Associations between neonatal hypoglycaemia and brain volumes, cortical thickness and white matter microstructure in mid-childhood: An MRI study

Neonatal Hypoglycemia and Neurocognitive Function at School Age: A Prospective Cohort Study

OBJECTIVE

To determine the relationship between transient neonatal hypoglycemia in at-risk infants and neurocognitive function at 6-7 years of corrected age.

STUDY DESIGN

The pre-hPOD Study involved children born with at least 1 risk factor for neonatal hypoglycemia. Hypoglycemia was defined as ≥1 consecutive blood glucose concentrations <47 mg/dl (2.6 mmol/L), severe as <36 mg/dl (2.0 mmol/L), mild as 36 to <47 mg/dL (2.0 to <2.6 mmol/L), brief as 1-2 episodes, and recurrent as ≥3 episodes. At 6-7 years children were assessed for cognitive and motor function (NIH-Toolbox), learning, visual perception and behavior. The primary outcome was neurocognitive impairment, defined as >1 SD below the normative mean in ≥1 Toolbox tests. The 8 secondary outcomes covered children's cognitive, motor, language, emotional-behavioral, and visual perceptual development. Primary and secondary outcomes were compared between children who did and did not experience neonatal hypoglycemia, adjusting for potential confounding by gestation, birthweight, sex and receipt of prophylactic dextrose gel (pre-hPOD intervention). Secondary analysis included assessment by severity and frequency of hypoglycemia.

RESULTS

Of 392 eligible children, 315 (80%) were assessed at school age (primary outcome, n = 308); 47% experienced hypoglycemia. Neurocognitive impairment was similar between exposure groups (hypoglycemia 51% vs 50% no hypoglycemia; aRD -4%, 95% CI -15%, 7%). Children with severe or recurrent hypoglycemia had worse visual motion perception and increased risk of emotional-behavioral difficulty.

CONCLUSION

Exposure to neonatal hypoglycemia was not associated with risk of neurocognitive impairment at school-age in at-risk infants, but severe and recurrent episodes may have adverse impacts.

TRIAL REGISTRATION

Hypoglycemia Prevention in Newborns with Oral Dextrose: the Dosage Trial (pre-hPOD Study): ACTRN12613000322730.

Diabetes mellitus in older persons with neurocognitive disorder: overtreatment prevalence and associated structural brain MRI findings

BACKGROUND

Tight diabetes control is often applied in older persons with neurocognitive disorder resulting in increased hypoglycemic episodes but little is known about the pattern of brain injury in these overtreated patients. This study aims to: (a) quantify the prevalence of diabetes overtreatment in cognitively impaired older adults in a clinical population followed in an academic memory clinic (b) identify risk factors contributing to overtreatment; and (c) explore the association between diabetes overtreatment and specific brain region volume changes.

METHODS

Retrospective study of older patients with type 2 diabetes and cognitive impairment who were diagnosed in a memory clinic from 2013 to 2020. Patients were classified into vulnerable and dependent according to their health profile. Overtreatment was defined when glycated hemoglobin was under 7% for vulnerable and 7.6% for dependent patients. Characteristics associated to overtreatment were examined in multivariable analysis. Grey matter volume in defined brain regions was measured from MRI using voxel-based morphometry and compared in patients over- vs. adequately treated.

RESULTS

Among 161 patients included (median age 76.8 years, range 60.8-93.3 years, 32.9% women), 29.8% were considered as adequately treated, 54.0% as overtreated, and 16.2% as undertreated. In multivariable analyses, no association was observed between diabetes overtreatment and age or the severity of cognitive impairment. Among patients with neuroimaging data (N = 71), associations between overtreatment and grey matter loss were observed in several brain regions. Specifically, significant reductions in grey matter were found in the caudate (adj β coeff: -0.217, 95%CI: [-0.416 to -0.018], p = .033), the precentral gyri (adj βcoeff:-0.277, 95%CI: [-0.482 to -0.073], p = .009), the superior frontal gyri (adj βcoeff: -0.244, 95%CI: [-0.458 to -0.030], p = .026), the calcarine cortex (adj βcoeff:-0.193, 95%CI: [-0.386 to -0.001], p = .049), the superior occipital gyri (adj βcoeff: -0.291, 95%CI: [-0.521 to -0.061], p = .014) and the inferior occipital gyri (adj βcoeff: -0.236, 95%CI: [-0.456 to - 0.015], p = .036).

CONCLUSION

A significant proportion of older patients with diabetes and neurocognitive disorder were subjected to excessively intensive treatment. The association identified with volume loss in several specific brain regions highlights the need to further investigate the potential cerebral damages associated with overtreatment and related hypoglycemia in larger sample.

Delivery room glucose to reduce the risk of admission hypoglycemia in preterm infants: a systematic literature review

AIMS

In order to mitigate early hypoglycemia in preterm infants, some clinicians have recently explored interventions such as delivery room commencement of dextrose infusions or delivery room administration of buccal dextrose gel. This review aimed to systematically investigate the literature regarding the provision of delivery room (prior to admission) parenteral glucose as a method to reduce the risk of initial hypoglycemia (measured at the time of NICU admission blood testing) in preterm infants.

MATERIALS AND METHODS

Using PRISMA guidelines a literature search (May 2022) was conducted using PubMed, Embase, Scopus, Cochrane Library, OpenGrey, and Prospero databases. The clinicaltrials.gov database was searched for possible completed/ongoing clinical trials. Studies that included moderate preterm (≤33⁺⁶ weeks) or younger birth gestations or very low birth weight (or smaller) infants, and that administered parenteral glucose in the delivery room were included. The literature was appraised via data extraction, narrative synthesis, and critical review of the study data.

RESULTS

A total of five studies (published 2014-2022) were eligible for inclusion (three before-after "quasi-experimental" studies, one retrospective cohort study, and one case-control study). Most included studies used intravenous dextrose as the intervention. Individual study effects (odds ratios) favored the intervention in all included studies. It was felt that the low number of studies, the variability in study design, and the nonadjustment for confounding co-interventions (co-exposures) precluded a meta-analysis. Quality assessment of the studies revealed a spectrum of bias from low to high risk, however, most studies had moderate to high risk of bias, and their direction of bias favored the intervention.

CONCLUSIONS

This extensive search and systematic appraisal of the literature indicates that there exists few studies (these are low grade and at moderate to high risk of bias) for the interventions of either intravenous or buccal dextrose given in the delivery room. It is not clear if these interventions impact on rates of early (NICU admission) hypoglycemia in these preterm infants. Obtaining intravenous access in the delivery room is not guaranteed and can be difficult in these small infants. Future research should consider various routes for commencing delivery room glucose in these preterm infants and should take the form of randomized controlled trials.

Oral dextrose gel to prevent hypoglycaemia in at-risk neonates

BACKGROUND

Neonatal hypoglycaemia is a common condition that can be associated with brain injury. Current practice usually includes early identification of at-risk infants (e.g. infants of diabetic mothers; preterm, small- or large-for-gestational-age infants), and prophylactic measures are advised. However, these measures often involve use of formula milk or admission to the neonatal unit. Dextrose gel is non-invasive, inexpensive and effective for treatment of neonatal hypoglycaemia. Prophylactic dextrose gel can reduce the incidence of neonatal hypoglycaemia, thus potentially reducing separation of mother and baby and supporting breastfeeding, as well as preventing brain injury. This is an update of a previous Cochrane Review published in 2021.

OBJECTIVES

To assess the effectiveness and safety of oral dextrose gel in preventing hypoglycaemia before first hospital discharge and reducing long-term neurodevelopmental impairment in newborn infants at risk of hypoglycaemia.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase and Epistemonikos in April 2023. We also searched clinical trials databases and the reference lists of retrieved articles.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs comparing oral dextrose gel versus placebo, no intervention, or other therapies for the prevention of neonatal hypoglycaemia. We included newborn infants at risk of hypoglycaemia, including infants of mothers with diabetes (all types), high or low birthweight, and born preterm (< 37 weeks), age from birth to 24 hours, who had not yet been diagnosed with hypoglycaemia.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias. We contacted investigators to obtain additional information. We used fixed-effect meta-analyses. We used the GRADE approach to assess the certainty of evidence.

MAIN RESULTS

We included two studies conducted in high-income countries comparing oral dextrose gel versus placebo in 2548 infants at risk of neonatal hypoglycaemia. Both of these studies were included in the previous version of this review, but new follow-up data were available for both. We judged these two studies to be at low risk of bias in 13/14 domains, and that the evidence for most outcomes was of moderate certainty. Meta-analysis of the two studies showed that oral dextrose gel reduces the risk of hypoglycaemia (risk ratio (RR) 0.87, 95% confidence interval (CI) 0.79 to 0.95; risk difference (RD) -0.06, 95% CI -0.10 to -0.02; 2548 infants; high-certainty evidence). Evidence from two studies showed that there may be little to no difference in the risk of major neurological disability at two years of age after oral dextrose gel (RR 1.00, 95% CI 0.59 to 1.68; 1554 children; low-certainty evidence). Meta-analysis of the two studies showed that oral dextrose gel probably reduces the risk of receipt of treatment for hypoglycaemia during initial hospital stay (RR 0.89, 95% CI 0.79 to 1.00; 2548 infants; moderate-certainty evidence) but probably makes little or no difference to the risk of receipt of intravenous treatment for hypoglycaemia (RR 1.01, 0.68 to 1.49; 2548 infants; moderate-certainty evidence). Oral dextrose gel may have little or no effect on the risk of separation from the mother for treatment of hypoglycaemia (RR 1.12, 95% CI 0.81 to 1.55; two studies, 2548 infants; low-certainty evidence). There is probably little or no difference in the risk of adverse effects in infants who receive oral dextrose gel compared to placebo gel (RR 1.22, 95% CI 0.64 to 2.33; two studies, 2510 infants; moderate-certainty evidence), but there are no studies comparing oral dextrose with other comparators such as no intervention or other therapies. No data were available on exclusive breastfeeding after discharge.

AUTHORS' CONCLUSIONS

Prophylactic oral dextrose gel reduces the risk of neonatal hypoglycaemia in at-risk infants and probably reduces the risk of treatment for hypoglycaemia without adverse effects. It may make little to no difference to the risk of major neurological disability at two years, but the confidence intervals include the possibility of substantial benefit or harm. Evidence at six to seven years is limited to a single small study. In view of its limited short-term benefits, prophylactic oral dextrose gel should not be incorporated into routine practice until additional information is available about the balance of risks and harms for later neurological disability. Additional large follow-up studies at two years of age or older are required. Future research should also be undertaken in other high-income countries, low- and middle-income countries, preterm infants, using other dextrose gel preparations, and using comparators other than placebo gel. There are three studies awaiting classification and one ongoing study which may alter the conclusions of the review when published.

Subcortical brain volumes in neonatal hypoxic-ischemic encephalopathy

BACKGROUND

Despite treatment with therapeutic hypothermia, hypoxic-ischemic encephalopathy (HIE) is associated with adverse developmental outcomes, suggesting the involvement of subcortical structures including the thalamus and basal ganglia, which may be vulnerable to perinatal asphyxia, particularly during the acute period. The aims were: (1) to examine subcortical macrostructure in neonates with HIE compared to age- and sex-matched healthy neonates within the first week of life; (2) to determine whether subcortical brain volumes are associated with HIE severity.

METHODS

Neonates (n = 56; HIE: n = 28; Healthy newborns from the Developing Human Connectome Project: n = 28) were scanned with MRI within the first week of life. Subcortical volumes were automatically extracted from T1-weighted images. General linear models assessed between-group differences in subcortical volumes, adjusting for sex, gestational age, postmenstrual age, and total cerebral volumes. Within-group analyses evaluated the association between subcortical volumes and HIE severity.

RESULTS

Neonates with HIE had smaller bilateral thalamic, basal ganglia and right hippocampal and cerebellar volumes compared to controls (all, p < 0.02). Within the HIE group, mild HIE severity was associated with smaller volumes of the left and right basal ganglia (both, p < 0.007) and the left hippocampus and thalamus (both, p < 0.04).

CONCLUSIONS

Findings suggest that, despite advances in neonatal care, HIE is associated with significant alterations in subcortical brain macrostructure.

IMPACT

Compared to their healthy counterparts, infants with HIE demonstrate significant alterations in subcortical brain macrostructure on MRI acquired as early as 4 days after birth. Smaller subcortical volumes impacting sensory and motor regions, including the thalamus, basal ganglia, and cerebellum, were seen in infants with HIE. Mild and moderate HIE were associated with smaller subcortical volumes.

The Effect of Postnatal Cytomegalovirus Infection on (Micro)structural Cerebral Development in Very Preterm Infants at Term-Equivalent Age

INTRODUCTION

There are some data indicating a negative impact of postnatal cytomegalovirus (CMV) infection on long-term neurodevelopmental outcome of preterm infants. So far, there is only little knowledge about a cerebral imaging correlate of these neurodevelopmental alterations induced by postnatal CMV infection in preterm infants. The aim of the current study was to investigate the effect of postnatal CMV infection on the incidence of brain injury and on microstructural brain maturation in very preterm infants at term-equivalent age.

METHODS

Infants <32 gestational weeks (02/2011-11/2018) received cerebral MRI including axial diffusion-weighted images at term-equivalent age. All infants were screened for CMV infection using urine/saliva samples, and infection was regarded as acquired postnatal if a sample became positive >5 postnatal days. We compared brain injury as well as fractional anisotropy and apparent diffusion coefficient in 14 defined cerebral regions between infants with and without postnatal CMV infection.

RESULTS

401 infants were eligible, of whom 18 (4.5%) infants had a postnatal CMV infection. There were no significant differences in rates of brain injury or in microstructural brain development between both groups. This applied equally to the subgroup of infants <28 gestational weeks.

CONCLUSION

Although infants with postnatal CMV infection were born more immature and more frequently suffered from complications related to immaturity, we neither observed a higher rate of preterm brain injury nor disadvantageous alterations in microstructural brain maturation at term-equivalent age.

Size at birth predicts later brain volumes

We aimed to investigate whether gestation at birth, birth weight, and head circumference at birth are still associated with brain volume and white matter microstructure at 9-10 years in children born late-preterm and at term. One hundred and eleven children born at ≥ 36 weeks gestation from the CHYLD Study cohort underwent brain magnetic resonance imaging at 9 to 10 years. Images were analysed using FreeSurfer for volumetric data and tract-based spatial statistics for diffusion data. Of the cohort, 101 children were included for volumetric analysis [boys, 49(49%); median age, 9.5 (range: 8.9-12.4) years]. Shorter gestation at birth, lower birthweight, and smaller birth head circumference were associated with smaller brain volumes at 9 to 10 years, both globally and regionally. Amongst the perinatal factors studied, head circumference at birth was the strongest predictor of later brain volumes. Gestation at birth and absolute birthweight were not associated with diffusion metrics of white matter skeleton. However, lower birthweight z-score was associated with higher fractional anisotropy and lower radial diffusivity. Our findings suggest that even in children born late preterm and at term, growth before birth and timing of birth are still associated with brain development in mid-childhood.

Neonatal hypoglycemia: lack of evidence for a safe management

Neonatal hypoglycemia affects up to 15% of all newborns. Despite the high prevalence there is no uniform definition of neonatal hypoglycemia, and existing guidelines differ significantly in terms of when and whom to screen for hypoglycemia, and where to set interventional thresholds and treatment goals. In this review, we discuss the difficulties to define hypoglycemia in neonates. Existing knowledge on different strategies to approach this problem will be reviewed with a focus on long-term neurodevelopmental outcome studies and results of interventional trials. Furthermore, we compare existing guidelines on the screening and management of neonatal hypoglycemia. We summarize that evidence-based knowledge about whom to screen, how to screen, and how to manage neonatal hypoglycemia is limited - particularly regarding operational thresholds (single values at which to intervene) and treatment goals (what blood glucose to aim for) to reliably prevent neurodevelopmental sequelae. These research gaps need to be addressed in future studies, systematically comparing different management strategies to progressively optimize the balance between prevention of neurodevelopmental sequelae and the burden of diagnostic or therapeutic procedures. Unfortunately, such studies are exceptionally challenging because they require large numbers of participants to be followed for years, as mild but relevant neurological consequences may not become apparent until mid-childhood or even later. Until there is clear, reproducible evidence on what blood glucose levels may be tolerated without negative impact, the operational threshold needs to include some safety margin to prevent potential long-term neurocognitive impairment from outweighing the short-term burden of hypoglycemia prevention during neonatal period.

Neurodevelopmental correlates of caudate volume in children born at risk of neonatal hypoglycaemia

BACKGROUND

Neonatal hypoglycaemia can lead to brain damage and neurocognitive impairment. Neonatal hypoglycaemia is associated with smaller caudate volume in the mid-childhood. We investigated the relationship between neurodevelopmental outcomes and caudate volume and whether this relationship was influenced by neonatal hypoglycaemia.

METHODS

Children born at risk of neonatal hypoglycaemia ≥36 weeks' gestation who participated in a prospective cohort study underwent neurodevelopmental assessment (executive function, academic achievement, and emotional-behavioural regulation) and MRI at age 9-10 years. Neonatal hypoglycaemia was defined as at least one hypoglycaemic episode (blood glucose concentration <2.6 mmol/L or at least 10 min of interstitial glucose concentrations <2.6 mmol/L). Caudate volume was computed using FreeSurfer.

RESULTS

There were 101 children with MRI and neurodevelopmental data available, of whom 70 had experienced neonatal hypoglycaemia. Smaller caudate volume was associated with greater parent-reported emotional and behavioural difficulties, and poorer prosocial behaviour. Caudate volume was significantly associated with visual memory only in children who had not experienced neonatal hypoglycaemia (interaction p = 0.03), but there were no other significant interactions between caudate volume and neonatal hypoglycaemia.

CONCLUSION

Smaller caudate volume is associated with emotional behaviour difficulties in the mid-childhood. Although neonatal hypoglycaemia is associated with smaller caudate volume, this appears not to contribute to clinically relevant neurodevelopmental deficits.

IMPACT

At 9-10 years of age, caudate volume was inversely associated with emotional-behavioural difficulties and positively associated with prosocial behaviour but was not related to executive function or educational achievement. Previous studies have suggested that neonatal hypoglycaemia may contribute to smaller caudate volume but exposure to neonatal hypoglycaemia did not appear to influence the relationship between caudate volume and behaviour. Among children not exposed to neonatal hypoglycaemia, caudate volume was also positively associated with visual memory, but no such association was detected among those exposed to neonatal hypoglycaemia. Understanding early-life factors that affect caudate development may provide targets for improving behavioural function.