Inhibition of Microglial Activation by Delayed Mild Hypothermia Reduced Preoligodendrocyte Injury in a Neonatal Rat Brain Slice Model

Periventricular leukomalacia (PVL), characterized by distinctive form of white matter injury, often arises after neonatal cardiac surgery. Proven therapies for PVL are absent. In this study, we designed to quest therapeutic effects of delayed mild hypothermia on PVL and its mechanism in a neonatal rat brain slice model. With the increase of delayed mild hypothermia-treating time, the reduced expression of myelin basic protein and loss of preoligodendrocytes were significantly attenuated after oxygen-glucose deprivation. In addition, the proportion of ionized calcium binding adapter molecule 1 (Iba-1)-positive cells and the expression of Iba-1 were apparently reduced with the increased duration of mild hypothermia treatment. Furthermore, the levels of tumor necrosis factor alpha and interleukin-6 reduced after the mild hypothermia treatment relative to the control. Inhibition of microglial activation with prolonged mild hypothermia may be a potential strategy for white matter protection during cardiopulmonary bypass and hypothermic circulatory arrest.

Perinatal outcome comparing triplets and singleton births at a reference maternity hospital

OBJECTIVE

The objective of the present study was to evaluate adverse perinatal outcome in a group of high order pregnancies pared with singletons by BW and GA at birth.

METHODS

Data was reviewed for all admissions of triplets and quadruplets in a 7 year period. For each study neonate we selected two singleton infants to constitute a control group. Variables analyzed included: respiratory distress syndrome, patent ductus arteriosus, intraventricular hemorrhage, necrotizing enterocolitis (NEC), bronchopulmonary dysplasia, retinopathy of prematurity and periventricular leukomalacia.

RESULTS

We studied a total of 128 multiple and 260 singleton infants. Mean gestational age and birth weight were similar in both groups (31.3 ± 2,5 wks e 31.5 ± 2,8 wks; 1470 ± 461 g vs 1495 ± 540 g). There was no significant difference between the groups in the majority of main morbidities. The incidence of NEC was higher in triplets (6.3 vs 0.8%, p value <0.01). Mortality was higher in singletons (9.6 vs 3.1%, p value <0.037).

CONCLUSIONS

Results show that major neonatal outcomes are very similar between multiples and singletons births when paired by gestational age and birth weight. NEC remained a significant morbidity in infants born from multiple gestations after adjustment for maternal and neonatal risk factors.

[Advances in medical care for extremely low birth weight infants worldwide]

Dramatic advances in neonatal medicine over recent decades have resulted in decreased mortality and morbidity rates for extremely low birth weight infants. However, the survival of these infants is associated with short- and long-term morbidity, including severe intraventricular hemorrhage, periventricular leukomalacia, nosocomial infection and necrotizing enterocolitis, bronchopulmonary dysplasia, retinopathy of prematurity and adverse long-term neurodevelopmental sequelae. This article reviewed the latest advances in the medical care for extremely low birth weight infants including survival rate, ethical issues and short- and long-term morbidity, domestically and abroad.

[Cerebral pathological evaluation following neural stem cells intraventricular transplantation in neonatal rats with periventricular leukomalacia]

OBJECTIVE

To evaluate the brain pathological changes following exdogenous neural stem cells (NSCs) intraventricular transplantation in neonatal rats with periventricular leukomalacia (PVL), and to explore the feasibility of NSCs transplantation for the treatment of PVL in premature infants.

METHODS

NSCs were prepared from E14 embryonic rat brain. Two-day-old neonatal rats were randomly divided into six groups: PVL, PVL+culture medium, PVL+NSCs, sham operation, sham operation+culture medium, and sham operation+NSCs (18-21 rats each group). Intraventricular transplantation of exdogenous NSCs was performed 72 hrs after PVL induction or sham operation. The cerebral pathological evaluation was undertaken by light microscopy 7, 14 and 21 days after transplantation.

RESULTS

The pathological changes in the cerebral white matter were gradually improved with the prolonged time after transplantation. After 21 days of transplantation, 50% of the cerebral white matter showed mild pathological changes and 50% of that showed severe pathological changes, with neuronal pathological scores of 1.28+/-0.86, in the untreated PVL group. In the PVL+NSCs group, 30% of normal white matter, 40% of mild and 30% of severe pathological changes in the white matter were observed, with neuronal pathological scores of 0.32+/-0.16, 21 days after transplantation. There were very significant differences in both of pathological changes in the cerebral white matter and neuronal pathological scores between the PVL and PVL+NSCs groups (x2=10.7, P<0.01; F=29.664, P<0.01).

CONCLUSIONS

Intraventricular transplantation of exdogenous NSCs can apparently improve cerebral white matter damage. It is suggested that intraventricular transplantation of NSCs is of a great potential feasibility for the treatment of PVL in premature infants.

[Periventricular leukomalacia in premature infants: from pathogenesis to treatment]

Prematurity is a major cause of cerebral palsy (CP). CP in preterm infants usually results from damage to the periventricular white matter, known as periventricular leukomalacia (PVL). The pathogenesis of PVL is controversial, with leading models suggesting either ischemic etiology or infection and inflammation as the root cause for the disease. Advances in understanding the biology of PVL may result in clinical interventions that reduce the burden of CP.

Outcomes in children experiencing neurologic insults as preterm neonates

Germinal matrix-intraventricular hemorrhage, periventricular hemorrhagic infarction, and periventricular leukomalacia are common brain injuries in preterm infants that can have significant long-term influences on children's development, physical skills, and cognitive functioning. Characteristics of preterm infants, including immature cerebrovascular autoregulation, fragility of blood vessels, and the presence of the germinal matrix, increase their vulnerability to neurologic injury. Grades I-II germinal matrix-intraventricular hemorrhage tends to have little-to-moderate long-term impact on cognitive and neuromotor development after the neonatal period, while more severe hemorrhage is associated with less optimistic developmental prognoses. Periventricular leukomalacia and ventriculomegaly in the neonate are associated with severe cognitive disabilities as well as with cerebral palsy. Neurodevelopmental strategies emerging from both the neonatal developmental care and early intervention models may have a place in the post-acute care of newborns who experienced these insults. Vigilant developmental screening and early developmental intervention are essential components of the follow-up nursing care for children whose medical histories include neonatal brain injury.

Effect of tilting on cerebral haemodynamics in preterm infants with periventricular leucencephalomalacia

AIM

Measurement of cerebral haemodynamics to detect impaired cerebral blood flow and impaired cerebral autoregulation might make prevention of brain lesions and especially periventricular leucencephalomalacia (PVL) achievable.

METHODS

Changes in cerebral blood volume (CBV) and the cerebral haemoglobin oxygenation index (cHbD) following tilting up and down in 10 preterm infants with PVL and 25 preterm infants without PVL, measured by near infrared spectroscopy (NIRS), were analysed. Tilting manoeuvres were recorded with a polysomnographic system in combination with NIRS. CBV and cHbD of the baseline phase (1 min before tilting) were compared with data from the post-tilting phase (1 min after tilting).

RESULTS

Changes in CBV and cHbD after tilting were significantly pronounced in infants with PVL compared with infants without PVL. CBV decreased in infants with PVL, by -0.099 +/- 0.081 ml 100 g(-1) brain (mean +/- SD) after tilting up, and increased by 0.106 +/- 0.104 ml 100 g(-1) brain after tilting down. CBV decreased in infants without PVL, by -0.041 +/- 0.068 ml 100 g(-1) brain after tilting up, and increased by 0.020 +/- 0.096 ml 100 g(-1) brain after tilting down. cHbD showed similar changes after tilting.

CONCLUSION

Changes in CBV and cHbD after tilting were pronounced in preterm infants with PVL and this may indicate reduced cerebral autoregulatory capacity.

Perinatal brain injury in the premature infant

APPROXIMATELY 85 PERCENT OF infants with birth weights ≤1,500 gm now survive.1 Infants with birth weights <1,000 gm—the group contributing most to this increase in survival—have the greatest incidence of brain injury. Overall, the rates of neurologic disability have remained the same; therefore, the survival of more high-risk infants has increased the absolute number of NICU graduates with neurologic deficits.2–4 This concerns all involved in the care and lives of premature infants.

Hemorrhagic-ischemic cerebral injury in the preterm infant: current concepts

PV-IVH and adjacent white matter injury remains a significant problem in the premature infant. The potential mechanisms contributing to injury are complex and involve factors related to blood flow and its regulation, as well as cellular mediators including cytokines, free radical formation, and excitotoxin release. Although a reduction in the occurrence of severe IVH can be achieved with indomethacin, it does translate into long-term neurodevelopmental benefit. This reinforces the concept of a more diffuse injury to brain in sick premature infants than is apparent from the appearance of current neuroimaging techniques.

Periventricular leukomalacia: pathophysiological concerns due to immature development of the brain

Periventricular leukomalacia (PVL) is a result of injury and necrosis of myelinated fibers around the lateral ventricles. PVL is now considered the principal form of brain injury in preterm infants. This injury can have long-term effects on physical, motor, sensory, cognitive, and social development. Some proposed pharmacological treatments being considered to aid in prevention of this injury are raising concerns because they have failed to show evidence of efficacy or have potential for deleterious long-term effects. Current treatment is aimed at injury prevention; therefore, nurses play a critical role. Awareness of the pathophysiologic concerns about preterm neonates can help nurses focus their assessments to identify patients at risk.

Advances in postnatal neuroimaging: relevance to pathogenesis and treatment of brain injury

The human brain is susceptible to a wide variety of insults. The permanent residua of these abnormalities are represented in dysfunction of one or more areas of neurodevelopment. A full understanding of normal brain development, mechanisms of brain injury, and consequences for subsequent brain development is required to determine which infants are at risk for neurodevelopmental handicap, and to monitor the effects of new treatments and management regimens designed to prevent these disabilities. Advanced magnetic resonance techniques, such as quantitative morphometric magnetic resonance techniques, diffusion-weighted magnetic resonance techniques, and magnetic resonance spectroscopy applied to the study of early human brain development have given us a better understanding of the pathophysiologic mechanisms of brain injury and its effects on subsequent brain development. Magnetic resonance imaging has provided an invaluable tool for the study of the fetal and newborn brain in vivo.

Management of single fetal death in twin-to-twin transfusion syndrome: a role for fetal blood sampling

OBJECTIVE

Intrauterine death of one twin in monochorionic pregnancies is associated with an increased mortality and morbidity of the cotwin. This is likely to occur as a consequence of acute hemodynamic changes due to feto-fetal hemorrhage at the time of death of the cotwin. We assessed the role of fetal blood sampling and intrauterine transfusion to rescue the survivor.

MATERIALS AND METHODS

We managed 12 cases of single intrauterine death at between 17 and 26 weeks' gestation in monochorionic twins complicated by twin-to-twin transfusion syndrome (TTTS). All these cases had been treated either by laser therapy or by serial amniodrainage. When the demise of one twin occurred, ultrasound-guided fetal blood sampling was performed in the surviving twin using a 20-gauge needle within 24 h of death. Intrauterine transfusion was performed at the same time in cases where the survivor was anemic. All survivors were assessed in the neonatal period and at 1 year of age.

RESULTS

Six of the 12 surviving fetuses were found to be anemic and underwent intrauterine transfusion. All fetuses survived the procedure. Four of these fetuses had normal neurological development at 1 year of age. Periventricular leukomalacia developed in one case and the patient underwent termination of pregnancy at 34 weeks. In one case delivery occurred at 34 weeks' gestation and the baby developed periventricular leukomalacia at 1 month of age. In all six non-anemic fetuses pediatric examination was normal at birth and at 1 year of age.

CONCLUSION

Intrauterine death of one monochorionic twin in TTTS puts the survivor at high risk of intrauterine death or of developing ischemic/hypoxic lesions. Our results suggest that fetal blood sampling is a useful diagnostic tool to identify those fetuses that are not anemic and hence unlikely to be at risk of developing a cerebral lesion.

National survey of periventricular leukomalacia in Japan

BACKGROUND

Clarification of the present status of periventricular leukomalacia (PVL) in Japan.

METHODS

Questionnaires were mailed to the leading neonatal intensive care units (NICU) and rehabilitation centers for children.

RESULTS

The incidence of PVL in the group of surviving preterm infants of gestational ages less than 33 weeks was 4.8-4.9% on ultrasound and 7.7-7.9% on magnetic resonance imaging and/or computed tomography. The incidence of PVL did not decrease between 1990 and 1994. The incidence of PVL in the NICU varied from 0 to 47.1%. Infants from multiple pregnancies had a higher incidence (9.1%) of PVL than those from single pregnancies (6.2%). The proportion of PVL in all patients in rehabilitation centers with cerebral palsy (CP) has increased recently.

CONCLUSIONS

It was roughly calculated that about 750 cases of CP with PVL occurred annually in Japan, thus accounting for about one-third of the total number of cases of CP.

[Conservative treatment of non-resorptive hydrocephalus in premature infants]

Following perinatal asphyxia and intracranial hemorrhage frequently progressive ventricular dilatation develops in preterm infants. Most common is communicating hydrocephalus due to obliterative arachnoiditis. Ventricular dilatation is reported to affect normal brain development and early therapy is recommended. Cerebrospinal fluid shunting is still accompanied by multiple complications, esp. in preterm infants with a birth-weight below 1,500 g. Seven preterm infants, born between the 27th and 34th gestational week with a birthweight of 910-1,940 g were medically treated for their progressive communicating hydrocephalus. The therapy consisted of intermittant lumbar punctures, medication of acetazolamide and furosemide as well as electrolyte and base replacement. Therapy was started at the 14th-31st postnatal day and lasted from 46 to 149 days. In all children the ventricular dilatation diminished. A steady state of cerebrospinal fluid production and absorption was regained in four children. Due to reoccurrence of ventricular dilatation shunting was performed in three others at the age of more than 3 months and with a weight of 3,620-5,170 g. Thus, medical therapy of hydrocephalus provides time for development of preterm infants, delay of shunting procedures and normalisation of cerebrospinal fluid dynamics.