Mild hypoxic-ischemic encephalopathy (HIE): timing and pattern of MRI brain injury

Long-Term Outcomes Following Hypoxic Ischemic Encephalopathy

Hypoxic ischemic encephalopathy (HIE) is the most common cause of neonatal encephalopathy and results in significant morbidity and mortality. Long-term outcomes of the condition encompass impairments across all developmental domains. While therapeutic hypothermia (TH) has improved outcomes for term and late preterm infants with moderate to severe HIE, trials are ongoing to investigate the use of TH for infants with mild or preterm HIE. There is no evidence that adjuvant therapies in combination with TH improve long-term outcomes. Numerous trials of various adjuvant therapies are underway in the quest to further improve outcomes for infants with HIE.

Neonatal well-being and timing of brain injury in persons with cerebral palsy born at term or late preterm

AIM

To describe the distribution of neuroimaging patterns in a term/late preterm population-based cohort with cerebral palsy (CP), ascertain associations between neuroimaging patterns and neonatal well-being, estimate the proportion with antenatal or perinatal timing of neuropathology, and apply this information to the understanding of common mechanisms of brain injury and causal pathways.

METHOD

The cohort for this observational study comprised 1348 persons born between 1999 and 2017 in Victoria, Australia. Using algorithms designed for the study, neonatal well-being and timing of brain injury were tabulated for the whole cohort and across neuroimaging patterns and birth epochs.

RESULTS

Clinical and demographic profiles, neonatal well-being, and timing of brain injury differed across neuroimaging patterns. An estimated 57% of the cohort had a complicated neonatal period. Timing of brain injury was antenatal in 57% and perinatal in 41%. A decrease in the relative proportions of perinatal timing of brain injury was observed over a period when the rates of CP in live births at term decreased.

INTERPRETATION

This study begins to bridge the knowledge gap about causation in CP, moving towards better description of the main mechanisms of brain injury and their contribution within CP cohorts, and facilitating the ability to monitor changes over time and the success of preventive measures.

WHAT THIS PAPER ADDS

In a population-based, term/late preterm cohort with cerebral palsy, 57% had a complicated neonatal period. In the same cohort, 57% had presumed antenatal timing of brain injury. The relative proportion with perinatal injury decreased over time.

Amplitude-Integrated Electroencephalography Evolution and Magnetic Resonance Imaging Injury in Mild and Moderate to Severe Neonatal Encephalopathy

OBJECTIVE

This study aimed to describe the evolution of amplitude-integrated electroencephalography (aEEG) in neonatal encephalopathy (NE) during therapeutic hypothermia (TH) and evaluate the association between aEEG parameters and magnetic resonance imaging (MRI) injury.

STUDY DESIGN

aEEG data of infants who underwent TH were reviewed for background, sleep wake cycling (SWC), and seizures. Conventional electroencephalography (cEEG) background was assessed from the reports. Discordance of background on aEEG and cEEG was defined if there was a difference in the severity of the background. MRI injury (total score ≥ 5) was assessed by using the Weeke scoring system.

RESULTS

A total of 46 infants were included; 23 (50%) with mild NE and 23 (50%) with moderate to severe NE. Comparing mild NE with moderate to severe NE, the initial aEEG background differed with more mild being continuous (70 vs. 52%), with fewer being discontinuous (0 vs. 22%) and flat tracing (0 vs. 4%), whereas burst suppression (4 vs. 4%) and low voltage (26 vs. 18%) did not differ. There was a notably common discordance between the background assessment on cEEG with aEEG in 82% with continuous and 40% low voltage aEEG background. MRI abnormalities were identified in four infants with mild NE and seven infants with moderate to severe NE. MRI injury was associated with aEEG seizures in infants with moderate to severe NE.

CONCLUSION

aEEG seizures are useful to predict MRI injury in moderate to severe NE infants. There is a large discrepancy between aEEG, cEEG, and MRI in neonates treated by TH.

KEY POINTS

· MRI injury was identified in 29% of moderate NE infants and in 50% of severe NE infants.. · aEEG seizures were associated with MRI injury in the moderate to severe NE infants.. · MRI injury was identified in 16% infants with mild NE.. · Mild NE infants with normal aEEG were unlikely to have MRI injury.. · There was a large discrepancy between aEEG, cEEG, and MRI in infants treated by TH..

MicroRNA-124 negatively regulates STAT3 to alleviate hypoxic-ischemic brain damage by inhibiting oxidative stress

MicroRNA-124 (miR-124) is implicated in various neurological diseases; however, its significance in hypoxic-ischaemic brain damage (HIBD) remains unclear. This study aimed to elucidate the underlying pathophysiological mechanisms of miR-124 in HIBD. In our study performed on oxygen-glucose deprivation followed by reperfusion (OGD)/R-induced primary cortical neurons, a substantial reduction in miR-124 was observed. Furthermore, the upregulation of miR-124 significantly mitigated oxidative stress, apoptosis, and mitochondrial impairment. We demonstrated that miR-124 interacts with the signal transducer and activator of transcription 3 (STAT3) to exert its biological function using the dual-luciferase reporter gene assay. As the duration of OGD increased, miR-124 exhibited a negative correlation with STAT3. STAT3 overexpression notably attenuated the protective effects of miR-124 mimics, while knockdown of STAT3 reversed the adverse effects of the miR-124 inhibitor. Subsequently, we conducted an HIBD model in rats. In vivo experiments, miR-124 overexpression attenuated cerebral infarction volume, cerebral edema, apoptosis, oxidative stress, and improved neurological function recovery in HIBD rats. In summary, the neuroprotective effects of the miR-124/STAT3 axis were confirmed in the HIBD model. MiR-124 may serve as a potential biomarker with significant therapeutic implications for HIBD.

Brain Injury Outcomes after Adjuvant Erythropoietin Neuroprotection for Moderate or Severe Neonatal Hypoxic-Ischemic Encephalopathy: A Report from the HEAL Trial

INTRODUCTION

Erythropoietin (Epo) is a putative neuroprotective therapy that did not improve overall outcomes in a phase 3 randomized controlled trial for neonates with moderate or severe hypoxic-ischemic encephalopathy (HIE). However, HIE is a heterogeneous disorder, and it remains to be determined whether Epo had beneficial effects on a subset of perinatal brain injuries.

METHODS

This study was a secondary analysis of neuroimaging data from the High-dose Erythropoietin for Asphyxia and Encephalopathy (HEAL) Trial, which was conducted from 2016 - 2021 at 17 sites involving 23 US academic medical centers. Participants were neonates >36 weeks' gestation undergoing therapeutic hypothermia for moderate or severe HIE who received 5 doses of study drug (Epoetin alpha 1000 U/kg/dose) or placebo in the first week of life. Treatment assignment was stratified by trial site and severity of encephalopathy. The primary outcome was the locus, pattern and acuity of brain injury as determined by three independent readers using a validated HIE Magnetic Resonance Imaging (MRI) scoring system.

RESULTS

Of the 500 infants enrolled in HEAL, 470 (94%) had high quality MRI data obtained at a median of 4.9 days of age (IQR 4.5 - 5.8). The incidence of injury to the deep grey nuclei, cortex, white matter, brainstem and cerebellum was similar between Epo and placebo groups. Likewise, the distribution of injury patterns was similar between groups. Among infants imaged at less than 8 days (n=414), 94 (23%) evidenced only acute, 93 (22%) only subacute and 89 (21%) both acute and subacute injuries, with similar distribution across treatment groups.

CONCLUSION

Adjuvant erythropoietin did not reduce the incidence of regional brain injury. Subacute brain injury was more common than previously reported, which has key implications for the development of adjuvant neuroprotective therapies for this population.

MRI features of neuronal intranuclear inclusion disease, combining visual and quantitative imaging investigations

OBJECTIVE

To observe the radiological characteristics of Neuronal Intranuclear Inclusion Disease (NIID) on lesion locations and diffusion property using quantitative imaging analysis.

METHODS

Visual inspection and quantitative analyses were performed on MRI data from 31 retrospectively included patients with NIID. Frequency heatmaps of lesion locations on T2WI and DWI were generated using voxel-wise analysis. Gray matter volume (GMV), white matter volume (WMV) and diffusion property of apparent diffusion coefficient (ADC) values of patients were voxel-wisely compared with healthy controls. Moreover, the ADC values within the DWI-detected lesion were compared with those within the adjacent cortical gray matter and white matter. Voxel-based lesion symptom mapping (VLSM) techniques, were used to determine the relationship between DWI lesion location and disease durations.

RESULTS

By visual inspection on the imaging findings, we proposed an "cockscomb flower sign" for describing the radiological feature of DWI hyperintensity within the corticomedullary junction. A "T2WI-DWI mismatch of spatial distribution" pattern was also revealed with visual inspection and frequency heatmaps, for describing the feature of a wider lesion distribution covering white matter shown on T2WI than that on DWI. Voxel-based morphometry comparison revealed that wildly reduced GMV and WMV, both the lesion areas detected by DWI and T2WI demonstrated ADC increase in patients. Furthermore, the ADC values within the DWI-detected lesion were intermediate between the adjacent cortex and the deep white matter with highest ADC. VLSM analysis revealed that frontal lobe, parietal lobe and internal capsule damage were associated with higher NIID durations.

CONCLUSION

NIID features with "cockscomb flower-like" DWI hyperintensity in area of corticomedullary junction, based on a "T2WI-DWI mismatch of spatial distribution" of lesion locations. The pathological substrate of corticomedullary junction hyperintensity on DWI, can not be explained as diffusion restriction. These typical radiological features of brain MRI would be helpful for diagnosis of NIID.

Effect of Leuprolide Acetate, a GnRH Agonist, on Neuroinflammation and Anxiety-Like Behavior after Mild Hypoxic-Ischemic Encephalopathy in Rat Model

BACKGROUND

Mild hypoxic-ischemic encephalopathy (HIE) is a condition that predisposes to negative outcomes such as neuroanatomical injury, mood disorders, and motor or cognitive disabilities. The neuroinflammation plays an important role in the neurological damage; therefore, reducing it could provide neuroprotection. The leuprolide acetate (LA) has shown to have neuroregenerative and immunomodulator properties in other nervous system injuries.

OBJECTIVE

The aim of this study was to evaluate the immunomodulatory effect of LA in the acute phase of mild HIE and its effects in motor activity and behavior in a subacute phase.

METHOD

Forty-five Wistar rats on postnatal day 7 were divided into Sham, HIE treated with saline solution (HIE-SS), and HIE-LA. The HIE was performed cutting of the right carotid artery followed by 60 min of hypoxia. The expression of the inflammatory cytokines interleukin (IL)-1β, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, and the chemokine CXCL-1 were evaluated 72 h after HIE by RT-qPCR and the motor activity and behavior were evaluated by open field test at postnatal day 33.

RESULTS

HIE-SS animals showed increased expression of IL-1β, TNF-α, IFN-γ, and CXCL-1 genes in injured tissue. However, the HIE-LA group exhibited similar expression levels of IL-1β and TNF-α to the Sham group, while IFN-γ and CXCL-1 mRNA expression were attenuated with LA treatment. LA treatment also prevented anxiety-like behavior in the open field test.

CONCLUSION

Treatment with LA partially reverses HIE-induced neuroinflammation and prevents anxiety-like behavior in neonatal rats.

Can radiomics be used to detect hypoxic-ischemic encephalopathy in neonates without magnetic resonance imaging abnormalities?

BACKGROUND

No study has assessed normal magnetic resonance imaging (MRI) findings to predict potential brain injury in neonates with hypoxic-ischemic encephalopathy (HIE).

OBJECTIVE

We aimed to evaluate the efficacy of MRI-based radiomics models of the basal ganglia, thalami and deep medullary veins to differentiate between HIE and the absence of MRI abnormalities in neonates.

MATERIALS AND METHODS

In this study, we included 38  full-term neonates with HIE and normal MRI findings and 89 normal neonates. Radiomics features were extracted from T1-weighted images, T2-weighted images, diffusion-weighted imaging and susceptibility-weighted imaging (SWI). The different models were evaluated using receiver operating characteristic curve analysis. Clinical utility was evaluated using decision curve analysis.

RESULTS

The SWI model exhibited the best performance among the seven single-sequence models. For the training and validation cohorts, the area under the curves (AUCs) of the SWI model were 1.00 and 0.98, respectively. The combined nomogram model incorporating SWI Rad-scores and independent predictors of clinical characteristics was not able to distinguish HIE in patients without MRI abnormalities from the control group (AUC, 1.00). A high degree of fitting and favorable clinical utility was detected using the calibration curve with the Hosmer-Lemeshow test. Decision curve analysis was used for the SWI, clinical and combined nomogram models. The decision curve showed that the SWI and combined nomogram models had better predictive performance than the clinical model.

CONCLUSIONS

HIE can be detected in patients without MRI abnormalities using an MRI-based radiomics model. The SWI model performed better than the other models.

BOston Neonatal Brain Injury Dataset for Hypoxic Ischemic Encephalopathy (BONBID-HIE): Part I. MRI and Manual Lesion Annotation

Hypoxic ischemic encephalopathy (HIE) is a brain injury that occurs in 1 ~ 5/1000 term neonates. Accurate identification and segmentation of HIE-related lesions in neonatal brain magnetic resonance images (MRIs) is the first step toward predicting prognosis, identifying high-risk patients, and evaluating treatment effects. It will lead to a more accurate estimation of prognosis, a better understanding of neurological symptoms, and a timely prediction of response to therapy. We release the first public dataset containing neonatal brain diffusion MRI and expert annotation of lesions from 133 patients diagnosed with HIE. HIE-related lesions in brain MRI are often diffuse (i.e., multi-focal), and small (over half the patients in our data having lesions occupying <1% of brain volume). Segmentation for HIE MRI data is remarkably different from, and arguably more challenging than, other segmentation tasks such as brain tumors with focal and relatively large lesions. We hope that this dataset can help fuel the development of MRI lesion segmentation methods for HIE and small diffuse lesions in general.

Distribution of IntraThalamic Injury According to Nuclei and Vascular Territories in Children With Term Hypoxic-Ischemic Injury

BACKGROUND

Term hypoxic-ischemic injury (HII) on magnetic resonance imaging (MRI) is described as the basal ganglia thalamus [BGT], watershed [WS], or combined [BGT/WS] groups. We aimed to determine differences between HII groups in intrathalamic distribution.

METHODS

Delayed MRIs of children with HII and thalamic injury were reviewed. Custom tools were placed over T2-weighted and/or fluid-attenuated inversion recovery axial images to determine distribution of intrathalamic injury: (1) six subjective (whole/near-whole, central, anterior, posterior, lateral, medial); (2) four nuclear (anterior [AN], ventrolateral [VLN], medial [MN], and pulvinar [PN]); and (3) three arterial (thalamoperforating arteries [TPA], thalamogeniculate arteries [TGA], and posterior choroidal arteries [PCA]) locations. We compared the frequency of injury of the aforementioned intrathalamic locations between HII groups.

RESULTS

The 128 children (mean age at MRI 7.35 ± 3.6 years) comprised 41% (n = 53) BGT, 26% (n = 33) WS, and 33% (n = 42) BGT/WS. The VLN was the most frequent injured nuclear region (66%, n = 85), and the TGA (93%, n = 128) was the most frequent arterial region involved. VLN injury occurred more frequently in the BGT group (P < 0.001), PN in the WS group (P < 0.001), and AN (P < 0.001), MN (P < 0.001), PN (P = 0.001), and all nuclei together (P < 0.001) in the BGT/WS group. The combination of all vascular territories was significantly associated with BGT/WS (P < 0.001).

CONCLUSIONS

There are significant differences in intrathalamic nuclear and arterial injuries between the different types of HII.

Protective effect of isoflurane preconditioning on neurological function in rats with HIE

Hypoxic-ischemic encephalopathy (HIE) is an important cause of neonatal death and disability, which can lead to long-term neurological and motor dysfunction. Currently, inhalation anesthetics are widely used in surgery, and some studies have found that isoflurane (ISO) may have a positive effect on neuroprotection. In this paper, we investigated whether ISO pretreatment has a neuroprotective effect on the neurological function of HIE rats. Here, 7-day-old neonatal rats were randomly divided into a sham group, a hypoxic-ischemic (HI) group, and an ISO pretreatment (pretreatment) group. The pretreatment group was pretreated with 2% ISO for 1 h, followed by the HI group to establish an HI animal model. The HI‑induced neurological injury was evaluated by Zea‑Longa scores and triphenyltetrazolium (TTC) staining. Neuronal number and histomorphological changes were observed with Nissl staining and Hematoxylin-eosin (HE) staining. In addition, motor learning memory function was evaluated by the Morris water maze (MWM), the Y-maze, and the rotarod tests. HI induced severe neurological dysfunction, brain infarction, and cell apoptosis as well as obvious neuron loss in neonatal rats. In the MWM, the rats in the pretreatment group showed a decrease in escape latency (p = 0.042), indicating that pretreatment with ISO could improve the learning ability of HI rats. The results of Nissl staining showed that in the HI group, there was an irregular arrangement of neurons and nuclear fixation; however, the cell damage was significantly reduced and the total number of neurons was increased after ISO pretreatment (p < 0.001). In conclusion, ISO pretreatment improved cognitive function and attenuated HI-induced reduction of Nissl-positive cells and spatial memory impairment, suggesting that pretreatment with ISO before HI modeling could reduce neuronal cell death in the hippocampus after HI.

Impact of Hypoxia-Ischemia on Neurogenesis and Structural and Functional Outcomes in a Mild-Moderate Neonatal Hypoxia-Ischemia Brain Injury Model

Hypoxic-ischemic encephalopathy (HIE) is a common type of brain injury caused by a lack of oxygen and blood flow to the brain during the perinatal period. The incidence of HIE is approximately 2−3 cases per 1000 live births in high-income settings; while in low- and middle-income countries, the incidence is 3−10-fold higher. Therapeutic hypothermia (TH) is the current standard treatment for neonates affected by moderate−severe HIE. However, more than 50% of all infants with suspected HIE have mild encephalopathy, and these infants are not treated with TH because of their lower risk of adverse outcomes. Despite this, several analyses of pooled data provide increasing evidence that infants who initially have mild encephalopathy may present signs of more significant brain injury later in life. The purpose of this study was to expand our knowledge about the effect of mild−moderate hypoxia-ischemia (HI) at the cellular, structural, and functional levels. An established rat model of mild−moderate HI was used, where postnatal day (P) 7 rats were exposed to unilateral permanent occlusion of the left carotid artery and 90 min of 8% hypoxia, followed by TH or normothermia (NT) treatment. The extent of injury was assessed using histology (P14 and P42) and MRI (P11 and P32), as well as with short-term and long-term behavioral tests. Neurogenesis was assessed by BrdU staining. We showed that mild−moderate HI leads to a progressive loss of brain tissue, pathological changes in MRI scans, as well as an impairment of long-term motor function. At P14, the median area loss assessed by histology for HI animals was 20% (p < 0.05), corresponding to mild−moderate brain injury, increasing to 55% (p < 0.05) at P42. The data assessed by MRI corroborated our results. HI led to a decrease in neurogenesis, especially in the hippocampus and the lateral ventricle at early time points, with a delayed partial recovery. TH was not neuroprotective at early time points following mild−moderate HI, but prevented the increase in brain damage over time. Additionally, rats treated with TH showed better long-term motor function. Altogether, our results bring more light to the understanding of pathophysiology following mild-moderate HI. We showed that, in the context of mild-moderate HI, TH failed to be significantly neuroprotective. However, animals treated with TH showed a significant improvement in motor, but not cognitive long-term function. These results are in line with what is observed in some cases where neonates with mild HIE are at risk of neurodevelopmental deficits in infancy or childhood. Whether TH should be used as a preventive treatment to reduce adverse outcomes in mild-HIE remains of active interest, and more research has to be carried out in order to address this question.