Preterm twin gestation and cystic periventricular leucomalacia

Determination of Predictors of Brain Injury in Very Preterm Infants - A Retrospective Cohort Study

Background

Despite decades of research, there is inadequate evidence on the etiological factors of brain injury in preterm infants.

Objective

To study the perinatal risk factors for preterm brain injury and to assess their strength of association.

Methods

In this retrospective cohort study, we included infants born at <32 weeks' gestation and had either magnetic resonance imaging (MRI) or cranial ultrasound (CUS) performed at term equivalent age. Significant brain injury was diagnosed based on Kidokoro global brain injury score was ≥4 in MRI or cystic periventricular leukomalacia in CUS.

Results

Among the 698 infants, 48 had significant brain injury and 650 were taken as controls. In multiple logistic regression, intraventricular hemorrhage (IVH) grade 3-4 [adjusted odds ratio, 92.892 (19.495-442.619)], culture-positive sepsis [4.162 (1.729-10.021)], prolonged ventilation [3.688 (1.087-12.510)], and small for gestational age (SGA) [2.645 (1.181-5.924] were associated with greater risk of preterm brain injury.

Conclusion

Severe IVH, culture-positive sepsis, prolonged ventilation and SGA were significant risk factors for preterm brain injury with severe IVH being the most significant contributing factor.

Risk Factors for Periventricular Leukomalacia in Preterm Infants: A Systematic Review, Meta-analysis, and GRADE-Based Assessment of Certainty of Evidence

BACKGROUND

We analyzed the certainty of evidence (CoE) for risk factors of periventricular leukomalacia (PVL) in preterm neonates, a common morbidity of prematurity.

METHODS

Medline, CENTRAL, Embase, and CINAHL were searched. Cohort and case-control studies and randomised randomized controlled trials were included. Data extraction was performed in duplicate. A random random-effects meta-analysis was utilizedused. CoE was evaluated as per Grading of Recommendations Assessment, Development and Evaluation (GRADE) guidelines.

RESULTS

One hundred eighty-six studies evaluating 95 risk factors for PVL were included. Of the 2,509,507 neonates assessed, 16,569 were diagnosed with PVL. Intraventricular hemorrhage [adjusted odds ratio: 3.22 (2.52-4.12)] had moderate CoE for its association with PVL. Other factors such as hypocarbia, chorioamnionitis, PPROM >48 hour, multifetal pregnancy reduction, antenatal indomethacin, lack of antenatal steroids, perinatal asphyxia, ventilation, shock/hypotension, patent ductus arteriosus requiring surgical ligation, late-onset circulatory collapse, sepsis, necrotizing enterocolitis, and neonatal surgery showed significant association with PVL after adjustment for confounders (CoE: very low to low). Amongst the risk factors associated with mother placental fetal (MPF) triad, there was paucity of literature related to genetic predisposition and defective placentation. Sensitivity analysis revealed that the strength of association between invasive ventilation and PVL decreased over time (P < 0.01), suggesting progress in ventilation strategies. Limited studies had evaluated diffuse PVL.

CONCLUSION

Despite decades of research, our findings indicate that the CoE is low to very low for most of the commonly attributed risk factors of PVL. Future studies should evaluate genetic predisposition and defective placentation in the MPF triad contributing to PVL. Studies evaluating exclusively diffuse PVL are warranted.

Spontaneous hypocarbia without mechanical ventilation in preterm infants with cystic periventricular leukomalacia

AIM

Hypocarbia induced by mechanical ventilation has been considered a main cause of cystic periventricular leukomalacia (cPVL). However, hypocarbia may occur spontaneously in response to intracellular metabolic acidosis. We aimed to assess whether hypocarbia is more common during mechanical respiratory support than during spontaneous ventilation in infants with cPVL.

METHOD

In this single-centre, retrospective chart analysis, we compared partial pressure of carbon dioxide (pCO₂ ) during the first 96 hours of life in infants with cPVL during endotracheal mechanical ventilation, non-invasive respiratory support, or without respiratory support.

RESULTS

Cystic periventricular leukomalacia was diagnosed in 23 infants born between 2006 and 2017. Gestational age was 24 weeks in two infants and ranged between 28 and 32 weeks in 21 infants. In these 21 infants, pCO₂ less than 35 mm Hg during the first 96 ours of life accounted for 9/60 (15%) measurements during endotracheal mechanical ventilation, 16/116 (14%) during non-invasive respiratory support and 14/42 (33%) in infants without respiratory support (P = .014).

CONCLUSION

In our series of infants with cPVL, hypocarbia was more common without respiratory support than during endotracheal mechanical ventilation and non-invasive respiratory support. This would suggest that hypocarbia is a symptom rather than a cause of cPVL in these infants.

Risk factors for brain damage among preterm twins

AIM

To evaluate the perinatal and postnatal risk factors for various brain pathologies among preterm twins.

METHODS

Retrospective data of 104 twin pairs of which one of the siblings had evidence of abnormal head ultrasound (HUS) and its co-twin with normal HUS served as control.

RESULTS

Abnormal HUS consisted of periventricular echodensities among 69 infants, intraventricular hemorrhage among 28 infants, cystic periventricular leukomalacia among 10 infants, and other parenchymal brain pathologies among 5 infants. Perinatal and postnatal complications were similar between study and controls. Siblings with severe brain pathologies were ventilated for longer time over their co-twins. In 10 out of 11 cases of discordant twins (≥20%) with severe brain pathology, the severe pathology was recorded in the larger sibling.

CONCLUSIONS

Our study results, which included matched preterm twin pairs for study/control groups to evaluate risk factors for the overall evidence of brain injury, could not determine specific risk factors for these brain pathologies. The finding that severe brain pathologies were more common among the larger co-twin requires further study of and attention to short- and long-term outcomes and the potential conflicts that may arise.

Focal necrosis and disturbed myelination in the white matter of newborn infants: a tale of too much or too little oxygen

White matter disease in preterm infants comes along with focal destructions or with diffuse myelination disturbance. Recent experimental work with transgenic mice paves the way for a unifying molecular model for both types of brain injury, placing oxygen sensing by oligodendrocyte precursor cells (OPCs) at the center stage. Mice genetically altered to mimic high local oxygen tension in oligodendroglia lineage cells (via deletion of hypoxia-inducible factor, HIF) develop white matter disease resembling cystic periventricular leukomalacia within the first 7 days of life. Mice in which local hypoxia is mimicked in oligodendroglial cells (via genetic inhibition of HIF decay) display arrested OPC maturation and subsequent hypomyelination, reminiscent of the diffuse white matter disease observed in preterm infants and infants with congenital heart disease. These recent experimental findings on oxygen sensing and myelination are awaiting integration into a clinical framework. Gene regulation in response to hyperoxia or hypoxia, rather than oxidative stress, may be an important mechanism underlying neonatal white matter disease.

Discordance in neonatal risk factors and early childhood outcomes of very low birth weight (<1.5 kg) twins

OBJECTIVE

To examine the rates of discordance in neonatal risk factors and neurodevelopmental outcomes within very low birth weight twin pairs and the factors associated with discordant outcomes.

STUDY DESIGN

Rates of neonatal risk factors and neurodevelopmental outcomes, and discordance in outcomes were examined for 88 very low birth weight twin pairs born between 1990 and 2005 and followed through 20 months' corrected age.

RESULT

Discordance rates ranged from 17 to 42% for neonatal risk factors and from 18 to 31% for neurodevelopmental outcomes. In regression analysis, affected co-twins were significantly more likely to have had an abnormal cerebral ultrasound than their unaffected co-twins in pairs discordant for cerebral palsy (odds ratio (OR): 13.00, 95% confidence interval (CI): 2.22 to 76.03)) and in pairs discordant for neurodevelopmental impairment (OR: 4.00, 95% CI: 1.13 to 14.18). Outcomes and discordance in outcomes were similar for monochorionic and dichorionic pairs.

CONCLUSION

Despite shared genetics and risk factors, twins may have discordant outcomes. Information on discordant neonatal and neurodevelopmental outcomes is important for counseling families of twins.

Preterm twin and triplet pregnancies are at increased risk for the development of cystic periventricular leukomalacia

BACKGROUND

An increased risk of cerebral palsy in multiples has been reported.

AIMS

To determine the risk for the development of periventricular leukomalacia (PVL) of twin and triplet pregnancy.

STUDY DESIGN

Retrospective single-centre study at a tertiary care university hospital.

SUBJECTS

Infants ≤ 35 weeks gestational age born between 1988 and 2008.

OUTCOME MEASURES

Risk of twin and triplet compared to singleton pregnancy regarding development of PVL in one offspring.

RESULTS

Of 6195 infants 117 singletons and 39 multiples were diagnosed as having cystic PVL. Perinatal data did not differ as did not ultrasonographic findings and neurologic outcome. The relative risk (RR) of a twin pregnancy resulting in at least one infant with PVL when born prior to 36 weeks was 2.181 (CI 95% 1.474-3.228, p < .0001), and 6.793 (CI 95% 2.470-13.108, p < .0001) of a triplet pregnancy. In-vitro fertilisation was present in 3% of affected twins compared to 100% in triplets (p < .001).

CONCLUSION

We found an increased risk for PVL in preterm twin and triplet pregnancies.

Episodes of hypocarbia and early-onset sepsis are risk factors for cystic periventricular leukomalacia in the preterm infant

BACKGROUND

Septic episodes in preterm infants recently have been reported to be associated with periventricular leukomalacia (PVL). The role of hypocarbia as an independent risk factor for PVL in clinical studies raises many questions without conclusive answers.

AIMS

To evaluate risk factors for cystic PVL focussing on the influence of hypocarbia.

STUDY DESIGN

Retrospective single centre case-control study.

SUBJECTS

Preterm infants 24 to 35 weeks of gestational age and matched (1:2 for gender, birth year, gestational age and birth weight) controls.

OUTCOME MEASURES

Multivariate analysis of perinatal factors being associated with cystic PVL diagnosed by serial ultrasound examinations.

RESULTS

Univariate analysis of risk factors revealed lower 5 and 10 min Apgar scores, and higher rates of neonatal seizures, early-onset sepsis, neonatal steroids, respiratory distress syndrome with surfactant replacement therapy, and episodes of hypocarbia significantly being associated with PVL. Multivariate analysis using a logistic regression model revealed early-onset sepsis and hypocarbia being significantly associated with PVL (p=.022 and .024, respectively). Lowest PaCO(2) values did not differ as did not the duration of hypocarbia, but the onset of hypocarbia was significantly later in PVL cases compared to controls (mean 26 vs. 15 h, p=.033). Neurodevelopmental follow-up at a median time of 46 months was poor showing 88% of the cases having an adverse neurological outcome.

CONCLUSION

We found early-onset sepsis and episodes of hypocarbia within the first days of life being independently associated with PVL.

Periventricular leucomalacia (PVL)-like lesions in two neonatal cynomolgus monkeys (Macaca fascicularis)

Periventricular leucomalacia (PVL) is a lesion of immature cerebral white matter that occurs in the perinatal period. In man, PVL is the predominant form of brain injury and a cause of cerebral palsy and cognitive deficits in premature infants. PVL affects fetuses and newborns, particularly those who have undergone oxygen deprivation as may occur in premature birth. Many clinical and pathological studies of PVL have been performed in man, but there is no clear definition of PVL in animals. A few spontaneous PVL-like cases in puppies or experimental cases in other animal species have been reported. The present study reports the histopathological and immunohistochemical features of PVL-like lesions in two neonatal cynomolgus monkeys. In both cases, there was cerebral white matter necrosis with marked infiltration of lipid-laden phagocytes and a reduction of neurons in the cerebral cortex. In case 1 there was extensive cavitation of the cerebral white matter. In case 2 there was reactive astrocytosis associated with a decrease in oligodendroglial cells and a decrease in cerebral white matter myelin. To our knowledge, this is the first report of PVL-like leucoencephalomalacia in non-human primates.

High postnatal oxidative stress in neonatal cystic periventricular leukomalacia

Oxidative stress plays an important role in cystic periventricular leukomalacia (PVL). We performed a case-control study of preterm infants delivered at <35 weeks of gestation between January 2003 and December 2006. Patients were stratified into three groups, according to age at which cysts were initially identified: 10 days old (early cystic PVL; n=10), >10 days old (late cystic PVL; n=12); and no cystic PVL (controls; n=22). Serum total hydroperoxide, biological antioxidant potential and oxidative stress index (calculated as total hydroperoxide/biological antioxidant potential) were measured within 3h after birth. Frequencies of preterm rupture of membrane and chorioamnionitis were significant higher in early cystic PVL than in late cystic PVL or controls. Duration of oxygen treatment and mechanical ventilation and frequency of apnea were significantly higher in late cystic PVL than in controls or early cystic PVL. Serum total hydroperoxide levels and oxidative stress index were significantly higher in early cystic PVL than in late cystic PVL or controls (p<0.05, respectively). Postnatal duration until cyst identification displayed a significant negative correlation with oxidative stress index and total hydroperoxide level (r=-0.497, p<0.05; r=-0.50, p<0.05, respectively). These findings suggest that early onset of cystic PVL might be due to either antenatal or intrapartum factors, but late onset might be due to postnatal factors. In the pathophysiology and therapy of cystic PVL, oxidative stress and onset timing appear crucial. This is the first study to reveal that neonates experiencing much more oxidative stress at birth show earlier onset of cystic PVL.

Minimising neonatal brain injury: how research in the past five years has changed my clinical practice

With improving neonatal survival for extremely premature babies, the challenge for neonatology is to improve outcome of surviving babies. This review concentrates on best evidence emerging in recent years on prevention of brain damage by early administration of drugs as well as avoidance of induced brain damage by hyperventilation and dexamethasone therapy given postnatally for chronic lung disease.

Correlation of grading and duration of periventricular echodensities with neurodevelopmental outcome in preterm infants

BACKGROUND

Transient periventricular echodensities (PVE) in preterm infants affect neurodevelopmental outcome.

OBJECTIVE

To correlate the duration and grading of PVE with neurodevelopmental outcome.

MATERIALS AND METHODS

A retrospective, single-centre cohort study of infants with PVE diagnosed by ultrasonography from 1995 to 2000 with blinded grading and recognition of duration of PVE.

RESULTS

A total of 72 infants (median gestational age 32 weeks, median birth weight 1,668 g) were diagnosed as having PVE. Minor neurological abnormalities were diagnosed in seven (10%), cerebral palsy in six (8%), developmental delay in seven (10%), and mild mental retardation in two (3%) of the infants. Differences regarding adverse outcome were not significant between infants with severity grade 1 compared to severity grade 2 (16% and 22%, respectively). There was a significant increase in adverse neurodevelopmental outcome with increasing duration of PVE. Of 33 infants with duration of PVE<7 days, 1 (3%) had an adverse neurodevelopmental outcome, compared to 6 (24%) of 25 infants with a duration of PVE of 7-14 days, and 6 (43%) of 14 infants with a duration of PVE>14 days (P<0.002, RR 7.920, 95% CI 1.017-61.661; P<0.001, RR 14.143, 95% CI 1.871-106.895, respectively).

CONCLUSION

The duration, but not the grading, of transient PVE was significantly correlated with neurodevelopmental outcome.

Differential Diagnosis of Intracranial Cystic Lesions at Head US: Correlation with CT and MR Imaging

The differential diagnosis of intracranial cystic lesions at head ultrasonography (US) includes a broad spectrum of conditions: (a) normal variants, (b) developmental cystic lesions, (c) cysts due to perinatal injury, (d) vascular cystlike structures, (e) hemorrhagic cysts, and (f) infectious cysts. These lesions vary in prevalence from common (cavum of the septum pellucidum, subependymal cyst, choroid plexus cyst) to rare (vein of Galen malformation). US can provide important information about the anatomic location, size, and shape of the lesions as well as their mass effect on adjacent structures. Differential diagnosis may be difficult because there is substantial overlap of US features between many of these conditions. However, if careful attention is paid to the location and characteristics of the cyst, a more specific diagnosis may be suggested. Understanding the spectrum of appearances of the various intracranial cystic lesions at head US improves the diagnostic yield, enables one to understand their pathogenesis, and facilitates patient care.

Periventricular Leukomalacia with Late-Onset Circulatory Dysfunction of Premature Infants: Correlation with Severity of Magnetic Resonance Imaging Findings and Neurological Outcomes

The incidence of late-onset circulatory dysfunction (LCD) of premature infants, which is characterized by sudden hypotension and oliguria, has recently increased in Japan. This condition suddenly occurs after several days of age without obvious causes in preterm infants with stable respiration and circulation. Intravenous steroids frequently improve the hypotension. The main problem with LCD is the subsequent and frequent onset of periventricular leukomalacia (PVL), and neurological development appears to be worse in PVL patients with LCD than those without LCD. The aim of this study was to determine whether the severity of magnetic resonance imaging (MRI) findings and neurological outcomes differ between infants who developed PVL after LCD and those who developed PVL without LCD. We retrospectively studied preterm infants who were delivered at less than 33 weeks of gestation between the years 2000 and 2003. During the study period, 10 and 26 infants developed PVL with and without LCD, respectively. The incidence of severe or moderate MRI findings was significantly higher in PVL patients with LCD (100%) than those without LCD (50%; p < 0.05). The incidence of severe cerebral palsy was 88% in PVL infants with LCD and 43% in PVL infants without LCD (p < 0.05). Moreover, the incidence of visual disorders was significantly higher in PVL infants with LCD (63%) than those without LCD (9%; p < 0.01). In conclusion, neurological outcomes are worse in preterm infants who develop PVL with LCD than those without LCD, which is well correlated to the severity judged by MRI findings.

Cerebellar hemorrhage in the preterm infant: ultrasonographic findings and risk factors

Cerebellar hemorrhage (CBH) in premature infants is increasingly diagnosed secondary to improved neuroimaging techniques and survival of very small preterm infants. Information is limited, however, on the incidence, topography, and risk factors for CBH in the preterm infant.

OBJECTIVES

To define the incidence of CBH in preterm infants diagnosed by neonatal cranial ultrasound (US), describe the sonographic features of CBH, and identify maternal and perinatal risk factors associated with this lesion.

METHODS

A systematic electronic database search identified preterm infants born 1998-2002 with US diagnosis of CBH. For 35 cases of CBH we double-matched (according to gestational age, gender, and year of birth) 70 preterm controls with normal cranial USs and performed detailed medical-record reviews for both patients and controls.

RESULTS

Unilateral CBH was seen in 25 patients (71%), vermian hemorrhage was seen in 7 (20%), and combined bihemispheric and vermian hemorrhage was seen in 3 (9%). Isolated CBH occurred in 8 patients (23%); the remaining infants had associated supratentorial lesions. The incidence of CBH in preterm infants weighing <750 g at birth showed significant increase over the study period. Univariate analyses identified maternal, intrapartum, and early postnatal hemodynamic risk factors; multivariate regressions indicated that emergent caesarian section, patent ductus arteriosus, and lower 5-day minimum pH independently increased the odds of CBH. Neonatal mortality and morbidity were significantly higher among patients with CBH compared with preterm controls.

CONCLUSIONS

CBH is an important complication of extreme preterm birth and has been underrecognized in surviving preterm infants. Predictors of CBH seem to be multifactorial and include combined maternal, intrapartum, and early postnatal factors.