatal molecular and imaging assessments of placenta and be applied in well-designed studies in large representative populations to better define the links between placental dysfunction and NE.

Interobserver Reliability for Identifying Specific Patterns of Placental Injury as Defined by the Amsterdam Classification

CONTEXT.—

Placental pathology is an essential tool for understanding neonatal illness. The recent Amsterdam international consensus has standardized criteria and terminology, providing harmonized data for research and clinical care.

OBJECTIVE.—

To evaluate the interobserver reliability of these criteria between pathologists at different levels of experience using digitally scanned slides from placentas in a birth population including a large proportion of normal deliveries.

DESIGN.—

This was a secondary analysis of selected placentas from a large case-control study of placental lesions associated with neonatal encephalopathy. Histologic slides from 80 placentas were digitally scanned and blindly evaluated by 6 pathologists. Interobserver reliability was assessed by positive and negative agreement, Fleiss κ, and interrater correlation coefficients.

RESULTS.—

Overall agreement on the diagnosis, grading, and staging of acute chorioamnionitis and villitis of unknown etiology was moderate to good for all observers and good to excellent for a subset of 4 observers. Agreement on the diagnosis and subtyping of fetal vascular malperfusion was poor to fair for all observers and fair to moderate for the subset of 4 pathologists. Agreement on accelerated villous maturation was poor.

CONCLUSIONS.—

This study critically evaluates interobserver reliability for lesions defined by the Amsterdam consensus using scanned images with a low frequency of pathologic lesions. Although reliability was good to excellent for inflammatory lesions, lower reliability for vascular lesions emphasizes the need to more explicitly define the specific histologic features and boundaries for these patterns.

Brain arteriolosclerosis

Brain arteriolosclerosis (B-ASC), characterized by pathologic arteriolar wall thickening, is a common finding at autopsy in aged persons and is associated with cognitive impairment. Hypertension and diabetes are widely recognized as risk factors for B-ASC. Recent research indicates other and more complex risk factors and pathogenetic mechanisms. Here, we describe aspects of the unique architecture of brain arterioles, histomorphologic features of B-ASC, relevant neuroimaging findings, epidemiology and association with aging, established genetic risk factors, and the co-occurrence of B-ASC with other neuropathologic conditions such as Alzheimer's disease and limbic-predominant age-related TDP-43 encephalopathy (LATE). There may also be complex physiologic interactions between metabolic syndrome (e.g., hypertension and inflammation) and brain arteriolar pathology. Although there is no universally applied diagnostic methodology, several classification schemes and neuroimaging techniques are used to diagnose and categorize cerebral small vessel disease pathologies that include B-ASC, microinfarcts, microbleeds, lacunar infarcts, and cerebral amyloid angiopathy (CAA). In clinical-pathologic studies that factored in comorbid diseases, B-ASC was independently associated with impairments of global cognition, episodic memory, working memory, and perceptual speed, and has been linked to autonomic dysfunction and motor symptoms including parkinsonism. We conclude by discussing critical knowledge gaps related to B-ASC and suggest that there are probably subcategories of B-ASC that differ in pathogenesis. Observed in over 80% of autopsied individuals beyond 80 years of age, B-ASC is a complex and under-studied contributor to neurologic disability.

The epidemiology of FIRS in term and late preterm births

The definition of FIRS requires systemic inflammation and elevated levels of IL-6 in fetal plasma. That definition does not specify how systemic inflammation is to be recognized, and perinatal measurement of IL-6 is not a standard procedure. FIRS has not been examined in a population-based study that included post-neonatal outcome so its incidence and natural history are not known. The overlap, and similarities and differences, of FIRS as compared with other causes of neonatal encephalopathy, and how these relate to findings in the placenta, have not been jointly examined in a generalizable sample. FIRS has chiefly been discussed in the obstetric literature because of the need for decisions about management of delivery and antibiotic use. If the term "FIRS" is to be employed in other contexts, consensus should be sought as to which clinical, placental, and laboratory findings are most appropriate for identification of perinatal inflammatory processes, infectious or sterile.

The Placenta in Neonatal Encephalopathy: A Case-Control Study

OBJECTIVE

We assessed whether specific histologic placental lesions were associated with risk for neonatal encephalopathy, a strong predictor of death or cerebral palsy.

STUDY DESIGN

Case-control study of singletons with gestational ages ≥35 weeks. Data were abstracted from a prospectively collected database of consecutive births at a hospital in which placental samples from specified sites are collected and stored for all inborn infants. Placentas of infants with neonatal encephalopathy were compared with randomly selected control infants (ratio of 1:3). Placental histologic slides were read by a single experienced perinatal pathologist unaware of case status, using internationally recommended definitions and terminology. Findings were grouped into inflammatory, maternal, or fetal vascular malperfusion (FVM) and other lesions.

RESULTS

Placental samples were available for 73 of 87 (84%) cases and 253 of 261 (97%) controls. Delivery complications and gross placental abnormalities were more common in cases, of whom 4 died. Inflammation and maternal vascular malperfusion did not differ, and findings consistent with global FVM were more frequent in case (20%) than control (7%) placentas (P = .001). There was a trend toward more segmental FVM and high-grade FVM (fetal thrombotic vasculopathy) among cases. Some type of FVM was observed in 24% of placentas with neonatal encephalopathy. In infants with both neonatal encephalopathy and placental FVM, more often than in infants with neonatal encephalopathy without FVM, electronic fetal monitoring tracings were considered possibly or definitely abnormal (P = .028).

CONCLUSIONS

Vascular malperfusion of subacute or chronic origin on the fetal side of the placenta was associated with increased risk of neonatal encephalopathy.

Electronic fetal monitoring, cerebral palsy, and caesarean section: assumptions versus evidence

Given evidence that cerebral palsy is not reduced by electronic fetal monitoring, Karin Nelson, Thomas Sartwelle, and Dwight Rouse ask why routine monitoring and related litigation continue to contribute to high rates of caesarean births

Does aetiology of neonatal encephalopathy and hypoxic-ischaemic encephalopathy influence the outcome of treatment?

Neonatal encephalopathy, a clinical syndrome affecting term-born and late preterm newborn infants, increases the risk of perinatal death and long-term neurological morbidity, especially cerebral palsy. With the advent of therapeutic hypothermia, a treatment designed for hypoxic or ischaemic injury, associated mortality and morbidity rates have decreased. Unfortunately, only about one in eight neonates (95% confidence interval) who meet eligibility criteria for therapeutic cooling apparently benefit from the treatment. Studies of infants in representative populations indicate that neonatal encephalopathy is a potential result of a variety of antecedents and that asphyxial complications at birth account for only a small percentage of neonatal encephalopathy. In contrast, clinical case series suggest that a large proportion of neonatal encephalopathy is hypoxic or ischaemic, and trials of therapeutic hypothermia are specifically designed to include only infants exposed to hypoxia or ischaemia. This review addresses the differences, definitional and methodological, between infants studied and investigations undertaken, in population studies compared with cooling trials. It raises the question if there may be subgroups of infants with a clinical diagnosis of hypoxic-ischaemic encephalopathy (HIE) in whom the pathobiology of neonatal neurological depression is not fundamentally hypoxic or ischaemic and, therefore, for whom cooling may not be beneficial. In addition, it suggests approaches to future trials of cooling plus adjuvant therapy that may contribute to further improvement of care for these vulnerable neonates.

Fetal growth restriction and risk of cerebral palsy in singletons born after at least 35 weeks' gestation

OBJECTIVE

The objective of the study was to improve the understanding of etiological paths to cerebral palsy (CP) that include fetal growth restriction by examining factors associated with growth restriction that modify CP risk.

STUDY DESIGN

In a total population of singletons born at or after 35 weeks, there were 493 children with CP and 508 matched controls for whom appropriateness of fetal growth could be estimated. Fetal growth was considered markedly restricted if birthweight was more than 2 SD below optimal for gender, gestation, maternal height, and parity. We examined maternal blood pressure in pregnancy, smoking, birth asphyxia, and major birth defects recognized by age 6 years as potential modifiers of CP risk in growth-restricted births.

RESULTS

More than 80% of term and late preterm markedly growth-restricted singletons were born following a normotensive pregnancy and were at statistically significantly increased risk of CP (odds ratio, 4.81; 95% confidence interval, 2.7-8.5), whereas growth-restricted births following a hypertensive pregnancy were not. Neither a clinical diagnosis of birth asphyxia nor potentially asphyxiating birth events occurred more frequently among growth-restricted than among appropriately grown infants with CP. Major birth defects, particularly cerebral defects, occurred in an increasing proportion of CP with increasing growth deficit. The factor most predictive of CP in growth-restricted singletons was a major birth defect, present in 53% of markedly growth-restricted neonates with later CP. Defects observed in CP were similar whether growth restricted or not, except for an excess of isolated congenital microcephaly in those born growth restricted. The highest observed CP risk was in infants with both growth restriction and a major birth defect (8.9% of total CP in this gestational age group, 0.4% of controls: odds ratio, 30.9; 95% confidence interval, 7.0-136).

CONCLUSION

The risk of CP was increased in antenatally growth-restricted singletons born at or near term to normotensive mothers. In growth-restricted singletons, a major birth defect was the dominant predictor, associated with a 30-fold increase in odds of CP. Identification of birth defects in the growth-restricted fetus or neonate may provide significant prognostic information.

Seizures, encephalopathy, and vaccines: experience in the National Vaccine Injury Compensation Program

OBJECTIVES

To describe the demographic and clinical characteristics of children for whom claims were filed with the National Vaccine Injury Compensation Program (VICP) alleging seizure disorder and/or encephalopathy as a vaccine injury.

STUDY DESIGN

The National VICP within the Department of Health and Human Services compensates individuals who develop medical problems associated with a covered immunization. We retrospectively reviewed medical records of children younger than 2 years of age with seizures and/or encephalopathy allegedly caused by an immunization, where a claim was filed in the VICP between 1995 through 2005.

RESULTS

The VICP retrieved 165 claims that had sufficient clinical information for review. Approximately 80% of these alleged an injury associated with whole-cell diphtheria, pertussis (whooping cough), and tetanus or tetanus, diphtheria toxoids, and acellular pertussis vaccine. Pre-existing seizures were found in 13% and abnormal findings on a neurologic examination before the alleged vaccine injury in 10%. A final diagnostic impression of seizure disorder was established in 69%, of whom 17% (28 patients) had myoclonic epilepsy, including possible severe myoclonic epilepsy of infancy. Specific conditions not caused by immunization, such as tuberous sclerosis and cerebral dysgenesis, were identified in 16% of subjects.

CONCLUSION

A significant number of children with alleged vaccine injury had pre-existing neurologic or neurodevelopmental abnormalities. Among those developing chronic epilepsy, many had clinical features suggesting genetically determined epilepsy. Future studies that include genotyping may allow more specific therapy and prognostication, and enhance public confidence in vaccination.

Neuroimaging in the evaluation of neonatal encephalopathy

BACKGROUND AND OBJECTIVE

Computed tomography (CT) is still used for neuroimaging of infants with known or suspected neurologic disorders. Alternative neuroimaging options that do not expose the immature brain to radiation include MRI and cranial ultrasound. We aim to characterize and compare the use and findings of neuroimaging modalities, especially CT, in infants with neonatal encephalopathy.

METHODS

The Vermont Oxford Network Neonatal Encephalopathy Registry enrolled 4171 infants (≥36 weeks' gestation or treated with therapeutic hypothermia) between 2006 and 2010 who were diagnosed with encephalopathy in the first 3 days of life. Demographic, perinatal, and medical conditions were recorded, along with treatments, comorbidities, and outcomes. The modality, timing, and results of neuroimaging were also collected.

RESULTS

CT scans were performed on 933 of 4107 (22.7%) infants, and 100 of 921 (10.9%) of those received multiple CT scans. Compared with MRI, CT provided less detailed evaluation of cerebral injury in areas of prognostic significance, but was more sensitive than cranial ultrasound for hemorrhage and deep brain structural abnormalities.

CONCLUSIONS

CT is commonly used for neuroimaging in newborn infants with neonatal encephalopathy despite concerns over potential harm from radiation exposure. The diagnostic performance of CT is inferior to MRI in identifying neonatal brain injury. Our data suggest that using cranial ultrasound for screening, followed by MRI would be more appropriate than CT at any stage to evaluate infants with neonatal encephalopathy.

The association of cerebral palsy with birth asphyxia: a definitional quagmire

AIM

The aim of this study was to investigate whether current literature provides a useful body of evidence reflecting the proportion of cerebral palsy (CP) that is attributable to birth asphyxia.

METHOD

We identified 23 studies conducted between 1986 and 2010 that provided data on intrapartum risks of CP.

RESULTS

The proportion of CP with birth asphyxia as a precursor (case exposure rate) varied from less than 3% to over 50% in the 23 studies reviewed. The studies were heterogeneous in many regards, including the definitions for birth asphyxia and the outcome of CP.

INTERPRETATIONS

Current data do not support the belief, widely held in the medical and legal communities, that birth asphyxia can be recognized reliably and specifically, or that much of CP is due to birth asphyxia. The very high case exposure rates linking birth asphyxia to CP can probably be attributed to several factors: the fact that the clinical picture at birth cannot specifically identify birth asphyxia; the definition of CP employed; and confusion of proximal effects - results - with causes. Further research is needed.

Antecedents of neonatal encephalopathy in the Vermont Oxford Network Encephalopathy Registry

BACKGROUND

Neonatal encephalopathy (NE) is a major predictor of death and long-term neurologic disability, but there are few studies of antecedents of NE.

OBJECTIVES

To identify antecedents in a large registry of infants who had NE.

METHODS

This was a maternal and infant record review of 4165 singleton neonates, gestational age of ≥ 36 weeks, meeting criteria for inclusion in the Vermont Oxford Network Neonatal Encephalopathy Registry.

RESULTS

Clinically recognized seizures were the most prevalent condition (60%); 49% had a 5-minute Apgar score of ≤ 3 and 18% had a reduced level of consciousness. An abnormal maternal or fetal condition predated labor in 46%; maternal hypertension (16%) or small for gestational age (16%) were the most frequent risk factors. In 8%, birth defects were identified. The most prevalent birth complication was elevated maternal temperature in labor of ≥ 37.5 °C in 27% of mothers with documented temperatures compared with 2% to 3.2% in controls in population-based studies. Clinical chorioamnionitis, prolonged membrane rupture, and maternal hypothyroidism exceeded rates in published controls. Acute asphyxial indicators were reported in 15% (in 35% if fetal bradycardia included) and inflammatory indicators in 24%. Almost one-half had neither asphyxial nor inflammatory indicators. Although most infants with NE were observably ill since the first minutes of life, only 54% of placentas were submitted for examination.

CONCLUSIONS

Clinically recognized asphyxial birth events, indicators of intrauterine exposure to inflammation, fetal growth restriction, and birth defects were each observed in term infants with NE, but much of NE in this large registry remained unexplained.

Biomarkers of brain injury in neonatal encephalopathy treated with hypothermia

OBJECTIVE

To determine if early serum S100B and neuron-specific enolase (NSE) levels are associated with neuroradiographic and clinical evidence of brain injury in newborns with encephalopathy.

STUDY DESIGN

Patients who received therapeutic whole-body hypothermia were prospectively enrolled in this observational study. Serum specimens were collected at 0, 12, 24, and 72 hours of cooling. S100B and NSE levels were measured by enzyme linked immunosorbent assay. Magnetic resonance imaging was performed in surviving infants at 7-10 days of life. Standardized neurologic examination was performed by a child neurologist at 14 days of life. Multiple linear regression analyses were performed to evaluate the association between S100B and NSE levels and unfavorable outcome (death or severe magnetic resonance imaging injury/significant neurologic deficit). Cutoff values were determined by receiver operating curve analysis.

RESULTS

Newborns with moderate to severe encephalopathy were enrolled (n = 75). Median pH at presentation was 6.9 (range, 6.5-7.35), and median Apgar scores of 1 at 1 minute, 3 at 5 minutes, and 5 at 10 minutes. NSE and S100B levels were higher in patients with unfavorable outcomes across all time points. These results remained statistically significant after controlling for covariables, including encephalopathy grade at presentation, Apgar score at 5 minutes of life, initial pH, and clinical seizures.

CONCLUSION

Elevated serum S100B and NSE levels measured during hypothermia were associated with neuroradiographic and clinical evidence of brain injury in encephalopathic newborns. These brain-specific proteins may be useful immediate biomarkers of cerebral injury severity.

The Vermont Oxford Neonatal Encephalopathy Registry: rationale, methods, and initial results

Background

In 2006, the Vermont Oxford Network (VON) established the Neonatal Encephalopathy Registry (NER) to characterize infants born with neonatal encephalopathy, describe evaluations and medical treatments, monitor hypothermic therapy (HT) dissemination, define clinical research questions, and identify opportunities for improved care.

Methods

Eligible infants were ≥ 36 weeks with seizures, altered consciousness (stupor, coma) during the first 72 hours of life, a 5 minute Apgar score of ≤ 3, or receiving HT. Infants with central nervous system birth defects were excluded.

Results

From 2006–2010, 95 centers registered 4232 infants. Of those, 59% suffered a seizure, 50% had a 5 minute Apgar score of ≤ 3, 38% received HT, and 18% had stupor/coma documented on neurologic exam. Some infants experienced more than one eligibility criterion. Only 53% had a cord gas obtained and only 63% had a blood gas obtained within 24 hours of birth, important components for determining HT eligibility. Sixty-four percent received ventilator support, 65% received anticonvulsants, 66% had a head MRI, 23% had a cranial CT, 67% had a full channel encephalogram (EEG) and 33% amplitude integrated EEG. Of all infants, 87% survived.

Conclusions

The VON NER describes the heterogeneous population of infants with NE, the subset that received HT, their patterns of care, and outcomes. The optimal routine care of infants with neonatal encephalopathy is unknown. The registry method is well suited to identify opportunities for improvement in the care of infants affected by NE and study interventions such as HT as they are implemented in clinical practice.

Neurologic complaints in young children in the ED: when is cranial computed tomography helpful?

MAIN OBJECTIVE

The objective of this study is to describe the use of emergent head computed tomography (CT) in young children and ask in which circumstances scans contributed to immediate management.

METHODS

We reviewed electronic records of children, aged 1 month through 6 years, who received a head CT at a large suburban emergency department between February 2008 and February 2009. Age, sex, chief complaint, history, physical examination, indication for and results of head CT, red flags in history or physical examination, final disposition, and number of head CT scans performed to date were recorded. Abnormalities on CT scans were classified as significant or incidental, and subsequent interventions were documented.

RESULTS

Emergent head CTs were performed on 394 children. The most common indications were trauma, 65%; seizure, 11%; and headache, 6%. Computed tomographic abnormalities were found in 40% (154 children): 32 significant findings,104 incidental findings, and 22 preexisting abnormalities. Four children with significant findings required immediate intervention. They all had red flags in both history and physical examination, and 3 of 4 children had known preexisting pathology; 1 child had nonaccidental trauma. Only 1 child had a significantly abnormal CT with no identifiable red flags; this child was admitted for observation and was discharged within 24 hours. Approximately a third of children had no readily identifiable red flag for the CT scans that they received. Of note, 20% of the young children had received more than 1 head CT scan to date, and 6% had between 6 and 20 scans.

CONCLUSIONS

Every child in this sample who required emergency intervention had red flags on history and physical examination. The 35% of CT scans performed in young children without red flags did not contribute usefully to their acute management.

Parent-child agreement in the reporting of headaches in a national sample of adolescents

The aim of this article is to assess the concordance between parent and adolescent headache ratings in a representative sample of 6483 US adolescents (aged 13-18 years). Headaches were assessed using modified criteria from the International Headache Society's International Classification of Headache Disorders, Second Edition. Caregiver report was based on a self-administered questionnaire. Overall concordance between caregivers and adolescents on the presence or absence of headaches was quite low (κ = 0.39). Female caregivers were twice as likely as male caregivers to report headaches in their offspring. Positive endorsement of headaches in offspring by caregivers was associated with adolescent-reported chronic headaches, longer headache duration, and photophobia or phonophobia. These findings suggest that relying solely on parent report may result in an underestimate of the true prevalence of headaches in the general population. In addition, collecting information from both parents and adolescents could be critical to effective treatment and prevention of the severe consequences of migraine.

Neonatally measured immunoglobulins and risk of autism

Previous studies indicate that prenatal exposure to infections is a possible pathway through which autism spectrum disorders (ASD) could be initiated. We investigated whether immunoglobulin levels in archived specimens obtained from newborns subsequently diagnosed with ASD are different from levels in newborn specimens from controls. Children with ASD born in six California counties in 1994 were ascertained through records of the California Department of Developmental Services (DDS) and Kaiser Permanente; controls were randomly selected using birth certificates. Archived newborn blood specimens were obtained from the California Genetic Disease Screening Program (GDSP) for N = 213 cases and N = 265 controls and assayed to determine levels of total IgG, antigen-specific IgG to selected common pathogens, total IgM, total IgA, and C-reactive protein (CRP). We did not find measurable levels of total IgM or IgA in any neonate and measurable CRP was present in only a few. No antigen-specific IgG antibodies were elevated in cases compared to controls and total IgG levels were lower. In adjusted models, a 10-unit increase in total IgG yielded an OR = 0.72 (95% CI 0.56, 0.91); a significantly decreasing trend in risk of ASD was observed across increasing exposure quartiles of total IgG (P = 0.01). The finding of lower IgG in cases may indicate maternal immune dysfunction during gestation and/or impaired transplacental transfer of immunoglobulins. Further investigation of IgG levels in newborns and the mechanisms by which they might be associated with ASD are warranted.

Headache and biomarkers predictive of vascular disease in a representative sample of US children

OBJECTIVE

To examine the association of childhood headache disorders with markers of risk for cardiovascular and cerebrovascular disease.

DESIGN

Information was collected on severe or recurrent headache or migraine in childhood or adolescence and on biomarkers predictive of vascular disease.

SETTING

The National Health and Nutrition Survey, a nationally representative health survey.

PARTICIPANTS

Children or adolescents aged 4 to 19 years (n = 11 770) who took part in the National Health and Nutrition Survey in 1999 through 2004.

MAIN EXPOSURE

Headache.

MAIN OUTCOME MEASURES

Body mass index; levels of C-reactive protein, homocysteine, serum and red blood cell folate, vitamin B(12), methylmalonic acid, total cholesterol, high-density lipoprotein cholesterol, non-high-density lipoprotein cholesterol, triglycerides, and uric acid; and platelet count.

RESULTS

Mean values for body mass index, C-reactive protein, and homocysteine were higher in children with than without headaches, and more children with headaches were in the highest quintile of risk for these factors. Serum and red blood cell folate levels were lower in children with headache. More children with headache were in the highest quintile of risk for 3 or more of these factors.

CONCLUSIONS

Several important risk factors for long-term vascular morbidity cluster in children and adolescents with severe or recurrent headache or migraine. Further study and screening of children with headaches may permit improved preventive management.

Headache in young children in the emergency department: use of computed tomography

OBJECTIVE

The goal was to determine whether computed tomographic (CT) scans led to better acute care of young children with headache presenting the emergency department (ED).

METHODS

We examined the records of 364 children 2 to 5 years of age who presented with headache to a large urban ED between July 1, 2003, and June 30, 2006. By reviewing initial history and examination findings, we first identified patients with secondary headaches (ie, with readily identifiable explanations such as ventriculoperitoneal shunts, known brain tumors, or acute illnesses, such as viral syndromes, fever, probable meningitis, or trauma). Charts for the remaining patients were reviewed for headache history, neurologic examination findings, laboratory and neuroimaging results, final diagnosis, and disposition.

RESULTS

On the basis of initial history and physical examination results, 306 children (84%) had secondary headaches. For 72% of those children, acute febrile illnesses and viral respiratory syndromes accounted for the headaches. Among the 58 children (16%) who had no recognized central nervous system disease or systemic illness at presentation, 28% had CT scans performed. Of those, 1 scan yielded abnormal results, showing a brainstem glioma; the patient demonstrated abnormal neurologic examination findings on the day of presentation. For 15 (94%) of 16 patients, the CT scans did not contribute to diagnosis or management. For 59% of children with apparently primary headaches, no family history was recorded.

CONCLUSION

For young children presenting to the ED with headache but normal neurologic examination findings and nonworrying history, CT scans seldom lead to diagnosis or contribute to immediate management.

Headache in a national sample of American children: prevalence and comorbidity

The purpose of this study was to determine the prevalence, sociodemographic correlates, and comorbidity of recurrent headache in children in the United States. Participants were individuals aged 4 to 18 years (n = 10,198) who participated in the National Health and Nutrition Examination Surveys. Data on recurrent and other health conditions were analyzed. Frequent or severe headaches including migraine in the past 12 months were reported in 17.1% of children. Asthma, hay fever, and frequent ear infections were more common in children with headache, with at least 1 of these occurring in 41.6% of children with headache versus 25.0% of children free of headache. Other medical problems associated with childhood headaches include anemia, overweight, abdominal illnesses, and early menarche. Recurrent headache in childhood is common and has significant medical comorbidity. Further research is needed to understand biologic mechanisms and identify more homogeneous subgroups in clinical and genetic studies.

Unintended changes in cognition, mood, and behavior arising from cell-based interventions for neurological conditions: ethical challenges

The prospect of using cell-based interventions (CBIs) to treat neurological conditions raises several important ethical and policy questions. In this target article, we focus on issues related to the unique constellation of traits that characterize CBIs targeted at the central nervous system. In particular, there is at least a theoretical prospect that these cells will alter the recipients' cognition, mood, and behavior-brain functions that are central to our concept of the self. The potential for such changes, although perhaps remote, is cause for concern and careful ethical analysis. Both to enable better informed consent in the future and as an end in itself, we argue that early human trials of CBIs for neurological conditions must monitor subjects for changes in cognition, mood, and behavior; further, we recommend concrete steps for that monitoring. Such steps will help better characterize the potential risks and benefits of CBIs as they are tested and potentially used for treatment.

Candidate genes and cerebral palsy: a population-based study

OBJECTIVE

The objective of this study was to examine whether selected genetic polymorphisms in the infant are associated with later-diagnosed cerebral palsy.

METHODS

A population-based case-control study was conducted of 28 single-nucleotide polymorphisms measured in newborn screening blood spots. A total of 413 children with later-diagnosed cerebral palsy were born to white women in South Australia in 1986-1999, and there were 856 control children. Distributions of genotypic frequencies were examined in total cerebral palsy, in gestational age groups, and by types of cerebral palsy and gender. Genotyping was performed by using a TaqMan assay.

RESULTS

For inducible nitric-oxide synthase, possession of the T allele was more common in all children with cerebral palsy and for heterozygotes who were born at term. For lymphotoxin alpha, homozygous variant status was associated with risk for cerebral palsy and with spastic hemiplegic or quadriplegic cerebral palsy. Among term infants, heterozygosity for the endothelial protein C receptor single-nucleotide polymorphism was more frequent in children with cerebral palsy. In preterm infants, the variant A allele of interleukin 8 and heterozygosity for the beta-2 adrenergic receptor were associated with cerebral palsy risk. Interleukin 8 heterozygote status was associated with spastic diplegia. Variants of several genes were associated with cerebral palsy in girls but not in boys.

CONCLUSIONS

Two of the 28 single-nucleotide polymorphisms examined were associated with all types of spastic cerebral palsy in both gestational age groups and others with cerebral palsy in gestational age or cerebral palsy subgroups. Some of these associations support previous findings. There may be a genetic contribution to cerebral palsy risk, and additional investigation is warranted of genes and gene-environment interactions in cerebral palsy.

Diagnostic value of lumbar puncture in afebrile infants with suspected new-onset seizures

No established guidelines address the need for lumbar puncture in fever-free infants younger than 6 months of age with a first seizure. We analyzed cerebrospinal fluid results in infants and found that lumbar puncture adds little diagnostic value to the evaluation of young, well-appearing infants presenting with possible new-onset seizures.

Cell-based interventions for neurologic conditions: ethical challenges for early human trials

BACKGROUND

Attempts to translate basic stem cell research into treatments for neurologic diseases and injury are well under way. With a clinical trial for one such treatment approved and in progress in the United States, and additional proposals under review, we must begin to address the ethical issues raised by such early forays into human clinical trials for cell-based interventions for neurologic conditions.

METHODS

An interdisciplinary working group composed of experts in neuroscience, cell biology, bioethics, law, and transplantation, along with leading disease researchers, was convened twice over 2 years to identify and deliberate on the scientific and ethical issues raised by the transition from preclinical to clinical research of cell-based interventions for neurologic conditions.

RESULTS

While the relevant ethical issues are in many respects standard challenges of human subjects research, they are heightened in complexity by the novelty of the science, the focus on the CNS, and the political climate in which the science is proceeding.

CONCLUSIONS

Distinctive challenges confronting US scientists, administrators, institutional review boards, stem cell research oversight committees, and others who will need to make decisions about work involving stem cells and their derivatives and evaluate the ethics of early human trials include evaluating the risks, safety, and benefits of these trials, determining and evaluating cell line provenance, and determining inclusion criteria, informed consent, and the ethics of conducting early human trials in the public spotlight. Further study and deliberation by stakeholders is required to move toward professional and institutional policies and practices governing this research.

Ischemic perinatal stroke: summary of a workshop sponsored by the National Institute of Child Health and Human Development and the National Institute of Neurological Disorders and Stroke

Ischemic perinatal stroke is a disorder associated with significant long-term neurologic morbidity. With an estimated incidence of 1 in 2300 to 5000 births, stroke is more likely to occur in the perinatal period than at any time in childhood. The incidence of ischemic perinatal stroke ranks second only to that of strokes in the elderly population. Although ischemic perinatal stroke is a well-recognized disorder, many aspects remain to be studied. There is no consensus on its terminology, definition, or classification. Several risk factors have been identified, but their precise roles in causing stroke are not well understood. There are no reliable predictors of ischemic perinatal stroke on which to base prevention or treatment strategies. To review these important issues and propose a research agenda, the National Institute of Child Health and Human Development and the National Institute of Neurological Disorders and Stroke convened a workshop in August 2006. This article provides a summary of the workshop.

In utero exposure to antiepileptic drugs: teratogenicity and neonatal morbidity

Clinical studies have extensively documented the various risks posed by in utero exposure to antiepileptic drugs (AEDs). However, it is difficult to sort out the extent to which any given AED is responsible for a particular outcome, given the disparities in patients taking the drugs, their type and severity of epilepsy, and the various possible AEDs, as well as the vast number of outcomes that could be assessed. This review focuses on AED exposure during pregnancy and how it affects the risks of neonatal morbidity and major congenital malformations.

Perinatal ischemic stroke

Perinatal ischemic stroke is not rare in term and near-term infants and is an important antecedent of long-term neurological disability, including congenital hemiplegia (hemiplegic cerebral palsy) and seizure and cognitive disorders. Changes in maternal hemostasis occur in pregnancy and are amplified in the period immediately surrounding birth; stroke and other thromboembolic events are more frequent in both mother and infant in this period. The vasculature and hemostatic mechanisms of placenta as well as brain are likely to be important in the pathobiology of perinatal stroke. Maternal and infant thrombophilias, genetic and acquired, play a role. Rarely is >1 child in a sibship affected, and environmental factors-substantially less studied, to date--are likely to be key determinants of risk.

Genetic polymorphisms and spontaneous preterm birth

OBJECTIVE

To examine whether selected genetic polymorphisms in the infant are associated with spontaneous preterm birth (less than 37 weeks) among children with or without later-diagnosed cerebral palsy.

METHODS

Exploratory case-control study investigating the relationship of gestational age at delivery to 31 single nucleotide polymorphisms measured in newborn screening bloodspots. Among all 443 children with later-diagnosed cerebral palsy born to white women in South Australia in 1986-1999, 234 were born after spontaneous onset of labor, and 108 of these were preterm (gestational age less than 37 weeks). The comparison group was 549 infants born after spontaneous onset of labor, of whom 147 were preterm. Distributions of genotypic frequencies were examined in preterm compared with term infants with and without cerebral palsy. Genotyping was performed using a Taqman assay.

RESULTS

In children without cerebral palsy, preterm birth after spontaneous onset of labor was more frequent in association with a variant of the beta2 adrenergic receptor gene (ADRB2 Q27E, P=.003), inducible nitric oxide synthase (iNOS or NOS2A, P=.042), or thrombomodulin (G127A, P=.006). Among children with cerebral palsy, preterm birth was associated with polymorphisms in genes for endothelial nitric oxide synthase (eNOS -922, P=.012), plasminogen activator inhibitor-2 (P=.015 and .019), and alpha adducin (ADD1, P=.047).

CONCLUSION

We confirm previous observations that variants of the beta adrenergic receptor and of nitric oxide synthase are associated with prematurity, and suggest that genetic variants of the placental antifibrinolytic plasminogen activator inhibitor-2, and thrombomodulin and alpha adducin may be contributors to risk of spontaneous preterm birth.

LEVEL OF EVIDENCE

II.

Thrombophilias, Perinatal Stroke, and Cerebral Palsy

Perinatal ischemic stroke has become recognized as a not-rare adverse outcome of pregnancy and a common cause of chronic neurologic disability in children. This review discusses the clinical entity, perinatal stroke, and its relationship to thrombophilias, inherited and acquired, and to maternal and pregnancy factors.

Selected neurotrophins, neuropeptides, and cytokines: developmental trajectory and concentrations in neonatal blood of children with autism or Down syndrome

Using a double-antibody immunoaffinity assay (Luminex) and ELISA technology, we measured concentrations of certain neurotrophins, neuropeptides, and cytokines in pooled samples (one to three subjects per sample) eluted from archived neonatal blood of children with later-diagnosed autism, Down syndrome, very preterm birth, or term control infants. We also measured analytes in blood from healthy adult controls. Case or control status for infant subjects was ascertained by retrospective review of service agency medical records. We observed inhibitory substances in eluates from archived bloodspots, especially marked for measurement of BDNF. Concentrations in control subjects differed by age: BDNF rose markedly with age, while NT-3 and NT-4/5 concentrations were lower in adults than in newborn infants. IL-8 concentrations were higher in newborn infants, preterm and term, than in adults. Considered by diagnostic group, total protein was higher in Down syndrome than in either autism or control subjects. In infants with Down syndrome, concentrations of IL-8 levels were higher than in controls, whether or not corrected for total protein; NT-3 and CGRP were lower and VIP higher. In samples from autistic subjects, NT-3 levels were significantly lower than controls and an increase in VIP approached statistical significance. Concentrations of NT-4/5 and CGRP were correlated in infants with autism but not in Down syndrome or controls. Some of these results differ from earlier findings using a single-antibody recycling immunoaffinity chromatography (RIC) system. We discuss interrelationships of VIP, NT-3 and IL-8 and their potential relevance to features of the neuropathology of autism or Down syndrome.

Expert medical testimony: Responsibilities of medical societies

Expert witnesses for plaintiff and defense should be able to provide evidence-based literature to support their testimony in depositions and in the courtroom. Specialty societies, such as the American Academy of Neurology, should be willing to review complaints about unsubstantiated testimony and, at times, publicly discipline offending experts.

Prothrombotic factors in children with stroke or porencephaly

OBJECTIVE

This study compared the frequencies of genetic and functional coagulation abnormalities in children with arterial ischemic stroke or porencephaly with frequencies in previously published studies.

METHODS

A series of 59 children (age 0-18 years) with arterial ischemic stroke or porencephaly were referred to the National Institutes of Health. A blood sample, buccal smear sample, questionnaire, and pedigree were requested for each child. Blood samples were analyzed for protein C (PC); protein S; antithrombin (AT); activated PC resistance (APCR); lipoprotein (a) [Lp(a)]; lupus anticoagulant; anticardiolipin antibodies; and the methylenetetrahydrofolate reductase C677T (MTHFR), factor V G1619A, factor II G20210A (PT), plasminogen activator inhibitor-1 4G6755G, and tissue factor pathway inhibitor C536T mutations. The frequency of each coagulation abnormality was compared with published international pediatric stroke case and control rates.

RESULTS

At least 1 prothrombotic abnormality was identified in 63% (36 of 57) of children studied, including plasminogen activator inhibitor-1 4G6755G (15 of 56), MTHFR (12 of 56), elevated Lp(a) (12 of 59), APCR (11 of 58), factor V G1619A (5 of 57), PT (3 of 57), PC deficiency (1 of 59), and AT deficiency (1 of 59). The MTHFR mutation, elevated Lp(a), the PT mutation, and AT deficiency rates were similar to rates in cases and more common than control subjects in previously published studies. The rate of children with APCR or multiple abnormalities was higher than in previous pediatric stroke studies. A family history of early thrombosis was identified in one third of the children with a prothrombotic abnormality.

CONCLUSIONS

Two thirds of children in this study had at least 1 of the prothrombotic risk factors tested, and several children had multiple risk factors. These results provide additional evidence that prothrombotic abnormalities are common among children with AIS or porencephaly.

Genetic polymorphisms and cerebral palsy in very preterm infants

In the present study, we examine whether selected genetic polymorphisms contribute to the development of cerebral palsy (CP) in very preterm infants. Subjects were 96 singleton infants with later-diagnosed CP and 119 control children, white non-Hispanic (n for CP=74, controls=88) or white Hispanic (CP=22, controls=31), born <32 wk gestation. Presence of CP was identified through state service agencies, with review of medical records. DNA extracted from archived neonatal blood was genotyped using multi-locus polymerase chain reaction amplification and immobilized sequence-specific oligonucleotide probes. Single nucleotide polymorphisms (SNPs) showing evidence of association with development of CP were endothelial nitric oxide synthase (eNOS) A(-922)G, factor 7 (F7) arg353gln and del(-323)10bp-ins, and lymphotoxin A (LTA) thr26asn. In white non-Hispanic children, beta-2 adrenergic receptor gln27glu was associated with CP risk; in Hispanic children, plasminogen activator inhibitor-1 (PAI-1) 4G(-675)5G and G11053T were associated with risk of CP. In a logistic regression considering these SNPs simultaneously in non-Hispanics, an association with CP was observed for heterozygotes of eNOS -922 (OR 3.0, CI 1.4-6.4), F7 (OR 2.7, CI 1.1-6.5), LTA (OR 2.1, CI 1.0-4.6), and PAI-1 (OR 3.2, CI 1.2-8.7). Factor 5, Factor 2, methylene tetrahydrofolate reductase, tumor necrosis factor-alpha, and other SNPs tested were not significantly associated with CP risk. We conclude that further study of genetic factors that may influence susceptibility to CP in very preterm infants is warranted.

Perinatal Arterial Stroke: Understanding Mechanisms and Outcomes

Arterial ischemic infarction occurring around the time of birth is an increasingly recognized cause of neurological disability in children. The rate of arterial infarction in neonates is as high as the annual incidence of large-vessel ischemic stroke in adults. Factors contributing to this increased risk of stroke among neonates include complications that occur before, during, and after delivery. Maternal conditions that have been associated with perinatal stroke in the fetus include prothrombotic disorders, cocaine abuse, and placental complications such as chorioamnionitis and placental vasculopathy. In many cases, the placenta is suspected to be the underlying embolic source for perinatal stroke, although data on placental pathology is often lacking. During the delivery process, an infant may develop a cervical arterial dissection that leads to stroke. Several conditions in the neonatal period predispose to perinatal stroke including prothrombotic disorders, congenital heart disease, meningitis, and systemic infection. Perinatal stroke may present with neonatal seizures during the first weeks of life or may be asymptomatic until months later when the infant is first noted to have pathological handedness. The outcome of perinatal stroke is variable and depends on severity, anatomic localization, and other factors not yet well characterized. As many as 50% of infants with documented stroke recognized in the newborn period do not develop a hemiparesis. The incidence, clinical presentation, pathogenesis, risk factors, and outcome of this increasingly recognized disorder are reviewed.