Intraventricular hemorrhage in the preterm infant

A Review of the Occurrence of Intraventricular Hemorrhage in Preterm Newborns and its Future Neurodevelopmental Consequences

Intraventricular hemorrhage (IVH) is a type of bleeding that occurs through the germinal matrix and comes through the ependymal cells into the ventricular cavity. It is mostly seen in preterm neonates but can also be seen sometimes in term neonates. Various factors predispose to preterm delivery; it can be spontaneous or medically induced. Spontaneous IVH occurs in cases of intrauterine infections in the mother, and it can be induced in cases of medical emergencies such as preeclampsia and eclampsia. The brain of a preterm newborn is not fully developed as it does not have pericytes and proteins, so it can bleed very quickly, which can cause IVH. Also, the vessels supplying the germinal matrix are immature and highly vascularized. IVH has four grades based on findings detected on cranial ultrasound and MRI. Management includes medical and surgical management; medical management includes phenobarbitone used for seizures and prophylaxis. Surgical management includes drainage, irrigation, and fibrinolytic therapy (DRIFT), and neuro-endoscopic lavage. IVH causes various short-term and long-term neurodevelopmental consequences. Long-term complications include cerebral palsy and intellectual disability, which hamper the life of the child. It mainly presents with seizures, flaccidity, decerebrate posture, etc. Various preventive measures can be taken to tackle IVH in newborns. First of all, preterm delivery should be avoided, and intrauterine infections in mothers should be treated. The administration of corticosteroids should be done for all preterm deliveries as it helps in the maturation of organs. The administration of magnesium sulfate should be done as it is neuroprotective and reduces cerebral palsy in the future. Delayed cord clamping is to be done to reduce recurrent blood transfusions and decrease the risk of IVH. This article explains the pathogenesis, management, prevention, and future outcomes of IVH.

Navigating the Complexities of Intraventricular Hemorrhage in Preterm Infants: An Updated Review

Intraventricular hemorrhage (IVH) is a type of bleeding that occurs in the ventricular cavity of the brain. In this comprehensive study, we provide a summary of the pathogenesis, diagnosis, and treatment of intraventricular hemorrhage in premature infants. Preterm babies are at high risk of developing IVH because their germinal matrix is not fully developed, making their blood vessels more prone to rupture. However, that is not necessarily the case in all preterm babies as the inherent structure of the germinal matrix makes it more susceptible to hemorrhage. Incidences of IVH are discussed based on recent data which states that around 12,000 premature infants in the United States experience IVH each year. Although grades I and II make up the majority of IVH cases and are frequently asymptomatic, IVH remains a significant issue for premature infants in neonatal intensive care facilities worldwide. Grades I and II have been linked to mutations in the type IV procollagen gene, COL4A1, as well as prothrombin G20210A and factor V Leiden mutations. Intraventricular hemorrhage can be detected using brain imaging in the first seven to 14 days following delivery. This review also shines a light on reliable methods for identifying IVH in premature newborns like cranial ultrasound and magnetic resonance imaging along with the treatment of IVH which is primarily supportive and involves the management of intracranial pressure, the correction of coagulation abnormalities, and the prevention of seizures.

Neurodevelopmental Outcome at Two Years for Preterm Infants With Intraventricular Hemorrhage: A Case-Control Study

BACKGROUND

High-grade intraventricular hemorrhage (IVH), including grade III and grade IV IVH, is known to impact neurodevelopmental outcome of preterm infants, but prognosis remains difficult to establish due to confounding factors and significant variations in the reported outcomes. The aim of this study was to compare the neurodevelopmental outcome of preterm infants with or without severe IVH.

METHODS

A retrospective case-control study was conducted including preterm infants with gestational age <32 weeks hospitalized between 2009 and 2017 in a level III neonatal intensive care unit. This study included 73 cases with high-grade IVH and 73 controls who were matched to cases, based on the same gestational age, birth weight, sex, and year of birth. The neurodevelopmental outcome was compared at two years of age corrected for prematurity between cases and controls. Neurodevelopmental impairment was defined as cerebral palsy, hearing deficiency, visual impairment, or developmental delay. Multivariate analysis was used to identify whether high-grade IVH was an independent risk factor for neurodevelopmental impairment.

RESULTS

In univariate analysis, high-grade IVH was associated with death or poor neurodevelopmental outcome at two years of age corrected for prematurity (odds ratio [OR], 16.3; 95% confidence interval [CI], 5.93 to 57.8; P < 0.001), and this association remained significant after adjusting for confounding factors including neonatal infection and bronchopulmonary dysplasia in multivariate analysis (OR, 8.71; 95% CI, 2.48 to 38.09; P = 0.002).

CONCLUSIONS

This study highlights the impact of high-grade IVH as an independent risk factor of poor neurodevelopmental outcomes in very preterm infants and suggests that early interventions could improve the prognosis of these infants.

Sodium supply from administered blood products was associated with severe intraventricular haemorrhage in extremely preterm infants

Aim

The aim of this study was to investigate the associations between sodium supply, fluid volume, sodium imbalances and severe intraventricular haemorrhage (IVH) in extremely preterm (EPT) infants.

Methods

We used data from the EXtremely PREterm infants in Sweden Study (EXPRESS) cohort consisting of all infants born at 22 to 26 gestational weeks from 2004 to 2007 and conducted a nested case–control study. For every infant with severe IVH (grade 3 or peri‐ventricular haemorrhagic infarction), one IVH‐free control infant with the birthday closest to the case infant and matched for hospital, sex, gestational age and birth weight was selected (n = 70 case–control pairs).

Results

Total sodium supply and fluid volume were higher in infants with severe IVH compared with controls [daily total sodium supply until postnatal Day 2: mean ± SD (mmol/kg/day): 5.49 ± 2.53 vs. 3.95 ± 1.91, p = 0.009]. These differences were accounted for by sodium and fluid from transfused blood products. High plasma sodium concentrations or large sodium fluctuations were not associated with severe IVH.

Conclusion

Our results suggest a relationship between sodium‐rich transfusions of blood products and severe IVH in EPT infants. It is unclear whether this is an effect of sodium load, volume load or some other transfusion‐related factor.

Rate of head ultrasound abnormalities at one month in very premature and extremely premature infants with normal initial screening ultrasound

BACKGROUND

Premature infants are at risk for multiple types of intracranial injury with potentially significant long-term neurological impact. The number of screening head ultrasounds needed to detect such injuries remains controversial.

OBJECTIVE

To determine the rate of abnormal findings on routine follow-up head ultrasound (US) performed in infants born at ≤ 32 weeks' gestational age (GA) after initial normal screening US.

MATERIALS AND METHODS

A retrospective study was performed on infants born at ≤ 32 weeks' GA with a head US at 3-5 weeks following a normal US at 3-10 days at a tertiary care pediatric hospital from 2014 to 2020. Exclusion criteria included significant congenital anomalies, such as congenital cardiac defects necessitating surgery, congenital diaphragmatic hernia or spinal dysraphism, and clinical indications for US other than routine screening, such as sepsis, other risk factors for intracranial injury besides prematurity, or clinical neurological abnormalities. Ultrasounds were classified as normal or abnormal based on original radiology reports. Images from initial examinations with abnormal follow-up were reviewed.

RESULTS

Thirty-three (14.2%) of 233 infants had 34 total abnormal findings on follow-up head US after normal initial US. Twenty-seven infants had grade 1 germinal matrix hemorrhage, and four had grade 2 intraventricular hemorrhage. Two had periventricular echogenicity and one had a focus of cerebellar echogenicity that resolved and was determined to be artifactual.

CONCLUSION

When initial screening head ultrasounds in premature infants are normal, follow-up screening ultrasounds are typically also normal. Abnormal findings are usually limited to grade 1 germinal matrix hemorrhage.

The impact of initial hematocrit values after birth on peri-/intraventricular hemorrhage in extremely low birth weight neonates

AIM

Peri-/intaventricular hemorrhage (P/IVH) is a common condition in preterm neonates and is responsible for substantial adverse neurological outcome especially in extremely low birth weight infants. As hematocrit after birth is a surrogate marker for blood volume, this study aimed to evaluate the effect of initial hematocrit values after birth on P/IVH development in extreme low birth weight (ELBW) neonates.

PATIENTS AND METHODS

A prospective cohort analysis of 92 eligible ELBW neonates was performed. The relationship between initial hematocrit values in ELBW neonates after birth and subsequent development of P/IVH was examined.

RESULTS

Twenty-nine of 92 infants developed P/IVH. There were significant differences in initial Hct and maximum carbon dioxide (max PCO₂) in the first 3 days levels in the P/IVH group compared with no P/IVH group. Initial Hct level at birth in the P/IVH group were significantly lower than the no P/IVH group while max PCO₂ in the first 3 days were found to be significantly high in the P/IVH group. There were no significant differences in other baseline demographic, perinatal, and neonatal characteristics while in univariate analysis, higher gestational age and initial Hct were associated with decreased likelihood of P/IVH. In multiple regression analysis after adjustment, only initial Hct remained significantly associated with P/IVH. There was no difference between the population by subgroups of IVH (IVH I-II and IVH III-IV) according to hematocrit and the severity of IVH.

CONCLUSION

Higher initial Hct at birth is associated with decreased P/IVH in ELBW infants. We hypothesized the argument that ELBW infants who have lower initial Hct at birth have less suboptimal volume status that predisposing lower cerebral blood flow and the resultant decrease in cerebral blood flow precede the development of P/IVH.

Intraventricular Hemorrhage in Very Preterm Infants: A Comprehensive Review

Germinal matrix-intraventricular-intraparenchymal hemorrhage (GMH-IVH-IPH) is a major complication of very preterm births before 32 weeks of gestation (WG). Despite progress in clinical management, its incidence remains high before 27 WG. In addition, severe complications may occur such as post-hemorrhagic hydrocephalus and/or periventricular intraparenchymal hemorrhage. IVH is strongly associated with subsequent neurodevelopmental disabilities. For this review, an automated literature search and a clustering approach were applied to allow efficient filtering as well as topic clusters identification. We used a programmatic literature search for research articles related to intraventricular hemorrhage in preterms that were published between January 1990 and February 2020. Two queries ((Intraventricular hemorrhage) AND (preterm)) were used in PubMed. This search resulted in 1093 articles. The data manual curation left 368 documents that formed 12 clusters. The presentation and discussion of the clusters provide a comprehensive overview of existing data on the pathogenesis, complications, neuroprotection and biomarkers of GMH-IVH-IPH in very preterm infants. Clinicians should consider that the GMH-IVH-IPH pathogenesis is mainly due to developmental immaturity of the germinal matrix and cerebral autoregulation impairment. New multiomics investigations of intraventricular hemorrhage could foster the development of predictive biomarkers for the benefit of very preterm newborns.

Post hemorrhagic hydrocephalus and neurodevelopmental outcomes in a context of neonatal intraventricular hemorrhage: an institutional experience in 122 preterm children

BACKGROUND

Intraventricular hemorrhage (IVH) is a frequent complication in extreme and very preterm births. Despite a high risk of death and impaired neurodevelopment, the precise prognosis of infants with IVH remains unclear. The objective of this study was to evaluate the rate and predictive factors of evolution to post hemorrhagic hydrocephalus (PHH) requiring a shunt, in newborns with IVH and to report their neurodevelopmental outcomes at 2 years of age.

METHODS

Among all preterm newborns admitted to the department of neonatalogy at Rouen University Hospital, France between January 2000 and December 2013, 122 had an IVH and were included in the study. Newborns with grade 1 IVH according to the Papile classification were excluded.

RESULTS

At 2-year, 18% (n = 22) of our IVH cohort required permanent cerebro spinal fluid (CSF) derivation. High IVH grade, low gestational age at birth and increased head circumference were risk factors for PHH. The rate of death of IVH was 36.9% (n = 45). The rate of cerebral palsy was 55.9% (n = 43) in the 77 surviving patients (49.4%). Risk factors for impaired neurodevelopment were high grade IVH and increased head circumference.

CONCLUSION

High IVH grade was strongly correlated with death and neurodevelopmental outcome. The impact of an increased head circumference highlights the need for early management. CSF biomarkers and new medical treatments such as antenatal magnesium sulfate have emerged and could predict and improve the prognosis of these newborns with PHH.

Early lumbar puncture and risk of intraventricular hemorrhage in very low birth weight infants

BACKGROUND

Lumbar puncture (LP) is the gold standard for diagnosing meningitis; however it is unknown whether early LP (≤3days of life) is associated with increased risk of intraventricular hemorrhage (IVH) in very low birth weight (VLBW) infants.

OBJECTIVE

To determine whether early LP in VLBW infants is associated with severe IVH.

METHODS

VLBW infants from a cohort of 1,158,789 infants discharged from 382 neonatal intensive care units (1997-2015) were enrolled.

EXCLUSION CRITERIA

infants with major congenital anomalies, outborns, died/transferred prior to day of life 3, and those who had an LP performed only after day of life 3. Logistic regression was used to determine the association between early LP and the incidence of severe IVH (IVH grades 3/4) by 28days of life for each day of life from day 0 (birth) to day 3, adjusting for clinical covariates.

RESULTS

106,461 infants were included: 754 received an LP on Day-0, 640 on Day-1, 559 on Day-2 and 483 on Day-3. Severe IVH occurred in 4% (4130/104,025) of the infants in the no LP group and 9% (217/2436) of the LP group. Severe IVH was higher for infants with early LP: adjusted OR (95% confidence interval)=2.64 (1.96-3.54) on Day-0; 2.21 (1.61-3.04) on Day-1; 1.55 (1.03-2.34) on Day-2; and 2.25 (1.50-3.38) on Day-3.

CONCLUSIONS

Early LP was associated with severe IVH in VLBW infants by 28days of life. LP is either a surrogate for an unrecognized factor or is itself associated with an increased risk of IVH.

The combined exposure to intra-amniotic inflammation and neonatal respiratory distress syndrome increases the risk of intraventricular hemorrhage in preterm neonates

OBJECTIVE

To evaluate the impact of combined exposure to intra-amniotic inflammation and neonatal respiratory distress syndrome (RDS) on the development of intraventricular hemorrhage (IVH) in preterm neonates.

METHODS

This retrospective cohort study includes 207 consecutive preterm births (24.0-33.0 weeks of gestation). Intra-amniotic inflammation was defined as an amniotic fluid matrix metalloproteinase-8 concentration >23 ng/mL. According to McMenamin's classification, IVH was defined as grade II or higher when detected by neurosonography within the first weeks of life.

RESULTS

(1) IVH was diagnosed in 6.8% (14/207) of neonates in the study population; (2) IVH was frequent among newborns exposed to intra-amniotic inflammation when followed by postnatal RDS [33% (6/18)]. The frequency of IVH was 7% (8/115) among neonates exposed to either of these conditions - intra-amniotic inflammation or RDS - and 0% (0/64) among those who were not exposed to these conditions; and (3) Neonates exposed to intra-amniotic inflammation and postnatal RDS had a significantly higher risk of IVH than those with only intra-amniotic inflammation [odds ratio (OR) 4.6, 95% confidence interval (CI) 1.1-19.3] and those with RDS alone (OR 5.6, 95% CI 1.0-30.9), after adjusting for gestational age.

CONCLUSION

The combined exposure to intra-amniotic inflammation and postnatal RDS markedly increased the risk of IVH in preterm neonates.

Antenatal corticosteroid treatment for the prevention of peri-intraventricular haemorrhage in preterm newborns: a retrospective cohort study using transfontanelle ultrasonography

Objective

The objective of this study was to assess the correlation between antenatal corticosteroids and peri-intraventricular haemorrhage (PIVH) using transfontanelle ultrasonography, as well as to evaluate the risk factors for its incidence.

Methods

We performed a retrospective cohort study using medical records of preterm newborns. The protocol for maternal corticoid administration for foetal lung maturation included dexamethasone 4 mg (intramuscular) 8/8 hours per 48 hours, with one cycle per week. The diagnosis of periintraventricular haemorrhage was based on transfontanelle ultrasonography, using the Papile’s classification. The following risk factors for peri-intraventricular haemorrhage were assessed: birth weight, gestational age at delivery, type of delivery, newborn’s sex, surfactant administration, premature rupture of membranes and previous history of infection during the current pregnancy. The student’s t-test and chi-square test were used for statistical analysis.

Results

Our sample population included 184 preterm newborns. Transfontanelle ultrasonography revealed peri-intraventricular haemorrhage in 32 (74.4%) and periventricular leukomalacia in 11 (25.6%) newborns. Grade I haemorrhage was found in 20 (62.5%), grade II in five (15.6%), and grade III in seven (21.8%) newborns, as in accordance with Papile’s classification. Vaginal delivery (p = 0.010), birth weight <1500 g (p = 0.024), gestational age at delivery ≤32 weeks (p = 0.018), and previous history of infection during pregnancy (p = 0.013) were considered risk factors for peri-intraventricular haemorrhage in preterm newborns.

Conclusion

Maternal corticoid administration for foetal lung maturation showed a protective effect against peri-intraventricular haemorrhage in preterm newborns. The risk factors for peri-intraventricular haemorrhage were determined.

Ventriculomegaly in very-low-birthweight infants with Down syndrome

AIM

The prevalence of Down syndrome in infants with fetal ventriculomegaly is 5% to 10%; however, the converse, the prevalence of cerebral ventriculomegaly in live-born infants with Down syndrome, is not well established. Because cranial ultrasounds are performed on most very-low-birthweight (VLBW) infants (birthweight <1500g), our aim was to examine ultrasound abnormalities of VLBW infants to determine prevalence of ventriculomegaly and intraventricular hemorrhage (IVH) in VLBW infants with Down syndrome, and whether VLBW infants with Down syndrome are at higher risk for cranial ultrasound abnormalities, compared with the already elevated risk in other VLBW infants.

METHOD

This study comprised retrospective analysis of data from Pediatrix BabySteps Clinical Data Warehouse. The study population consisted of 121 736 VLBW infants (61 869 males, 59 867 females), born between 1996 and 2013, of whom 441 had Down syndrome (233 males, 208 females; mean gestational age 30wks, standard deviation [SD] 2.8wks). Logistic regression was used to calculate odds of ventriculomegaly and IVH for Down syndrome.

RESULTS

Prevalence of ventriculomegaly in Down syndrome was 5.2% compared with 0.8% in other VLBW infants. Multivariate analysis indicated 5.8× odds (95% confidence interval [CI] 3.4-9.7) of ventriculomegaly in Down syndrome and 0.9× odds (95% CI 0.7-1.1) of IVH for Down syndrome.

INTERPRETATION

Very preterm infants with Down syndrome are at increased risk for ventriculomegaly (but not for IVH) compared with other infants born very preterm.

Cerebral blood flow assessment of preterm infants during respiratory therapy with the expiratory flow increase technique

Objective:

To assess the impact of respiratory therapy with the expiratory flow increase technique on cerebral hemodynamics of premature newborns.

Methods:

This is an intervention study, which included 40 preterm infants (≤34 weeks) aged 8-15 days of life, clinically stable in ambient air or oxygen catheter use. Children with heart defects, diagnosis of brain lesion and/or those using vasoactive drugs were excluded. Ultrasonographic assessments with transcranial Doppler flowmetry were performed before, during and after the increase in expiratory flow session, which lasted 5min. Cerebral blood flow velocity and resistance and pulsatility indices in the pericallosal artery were assessed.

Results:

Respiratory physical therapy did not significantly alter flow velocity at the systolic peak (p=0.50), the end diastolic flow velocity (p=0.17), the mean flow velocity (p=0.07), the resistance index (p=0.41) and the pulsatility index (p=0.67) over time.

Conclusions:

The expiratory flow increase technique did not affect cerebral blood flow in clinically-stable preterm infants.

[Cerebral blood flow assessment of preterm infants during respiratory therapy with the expiratory flow increase technique]

OBJECTIVE

To assess the impact of respiratory therapy with the expiratory flow increase technique on cerebral hemodynamics of premature newborns.

METHODS

This is an intervention study, which included 40 preterm infants (≤34 weeks) aged 8-15 days of life, clinically stable in ambient air or oxygen catheter use. Children with heart defects, diagnosis of brain lesion and/or those using vasoactive drugs were excluded. Ultrasonographic assessments with transcranial Doppler flowmetry were performed before, during and after the increase in expiratory flow session, which lasted 5minutes. Cerebral blood flow velocity and resistance and pulsatility indices in the pericallosal artery were assessed.

RESULTS

Respiratory physical therapy did not significantly alter flow velocity at the systolic peak (p=0.50), the end diastolic flow velocity (p=0.17), the mean flow velocity (p=0.07), the resistance index (p=0.41) and the pulsatility index (p=0.67) over time.

CONCLUSIONS

The expiratory flow increase technique did not affect cerebral blood flow in clinically-stable preterm infants.

Comparison of new modeling methods for postnatal weight in ELBW infants using prenatal and postnatal data

OBJECTIVES

Postnatal infant weight curves are used to assess fluid management and evaluate postnatal nutrition and growth. Traditionally, postnatal weight curves are based on birth weight and do not incorporate postnatal clinical information. The aim of the present study was to compare the accuracy of birth weight-based weight curves with weight curves created from individual patient records, including electronic records, using 2 predictive modeling methods, linear regression (LR) and an artificial neural network (NN), which apply mathematical relations between predictor and outcome variables.

METHODS

Perinatal demographic and postnatal nutrition data were collected for extremely-low-birth-weight (ELBW; birth weight <1000 g) infants. Static weight curves were generated using published algorithms. The postnatal predictive models were created using the demographic and nutrition dataset.

RESULTS

Birth weight (861 ± 83 g, mean ± 1 standard deviation [SD]), gestational age (26.2 ± 1.4 weeks), and the first month of nutrition data were collected from individual health records for 92 ELBW infants. The absolute residual (|measured-predicted|) for weight was 84.8 ± 74.4 g for the static weight curves, 60.9 ± 49.1 g for the LR model, and 12.9 ± 9.2 g for the NN model, analysis of variance: both LR and NN P<0.01 versus static curve. NPO (nothing by mouth) infants had greater weight curve discrepancies.

CONCLUSIONS

Compared with birth weight-based and logistic regression-generated weight curves, NN-generated weight curves more closely approximated ELBW infant weight curves, and, using the present electronic health record systems, may produce weight curves better reflective of the patient's status.

Neurodevelopmental outcomes of extremely preterm infants

Survival of extremely preterm infants has improved since 2000. Neurodevelopmental impairment rates remain high at the limits of viability. Although improved survival and neurodevelopmental impairment rates are associated with higher gestational age and more recent year of birth, significant variability in findings among geographic areas and networks is evident, and seems related to differences in population, management style, regional protocols, definitions, and outcome assessments. Outcome studies during adolescence and young adult age are needed to determine the long-term impact of extremely preterm birth.

Predictive value of the Bayley scales of infant development on development of very preterm/very low birth weight children: a meta-analysis

BACKGROUND AND AIMS

The Bayley scales of infant development (BSID) is the most widely used measure to assess neurodevelopment of very preterm (gestational age ≤32 weeks) and very low birth weight (VLBW, ≤1500 g) infants in the first three years of life. This meta-analysis determines the predictive value of the mental developmental index (MDI) and the psychomotor developmental index (PDI)/motor composite, collectively referred to as Bayley motor scale, of the BSID-I, -II and Bayley-III for later cognitive and motor functioning in very preterm/VLBW children.

METHODS

Cochrane Library, PubMed, PsychINFO and CINAHL were searched for English-language peer-reviewed studies published before March 2013. Studies were included if they reported odds ratios or correlations between the MDI or Bayley motor scale scores obtained in the first three years of life, and standardized cognitive or motor assessment obtained later in life in very preterm/VLBW children. Meta-analytic methods were applied to aggregate available data.

RESULTS

A total of 16 studies met inclusion criteria. Across 14 studies (n=1330 children), MDI scores were strongly predictive for later cognitive functioning, r=0.61 (95% CI: 0.57-0.64), explained variance 37%, p<.001. The relationship between MDI scores and later cognitive function was not mediated by birth weight (p=.56), gestational age (p=.70), and time interval between assessments (p=.55). Across five studies (n=555 children), Bayley motor scale scores were moderately predictive for later motor function, r=0.34 (95% CI: 0.26-0.42), explained variance 12%, p<.001.

CONCLUSIONS

In very preterm/VLBW children, MDI scores explain 37% of the variance in later cognitive functioning, whereas Bayley motor scale scores explain 12% of later motor function. Thus a large proportion of the variance remains unexplained, underlining the importance of enhancing prediction of developmental delay in very preterm children.

Neutral head positioning in premature infants for intraventricular hemorrhage prevention: an evidence-based review

With the advancement of neonatal medicine during the past several decades, premature and critically ill infants are living past the neonatal period and surviving. The survival of these infants at smaller birth weights and younger gestational ages puts them at an increased risk for intraventricular hemorrhages (IVHs). Although shifts in cerebral perfusion have been linked to the development of these brain bleeds, many seemingly benign care activities have been linked to changes in cerebral blood flow patterns, possibly contributing to IVHs. The purpose of this article is to evaluate the current evidence to determine if the practice of midline positioning for infants born less than 32 weeks gestation for possible IVH prevention is supported by the literature. Many of the researchers involved in these studies attributed the consequential venule leakage of blood to occlusion of the jugular venous drainage system following a turn in the position of the head. Additionally, the articles that examined the connection between the effects of head tilting on brain hemodynamics attributed changes on the infants' potential inability to autoregulate cerebral blood flow adequately. Both of these findings were linked to the development of IVHs. Based on physiologic data and expert opinion, the authors found support in the literature and recommend implementing a plan of care that includes midline head positioning for premature infants.

Comparative effects of glucose- and mannitol-induced osmolar stress on blood-brain barrier function in ovine fetuses and lambs

We examined the effects of hyperglycemic hyperosmolality on blood-brain barrier (BBB) permeability during development. We hypothesized that the barrier becomes more resistant to hyperglycemic hyperosmolality during development, and the immature BBB is more resistant to glucose than to mannitol hyperosmolality. We quantified the BBB response to hyperosmolality with the blood-to-brain transfer constant (K(i)) in immature fetuses, premature, and newborn lambs. K(i) increased as a function of increases in osmolality. A segmented regression model described the relationship between K(i) and osmolality. At lower osmolalities, changes in K(i) were minimal but after a threshold, increases were linear. We examined responses of K(i) to hyperglycemic hyperosmolality by comparing the thresholds and slopes of the second regression segments. Lower thresholds and steeper slopes indicate greater vulnerability to hyperosmolality. Thresholds increased (P<0.05) during development in pons and superior colliculus. Thresholds were higher (P<0.05) during glucose than mannitol hyperosmolality in thalamus, superior colliculus, inferior colliculus and medulla of premature lambs, and in cerebrum and cerebellum of newborns. We conclude that BBB permeability increased as a function of changes in glucose osmolality, the barrier becomes more resistant to glucose hyperosmolality in two brain regions during development, and the barrier is more resistant to glucose than to mannitol hyperosmolality in some brain regions of premature and newborn lambs.

Correlation between fetal heart rate reactivity and mortality and severe neurological morbidity in extremely low birth weight infants

OBJECTIVE

To determine the correlation between specific fetal heart rate (FHR) abnormalities and the incidence of death, severe (grade 3-4) intraventricular hemorrhage (IVH) and periventricular echogenicity (PVE) in extremely low birth weight infants (ELBW) within the first 4 days after birth.

METHODS

The study included live-born ELBW infants ≤ 30 weeks' gestation who were born in 2000-2007 at Kaplan Medical Center, Rehovot, Israel, and, who had FHR monitoring during the 24 h before delivery and cranial ultrasound during the first 4 days of life. FHR pattern was analyzed for the presence of baseline rate, reactivity, variability and decelerations.

RESULTS

96 infants with mean birth weight 757 ± 150 g and mean gestational age 25.8 ± 1.5 weeks were included. By 4 days of life, 23/96 (24%) died, 17/96 (18%) developed severe IVH and 31/96 (32%) had PVE. Absence of reactivity was significantly associated with increase in both death (p = 0.02, OR 3.45, 95% CI: 1.22-9.47 and severe IVH (p = 0.029, OR 3.33, 95% CI: 1.25-10) but not with PVE. Other FHR parameters were not associated with adverse outcome.

CONCLUSION

These results suggest that FHR reactivity may be of value in predicting short-term outcome in ELBW infants. This may be helpful in counseling parents with imminent extremely preterm birth.

Hypernatremia and grade III/IV intraventricular hemorrhage among extremely low birth weight infants

OBJECTIVE

To identify the risk factors contributing to intraventricular hemorrhage (IVH) in extremely low birth weight infants during early postnatal life, after appropriate matching for gestational age (GA) and birth body weight (BBW).

STUDY DESIGN

A case-control retrospective study was designed to evaluate preterm infants with a GA ≤ 26 weeks and a BBW ≤ 1000 g admitted to our hospital during a 7.5-year period. From a cohort of 347 preterm infants, 36 infants (10.7%) had severe IVH (grades III and/or IV). We selected a control group of 36 preterm infants without IVH who were closely matched for GA (± 1 week) and body weight (± 100 g). Univariate and multivariate logistic regression analyses were performed to identify risk factors for severe IVH.

RESULT

The GA and BBW of the IVH and control groups were 24.6 ± 1 weeks and 764.4 ± 118.5 g, and 24.8 ± 0.9 weeks and 771.5 ± 125.9 g, respectively. Vaginal delivery, male sex, resuscitation in the delivery room, high sodium serum levels (meq l(-1)) (162.6 vs 148.8), fluctuation of serum sodium (meq l(-1)) (17.3 vs 6.2), pH, PaCO(2), hemoglobin and platelet counts were associated with an increased risk of severe IVH. Multivariate logistic regression indicated that sodium fluctuations >13 meq l(-1), vaginal delivery, male sex and hemoglobin fluctuations are strongly associated with the development of severe IVH.

CONCLUSION

Hypernatremia and fluctuations of sodium seem to be related to early severe IVH among preterm infants; however, further studies are required to clarify the causal relationship.

Effect of the dose volume of perfluorocarbon when starting partial liquid ventilation

OBJECTIVE

Very preterm neonates are prone to brain injury if cerebral blood flow fluctuates. Partial liquid ventilation (PLV) may benefit any lung disease but giving 30 mL/kg of perfluorocarbon when starting PLV increases cortical cerebral blood flow velocity. We aimed to determine if varying the initial dose of perfluorocarbon alters the effect on cerebral blood flow velocity when starting PLV.

METHODS

In this randomised, controlled trial with historical comparison 24 preterm lambs received one of three loading doses of intratracheal perfluorocarbon liquid over 20 min when starting PLV: 20, 30 or 40 mL/kg. Data on respiratory mechanics, haemodynamics and cerebral blood flow velocity, measured with laser Doppler, were collected continuously for 30 min from the start of dosing.

RESULTS

Cortical cerebral blood flow velocity increased over time in all three groups (two-way ANOVA, P= 0.007). There was no difference between groups (two-way ANOVA, P= 0.26). There was no difference between groups in cortical cerebral blood flow velocity variability (P= 0.68), blood pressure (P= 0.96) or heart rate (P= 0.46). The was no statistically significant difference in PaCO(2) between groups measured at baseline and at 30 min after starting PLV (P= 0.51).

CONCLUSIONS

  Cortical cerebral blood flow velocity and its variability are not affected by varying doses of tracheal perfluorocarbon (20, 30 or 40 mL/kg) at the start of PLV in preterm lambs.

General evaluation of periventricular-intraventricular hemorrhage in premature infants in mainland China

OBJECTIVE

To explore the incidence and analyze the high risk factors of PIVH in premature infants in mainland China.

MATERIALS AND METHODS

A total of 1122 premature infants at <37 weeks gestation were enrolled in this study. All the infants received intracranial ultrasound examinations within 1 week after birth, and the perinatal data were recorded to analyze the high risk factors for PIVH.

RESULTS

The results showed that the incidence rate of PIVH was 55.2% in mainland Chinese population. Among these cases, mild degrees of PIVH accounted for 82.2% and severe degrees of PIVH accounted for only 17.8%. The most important risk factors related to PIVH were low gestational age, low birth weight, low Apgar score and ventilatory treatment, etc.

CONCLUSIONS

It suggested that there were many high risk factors related to PIVH in premature infants and a screening cutoff point of 2000 g appeared to be more adequate for China.

Elevated cerebral pressure passivity is associated with prematurity-related intracranial hemorrhage

OBJECTIVES

Cerebral pressure passivity is common in sick premature infants and may predispose to germinal matrix/intraventricular hemorrhage (GM/IVH), a lesion with potentially serious consequences. We studied the association between the magnitude of cerebral pressure passivity and GM/IVH.

PATIENTS AND METHODS

We enrolled infants <32 weeks' gestational age with indwelling mean arterial pressure (MAP) monitoring and excluded infants with known congenital syndromes or antenatal brain injury. We recorded continuous MAP and cerebral near-infrared spectroscopy hemoglobin difference (HbD) signals at 2 Hz for up to 12 hours/day and up to 5 days. Coherence and transfer function analysis between MAP and HbD signals was performed in 3 frequency bands (0.05-0.25, 0.25-0.5, and 0.5-1.0 Hz). Using MAP-HbD gain and clinical variables (including chorioamnionitis, Apgar scores, gestational age, birth weight, neonatal sepsis, and Score for Neonatal Acute Physiology II), we built a logistic regression model that best predicts cranial ultrasound abnormalities.

RESULTS

In 88 infants (median gestational age: 26 weeks [range 23-30 weeks]), early cranial ultrasound showed GM/IVH in 31 (37%) and parenchymal echodensities in 10 (12%) infants; late cranial ultrasound showed parenchymal abnormalities in 19 (30%) infants. Low-frequency MAP-HbD gain (highest quartile mean) was significantly associated with early GM/IVH but not other ultrasound findings. The most parsimonious model associated with early GM/IVH included only gestational age and MAP-HbD gain.

CONCLUSIONS

This novel cerebrovascular monitoring technique allows quantification of cerebral pressure passivity as MAP-HbD gain in premature infants. High MAP-HbD gain is significantly associated with GM/IVH. Precise temporal and causal relationship between MAP-HbD gain and GM/IVH awaits further study.

The effects of perinatal morbidity and environmental factors on health status of preterm children at age 12

Children born prematurely have later morbidity, yet little is known about their health in adolescence. This study examined multiple dimensions of health at age 12 and the predictors of biological, behavioral, social, and physical environmental factors. Analysis of variance and logistic regression models were tested. Perinatal morbidity predicted health at age 12. Preterm status increases the risk of later alterations in health. Bronchopulmonary dysplasia, necrotizing enterocolitis, intraventricular hemorrhage, small-for-gestational age, parental perception of child health, and parental psychological distress affect later health. Prematurity and perinatal morbidity continue to impact child health 12 years after birth.

Continuity between Fetal and Neonatal Neurobehavior

As the development of the brain is unique and continuing process throughout the gestation and after birth, it is expected that there is also continuity of fetal and neonatal movements which are the best functional indicator of developmental processes of the brain. Understanding the relation between fetal and infant behavior and developmental processes of the brain in different periods of gestation may make achievable the distinction between normal and abnormal brain development. Epidemiological studies revealed that many neurologically impaired infants belong to low risk population, which means that they seemed to be developmentally normal as fetuses and as infants, while later childhood neurological disability was diagnosed. Which methods of neurological assessment are available for that purpose? Prenatally we have not many possibilities for neurological assessment, while postnatally the repertoire of diagnostic possibilities is increasing. Among the postnatally available methods for neurological assessment, the most important are: clinical neurological assessment, neuroimaging methods, assessment of general movements (GMs) and combinations. Postnatal neurological assessment is probably easier to perform than prenatal, by using a simple and suitable for everyday work screening clinical test with good reliability, specificity and sensitivity.

There is a possibility for the early and simple neurological assessment of the term and preterm newborns with the aim to detect associated risks and anticipate long-term outcome of the infant, and to establish a possible causative link between pregnancy course and neurodevelopmental outcome. The evaluation of infant's developmental optimality should be assessed in order to investigate whether the infant is neurologically normal or damaged. Neurological assessment at term by Amiel-Tison (ATNAT) is taking into account neurological maturation exploring so called lower subcortical system developing earlier from the reticular formation, vestibular nuclei and tectum, and upper cortical system developing from the corticospinal pathways.

Conventional acquisition neuroimaging techniques together with modern diffusion neuroimaging techniques can identify typical patterns of brain injury, even in the early course of the disease. However, even though highly suggestive, these patterns cannot be considered as pathognomonic. Nevertheless neuroimaging methods alone are not sufficient to predict the neurological outcome in neonates from highrisk population.

Prechtl stated that spontaneous motility, as the expression of spontaneous neural activity, is a marker of brain proper or disturbed function. The observation of unstimulated fetus or infant which is the result of spontaneous behavior without sensory stimulation is the best method to assess its central nervous system capacity. All endogenously generated movement patterns from un-stimulated central nervous system could be observed as early as from the 7-8 weeks of postmenstrual age, with developing a reach repertoire of movements within the next two or three weeks, continuing to be present for 5 to 6 months postnatally. This remarkable fact of the continuity of endogenously generated activity from prenatal to postnatal life is the great opportunity to find out those high-risk fetuses and infants in whom development of neurological impairment is emerging. The most important among those movements are GMs involving the whole body in a variable sequence of arm, leg, neck and trunk movements, with gradual beginning and the end. They wax and wane in intensity, force and speed being fluent and elegant with the impression of complexity and variability. Assessment of GMs in high-risk newborns has significantly higher predictive value for later neurological development than neurological examination. Kurjak and co-workers conducted a study by 4D ultrasound and confirmed earlier findings made by 2D ultrasonography, that there is behavioral pattern continuity from prenatal to postnatal life. Assessment of neonatal behavior is a better method for early detection of cerebral palsy than neurological examination alone.

Are we approaching the era when there will be applicable neurological test for fetus and assessment of neonate will be just the continuation? This is still not easy question to answer, because even postnatally there are several neurological methods of evaluation, while in utero we are dealing with more complicated situation and less mature brain. Could neonatal assessment of neurologically impaired fetuses bring some new insights into their prenatal neurological status is still unclear and to be investigated. New scoring system for prenatal neurological assessment of the fetus proposed by Kurjak et al will give some new possibilities to detect fetuses at high neurological risk, although it is obvious that dynamic and complicated process of functional CNS development is not easy to investigate.

The aim of this review is to present continuity of the functional central nervous system assessment from prenatal to postnatal life.

Hyperglycemia is a risk factor for early death and morbidity in extremely low birth-weight infants

OBJECTIVES

The objectives of this study were to determine the prevalence of hyperglycemia in extremely low birth-weight infants and to determine whether hyperglycemia increases the risk of early adverse outcomes (death or intraventricular hemorrhage of grade 3 or 4) and/or affects the length of hospital stay among survivors without intraventricular hemorrhage.

METHODS

The charts of all extremely low birth-weight infants (n = 93) admitted to Texas Children's Hospital (Houston, TX) during 2001 were reviewed. The highest daily blood glucose concentrations, highest dopamine infusion rates, highest daily percentage of inspired oxygen, and mean blood sodium concentrations were averaged over the first week of life or before death or occurrence of grade 3 or 4 intraventricular hemorrhage. Among survivors without severe intraventricular hemorrhage, the time ratio for blood glucose concentrations of >150 mg/dL was calculated.

RESULTS

More than 50% of the infants had persistent blood glucose concentrations of >150 mg/dL during their first week of life. Early adverse outcomes were associated with the average highest daily blood glucose concentration through interaction with the Clinical Risk Index for Babies score and with the average highest daily percentage of inspired oxygen. The length of hospital stay was associated with the time ratio for blood glucose concentrations of >150 mg/dL through interaction with birth weight and the average highest daily percentage of inspired oxygen.

CONCLUSION

These data confirm the high prevalence of hyperglycemia among parenterally fed, extremely low birth-weight infants and show that high blood glucose concentrations increase the risk of early death and grade 3 or 4 intraventricular hemorrhage and the length of hospital stay among survivors without intraventricular hemorrhage, which suggests that prevention and treatment of hyperglycemia may improve the outcomes of extremely low birth-weight infants.

The incidence, timing, and predisposing factors of germinal matrix and intraventricular hemorrhage (GMH/IVH) in preterm neonates

BACKGROUND

Germinal matrix and intraventricular hemorrhage (GMH/IVH) is a known complication occurring in the first week of life in preterm neonates. However, the precise time of its occurrence and the ideal time to perform diagnostic imaging studies remain controversial. The purpose of this paper is to address these two issues in our patient population to allocate our resources to those at highest risk.

MATERIALS AND METHODS

This study included 282 premature newborns (under 37 weeks of gestation) that were admitted to our neonate ICU in a year's time and screened for GMH/IVH. They were grouped in four categories according to their weight at birth, and according to their gestational age. All patients had a daily cranial ultrasound during the first week. It was then repeated once in the second week and once in the third.

RESULTS

We found that the incidence of GMH/IVH among preterm neonates was 44.68%. It was inversely related to the weight and the age of the newborn. The onset of bleeding coordinated with the occurrence of hypoxia and respiratory distress requiring mechanical ventilation. The majorities occurred in the first 7 days of life; they were mostly grade I and II according to the Papule classification and silent for the most part. Complications were present in 41% of the survivors.

Neurodevelopmental outcome in children with intraventricular hemorrhage

To clarify the neurodevelopmental outcome in children with intraventricular hemorrhage, a follow-up study was performed for a consecutive group of 335 subjects in one tertiary center born between 1981 and 1999. Their mean gestation and birth weight were 28.1 weeks and 1162.2 gm, respectively. The follow-up period ranged from 3 to 20 years (mean: 7.5 years). The neurodevelopmental outcomes were normal in 188 (56.1%), cerebral palsy in 75 (22.4%), mental retardation in 34 (10.2%), and borderline intelligence in 38 (11.3%). There were statistically significant differences in the outcomes among the groups with different grades of intraventricular hemorrhage. Approximately 70% of the children with intraventricular hemorrhage grade 1 were normal, whereas only 15.4% of the children with intraventricular hemorrhage grade 4 were normal. Cerebral palsy was associated with as high as 71.2% in the patients with intraventricular hemorrhage grade 4. The overall incidence of epilepsy was 39/335 (11.6%). This study has not demonstrated clear improvement of the outcome in children with intraventricular hemorrhage between the 1980s and 1990s.

Volume-targeted ventilation and arterial carbon dioxide in neonates

OBJECTIVES

To review the arterial carbon dioxide tensions (PaCO(2)) in newborn infants ventilated using synchronized intermittent mandatory ventilation (SIMV) in volume guarantee mode (using the Dräger Babylog 8000+) with a unit policy targeting tidal volumes of approximately 4 mL/kg.

METHODS

Data on ventilator settings and arterial PaCO(2) levels were collected on all arterial blood gases (ABG; n = 288) from 50 neonates (<33 weeks gestational age) ventilated using the Dräger Babylog 8000+ ventilator (Dräger Medizintechnik GmbH, Lübeck, Germany) in SIMV plus volume guarantee mode. Data were analysed for all blood gases done on the entire cohort in the first 48 h of life and a subanalysis was done on the first gas for each infant (n = 38) ventilated using volume guarantee from admission to the nursery. The number of ABG showing severe hypocapnoea (PaCO(2) < 25 mmHg) and/or severe hypercapnoea (PaCO(2) > 65 mmHg) were determined.

RESULTS

The mean (SD) PaCO(2) during the first 48 h was 46.6 (9.0) mmHg. The mean (SD) PaCO(2) on the first blood gas of those infants commenced on volume guarantee from admission was 45.1 (12.5) mmHg. Severe hypo- or hypercapnoea occurred in 8% of infants at the time of their first blood gas measurement, and in <4% of blood gas measurements in the first 48 h.

CONCLUSIONS

Infants ventilated with volume guarantee ventilation targeting approximately 4 mL/kg (range: 2.9-5.1) have acceptable PaCO(2) levels at the first blood gas measurement and during the first 48 h of life; and avoid severe hypo- or hypercapnoea over 90% of the time.

Neurodevelopmental outcome in children with posthemorrhagic hydrocephalus

To determine the factors affecting the neurodevelopmental outcome in children with posthemorrhagic hydrocephalus, 78 children with intraventricular hemorrhage grade 3 or 4 were analyzed concerning the outcome in relation to the grade of intraventricular hemorrhage and intervention (surgical, medical, or no intervention) by means of a follow-up study. The mean age of the subjects at the last follow-up was 9.8 years. In children with intraventricular hemorrhage grade 4 with parenchymal hemorrhage, the outcomes in the group not requiring intervention were better than those in the groups requiring intervention, whereas in children with intraventricular hemorrhage grade 3 without parenchymal hemorrhage, there were no differences in the outcomes among the three groups with and without intervention. For the subjects who had undergone the same intervention, the outcomes in children with intraventricular hemorrhage grade 4 were worse than those in children with intraventricular hemorrhage grade 3. The outcomes in the children with surgical intervention only correlated with the grade of intraventricular hemorrhage. From these findings, we concluded that the outcomes in children with posthemorrhagic hydrocephalus were far more affected by the existence or extent of parenchymal hemorrhage than by the hydrocephalic process, which was suggested to be effectively controlled by the intervention.

Increased temporal lobe gyrification in preterm children

Preterm birth often results in significant learning disability, and previous magnetic resonance imaging (MRI) studies of preterm children have demonstrated reduction in overall cortical tissue with particular vulnerability in the temporal lobe. We measured cortical gyrification in 73 preterm and 33 term control children at 8 years of age and correlated these findings with tests of language ability to determine the associations among preterm birth, neurodevelopment and functional outcome. Preterm children demonstrated significantly increased bilateral temporal lobe gyrification index compared to term controls. Left temporal gyrification index was significantly negatively correlated with left temporal lobe gray matter volume as well as reading recognition scores in the preterm group. Cortical development in the temporal lobe appears to be differentially vulnerable to preterm birth.

Intraventricular hemorrhage in the premature neonate

Intraventricular hemorrhage in the premature neonate has been and continues to be a cause of morbidity and mortality in NICUs around the globe. Much information is available concerning the etiology and preventative and treatment strategies to reduce the incidence of IVH in this patient population. As neonatal caregivers are struggling to care for and protect infants who are surviving despite extreme prematurity, this survival is complicated by the infant's cerebral vasculature, which is very susceptible to hemorrhage; by respiratory problems that require the use of lifesaving, but potentially harmful, ventilation interventions; and by the infant's compromised ability to self-regulate vascular responses to stress. The preventative treatments being explored and proposed may come with debilitating and potentially lethal sequelae. Research continues, however. New recommendations are being proffered, and perhaps, in the near future, the incidence of IVH and its associated morbidity and mortality will decline dramatically.

Morphometric assessment of collagen accumulation in germinal matrix vessels of premature human neonates

Germinal matrix haemorrhage in premature neonates is commonly attributed to vascular immaturity, possibly related to an abbreviated process of angiogenesis. Terminal steps in the progression of angiogenesis are the formation of a subendothelial basal lamina containing collagen IV and an extracellular matrix containing collagens I and III. Immature vessels would predictably be deficient in these collagen subtypes. We analysed germinal matrix (GM), cortical, and white matter (WM) vessels with antibodies specific for collagens I, III and IV to test the hypothesis that GM vessels are immature. Brains were collected during post-mortem from prematurely born human neonates ranging in age from 17 weeks to 36 weeks postconception. All GM vessels were immunoreactive for collagen subtypes I, III and IV. Using digital image analysis, collagen IV immunoperoxidase-labelling was measured in vessels in GM, cortex and WM. Intensity values in GM and WM were normalized relative to cortical intensity within the same subject. At week 17 of gestation, GM vessels exhibited a higher concentration of collagen IV than did WM or cortical vessels. Regression analysis demonstrated that collagen intensity in GM was greater than that in cortex and WM at all stages. We conclude that GM vessels in even the youngest, prematurely born, viable neonates do not exhibit evidence of structural immaturity. The high incidence of GM haemorrhage in premature neonates may be related to factors other than a deficiency in accumulated collagen.

Asymmetry of Cerebral Blood Flow Velocity in Low Birth Weight Infants

BACKGROUND

In premature infants, intraventricular hemorrhage occurs more commonly in the left than the right hemisphere. We have demonstrated previously that cerebral blood flow velocity is lower in the left than the right middle cerebral artery in the first few hours after birth. This may be due to the open ductus arteriosus.

OBJECTIVE

To test the hypothesis that blood flow velocity is lower in the left than the right middle cerebral artery only when the ductus arteriosus is open.

STUDY DESIGN

Infants born at 25-33 weeks' gestation were enrolled. Middle cerebral artery blood flow velocities and coefficients of variation were measured on the left, followed by the right, on days 1 and 7 of life. Echocardiography identified 67 infants (25-33 weeks, 517-2,371 g) whose ductus arteriosus was open on day 1 and closed on day 7.

RESULTS

Systolic (26.4 +/- 7.4 vs. 29.6 +/- 7.2 cm/s), mean (12.4 +/- 4.0 vs. 15.6 +/- 4.6 cm/s) and end-diastolic (5.3 +/- 2.2 vs. 6.8 +/- 2.9 cm/s) blood flow velocities were lower (p < 0.01) and the corresponding coefficients of variation were higher (p < 0.01) on the left on day 1. Neither the absolute Doppler blood flow velocities nor the coefficients of variation differed between the left and right sides on day 7.

CONCLUSIONS

Blood flow velocity is lower and more variable in the left compared to the right middle cerebral artery on day 1 of life in premature infants. These differences are not found on day 7. We speculate that this difference is due to the associated ductus arteriosus patency.

Chronic neonatal hypoxia leads to long term decreases in the volume and cell number of the rat cerebral cortex

Preterm birth results in significant neurodevelopmental disability. The neonatal rodent model of chronic sublethal hypoxia faithfully mimics the effect of preterm birth on the developing brain. We employed this model to test the hypothesis that the hypoxia that accompanies preterm birth results in inappropriate signaling of apoptotic mechanisms in developing brain. We performed cortical cell counts, determinations of neuronal size and Western analyses of the apoptosis related proteins, Bcl-2 and Bax, in rat pups who were raised in chronic hypoxia (FiO2 9.5%) beginning on postnatal day 3 (P3) and extending for either 10 (P13) or 30 (P33) days. A third group of animals was exposed to 30 days of hypoxia followed by an additional 30 days in a normoxic environment (P63) to assess the potential for recovery from the initial effects of hypoxia. Age matched control pups were raised in room air throughout the experimental time period. Assessment of cortical cell number revealed a 25% reduction (P < 0.01) in total cell number following 30 days of hypoxic rearing. Glia were significantly reduced by 34% and 41% after 10 and 30 days of hypoxia, respectively, while neuron numbers were only significantly reduced (14%) after 30 days of hypoxia. Animals exposed to a hypoxic environment for 30 days followed by 30 days in a normoxic environment revealed some recovery of glial cell numbers, but no significant recovery of neuronal cell numbers. Measurement of cell size at both P13 and P33 revealed that neurons of layer III were significantly smaller in cross-sectional area in hypoxic compared with control rats (P < 0.01). However, no significant difference was noted in neuronal size following 30 days of normoxic recovery. Western blot analyses of Bcl-2 and Bax protein levels demonstrated a ratio favorable to Bax at multiple time points during the period of hypoxic exposure. These data suggest that chronic exposure to hypoxia during the perinatal period alters the production and maintenance of glial and neuronal cells and that glia and neurons demonstrate differential patterns of vulnerability and recovery following subsequent periods of normoxic exposure. It is hypothesized that the mechanisms responsible for these alterations in cortical cell number may depend on the state of differentiation of the different cell types at the time of hypoxic exposure.

Volumetric analysis of regional cerebral development in preterm children

Preterm birth is frequently associated with both neuropathologic and cognitive sequelae. This study examined cortical lobe, subcortical, and lateral ventricle development in association with perinatal variables and cognitive outcome. High-resolution volumetric magnetic resonance imaging scans were acquired and quantified using advanced image processing techniques. Seventy-three preterm and 33 term control children ages 7.3-11.4 years were included in the study. Results indicated disproportionately enlarged parietal and frontal gray matter, occipital horn, and ventricular body, as well as reduced temporal and subcortical gray volumes in preterm children compared with control subjects. Birth weight was negatively correlated with parietal and frontal gray, as well as occipital horn volumes. Intraventricular hemorrhage was associated with reduced subcortical gray matter. Ventricular cerebrospinal fluid was negatively correlated with subcortical gray matter volumes but not with white matter volumes. Maternal education was the strongest predictor of cognitive function in the preterm group. Preterm birth appears to be associated with disorganized cortical development, possibly involving disrupted synaptic pruning and neural migration. Lower birth weight and the presence of intraventricular hemorrhage may increase the risk for neuroanatomic abnormality.

Intracranial hemorrhage in premature neonates treated with extracorporeal membrane oxygenation correlates with conceptional age

OBJECTIVE

To determine the effect of patient age on the risk of intracranial hemorrhage (ICH) in premature neonates treated with extracorporeal membrane oxygenation (ECMO).

STUDY DESIGN

This was a retrospective cohort study of neonates of <37 weeks' gestation treated with ECMO in the years 1992 through 2000 and reported to the Extracorporeal Life Support Organization Registry (n=1524). The relation between ICH and patient age, defined as gestational age, postnatal age (PNA), and postconceptional age (PCA), was determined with the use of multiple logistic regression analysis.

RESULTS

PNA was inversely correlated with ICH in the univariate analysis (P=.01) but not in the multivariate analysis (P=.36). PCA showed a strong univariate correlation with decreasing ICH: 26% of patients </=32 weeks' PCA developed ICH as compared with 6% of patients with PCA of 38 weeks (P=.004). Multiple logistic regression identified as independent predictors of ICH: PCA (P=.005), sepsis (P=.004), acidosis (P=.0004), and treatment with sodium bicarbonate (P=.002). Gestational age was correlated with ICH in the multivariate model only when PNA was included.

CONCLUSIONS

Postnatal age is not a strong independent predictor of ICH in premature neonates treated with ECMO. PCA is the best age-related predictor of ECMO-related ICH in premature infants.

School performance in adolescents with and without periventricular-intraventricular hemorrhage in the neonatal period

Long-term sequelae of preterm birth have been studied extensively up until the age of 5 to 8 years. However, the cognitive development of adolescents born preterm has received limited attention. The objective of this study is to determine school performance in adolescents born very preterm. We have followed up a cohort of 484 infants born before 32 weeks of gestation in whom cranial ultrasound was routinely and systematically performed. School performance was assessed in the surviving adolescents at 14 years of age. The outcome variable divided the adolescents into three groups: (1) normal, (2) slow learners, and (3) special education. School performance data were obtained from 278 of 304 surviving adolescents; 129 performed normally, while 107 were slow learners, and 42 needed special education. From the unadjusted odds ratios for the need of special education by the various perinatal factors, only the odds ratio for periventricular-intraventricular hemorrhage was significantly associated (2.56, 95% confidence interval 1.17-4.86). Logistic regression analysis revealed that, after correction for possible confounding factors, the odds ratios for special education were significantly higher for adolescents with all grades of periventricular-intraventricular hemorrhage. Less than 50% of adolescents born before 32 weeks gestation perform normally in school. Periventricular-intraventricular hemorrhage, including the lower grades,does have an unfavorable additional effect on school performance.

Intraventricular Hemorrhage and Periventricular Leukomalacia in Preterm Infants

OBJECTIVE

To evaluate whether intraventricular hemorrhage and periventricular leukomalacia are characterized by different risk factors.

METHODS

In a cohort of 653 consecutive singleton neonates born after preterm membrane rupture, spontaneous preterm labor, or indicated preterm delivery at 24 to 33 weeks of gestation from January 1, 1993, to December 31, 2002, we evaluated the obstetric and histopathologic placental variables in reference to the development of intraventricular hemorrhage (n = 44), periventricular leukomalacia (n = 19), or no ultrasonographic cerebral lesion (n = 589). Excluded were stillbirths and congenital anomalies. Statistical analysis included Fisher exact test, Student t test, and stepwise logistic regression analysis with a 2-tailed P <.05 considered significant.

RESULTS

Multivariate analysis showed that occurrence of neonatal intraventricular hemorrhage and periventricular leukomalacia were associated only with spontaneous prematurity (odds ratio = 1.9; 95% confidence interval 1.1-3.4) and gestational age at delivery in weeks (odds ratio = 0.8; 95% confidence interval 0.7-0.9). Neonates with intraventricular hemorrhage did not differ from those with periventricular leukomalacia in any obstetric or neonatal variable, but there was a higher risk of neurodevelopmental delay associated with periventricular leukomalacia.

CONCLUSION

Among premature infants born at less than 34.0 weeks of gestation, intraventricular hemorrhage and periventricular leukomalacia share common clinical characteristics, with spontaneous preterm delivery and gestational age at delivery as the only independent antenatal predictors.