Prediction of periventricular leukomalacia. Part II: Selection of hemodynamic features using computational intelligence

OBJECTIVE

The objective of Part II is to analyze the dataset of extracted hemodynamic features (Case 3 of Part I) through computational intelligence (CI) techniques for identification of potential prognostic factors for periventricular leukomalacia (PVL) occurrence in neonates with congenital heart disease.

METHODS

The extracted features (Case 3 dataset of Part I) were used as inputs to CI based classifiers, namely, multi-layer perceptron (MLP) and probabilistic neural network (PNN) in combination with genetic algorithms (GA) for selection of the most suitable features predicting the occurrence of PVL. The selected features were next used as inputs to a decision tree (DT) algorithm for generating easily interpretable rules of PVL prediction.

RESULTS

Prediction performance for two CI based classifiers, MLP and PNN coupled with GA are presented for different number of selected features. The best prediction performances were achieved with 6 and 7 selected features. The prediction success was 100% in training and the best ranges of sensitivity (SN), specificity (SP) and accuracy (AC) in test were 60-73%, 74-84% and 71-74%, respectively. The identified features when used with the DT algorithm gave best SN, SP and AC in the ranges of 87-90% in training and 80-87%, 74-79% and 79-82% in test. Among the variables selected in CI, systolic and diastolic blood pressures, and pCO(2) figured prominently similar to Part I. Decision tree based rules for prediction of PVL occurrence were obtained using the CI selected features.

CONCLUSIONS

The proposed approach combines the generalization capability of CI based feature selection approach and generation of easily interpretable classification rules of the decision tree. The combination of CI techniques with DT gave substantially better test prediction performance than using CI and DT separately.

Assessment of neonatal electroencephalography (EEG) background by conventional and two amplitude-integrated EEG classification systems

OBJECTIVE

To determine the agreement among conventional electroencephalography (CEEG) terminology background classification and a simple and an advanced amplitude-integrated EEG (aEEG) system, and to evaluate whether aEEG interpreter experience or electrographic seizures affect this agreement.

STUDY DESIGN

CEEG background was classified by traditional interpretive criteria for 144 neonatal recordings, from which a single channel was converted to aEEGs. These aEEGs were independently interpreted by neonatologists according to the simple and advanced classification systems.

RESULTS

Interreader agreement was better with the simple aEEG system compared with the advanced aEEG system (multirater kappa, 0.66 vs 0.44). Fair-to-moderate agreement was found between both of the aEEG classification systems and CEEG (simple: kappa, 0.34 to 0.45; advanced: kappa, 0.36 to 0.45). Agreement did not vary significantly based on the aEEG interpreter experience or the presence of seizures.

CONCLUSIONS

Neonatologists found better agreement using the simple aEEG system regardless of their expertise or the presence of seizures. This finding has implications for patient selection in future multicenter neonatal neuroprotection studies.

Inattention, hyperactivity, and school performance in a population of school-age children with complex congenital heart disease

INTRODUCTION

There is a growing interest in characterizing the neurodevelopmental outcomes of school-age survivors of cardiac surgery. The purpose of this study was to examine a population of 5- to 10-year-old children who underwent newborn cardiac surgery for complex congenital heart disease to characterize and assess risk factors for problems with inattention and hyperactivity, as well as the use of remedial school services.

PATIENTS AND METHODS

This study was a cross-sectional analysis of patients who underwent newborn cardiac surgery and were enrolled in a neuroprotection trial conducted at our institution between 1992 and 1997. Parents and teachers completed questionnaires for the school-age child to elicit information pertaining to the child's general health and academic performance. The severity of hyperactivity and inattention were assessed by using 2 standardized questionnaires (Attention-Deficit/Hyperactivity Disorder Rating Scale-IV and Behavior Assessment System for Children). In addition to calculating descriptive estimates of their occurrence, single-covariate logistic regression models were specified and tested by using 3 different outcomes (inattention, hyperactivity, and use of remedial school services) and 14 different covariates representing preoperative, intraoperative, and postoperative factors.

RESULTS

Data were obtained from parents and/or teachers for 109 children. Fifty-three (49%) were receiving some form of remedial academic services, and 15% were assigned to a special-education classroom. The number of children receiving clinically significant scores for inattention and hyperactivity on the Behavior Assessment System for Children was 3 to 4 times higher than observed in the general population. On the Attention-Deficit/Hyperactivity Disorder Rating Scale-IV, 30% of the parents reported high-risk scores for inattention and 29% reported high-risk scores for hyperactivity. No perioperative factors were statistically associated with adverse outcomes.

CONCLUSION

In this cohort of children with complex congenital heart disease, a significant proportion of the children were at risk for inattention and hyperactivity, and nearly half were using remedial school services. We did not identify any perioperative risk factors, which correlated with high-risk scores or the use of remedial school services. Ongoing neurodevelopmental follow-up and screening are recommended in this vulnerable population.

Neurodevelopmental outcomes after staged palliation for hypoplastic left heart syndrome

OBJECTIVE

The goal was to determine the relative effects of underlying genetic factors and current management strategies on neurodevelopmental disabilities among one-year old survivors of palliation for hypoplastic left heart syndrome.

METHODS

Children who underwent staged reconstruction for hypoplastic left heart syndrome and variants were assessed at 1 year of age by using a neuromuscular examination and the Bayley Scales of Infant Development II, which provide the Mental Development Index and the Psychomotor Development Index. The effects of perioperative, operative, and genetic variables on developmental scores were evaluated.

RESULTS

The median birth weight was 3.3 kg (range: 2.1-4.5 kg). Eight-three patients (94%) underwent multiple operations with cardiopulmonary bypass during the first year of life (median: 2 operations). Seven patients (8%) required extracorporeal membrane oxygenation. Twenty-five patients (28%) had a confirmed or suspected genetic syndrome. At 1 year of age, the neuromuscular examination results were abnormal or suspect for 57 patients (65%). The median Mental Development Index score was 90, and 10 patients (11%) had scores of <70 (2 SDs below the general population mean). The median Psychomotor Development Index score was 73, and 42 patients (48%) had scores of <70. In multivariate analyses, younger gestational age, the presence of a genetic syndrome, and the need for preoperative intubation had significant negative effects on neurodevelopmental outcomes. No association was found with operative factors, including duration of deep hypothermic circulatory arrest.

CONCLUSIONS

At 1 year of age, there was a significant incidence of neurodevelopmental disabilities in children with hypoplastic left heart syndrome and variants; motor scores were particularly concerning. Many children had suspected or confirmed genetic syndromes, which negatively affected neurodevelopmental outcomes. Surgical variables did not affect neurologic outcomes.

Characterization of neonatal seizures by conventional EEG and single-channel EEG

OBJECTIVE

To perform a detailed, contemporary temporal-spatial characterization of neonatal seizures (NS) and to compare conventional EEG (CEEG) to single-channel EEG for NS detection.

METHODS

Digitally recorded CEEGs were reviewed for NS characteristics (quantity, duration, location of onset, peak-to-peak amplitude). The presence and characteristics of each NS were simultaneously noted in a single, derived EEG channel (C3-->C4).

RESULTS

Eight hundred fifty-one seizures from 125 CEEGs recorded were analyzed. Mean seizure rate was 7.0 NS/h (range: 0.5-21). Mean seizure burden (percent time CEEG showed NS at any location) was 24.8% (range: 0.7-86.9). Seizure rate was only moderately correlated with seizure burden (Spearman coefficient=0.58). Eighty-one percent of NS originated from central-temporal or midline vertex electrodes. Seventy-eight percent of NS appeared in the C3-->C4 channel.

CONCLUSIONS

Accurate measurement of NS burden requires detailed temporal-spatial characterization. The theoretical ceiling of sensitivity for NS detection in the single EEG channel C3-->C4 is high. However, further processing the raw EEG in limited electrode arrays may reduce the sensitivity of NS detection.

SIGNIFICANCE

CEEG is the gold standard for NS detection. However, reduced montage EEG techniques are increasingly available. This detailed contemporary temporal-spatial characterization of NS evaluates the potential limitations of reduced montage techniques.

Sensitivity of amplitude-integrated electroencephalography for neonatal seizure detection

BACKGROUND

Conventional electroencephalography remains the gold standard for the diagnosis and quantification of neonatal seizures. However, amplitude-integrated electroencephalography (aEEG) is being introduced to neonatal intensive care as an adjunct for neonatal seizure detection.

OBJECTIVES

This study's purpose was to determine the sensitivity of neonatal seizure detection in a single electroencephalogram channel (C3-->C4), used to simulate the raw signal from which aEEG is derived. We also aimed to determine the sensitivity of seizure detection by neonatologists by using aEEG and to establish those neonatal seizure characteristics that are associated with their correct detection by aEEG.

METHODS

Conventional electroencephalograms with neonatal seizures were reviewed for electroencephalogram background and neonatal seizure characteristics (site of onset, duration, and peak-to-peak amplitude). The presence, duration, and peak-to-peak amplitude of each seizure were simultaneously noted in a single electroencephalogram channel (C3-->C4). aEEGs generated from this channel were reviewed for background and seizures by 6 neonatologists with varying aEEG interpretation expertise.

RESULTS

A total of 851 neonatal seizures from 125 conventional electroencephalograms were analyzed. The patients' conceptional ages were 34 to 50 weeks. Because 94% of the conventional electroencephalograms had > or = 1 neonatal seizure visible in C3-->C4, and 78% of all neonatal seizures appeared in the C3-->C4 channel, the theoretical sensitivity of seizure detection in a single electroencephalogram channel was high. However, seizures were briefer and lower in amplitude in C3-->C4 compared with conventional electroencephalography. Neonatologists identified seizures in 22% to 57% of the 125 records of neonatal seizure. They detected 12% to 38% of the 851 individual seizures. Multivariate analysis revealed that the appearance of seizures in C3-->C4, neonatal seizure duration, seizure amplitude, seizure count per hour, and neonatologists' experience with aEEG interpretation all correlated with neonatal seizure detection.

CONCLUSIONS

Even among physicians who have extensive experience, many neonatal seizures are difficult to detect on an aEEG, especially when they are infrequent, brief, or of low amplitude.

Late cardiopulmonary and musculoskeletal exercise performance after repair for total anomalous pulmonary venous connection during infancy

OBJECTIVES

We evaluated cardiopulmonary function at rest and during exercise in children after surgical repair for total anomalous pulmonary venous connection.

BACKGROUND

Long-term assessment of cardiopulmonary function during exercise in children after repair for total anomalous pulmonary venous connection during infancy is limited.

METHODS

Resting lung function and cardiopulmonary function during maximal ramp cycle ergometry were evaluated in 27 patients (age = 11 +/- 4 years, 20 were male). Peak oxygen consumption, ventilatory anaerobic threshold, and physical working capacity were compared with normal reference values. Neurologic assessment included neuromuscular function, inattentiveness, and hyperactivity. Patient- and procedure-related variables were assessed for association with peak oxygen consumption, ventilatory anaerobic threshold, and physical working capacity.

RESULTS

Compared with healthy children, peak oxygen consumption (88% +/- 16% of predicted) and ventilatory anaerobic threshold (91% +/- 21% of predicted) were mildly reduced. Chronotropic impairment was observed in 7 patients (32%). Patients with impaired resting lung mechanics were more likely to have impairment in peak oxygen consumption (P < .05). Breathing reserve was normal. Specific anatomy and all operative factors did not have a significant impact on overall exercise performance. Composite score for fine and gross motor function was associated with lower ventilatory anaerobic threshold (P < .05).

CONCLUSIONS

Exercise performance is mildly impaired at long-term follow-up after total anomalous pulmonary venous connection repair during infancy. Residual pulmonary abnormalities are common and associated with lower exercise performance. Neurologic abnormalities are evident in a subgroup, but the impact on late exercise performance is inconclusive.

Aortic morphometry and microcephaly in hypoplastic left heart syndrome

Microcephaly is a marker of abnormal fetal cerebral development, and a known risk factor for cognitive dysfunction. Patients with hypoplastic left heart syndrome have been found to have an increased incidence of abnormal neurodevelopmental outcomes. We hypothesized that reduced cerebral blood flow from the diminutive ascending aorta and transverse aortic arch in the setting of hypoplastic left heart syndrome may influence fetal growth of the brain. The purpose of our study, therefore, was to define the prevalence of microcephaly in full-term infants with hypoplastic left heart syndrome, and to investigate potential cardiac risk factors for microcephaly. We carried out a retrospective review of full-term neonates with hypoplastic left heart syndrome. Eligible patients had documented indexes of birth weight, and measurements of length, and head circumference, as well as adequate echocardiographic images for measurement of the diameters of the ascending aorta and transverse aortic arch. We used logistic regression for analysis of the data. A total of 129 neonates met the criteria for inclusion, with 15 (12%) proving to have microcephaly. The sizes of their heads were disproportionately smaller than their weights (p less than 0.001) and lengths (p less than 0.001) at birth. Microcephaly was associated with lower birth weight (p less than 0.001), lower birth length (p equal to 0.007), and a smaller diameter of the ascending aorta (p equal to 0.034), but not a smaller transverse aortic arch (p equal to 0.619), or aortic atresia (p equal to 0.969). We conclude that microcephaly was common in this cohort of neonates with hypoplastic left heart syndrome, with the size of the head being disproportionately smaller than weight and length at birth. Microcephaly was associated with a small ascending aorta, but not a small transverse aortic arch. Impairment of somatic growth may be an additional factor in the development of microcephaly in these neonates.

Patient characteristics are important determinants of neurodevelopmental outcome at one year of age after neonatal and infant cardiac surgery

OBJECTIVE

Many studies of neurodevelopmental outcomes after neonatal and infant cardiac surgery have focused on potentially modifiable risk factors for adverse outcomes, primarily intraoperative management strategies and the use of deep hypothermic circulatory arrest. There is increasing evidence that patient-specific factors are more important determinants of outcome.

METHODS

We investigated predictors of neurodevelopmental outcomes at 1 year of age after neonatal and infant cardiac surgery in a subgroup of infants enrolled in a prospective study of apolipoprotein E (APOE) genotype and neurodevelopmental outcome. Children with a variety of 2-ventricle cardiac defects repaired with only 1 operation with cardiopulmonary bypass and no more than 1 episode of deep hypothermic circulatory arrest were included. Neurodevelopmental outcomes at 1 year of age included the Bayley Scales of Infant Development-II, which yield 2 indices, the Mental Developmental Index and the Psychomotor Developmental Index.

RESULTS

Two hundred forty-seven infants underwent surgical repair between October 1998 and April 2003 with 1 hospital death and 3 deaths before 1 year of age. Neurodevelopmental evaluation was performed in 188 (77%) of 243 survivors, including 56 patients with tetralogy of Fallot, 39 with transposition of the great arteries with intact ventricular septum, 34 with ventricular septal defects, and 59 with other defects. The median age at operation was 56 days (1-186 days), including 72 (38%) neonates. Confirmed or suspected genetic syndromes were present in 59 (31%) of 188 infants. Deep hypothermic circulatory arrest was used in 67 (35%) infants with a median duration of 34 minutes (1-80 minutes). For the entire cohort, the mean Mental Developmental Index was 90.6 +/- 14.9 and the mean Psychomotor Developmental Index was 81.6 +/- 17.2. For patients without genetic syndromes, the mean Mental Developmental Index was 93.7 +/- 13.6 and the mean Psychomotor Developmental Index was 85.1 +/- 14.6. For the entire cohort, predictors of lower scores for both the Mental Developmental Index and Psychomotor Developmental Index were presence of a confirmed or suspected genetic syndrome, lower birth weight, and presence of the APOE epsilon2 allele (all P < .04). Black race was associated with higher scores on the Psychomotor Developmental Index (P = .018). Lower nasopharyngeal temperature during cardiopulmonary bypass was associated with a lower score on the Psychomotor Developmental Index (P = .03) and was the only intraoperative factor that was a significant predictor of either the Mental or Psychomotor Developmental Index.

CONCLUSIONS

The strongest predictors of a worse neurodevelopmental outcome at 1 year of age were patient-specific factors including presence of a genetic syndrome, low birth weight, and presence of the APOE epsilon2 allele. Patient-specific factors eclipsed the use and duration of deep hypothermic circulatory arrest as predictors of worse neurodevelopmental outcomes.

The newborn drug development initiative workshop: Summary proceedings from the neurology group on neonatal seizures

BACKGROUND

The neonatal period eclipses all other epochs of the human life span for the highest incidence of seizures. Neonatal seizures are most commonly incited by serious acute illnesses such as hypoxic-ischemic encephalopathy, birth trauma, or infection.

OBJECTIVE

The goal of this article was to summarize some of the Neurology Group's discussion on neonatal seizures and their treatment with phenobarbital (PB).

METHODS

Information for this article was gathered from a workshop held March 29 and 30, 2004, in Baltimore, Maryland, as part of the Newborn Drug Development Initiative. A group of national experts was invited to form the Neurology Group to review certain aspects of neonatal seizures. Literature reviews were conducted using MEDLINE searches for original research studies, commentaries, and review articles between 1980 and 2004 using the key words neonatal seizures, treatment, and phenobarbital.

RESULTS

It has been empirically established that infants who experience seizures face substantially higher mortality and morbidity rates than those who do not. Basic research indicates that neonatal seizures themselves are not innocuous and actively contribute to adverse neurodevelopmental outcomes. Current worldwide clinical practice most often includes empiric treatment with PB for definite or suspected seizures in the newborn. Unfortunately, this common practice has never been proven by even a single, rigorous, randomized controlled trial. The Neurology Group identified the treatment of neonatal seizures with PB as an important topic in the practice of neonatal neurology for further investigation. Three possible frameworks for ethically acceptable, clinical treatment trials were explored. From these, a suitable scenario was selected-an electroencephalographer-blinded study of PB versus placebo in a homogeneous group of newborns who are at high risk of developing early subclinical electroencephalographic neonatal seizures (ENSs). Prospective video-electroencephalogram monitoring performed immediately after an insult (such as major cardiac surgery for a serious congenital heart defect) would establish the presence and number of subclinical ENSs. For a brief period of time, neonates with subclinical ENSs would be randomized to PB (dosed to match the PB-binding characteristics of the individual) or placebo. Clear criteria for escape from the study to active treatment are defined.

CONCLUSION

The investigation proposed here could refute or confirm the contemporary practice of PB administration as the first-line treatment of neonatal seizures.

Prolonged electroencephalogram monitoring for seizures and their treatment

This article reviews the diagnosis of neonatal seizures using routine electroencephalogram (EEG) examinations and long-term EEG monitoring. EEG is considered the gold standard for identifying the presence and quantifying the burden of neonatal seizures. The most common medication used to treat neonatal seizures is phenobarbital, although its efficacy has never been demonstrated by a formal, randomized, placebo-controlled drug trial.

Dystrophic neuritic processes in epileptic cortex

Cortical dysplasia is a frequent finding in cortical resections from children with refractory epilepsy. Diagnostic criteria and a classification scheme for cortical dysplasia has been proposed, though the relationship between specific cortical dysplasia features and their causal relationship with epilepsy is poorly understood. We reviewed 28 surgical resections from children and identified a common and easily recognized feature of cortical dysplasia: maloriented, misshapen and occasionally coarse neurofilament stained process forming a dystrophic neuritic background. The dystrophic neuritic background was associated with other features of cortical dysplasia in all 28 patients with cortical dysplasia, 26 with refractory epilepsy and 2 patients with other neurologic diagnoses. In seven children with refractory epilepsy due to other pathologic diagnosis such as vascular or glial lesions, the dystrophic neuritic background was only found in one patient with a ganglioglioma and other features suggestive of an associated cortical dysplasia. Our data indicate that a dystrophic neuritic background is a common and relatively specific neuropathologic finding in cortical dysplasia.

Neurodevelopmental outcome after early repair of a ventricular septal defect with or without aortic arch obstruction

OBJECTIVES

Cross-sectional studies of intermediate-term survivors of infant cardiac surgery have revealed a high frequency of neurodevelopmental disabilities. Few data exist regarding neurodevelopmental outcome of infants undergoing surgical intervention for a ventricular septal defect. The purpose of this study was to evaluate the neurodevelopmental outcome at 1 year of age of children who had surgical repair in infancy of a ventricular septal defect or a ventricular septal defect with aortic arch obstruction.

METHODS

Children who underwent repair of a ventricular septal defect or single-stage repair of a ventricular septal defect with aortic arch obstruction at less than 6 months of age were assessed at 1 year of age by using the Bayley Scales of Infant Development II, which yields the Mental Development Index and the Psychomotor Development Index, both with an expected mean of 100 +/- 15.

RESULTS

At 1 year, 55 patients (ventricular septal defect alone = 36; ventricular septal defect with aortic arch obstruction = 19) returned for evaluation. The mean Mental Development Index was 92.6 +/- 11.7, with 3 (5%) patients scoring 70 or less. The mean Psychomotor Development Index was 86.1 +/- 16.4, with 10 (18%) patients scoring 70 or less. Patients with a suspected or confirmed genetic syndrome had both a lower Mental Development Index score (P = .011) and a lower Psychomotor Development Index score (P = .001). Mental Development Index and Psychomotor Development Index were independent of anatomic (specifically aortic arch obstruction) and intraoperative factors (specifically deep hypothermic circulatory arrest).

CONCLUSIONS

Neurodevelopmental outcome at 1 year of age was within the normal limits for most patients who underwent repair of a ventricular septal defect or a ventricular septal defect with aortic arch obstruction during infancy.

Summary proceedings from the neurology group on neonatal seizures

One of the highest risk periods for seizures during the human life span is the first month of life. Most neonatal seizures are triggered by acute illness such as hypoxic-ischemic encephalopathy, stroke, or infection; rarely are they triggered by epilepsy per se. Seizures are the most common and important sign of acute neonatal encephalopathy, are a major risk for death or subsequent neurologic disability, and by themselves may contribute to an adverse neurodevelopmental outcome. Customary clinical practice includes visual monitoring of high-risk neonates for seizures, performance of a routine electroencephalogram (EEG) for suspicious clinical seizure activity, and empirical treatment with phenobarbital. Presently, however, there are no data that have unequivocally demonstrated the efficacy of barbiturates in the treatment of neonatal seizures. The neurology group recognizes an important need for randomized, placebo-controlled, ethically acceptable trials of phenobarbital efficacy and safety in the treatment of neonatal seizures. After exploring 3 possible frameworks for clinical trials of phenobarbital in the treatment of neonatal seizures, the neurology group ultimately focused on a multicenter, placebo-controlled, electroencephalographer-blinded study of phenobarbital versus placebo in a homogeneous group of newborns who are at high risk of developing early subclinical electroencephalographically detected neonatal seizures. Continuous video-EEG monitoring would establish the presence and number of seizures. Criteria for escape from the study to treatment are clearly defined. The proposed study could provide the first concrete evidence of treatment efficacy because (1) it examines a homogeneous patient population, (2) the recognition and quantification of seizures rests solely on the gold standard of seizure detection (EEG), and (3) the dosing of phenobarbital is matched specifically to the phenobarbital-binding characteristics of the individual treated. This study would affirm or refute the common practice of phenobarbital as the first-line treatment of neonatal seizures.

The relationship of postoperative electrographic seizures to neurodevelopmental outcome at 1 year of age after neonatal and infant cardiac surgery

OBJECTIVE

The occurrence of a seizure after the arterial switch operation is associated with a worse long-term neurodevelopmental outcome. The significance of seizures after neonatal and infant repair of other congenital heart defects is not known.

METHODS

A recent study at our institution demonstrated seizures documented by 48-hour electroencephalographic monitoring in 20 (11%) of 178 neonates and infants after surgery for complex congenital heart defects, including hypoplastic left heart syndrome or variants. The developmental outcomes of this cohort were evaluated at 1 year of age by using the Bayley Scales of Infant Development II, which yields 2 scores: the Mental Developmental Index and the Psychomotor Developmental Index.

RESULTS

Developmental evaluations were performed in 114 (70%) of 164 survivors, including 36 with hypoplastic left heart syndrome. Postoperative electroencephalographic seizures had occurred in 15 (13%) of 114 of the entire group and in 8 (22%) of 36 of those with hypoplastic left heart syndrome. For the entire cohort, the Mental Developmental Index was 92.3 +/- 13.5, and the Psychomotor Developmental Index was 79.9 +/- 18.8 for patients without seizures, compared with 90.3 +/- 10.7 and 74.4 +/- 19.3 for those with seizures (both P > .5). For the hypoplastic left heart syndrome subgroup, the Mental Developmental Index was 92.3 +/- 14.9, and the Psychomotor Developmental Index was 74.8 +/- 19.3 for patients with seizures, compared with 91.9 +/- 12.4 and 73.9 +/- 18.3 for those without seizures (both P > .5). A frontal onset of seizures was predictive of a lower score on the Psychomotor Developmental Index, but not on the Mental Developmental Index.

CONCLUSIONS

The occurrence of a seizure after cardiac operation is a marker of central nervous system injury. However, in this cohort of neonates and infants with complex congenital heart defects, the occurrence of a seizure was not predictive of a worse developmental outcome at 1 year of age as assessed by the Bayley Scales of Infant Development II.

Effect of congenital heart disease on neurodevelopmental outcomes within multiple-gestation births

OBJECTIVES

We sought to assess the effect of congenital heart disease requiring surgical intervention with cardiopulmonary bypass at 6 months of age or less on developmental outcomes and growth at 1 year of age while controlling for socioeconomic status, prematurity, home environment, and parental intelligence.

METHODS

We performed within-family comparison of 11 multiple-gestation births in which one child had congenital heart disease. At 1 year of age, the Bayley Scales of Infant Development II were administered, and growth parameters were assessed. Paired comparisons were made by using fixed effects regression conditioned on family.

RESULTS

The multiple-gestation subjects were mildly premature on average (mean gestational age, 35.4 +/- 3.0 weeks). At 1 year of age, children with congenital heart disease scored lower on the Mental Development Index (85.0 +/- 19.3 vs 93.9 +/- 16.0, P = .037) and the Psychomotor Development Index (76.6 +/- 16.9 vs 91.3 +/- 14.9, P = .015) on the Bayley Scales of Infant Development II than did their siblings without congenital heart disease. There were no differences between siblings in weight, height, or head circumference.

CONCLUSIONS

The presence of congenital heart disease requiring surgical intervention with cardiopulmonary bypass at 6 months of age or less is associated with a deficit in developmental achievement at 1 year of age, as measured by using the Bayley Scales of Infant Development II.

Increasing duration of deep hypothermic circulatory arrest is associated with an increased incidence of postoperative electroencephalographic seizures

OBJECTIVE

Electroencephalographic seizures have been shown to occur in 5% to 20% of neonates and infants after biventricular repair of a variety of cardiac defects. Occurrence of a seizure is a predictor of adverse long-term neurodevelopmental sequelae. The contemporary incidence of postoperative seizures after repair of cardiac defects such as hypoplastic left heart syndrome and other forms of single ventricle is not known.

METHODS

A prospective study of 178 patients less than 6 months of age undergoing cardiopulmonary bypass with or without deep hypothermic circulatory arrest (DHCA) was conducted at a single institution from September 2001 through March 2003 to identify postoperative seizures assessed by 48-hour continuous video electroencephalographic monitoring.

RESULTS

Cardiac defects included transposition of the great arteries with or without a ventricular septal defect (n = 12), ventricular septal defect with or without coarctation (n = 28), tetralogy of Fallot (n = 24), hypoplastic left heart syndrome or variant (n = 60), other functional single ventricle (n = 14), and other defects suitable for biventricular repair (n = 40). Median age at the time of the operation was 7 days (range, 1-188 days) and was 30 days or less in 110 (62%) patients. DHCA was used in 117 (66%) patients, with multiple episodes in 9 patients. Median total duration of DHCA was 40 minutes (range, 1-90 minutes). Electroencephalographic seizures were identified in 20 (11.2%) patients. Seizures occurred in 15 (14%) of 110 neonates and 5 (7%) of 68 older infants. Seizures occurred in 1 (4%) of 24 patients with tetralogy of Fallot, 1 (8%) of 12 with transposition of the great arteries, and 11 (18%) of 60 with hypoplastic left heart syndrome or variant. By stepwise logistic regression analysis, once increasing duration of total DHCA (P = .001) was considered, no other variable improved prediction of occurrence of a seizure. Patients with DHCA duration of more than 40 minutes had an increased incidence of seizures (14/58 [24.1%]) compared with those with a DHCA duration of 40 minutes or less (4/59 [6.8%], P = .04). The incidence of seizures for patients with a DHCA duration of 40 minutes or less was not significantly different from those in whom DHCA was not used (2/61 [3.3%], P = .38).

CONCLUSIONS

In the current era, continuous electroencephalographic monitoring demonstrates early postoperative seizures in 11.2% of a heterogeneous cohort of neonates and infants with complex congenital heart defects. Increasing duration of DHCA was identified as a predictor of seizures. However, the incidence of seizures in children with limited duration of DHCA was similar to that in infants undergoing continuous cardiopulmonary bypass alone.

Late neurodevelopmental outcome after repair of total anomalous pulmonary venous connection

Objective We sought to define the neurodevelopmental status of school-aged survivors of total anomalous pulmonary venous connection repaired during infancy. Methods All school-aged survivors of total anomalous pulmonary venous connection repair performed at a single institution were eligible. Thirty children returned for neurologic examination and neurodevelopmental testing. Results The median age at total anomalous pulmonary venous connection repair was 16 days (range, 1-141 days), and age at testing was 11 years (range, 6-19 years). Pulmonary venous return was supracardiac in 14 patients, infracardiac in 12 patients, cardiac in 3 patients, and mixed in 1 patient. Preoperative obstructed total anomalous pulmonary venous connection was present in 6 patients. Circulatory arrest was used in all repairs, with a median duration of 35 minutes (range, 17-55 minutes). At follow-up, microcephaly (head circumference <5%) was present in 28%. Neuromuscular examination was suspect or abnormal in 27%. Mean Full-scale IQ (95.3 +/- 18.5) and Verbal IQ (98.6 +/- 20.2) were not different from population norms, but Performance IQ (92.3 +/- 16.9) was significantly lower than population norms ( P = .02). Fine motor skills and visual-motor coordination were significantly impaired ( P < .01 for Grooved Pegboard and Test of Visual-Motor Integration). Patients with total anomalous pulmonary venous connection also had difficulty with tests of attention (Test of Everyday Attention for Children, P < .01), but results of tests of memory function were not significantly different from population norms. Conclusions School-aged survivors of infant total anomalous pulmonary venous connection repair exhibit a significant incidence of neurodevelopmental difficulties. Fine motor function, visual-motor integration, and attention are the most commonly affected domains. Evaluation of these children is indicated to identify those who are at risk for learning disabilities and who could benefit from early intervention.

Migrating partial seizures in infancy: expanding the phenotype of a rare seizure syndrome

PURPOSE

The constellation of early-onset, unprovoked, alternating electroclinical seizures and neurodevelopmental devastation was first described by Coppola et al. We report six new patients and the prospect of a more optimistic developmental outcome.

METHODS

Retrospective chart reviews were performed on six infants evaluated at the Children's Hospital of Philadelphia (five patients) and at Hershey Medical Center (one patient) who had electroclinically alternating seizures before age 6 months of age. Electroclinical characteristics and long-term follow-up were recorded.

RESULTS

All had unprovoked, early-onset (range, 1 day to 3 months; mean, 25 days) intractable electroclinical seizures that alternated between the two hemispheres. Each patient underwent comprehensive brain imaging and neurometabolic workups, which were unrevealing. In all patients, subsequently intractable partial seizures developed and often a progressive decline of head circumference percentile occurred with age. Three demonstrated severe developmental delay and hypotonia. All survived, and 7-year follow-up on one patient was quite favorable.

CONCLUSIONS

Our patients satisfied the seven major diagnostic criteria first described by Coppola et al. The prognosis of this rare neonatal-onset epilepsy syndrome from the original description and subsequent case reports was very poor, with 28% mortality, and the majority of survivors were profoundly retarded and nonambulatory. Our patient data validate the diagnostic criteria of this syndrome and further quantify a previously described observation of progressive decline of head circumference percentiles with age. Our data also suggest that the prognosis of this syndrome, although poor, is not as uniformly grim as the cases reported previously in the literature.

Electrographic Neonatal Seizures after Infant Heart Surgery

PURPOSE

Neonatal seizures are relatively common and an important early sign of acute encephalopathy in those who survive infant heart surgery. The contemporary occurrence of seizures in this setting is not fully known, and their electrographic characteristics are incompletely described. This study describes the characteristics of electrographic neonatal seizures (ENSs) in contemporary infants with congenital heart disease (CHD) surgically repaired by using cardiopulmonary bypass, with or without deep hypothermic circulatory arrest.

METHODS

Consecutive infants undergoing heart surgery were monitored by video-EEG for 48 h postoperatively to establish the time of first seizure, total number of ENSs, site(s) of ENS(s) origin and other characteristics.

RESULTS

ENSs occurred in 21 (11.5%) of 183 infants. None had clinically visible seizures. The mean time to the first ENS was 21 h (range, 10-36 h). The total number of ENSs among the entire cohort was 1,429. Mean total number of ENSs per patient over a 48-h period was 72 (range, 1-217). Phenobarbital administration was associated with a > or =50% reduction in seizure counts in five (41.7%) of 12 subjects.

CONCLUSIONS

ENSs were relatively common in a large, contemporary cohort of infants after infant heart surgery. A wide variation was noted in seizure burden, but many experienced numerous seizures. Electrographic neonatal seizures are a candidate outcome end point in future neuroprotection trials in this patient population.

Preoperative cerebral blood flow is diminished in neonates with severe congenital heart defects

OBJECTIVE

Impaired neurodevelopmental outcome represents a major morbidity for survivors of infant heart surgery for congenital heart defects. Previous studies in these neonates have reported preoperative microcephaly, periventricular leukomalacia, and other findings. The hypothesis of this study is that preoperative cerebral blood flow is substantially diminished and might relate to preoperative neurologic conditions.

METHODS

Preoperative brain magnetic resonance imaging was performed. Cerebral blood flow measurements in infants with congenital heart defects were obtained by using a novel noninvasive magnetic resonance imaging technique, pulsed arterial spin-label perfusion magnetic resonance imaging. Cerebral blood flow was measured before the operation under standard ventilation and repeated after increased carbon dioxide.

RESULTS

A total of 25 term infants were studied. The average age at the time of the operation was 4.4 +/- 4.6 days. Congenital heart defects varied widely. Microcephaly occurred in 24% (6/25). Baseline cerebral blood flow was 19.7 +/- 9.2 mL . 100 g -1 . min -1 (8.0-42.2 mL . 100 g -1 . min -1 ). Five patients had cerebral blood flow measurements of less than 10 mL . 100 g -1 . min -1 . Mean hypercarbic cerebral blood flow increased to 40.1 +/- 20.3 mL . 100 g -1 . min -1 (11.4-94.0 mL . 100 g -1 . min -1 , P < .001). Pairwise analyses found that low hemoglobin levels were associated with higher baseline cerebral blood flow values ( P = .04). Periventricular leukomalacia occurred in 28% (7/25) and was associated with decreased baseline cerebral blood flow values ( P = .05) and a smaller change in cerebral blood flow with hypercarbia ( P = .003).

CONCLUSIONS

Structural brain abnormalities are common in these neonates before surgical intervention. Preoperative cerebral blood flow for this cohort was low and drastically reduced in some patients. Low cerebral blood flow values were associated with periventricular leukomalacia. Carbon dioxide reactivity was preserved but might be compromised by some aspects of the cardiac anatomy. The full spectrum of cerebral blood flow measurements with this technique in congenital heart defects and their long-term significance require continued investigation.

Periventricular leukomalacia is common after neonatal cardiac surgery

OBJECTIVES

Periventricular leukomalacia is necrosis of the cerebral white matter adjacent to the lateral ventricles and results from injury to immature oligodendroglia. In infants without congenital heart disease, periventricular leukomalacia is associated with an increased incidence of developmental delay and attention deficit/hyperactivity disorder. The incidence of periventricular leukomalacia and the risk factors for development of periventricular leukomalacia after infant cardiac surgery are not known.

METHODS

Magnetic resonance imaging of the brain was performed 6 to 14 days after cardiac surgery utilizing cardiopulmonary bypass with or without deep hypothermic circulatory arrest in 105 neonates and infants < or = 6 months of age.

RESULTS

Median age at surgery was 6 days (range 1-178), with 82 neonates (age < or = 30 days). Periventricular leukomalacia was found in 44 of the neonates (54%) compared with 1 of 23 infants (4%). Forward logistic regression using age at surgery as a continuous variable identified a model containing longer total support time (cardiopulmonary bypass plus deep hypothermic circulatory arrest), lower systolic blood pressure at cardiac intensive care unit admission postoperatively, lower minimum diastolic blood pressure, and Po(2) in the first 48 hours after surgery. When age at surgery was considered as a dichotomous variable (neonate versus infant), younger age at surgery replaced systolic blood pressure, Po(2), and total support time in the model. Lower minimum diastolic blood pressure was a significant risk factor in both models.

CONCLUSIONS

Periventricular leukomalacia was found in >50% of neonates after cardiac surgery but rarely in older infants. Hypoxemia and hypotension in the early postoperative period, particularly diastolic hypotension, may be important risk factors for periventricular leukomalacia.

Apolipoprotein E genotype and neurodevelopmental sequelae of infant cardiac surgery

BACKGROUND

There has been increasing recognition of adverse neurodevelopmental sequelae in some children after repair of congenital heart defects. Even among children with the same cardiac defect, significant interindividual variation exists in developmental outcome. Polymorphisms of apolipoprotein E have been identified as a risk factor for worse neurologic recovery after central nervous system injury.

METHODS

A single-institution prospective study of patients <or=6 months of age undergoing cardiopulmonary bypass for repair of congenital heart defects was undertaken to evaluate the association between apolipoprotein E genotype and postoperative neurodevelopmental dysfunction. Developmental outcomes were evaluated at 1 year of age by using the Bayley Scales of Infant Development.

RESULTS

One-year evaluation was performed in 244 patients. After adjustment for preoperative and postoperative covariates-including gestational age, age at operation, sex, race, socioeconomic status, cardiac defect, and use of deep hypothermic circulatory arrest-the apolipoprotein E epsilon2 allele was associated with a worse neurologic outcome as assessed by the Psychomotor Developmental Index of the Bayley Scales of Infant Development (P =.036). Patients with the apolipoprotein E epsilon2 allele had approximately a 7-point decrease in the Psychomotor Developmental Index.

CONCLUSIONS

Apolipoprotein E epsilon2 allele carriers had significantly lower Psychomotor Development Index scores at 1 year of age after infant cardiac surgery. The effect was independent of ethnicity, socioeconomic status, cardiac defect, and use of deep hypothermic circulatory arrest. An effect of the apolipoprotein E epsilon4 allele was not detected. Genetic polymorphisms that decrease neuroresiliency and impair neuronal repair after central nervous system injury are important risk factors for neurodevelopmental dysfunction after infant cardiac surgery.

Dysplasia: a common finding in intractable pediatric temporal lobe epilepsy

BACKGROUND

Risk factors for temporal lobe epilepsy (TLE) include history of CNS infection, family history of epilepsy, and history of febrile convulsions (FC). Pre-existing cortical dysplasia (CD) may also predispose to refractory TLE, independent of other risk factors for epilepsy.

METHODS

The authors reviewed the neuropathologic features of surgical tissue from temporal lobectomies of 33 pediatric patients with refractory TLE, with and without a history of epilepsy risk factors.

RESULTS

CD was found in 64% (21/33) of all patients with refractory TLE, including 73% (11/15) patients with a history of FC, 66% (2/3) patients with CNS infections, and 83% (5/6) patients with a family history of epilepsy. Disrupted cortical lamination, dystrophic and maloriented neurons, and balloon cells characterized the CD found in the temporal neocortex.

CONCLUSION

CD was seen in 21 of 33 surgical specimens from children with refractory TLE, including those with and without other epilepsy risk factors.