Hypoglycemic injury to the immature brain

Hypoglycemia in Children: Major Endocrine-Metabolic Causes and Novel Therapeutic Perspectives

Hypoglycemia is due to defects in the metabolic systems involved in the transition from the fed to the fasting state or in the hormone control of these systems. In children, hypoglycemia is considered a metabolic-endocrine emergency, because it may lead to brain injury, permanent neurological sequelae and, in rare cases, death. Symptoms are nonspecific, particularly in infants and young children. Diagnosis is based on laboratory investigations during a hypoglycemic event, but it may also require biochemical tests between episodes, dynamic endocrine tests and molecular genetics. This narrative review presents the age-related definitions of hypoglycemia, its pathophysiology and main causes, and discusses the current diagnostic and modern therapeutic approaches.

Real-time continuous glucose monitoring in preterm infants (REACT): an international, open-label, randomised controlled trial

BACKGROUND

Hyperglycaemia and hypoglycaemia are common in preterm infants and have been associated with increased risk of mortality and morbidity. Interventions to reduce risk associated with these exposures are particularly challenging due to the infrequent measurement of blood glucose concentrations, with the potential of causing more harm instead of improving outcomes for these infants. Continuous glucose monitoring (CGM) is widely used in adults and children with diabetes to improve glucose control, but has not been approved for use in neonates. The REACT trial aimed to evaluate the efficacy and safety of CGM in preterm infants requiring intensive care.

METHODS

This international, open-label, randomised controlled trial was done in 13 neonatal intensive care units in the UK, Spain, and the Netherlands. Infants were included if they were within 24 h of birth, had a birthweight of 1200 g or less, had a gestational age up to 33 weeks plus 6 days, and had parental written informed consent. Infants were randomly assigned (1:1) to real-time CGM or standard care (with masked CGM for comparison) using a central web randomisation system, stratified by recruiting centre and gestational age (<26 or ≥26 weeks). The primary efficacy outcome was the proportion of time sensor glucose concentration was 2·6-10 mmol/L for the first week of life. Safety outcomes related to hypoglycaemia (glucose concentrations <2·6 mmol/L) in the first 7 days of life. All outcomes were assessed on the basis of intention to treat in the full analysis set with available data. The study is registered with the International Standard Randomised Control Trials Registry, ISRCTN12793535.

FINDINGS

Between July 4, 2016, and Jan 27, 2019, 182 infants were enrolled, 180 of whom were randomly assigned (85 to real-time CGM, 95 to standard care). 70 infants in the real-time CGM intervention group and 85 in the standard care group had CGM data and were included in the primary analysis. Compared with infants in the standard care group, infants managed using CGM had more time in the 2·6-10 mmol/L glucose concentration target range (mean proportion of time 84% [SD 22] vs 94% [11]; adjusted mean difference 8·9% [95% CI 3·4-14·4]), equivalent to 13 h (95% CI 5-21). More infants in the standard care group were exposed to at least one episode of sensor glucose concentration of less than 2·6 mmol/L for more than 1 h than those in the intervention group (13 [15%] of 85 vs four [6%] of 70). There were no serious adverse events related to the use of the device or episodes of infection.

INTERPRETATION

Real-time CGM can reduce exposure to prolonged or severe hyperglycaemia and hypoglycaemia. Further studies using CGM are required to determine optimal glucose targets, strategies to obtain them, and the potential effect on long-term health outcomes.

FUNDING

National Institute for Health Research Efficacy and Mechanisms Evaluation Programme.

Cost-effectiveness of real time continuous glucose monitoring to target glucose control in preterm infants

The optimal management of glucose levels in critical care remains an area for research due to the problems of balancing the risks of hyperglycemia versus hypoglycemia. This paper reports the first economic evaluation of real time continuous glucose monitoring to guide the clinical management of preterm infants, based on evidence from the REACT trial. Bivariate regression of costs (£, 2016-17 prices) and cases of adequate glucose control, with multiple imputation of missing data, was conducted. When the economic evaluation was restricted to the first week of life, real time continuous glucose monitoring was associated with increased costs and a statistically significant increase in adequate glucose control. When the assessment was performed over a time horizon extending to 36 weeks' corrected gestational age, real time CGM was dominant in health economic terms, i.e. associated with lower costs and better outcomes. These results largely remained robust to a range of sensitivity analyses and sub-group analyses designed to address uncertainty and heterogeneity surrounding the cost-effectiveness outcomes. This study suggests that the use of real time continuous glucose monitoring in preterm infants is associated with a high probability of cost-effectiveness.

Protocol of a randomised controlled trial of real-time continuous glucose monitoring in neonatal intensive care 'REACT'

INTRODUCTION

Hyperglycaemia is common in the very preterm infant and has been associated with adverse outcomes. Preventing hyperglycaemia without increasing the risk of hypoglycaemia has proved challenging. The development of real-time continuous glucose monitors (CGM) to inform treatment decisions provides an opportunity to reduce this risk. This study aims to assess the feasibility of CGM combined with a specifically designed paper guideline to target glucose control in the preterm infant.

METHODS AND ANALYSES

The Real Time Continuous Glucose Monitoring in Neonatal Intensive Care (REACT) trial is an international multicentre randomised controlled trial. 200 preterm infants ≤1200 g and ≤24 hours of age will be randomly allocated to either real-time CGM or standard care (with blinded CGM data collection). The primary outcome is time in target 2.6-10 mmol/L during the study intervention assessed using CGM. Secondary outcomes include efficacy relating to glucose control, utility including staff acceptability, safety outcomes relating to incidence and prevalence of hypoglycaemia and health economic analyses.

ETHICS AND DISSEMINATION

The REACT trial has been approved by the National Health Service Health Research Authority National Research Ethics Service Committee East of England (Cambridge Central); Medical Ethics Review Committee, VU University Medical Centre, Amsterdam, The Netherlands and the Research Ethics Committee, Sant Joan de Déu Research Foundation, Barcelona, Spain. Recruitment began in July 2016 and will continue until mid-2018. The trial has been adopted by the National Institute of Health Research Clinical Research Network portfolio (ID: 18826) and is registered with anInternational Standard Randomised Control Number (ISRCTN registry ID: 12793535). Dissemination plans include presentations at scientific conferences, scientific publications and efforts at stakeholder engagement.

TRIAL REGISTRATION NUMBER

ISRCTN12793535; Pre-results.

ABM clinical protocol #1: guidelines for blood glucose monitoring and treatment of hypoglycemia in term and late-preterm neonates, revised 2014

A central goal of The Academy of Breastfeeding Medicine is the development of clinical protocols for managing common medical problems that may impact breastfeeding success. These protocols serve only as guidelines for the care of breastfeeding mothers and infants and do not delineate an exclusive course of treatment or serve as standards of medical care. Variations in treatment may be appropriate according to the needs of an individual patient.

Glycemic Control in Pediatric Patients on Extracorporeal Membrane Oxygenation

OBJECTIVES To determine whether glycemic control has an effect on outcomes for pediatric patients on extracorporeal membrane oxygenation (ECMO) therapy, while controlling for multiple factors.

METHODS A single-center retrospective chart review was performed on 82 patients who required ECMO from January 1, 2008, to December 31, 2010. All glucose concentrations collected while patients were on ECMO were analyzed; multiple other factors that may have affected mortality were also recorded. Primary outcome was mortality, and secondary outcomes were length of time on ECMO and length of time until death or discharge from the hospital.

RESULTS Of 82 patients, 53 patients survived ECMO (64.6%). Glucose control had no effect on survival of patients on ECMO (p=0.56), even when controlling for multiple factors (p=0.48). Similarly, statistical evaluation showed no differences for hospital mortality in relationship to controlled serum glucose (p=0.50). Patients with controlled glucose spent an average of 31.5% more time on ECMO than non-controlled patients (p=0.048).

CONCLUSIONS In this study, glycemic control, defined as serum glucose concentration between 60 mg/dL and 250 mg/dL for &gt;95% of the time on ECMO, had no statistically significant effect on mortality for patients on ECMO. Future studies could focus on tighter glucose control or specific dextrose/glucose protocols to evaluate whether improved glucose control would have an effect on morbidity and mortality.

Long duration of hyperglycemia in the first 96 hours of life is associated with severe intraventricular hemorrhage in preterm infants

OBJECTIVE

To assess the association between severe intraventricular hemorrhage (IVH) and blood glucose variables during the first 96 hours of life in preterm infants.

STUDY DESIGN

Preterm infants with IVH grade 3-4 (n = 70) were compared with matched infants of similar gestational age and birth weight, but with no IVH (n = 108). Studied variables included the frequency and duration of hyper/hypoglycemic (>6.9/<3.3 mmol/L, respectively) events, the extreme slope of an event evolution, the maximal glucose value observed, and the "hyper/hypoglycemic index" representing a weighted average of the hyper/hypoglycemic amplitude.

RESULTS

The IVH group had significantly more hyperglycemic events (2.9 ± 1.7 vs 2.4 ± 1.8 events, P < .05) with longer duration (22.2 ± 14.2 vs 14.1 ± 12.5 hours, P < .001) and a higher hyperglycemic index (1.0 ± 0.9 vs 1.4 ± 1.0, P = .003) compared with the non-IVH controls. Respiratory distress syndrome, hypotension, and thrombocytopenia increased the adjusted OR for IVH. Hypoglycemia was not independently associated with IVH. Conversely, the increase in hyperglycemic duration was most prominently increasing the aOR for severe IVH (OR = 10.33, 95% CI = 10.0-10.6, P = .033).

CONCLUSION

Longer duration of hyperglycemia in the first 96 hours of life was most strongly associated with severe IVH in preterm infants. Consequently, interventional studies to determine the selective effect of continuous control of long-lasting hyperglycemia by appropriate and timed insulin treatment on the incidence of severe IVH are warranted.

Hypoglycemia in term newborns with a birth weight below the 10th percentile

BACKGROUND

Current recommendations suggest that routine screening for hypoglycemia should be performed in all term newborns with a birth weight (BW) below the 10th percentile. The impact of updated growth curves on the incidence of hypoglycemia in small-for-gestational-age (SGA) newborns has not been evaluated.

OBJECTIVES

To evaluate the occurrence and severity of hypoglycemia in term newborns with a BW between the 10th and fifth percentile, and below the fifth percentile, using recently updated growth curves.

DESIGN

A one-year prospective cohort study.

METHODS

Inclusion criteria were gestational age of 37 weeks or greater and BW below the 10th percentile. Neonatal hypoglycemia was defined as a blood glucose level of less than 2.6 mmol/L measured after 2 h of life. Blood glucose was measured routinely for all SGA infants during the first 36 h of life.

RESULTS

A total of 187 SGA infants met the study criteria: 85 infants with a BW between the 10th and fifth percentile, and 102 infants with a BW below the fifth percentile. The characteristics of the study cohort were similar between BW groups. Twenty-six per cent of the infants screened had at least one episode of hypoglycemia: 22% of infants in the 10th to fifth percentile group and 28% in the less than fifth percentile group. Hypoglycemia was symptomatic in four infants, all of whom were below the fifth percentile for BW. The mean (± SD) lowest blood glucose level was 2.1±0.4 mmol/L (range 0.6 mmol/L to 2.5 mmol/L) in the 10th to fifth percentile group and 2.0±0.5 mmol/L (range 0.8 mmol/L to 2.5 mmol/L) in the less than fifth percentile group (P=0.05).

CONCLUSION

The present study demonstrates a high incidence of hypoglycemia among SGA infants with a BW below the 10th percentile using updated growth curves. There was no difference in the incidence of hypoglycemia among SGA infants with a BW below the fifth percentile versus those with a BW between the 10th and fifth percentile.

Neurochemical changes in the rat occipital cortex and hippocampus after repetitive and profound hypoglycemia during the neonatal period: an ex vivo ¹H magnetic resonance spectroscopy study

The brain of a human neonate is more vulnerable to hypoglycemia than that of pediatric and adult patients. Repetitive and profound hypoglycemia during the neonatal period (RPHN) causes brain damage and leads to severe neurologic sequelae. Ex vivo high-resolution (1)H nuclear magnetic resonance (NMR) spectroscopy was carried out in the present study to detect metabolite alterations in newborn and adolescent rats and investigate the effects of RPHN on their occipital cortex and hippocampus. Results showed that RPHN induces significant changes in a number of cerebral metabolites, and such changes are region-specific. Among the 16 metabolites detected by ex vivo (1)H NMR, RPHN significantly increased the levels of creatine, glutamate, glutamine, γ-aminobutyric acid, and aspartate, as well as other metabolites, including succine, taurine, and myo-inositol, in the occipital cortex of neonatal rats compared with the control. By contrast, changes in these neurochemicals were not significant in the hippocampus of neonatal rats. When the rats had developed into adolescence, the changes above were maintained and the levels of other metabolites, including lactate, N-acetyl aspartate, alanine, choline, glycine, acetate, and ascorbate, increased in the occipital cortex. By contrast, most of these metabolites were reduced in the hippocampus. These metabolic changes suggest that complementary mechanisms exist between these two brain areas. RPHN appears to affect occipital cortex and hippocampal activities, neurotransmitter transition, energy metabolism, and other metabolic equilibria in newborn rats; these effects are further aggravated when the newborn rats develop into adolescence. Changes in the metabolism of neurotransmitter system may be an adaptive measure of the central nervous system in response to RPHN.

Cellular biology of end organ injury and strategies for prevention of injury

The interruption of placental blood flow induces circulatory responses to maintain cerebral, cardiac, and adrenal blood flow with reduced renal, hepatic, intestinal, and skin blood flow. If placental compromise is prolonged and/or severe, total circulatory failure is likely with cerebral hypoperfusion and resultant hypoxic ischemic cerebral injury with collateral renal, cardiac, and hepatic injury. Management strategies should be targeted at restoring cerebral perfusion and oxygen delivery and minimizing the extent of secondary injury. Specifically, the focus should include the judicious use of supplemental oxygen, avoidance of hypoglycemia and elevated temperature in the delivery room, and the early administration of therapeutic hypothermia to high-risk infants.

Comorbidity and metabolic context are crucial factors determining neurological sequelae of hypoglycaemia

AIM

To determine risk factors for neurological sequelae following hypoglycemia.

METHOD

We analysed the neurological outcome in 164 patients (mean age 10y 10mo, SD 5.9) following hypoglycemia due to three diseases with various metabolic contexts, different ages at onset, and combinations with comorbidity (fever/infection, hypoxia/ischemia): glycogen storage disease type I (GSDI) (21 patients, mean age at first hypoglycemic episode 3.8mo, SD 3.5); fatty acid β-oxidation defects (FAOD) (29 patients, mean age at first hypoglycemic episode 14.8mo, SD 12.6); and hyperinsulinism (HIns) (114 patients, mean age at first hypoglycemic episode 2.3mo, SD 4.7).

RESULTS

Risk factors of poor neurological outcome were aetiology (p<0.006), comorbidity (p<0.001), and prolonged convulsions (p<0.001). Ordinal logistic regression showed that comorbidity (p<0.001) and status epilepticus (p=0.002) were the main determinants of sequelae. Asymptomatic hypoglycemia did not lead to sequelae, whatever the aetiology. Age was not correlated to sequelae, whatever the aetiology. The highest prevalence of hypoglycemic sequelae was found in FAOD and HIns combined with comorbidity, the lowest in GSDI (p<0.001) in which hypoglycemia is often asymptomatic, associated with increased plasma lactate, and rarely combined with comorbidity.

INTERPRETATION

Hypoglycemia is severely deleterious for the brain in the context of fever/infection and/or hypoxia/ischemia, and status epilepticus. The metabolic context providing alternative fuels may improve neurological outcome.

Treatment of hypoxic-ischemic encephalopathy in newborns

Hypoxic-ischemic (HI) brain injury is the most common cause of encephalopathy and seizures in term newborn infants. There is no single, valid test for birth asphyxia leading to HI brain injury, and thus this disorder is often poorly characterized, and the timing and etiology of the injury can be difficult to ascertain. Optimal management of HI brain injury involves prompt resuscitation, careful supportive care including prevention of hyperthermia and hypoglycemia, and treatment of clinical and frequent or prolonged subclinical seizures. Recent evidence suggests that therapeutic hypothermia by selective head or whole-body cooling administered within 6 hours of birth reduces the incidence of death or moderate/severe disability at 12 to 22 months. Hypothermia is a promising new therapy that physicians should consider within the context of a registry or study. Optimal seizure treatment remains controversial because the most widely used drug, phenobarbital, has limited efficacy, and the value of monitoring and treating subclinical seizures is uncertain. There is compelling need for well-designed clinical trials to address treatment of ongoing brain injury in the setting of hypoxia-ischemia and seizures. Emerging evidence from preclinical studies suggests that future therapy for HI brain injury and neonatal encephalopathy will combine novel neuroprotective and anti-seizure agents. Pilot clinical trials of newer anticonvulsants are ongoing and will provide critical information for care of neonatal seizures.

A critical appraisal of Vlasselaers D, Milants I, Desmet L, et al: intensive insulin therapy for patients in paediatric intensive care: a prospective, randomised controlled study. Lancet 2009; 373:547-556

OBJECTIVE

To review findings and discuss implications of strict glycemic control in children.

DESIGN

Critical appraisal of a randomized controlled trial.

FINDINGS

This is the largest prospective randomized controlled trial to date, comparing intensive insulin therapy (glycemic targets: 50.4-79.2 mg/dL [2.8-4.4 mmol/L] and 70.2-99 mg/dL [3.9-5.5 mmol/L] [for infants and children, respectively]) and conventional insulin therapy (target: 180-215 mg/dl [10-11.9 mmol/L]) among critically ill children. Groups were similar at enrollment and had comparable forms of nutrition and glucose infusion rates. Steroid use and vasoactive-inotrope scores were not compared. Intensive insulin therapy reduced pediatric intensive care unit length of stay (primary outcome measure) and attenuated C-reactive protein concentrations >5 days. The effect of intensive insulin therapy on secondary outcome measures was precise in regards to significant reductions in secondary infection occurrence (absolute risk reduction = 7.6% [95% confidence interval: 0.6-14.4], number needed to treat = 14 [95% confidence interval: 7-179]) and need for vasoactive support beyond 2 days (absolute risk reduction = 10.4% [95% confidence interval: 3-17], number needed to treat = 10 [95% confidence interval: 6-30]). Mortality decreased with intensive insulin therapy (p = .038); however, this finding was imprecise (absolute risk reduction = 3.1% [95% confidence interval: 0.2-5.4], number needed to treat = 33 [95% confidence interval: 18.6-597.3]). The incidence of hypoglycemia was significantly higher with intensive insulin therapy (absolute risk increase = 23.5% [95% confidence interval: 20-25%], number needed to harm = 4 [95% confidence interval: 4-5]). Long-term effects on outcomes were not evaluated, and the authors recognize the need for such follow-up studies. This study demonstrated efficacy of intensive insulin therapy at the same institution where the original adult intensive insulin therapy trial was conducted, but it may not demonstrate effectiveness in populations other than postoperative cardiac patients, which composed the majority of patients enrolled or in institutions without a highly experienced nursing staff to manage intensive insulin therapy.

CONCLUSIONS

This was a well-designed single-center trial that serves as proof of concept. The effects of intensive insulin therapy on mortality require further investigation, and its practice may need refinement to reduce the risk of hypoglycemia. In the meantime, targeting age-adjusted fasting glucose ranges cannot be routinely recommended in critically ill children.

Current management of the infant who presents with neonatal encephalopathy

Neonatal encephalopathy after perinatal hypoxic-ischemic insult is a major contributor to global child mortality and morbidity. Brain injury in term infants in response to hypoxic-ischemic insult is a complex process evolving over hours to days, which provides a unique window of opportunity for neuroprotective treatment interventions. Advances in neuroimaging, brain monitoring techniques, and tissue biomarkers have improved the ability to diagnose, monitor, and care for newborn infants with neonatal encephalopathy as well as predict their outcome. However, challenges remain in early identification of infants at risk for neonatal encephalopathy, determination of timing and extent of hypoxic-ischemic brain injury, as well as optimal management and treatment duration. Therapeutic hypothermia is the most promising neuroprotective intervention to date for infants with moderate to severe neonatal encephalopathy after perinatal asphyxia and has currently been incorporated in many neonatal intensive care units in developed countries. However, only 1 in 6 babies with encephalopathy will benefit from hypothermia therapy; many infants still develop significant adverse outcomes. To enhance the outcome, specific diagnostic predictors are needed to identify patients likely to benefit from hypothermia treatment. Studies are needed to determine the efficacy of combined therapeutic strategies with hypothermia therapy to achieve maximal neuroprotective effect. This review focuses on important concepts in the pathophysiology, diagnosis, and management of infants with neonatal encephalopathy due to perinatal asphyxia, including an overview of recently introduced novel therapies.

Clinical outcome and magnetic resonance imaging findings in infants with hypoglycemia

The authors examined clinical outcome and cranial magnetic resonance imaging (MRI) findings in infants with hypoglycemia to determine the effects of hypoglycemia on the developing brain. A total of 110 infants with hypoglycemia were included in the study. Of the patients, 36 were females and 74 were males. The age of the infants was between 1 day and 22 months. Of the 110 infants, 47 were preterm neonates, 40 were term neonates, and 23 were older than 28 days. No difference in serum glucose level was noted between symptomatic and asymptomatic infants. The most common observed abnormal findings were hyperintense lesions, encephalomalacia, and cerebral atrophy. Abnormal MRI findings were found in 4% of preterm infants, in 32.5% of term infants, and in 43.5% of older infants. Abnormal MRI findings were statistically significantly more common in symptomatic infants than in asymptomatic infants. Of the infants, 45.5% of hypoglycemic infants had cerebral palsy and/or cerebral palsy plus epilepsy.

Akt2 modulates glucose availability and downstream apoptotic pathways during development

Glucose is the primary energy substrate for eukaryotic cells and the predominant substrate for the brain. Studies suggest that glucose serves an additional role in the regulation of cellular functions, including viability. Zebrafish is a tractable system for defining the cellular and molecular mechanisms perturbed by impaired glucose transport and metabolism. Previously, we demonstrated a critical role for the facilitative glucose transporter, Glut1, in the regulation of embryonic brain development. In this study, we aim to identify mediators in this Glut1-sensitive process by investigating the role of the antiapoptotic kinase, Akt2. Results show that abrogating expression of akt2 causes a phenotype strikingly similar to that observed when glut1 expression is inhibited. akt2-deficient embryos exhibit increased neuronal apoptosis, impaired glucose uptake, and death by 72 h postfertilization. Similar to what was observed in the glut1 morphants, inhibiting the expression of the proapoptotic protein, bad, in the context of impaired akt2 expression results in the inhibition of apoptosis and rescue of the morphant embryos. Intriguingly, overexpression of glut1 in the akt2 morphants was also able to rescue these embryos. Quantitative reverse transcription-PCR analysis revealed decreased glut1 transcript expression in akt2 morphant embryos. Taken together, these data suggest that Akt2 modulates glucose availability by regulating Glut1 expression at the transcript level. These data support a role for akt2 in an integrative pathway directly linking glucose, Glut1 expression, and activation of apoptosis and demonstrate the dependence of akt2 on glucose availability for the maintenance of cellular viability, particularly in the central nervous system.

Diagnosis of perinatal stroke I: definitions, differential diagnosis and registration

INTRODUCTION

Perinatal stroke can be divided into three subtypes: ischaemic stroke, either arterial or sinovenous and haemorrhagic stroke. For the sake of universal registration and to perform intervention studies, we propose a detailed diagnostic registration system for perinatal stroke taking 10 variables into account. These variables are discussed here and in the accompanying article.

MATERIAL AND RESULTS

Differentiation is needed from focal brain changes as a result of disorders other than stroke, whereby accurate timing is possible only when early neonatal imaging is available. Detailed templates are presented for arterial and venous vascular classification. AIS is further subdivided into single territory and complex infarction and some stratification is proposed in the complicated stroke group. This registration system has been applied to a retrospective cohort of 134 newborns with stroke (single-centre observation from 1999 to 2007) and the results are compared with published data. By applying this registration system, intervention studies for one homogeneous stroke type (e.g. complete middle cerebral artery stroke) may be facilitated.

CONCLUSION

Ten variables may be sufficient to register a perinatal stroke. These include gestational age, birthweight, gender, delivery mode, time of detection, presentation, type of stroke, vessel affected or type of cavity, imaging method at detection and clinical context.

Associated factors in neonatal hypoglycemic brain injury

Although associated factors are important for the occurrence of neural damage in neonatal hypoglycemia, they are not fully understood. Sixty patients with neonatal hypoglycemia were studied through a review of their medical records in Tottori University Hospital. The patients were classified into two main groups: Group I were patients who had mental retardation, developmental delay, cerebral palsy or epilepsy while Group II were those who were normal in their follow-up. Group I consisted of 12 patients while Group II consisted of 48 patients. The median gestational age was 38 weeks in Group I and 36.7 weeks in Group II. The frequencies of small for gestational age were similar in both groups. Blood glucose levels less than 15 mg/dl were more frequent in Group 1 (50.0%) than in Group 2 (14.6%) (P=0.015). Duration of hypoglycemia was longer in Group I (median, 14 h) than in Group II (median, 1.75 h) (p<0.001). The following factors were more frequent in Group I than in Group II: toxemia (33.3% and 8.3%, p=0.043), fetal distress (58.3% and 14.5%, p=0.004), an Apgar score of less than 5 at 1 min (33.3% and 6.4%, p=0.025), neonatal seizure (53.8% and 4.3%, p<0.001) and pathological jaundice (41.7% and 6.4%, p=0.006). Cranial CT or MRI revealed cerebral lesions in 8 of the 9 Group I patients in follow-up examinations. This study indicates that severe and prolonged neonatal hypoglycemia can cause cerebral lesions and other perinatal risk factors, such as hypoxia, neonatal seizure and pathological jaundice, would exacerbate hypoglycemic brain injuries.

Not all sweetness and light: the role of glycogen in hypoglycemic seizures

Factors Which Abolish Hypoglycemic Seizures Do Not Increase Cerebral Glycogen Content In Vitro. Abdelmalik PA, Liang P, Weisspapir M, Samoilova M, Burnham WM, Carlen PL. Neurobiol Dis 2008;29(2):201–209. Epub 2007 Aug 29. The brain is heavily dependant on glucose for its function and survival. Hypoglycemia can have severe, irreversible consequences, including seizures, coma and death. However, the in vivo content of brain glycogen, the storage form of glucose, is meager and is a function of both neuronal activity and glucose concentration. In the intact in vitro hippocampus isolated from mice aged postnatal days 8–13, we have recently characterized a novel model of hypoglycemic seizures, wherein seizures were abolished by various neuroprotective strategies. We had hypothesized that these strategies might act, in part, by increasing cerebral glycogen content. In the present experiments, it was found that neither decreasing temperature nor increasing glucose concentrations (above 2 mM) significantly increased hippocampal glycogen content. Preparations of isolated frontal neocortex in vitro do not produce hypoglycemic seizures yet it was found they contained significantly lower glycogen content as compared to the isolated intact hippocampus. Further, the application of either TTX, or a cocktail containing APV, CNQX and gabazine, to block synaptic activity, did not increase, but paradoxically decreased, hippocampal glycogen content in the isolated intact hippocampus. Significant decreases in glycogen were noted when neuronal activity was increased via incubation with l-aspartate (500 μM) or low Mg2+. Lastly, we examined the incidence of hypoglycemic seizures in hippocampi isolated from mice aged 15–19 and 22–24 days, and compared it to the incidence of hypoglycemic seizures of hippocampi isolated from mice aged 8–13 days described previously (Abdelmalik et al., 2007 Neurobiol Dis 26(3):646–660). It was noted that hypoglycemic seizures were generated less frequently, and had less impact on synaptic transmission in hippocmpi from PD 22–24 as compared to hippocampi from mice PD 15–19 or PD 8–13. However, hippocampi from 8- to 13-day-old mice had significantly more glycogen than the other two age groups. The present data suggest that none of the interventions which abolish hypoglycemic seizures increases glycogen content, and that low glycogen content, per se, may not predispose to the generation of hypoglycemic seizures.

Treatment of the term newborn with brain injury: simplicity as the mother of invention

Neonatal brain injury remains a common cause of developmental disability, despite tremendously enhanced obstetrical and neonatal care. The timing of brain injury occurs throughout gestation, labor, and delivery, providing an evolving form of brain injury and a moving target for therapeutic intervention. Nonetheless, markedly improved methods are available to identify those infants injured at birth, via clinical presentation with neonatal encephalopathy and neuroimaging techniques. Postischemic hypothermia has been shown to be of tremendous clinical promise in several completed and ongoing trials. As part of this approach to the treatment of the newborn, other parameters of physiologic homeostasis can and should be attended to, with strong animal and clinical evidence that their correction will have dramatic influence on the outcome of the newborn infant. This review addresses aspects of newborn care to which we can direct our attention currently, and which should result in a safe and efficacious improvement in the prognosis of the newborn with neonatal encephalopathy.

Neurologic sequelae of neonatal hypoglycemia in Kayseri, Turkey

Contrary to belief, neonatal hypoglycemia is relatively common and can cause more severe neurological sequelae than is currently believed. Prevention of hypoglycemic brain damage by hindering prolonged and profound neonatal hypoglycemia might contribute to psychomotor development. At Erciyes University, between December 1996 and 2005, of the patients who applied to Paediatric Neurology Department, 60 cases with a history of neonatal hypoglycemia were included in the study. The magnetic resonance imaging (MRI) scans and clinical records of all patients were reviewed retrospectively. It was noted that the sequelae with glucose levels of 0 0 to 40 were more serious and intense. The same results were also observed in cranial MRI evaluation. In conclusion, intractable epilepsy, mental motor retardation, cerebral palsy, and visual disturbance were found to be the most common and severe conditions affecting sufferers of neonatal hypoglycemia. In the first 3 days of life, the close monitoring of patients at risk is critical, and hospitalization of severe cases should be considered.

Post-resuscitation strategies to avoid ongoing injury following intrapartum hypoxia-ischemia

The interruption of placental blood flow during labor with redistribution of cardiac output resulting in increased flow to brain, heart, and adrenal glands at the expense of flow to kidney, gut, and skin can result in systemic organ as well as cerebral injury. Thus, post-resuscitation strategies should focus on both the management of potential systemic organ dysfunction and on methods of preventing ongoing brain injury in high-risk infants. General management strategies should include ventilator management to maintain pCO(2) values in the normal range, close attention to blood pressure to avoid hypotension, striving to avoid hypoglycemia, and control of seizures. Modest hypothermia administered within the first 6 hours has been shown to reduce neurodevelopmental deficits and death in those infants at highest-risk infants for developing hypoxic-ischemic brain injury.

Strict glycemic targets need not be so strict: a more permissive glycemic range for critically ill children

OBJECTIVE

The goal was to determine whether a more permissive glycemic target would be associated with a decreased incidence of hypoglycemia but not increased mortality rates in critically ill pediatric patients.

METHODS

This retrospective study evaluated clinical and laboratory data for 177 patients who underwent 211 consecutive surgical procedures for repair or palliation of congenital heart defects at Driscoll Children's Hospital. To establish the relationship between postoperative glycemia and subsequent morbidity and mortality rates, patients were stratified into 4 groups according to their median glucose levels, that is, euglycemia (60-125 mg/dL, 3.3-6.9 mmol/L), mild hyperglycemia (126-139 mg/dL, 6.9-7.7 mmol/L), moderate hyperglycemia (140-179 mg/dL, 7.7-9.9 mmol/L), or severe hyperglycemia (>or=180 mg/dL, >or=9.9 mmol/L). Postoperative outcomes for those groups also were compared with outcomes for a more permissive glycemic target group (90-140 mg/dL, 5-7.7 mmol/L).

RESULTS

The peak and mean blood glucose measurements and duration of hyperglycemia were not different for survivors and nonsurvivors in the first 24 hours after surgery. Nonsurvivors had higher peak glucose levels (389.3 +/- 162 mg/dL vs 274.4 +/- 106.3 mg/dL, 21.4 +/- 8.9 mmol/L vs 15.1 +/- 5.9 mmol/L) and longer duration of hyperglycemia (3.06 +/- 1.67 days vs 2.11 +/- 0.92 days) during the first 5 postoperative days, compared with survivors. Mortality rates were significantly higher for the moderate (38.8%) and severe (58.3%) hyperglycemia groups, compared with the euglycemia (6.02%) and permissive target (4.69%) groups. The incidence of hypoglycemia was significantly higher in the euglycemia group (31.8%), compared with the permissive target group (17.18%).

CONCLUSIONS

Postoperative hyperglycemia is associated with increased morbidity and mortality rates in children after surgical repair of congenital heart defects. A more permissive glycemic target is associated with a lower incidence of hypoglycemia but not increased mortality rates in these patients.

Hypoglycemia in infants and children

Our understanding of the many different causes of hypoglycemia has vastly expanded in recent years. Most hypoglycemic disorders in infants and children are due to defects in the metabolic systems involved in fasting adaptation or the hormone control of these systems. As a result of these defects, infants and children have an abnormal adaptation to fasting, which results in hypoglycemia. The "critical sample" allows one to assess the integrity of the fasting systems when hypoglycemic. An understanding of the pathophysiology of these disorders establishes a foundation for a rational approach in evaluating the etiology of the hypoglycemia and developing the most appropriate management plan.

Intervention strategies for neonatal hypoxic-ischemic cerebral injury

BACKGROUND

Accumulating evidence points to an evolving process of brain injury after intrapartum hypoxia-ischemia that initiates in utero and extends into a recovery period. It is during this recovery period that the potential for neuroprotection exists.

OBJECTIVE

This discussion briefly reviews the cellular characteristics of hypoxic-ischemic cerebral injury and the current and future therapeutic strategies aimed at ameliorating ongoing brain injury after intrapartum hypoxia-ischemia.

METHODS

As part of the Newborn Drug Development Initiative, the National Institute of Child Health and Human Development and the US Food and Drug Administration cosponsored a workshop held March 29 and 30, 2004, in Baltimore, Maryland. Information for this article was gathered during that workshop. Literature searches of MEDLINE (Ovid) and EMBASE (1996-2005) were also conducted; search terms included newborn, infant, hypoxia-ischemia, hypoxic-ischemic encephalopathy, asphyxia, pathogenesis, treatment, reperfusion injury, and mechanisms, as well as numerous interventions (ie, therapeutic hypothermia, magnesium, and barbiturates).

RESULTS

The acute brain injury results from the combined effects of cellular energy failure, acidosis, glutamate release, intracellular calcium accumulation, lipid peroxidation, and nitric oxide neurotoxicity that serve to disrupt essential components of the cell, resulting in death. Many factors, including the duration or severity of the insult, influence the progression of cellular injury after hypoxia-ischemia. A secondary cerebral energy failure occurs from 6 to 48 hours after the primary event and may involve mitochondrial dysfunction secondary to extended reactions from primary insults (eg, calcium influx, excitatory neurotoxicity, oxygen free radicals, or nitric oxide formation). Some evidence suggests that circulatory and endogenous inflammatory cells/mediators also contribute to ongoing brain injury. The goals of management of a newborn infant who has sustained a hypoxic-ischemic insult and is at risk for injury should include early identification of the infant at highest risk for evolving injury, supportive care to facilitate adequate perfusion and nutrients to the brain, attempts to maintain glucose homeostasis, and consideration of interventions to ameliorate the processes of ongoing brain injury. Recent evidence suggests a potential role for modest hypothermia (ie, a reduction in core body temperature to -34 degrees C) administered to high-risk term infants within 6 hours of birth. Either selective (head) or systemic (body) cooling reduces the incidence of death and/or moderate to severe disability at 18-month follow-up. Additional strategies-including the use of oxygen free radical inhibitors and scavengers, excitatory amino acid antagonists, and growth factors; prevention of nitric oxide formation; and blockage of apoptotic pathways-have been evaluated experimentally but have not been replicated in a systematic manner in the human neonate. Other avenues of potential neuroprotection that have been studied in immature animals include platelet-activating factor antagonists, adenosinergic agents, monosialoganglioside GM1, insulin-like growth factor-1, and erythropoietin.

CONCLUSIONS

Much progress has been made toward understanding the mechanisms contributing to ongoing brain injury after intrapartum hypoxia-ischemia. This should facilitate more specific pharmacologic intervention strategies that might provide neuroprotection during the reperfusion phase of injury.

Intrapartum maternal glycemic control in women with insulin requiring diabetes: a randomized clinical trial of rotating fluids versus insulin drip

OBJECTIVE

The purpose of this study was to determine whether continuous insulin infusion provides a greater degree of intrapartum maternal glycemic control than rotating between glucose and non-glucose containing intravenous fluids.

STUDY DESIGN

Laboring patients with pregestational or gestational diabetes were recruited and randomized to an "insulin drip" or "rotating fluids" protocol. The primary outcome measure was mean maternal capillary blood glucose (CBG) levels (mg/dL). Power analysis indicated that 16 patients were needed in each arm to find a difference of 10 mg/dL.

RESULTS

Fifteen patients were randomized to the rotating fluids protocol and 21 patients to an insulin drip. There was no difference in mean intrapartum maternal CBG levels (103.9 +/- 8.7 mg/dL and 103.2 +/- 17.9 mg/dL in the rotating fluids and insulin drip group, respectively, P = .89). Neonatal outcomes were also similar between the 2 treatment groups.

CONCLUSION

In patients with insulin requiring gestational diabetes, intrapartum glycemic control may be comparable with a standard adjusted insulin drip or a rotation of intravenous fluids between glucose and non-glucose containing fluids.

Ketones keep neurons alive

Ketogenic Diet Reduces Hypoglycemia-Induced Neuronal Death in Young Rats

Yamada KA, Rensing N, Thio LL

Neurosci Lett 2005;385(3):210–214

Hypoglycemia is an important complication of insulin treatment in diabetic children and may contribute to lasting cognitive impairment. Previous studies demonstrated that 21-day-old rats (P21) subjected to brief, repetitive episodes of hypoglycemia sustain cortical neuronal death. The developing brain is capable of utilizing alternative energy substrates acetoacetate and β-hydroxybutyrate. In these studies, we tested the hypothesis that the developing brain adapted to ketone utilization and provided with ketones during hypoglycemia by eating a ketogenic diet would sustain less brain injury compared to littermates fed a standard diet. Supporting this hypothesis, P21 rats weaned to a ketogenic diet and subjected to insulin-induced hypoglycemia at P25 had significantly less neuronal death than rats on a standard diet. This animal model may provide insight into the determinants influencing the brain's susceptibility to hypoglycemic injury.

Severe leukopenia and liver biochemistry changes in adult rabbits after calicivirus infection

Calicivirus infection is the major cause of the severe decrease in the stocks of wild and farm rabbits that has occurred worldwide during the last two decades. Adult rabbits (10-weeks-old) were experimentally infected with a calicivirus inoculum that killed all animals by causing rabbit haemorrhagic disease (RHD) within 24-62 h of infection. The rabbits were used to evaluate blood cell numbers and serum biochemistry every 6h, starting 12h after the inoculation of the caliciviruses. No significant changes in blood parameters were observed in most of the rabbits up to 18 h of infection. Severe leukopenia was seen 6h before death of the infected rabbits; both heterophils and lymphocytes contributed to the decrease in circulating white blood cells. Platelets were also severely decreased in number. Marked enhancement in liver enzymes was seen 6-12 h before death of the infected rabbits. There was also evidence both for cholestasis, as expressed by the elevated levels of direct (conjugated) bilirubin, and for hypoglycemia, an alteration that it is likely to contribute for the seizures that rabbits show during the late stages of RHD. Liver ultrastructure of rabbits that died from RHD revealed extensive hepatocyte vacuolization, severe changes in mitochondrial structure, and depletion of glycogen granules. We conclude that: (i) severe leukopenia characterizes the final hours of calicivirus-induced RHD; (ii) hypoglycemia and cholestasis precede death of rabbits from RHD; (iii) the kinetics of liver enzymes allows an accurate prediction of the time of death of rabbits from calicivirus-induced RHD.

Hypoxic-ischemic brain injury in the term infant-current concepts

An enhanced understanding of the cellular characteristics contributing to ongoing brain injury following intrapartum hypoxia-ischemia has resulted in the implementation of targeted neuroprotective strategies in the newborn period. This review briefly covers the pathogenesis of hypoxic-ischemic injury with an emphasis on reperfusion injury; the role of magnetic resonance imaging in the detection of such injury, and focuses on potential strategies both supportive and neuroprotective to prevent ongoing injury with a specific emphasis on modest hypothermia.

Lowered glucose suppressed the proliferation and increased the differentiation of murine neural stem cells in vitro

Cerebral ischemia is known to activate endogenous neural stem cells (NSCs), but its mechanisms remain unknown. Since lowered glucose supply seems to mediate ischemic actions, we examined the effect of low glucose on NSC activities in vitro. Low glucose applied during the proliferation period diminished EGF-induced proliferation of NSCs without affecting subsequent differentiation, but low glucose directly exposed during the differentiation period facilitated the differentiation of NSCs into neurons and astrocytes. These findings suggest that low glucose facilitated NSC differentiation, but it diminished NSC proliferation. Moreover, the effect of low glucose may be dependent on the timing of application.

Insulin, C-peptide, hyperglycemia, and central nervous system complications in diabetes

Diabetes is an increasingly common disorder which causes and contributes to a variety of central nervous system (CNS) complications which are often associated with cognitive deficits. There appear to be two types of diabetic encephalopathy. Primary diabetic encephalopathy is caused by hyperglycemia and impaired insulin action, which evolves in a diabetes duration-related fashion and is associated with apoptotic neuronal loss and cognitive decline. This appears to be particularly associated with insulin-deficient diabetes. Secondary diabetic encephalopathy appears to arise from hypoxic-ischemic insults due to underlying microvascular disease or as a consequence of hypoglycemia. This type of cerebral diabetic complication is more common in the type 2 diabetic population. Here, we will review the clinical and experimental data supporting this conceptual division of diabetic CNS complications and discuss the underlying metabolic, molecular, and functional aberrations.