Anatomical patterns and correlated MRI findings of non-perinatal hypoxic-ischaemic encephalopathy

Frequency of Cerebellar Abnormalities Associated With the Differing Magnetic Resonance Imaging Patterns of Term Hypoxic-Ischemic Injury in Children

BACKGROUND

We aimed to determine the frequency of cerebellar injury using delayed magnetic resonance imaging (MRI) in children with cerebral palsy, diagnosed with term hypoxic-ischemic injury (HII), and to characterize this for the different MRI patterns of HII.

METHODS

We retrospectively reviewed delayed MRI scans in children with cerebral palsy, of whom 1175 had term HII. The pattern of HII was classified into basal ganglia-thalamus (BGT) pattern, watershed (WS) pattern, combined BGT/WS, and multicystic HII. Cerebellar location (hemisphere versus vermis) and the MRI characteristics were documented overall and for each of the different patterns of HII, as well as the association with thalamic injury.

RESULTS

Cerebellar injury was found in 252 of 1175 (21.4%) (median age 6 years [interquartile range: 3 to 9 years]). Of these, 49% (124 of 252) were associated with a BGT pattern, 13% (32 of 252) with a WS pattern, 28% (72 of 252) with a combined BGT/WS pattern, and 10% (24 of 252) with a multicystic pattern. The vermis was abnormal in 83% (209 of 252), and the hemispheres were abnormal in 34% (86 of 252) (with 17% [43 of 252] showing both vermis and hemispheric abnormality).

CONCLUSIONS

Over a fifth of patients with cerebral palsy due to HII had a cerebellar abnormality on delayed MRI, most commonly involving the vermis (83%), and as part of a BGT pattern of injury in just under half of these likely reflecting the association of cerebellar vermis injury with profound insults.

Technical feasibility of multimodal imaging in neonatal hypoxic-ischemic encephalopathy from an ovine model to a human case series

Hypoxic-ischemic encephalopathy (HIE) secondary to perinatal asphyxia occurs when the brain does not receive enough oxygen and blood. A surrogate marker for "intact survival" is necessary for the successful management of HIE. The severity of HIE can be classified based on clinical presentation, including the presence of seizures, using a clinical classification scale called Sarnat staging; however, Sarnat staging is subjective, and the score changes over time. Furthermore, seizures are difficult to detect clinically and are associated with a poor prognosis. Therefore, a tool for continuous monitoring on the cot side is necessary, for example, an electroencephalogram (EEG) that noninvasively measures the electrical activity of the brain from the scalp. Then, multimodal brain imaging, when combined with functional near-infrared spectroscopy (fNIRS), can capture the neurovascular coupling (NVC) status. In this study, we first tested the feasibility of a low-cost EEG-fNIRS imaging system to differentiate between normal, hypoxic, and ictal states in a perinatal ovine hypoxia model. Here, the objective was to evaluate a portable cot-side device and perform autoregressive with extra input (ARX) modeling to capture the perinatal ovine brain states during a simulated HIE injury. So, ARX parameters were tested with a linear classifier using a single differential channel EEG, with varying states of tissue oxygenation detected using fNIRS, to label simulated HIE states in the ovine model. Then, we showed the technical feasibility of the low-cost EEG-fNIRS device and ARX modeling with support vector machine classification for a human HIE case series with and without sepsis. The classifier trained with the ovine hypoxia data labeled ten severe HIE human cases (with and without sepsis) as the "hypoxia" group and the four moderate HIE human cases as the "control" group. Furthermore, we showed the feasibility of experimental modal analysis (EMA) based on the ARX model to investigate the NVC dynamics using EEG-fNIRS joint-imaging data that differentiated six severe HIE human cases without sepsis from four severe HIE human cases with sepsis. In conclusion, our study showed the technical feasibility of EEG-fNIRS imaging, ARX modeling of NVC for HIE classification, and EMA that may provide a biomarker of sepsis effects on the NVC in HIE.

Coronavirus Disease: Subacute to Chronic Neuroimaging Findings

Several neurologic disorders are associated with coronavirus disease 2019 (COVID-19). In this article, clinical syndromes typically occurring in the subacute to chronic phase of illness and their neuroimaging findings are described with discussion of their COVID-19 specific features and prognosis. Proposed pathogenic mechanisms of these neuroimaging findings and challenges in determining etiology are reviewed.

Differential Glial Chitotriosidase 1 and Chitinase 3-like Protein 1 Expression in the Human Primary Visual Cortex and Cerebellum after Global Hypoxia-Ischemia

Here, we studied the neuroinflammation- and ischemia-related glial markers chitotriosidase 1 (CHIT1) and chitinase-3-like protein 1 (CHI3L1, alias YKL-40) in the human striate cortex and cerebellum at different time points after global hypoxic-ischemic brain injury (HIBI). Both regions differ considerably in their glial cell population but are supplied by the posterior circulation. CHIT1 and CHI3L1 expression was compared to changes in microglial (IBA1, CD68), astrocytic (GFAP, S100β), and neuronal markers (H&E, neurofilament heavy chain, NfH; calretinin, CALR) using immunohistochemistry and multiple-label immunofluorescence. Initial striatal cortical and cerebellar Purkinje cell damage, detectable already 1/2 d after HIBI, led to delayed neuronal death, whereas loss of cerebellar NfH-positive stellate and CALR-positive granule cells was variable. During the first week post-HIBI, a transient reduction of IBA1-positive microglia was observed in both regions, and fragmented/clasmatodendritic cerebellar Bergmann glia appeared. In long-term survivors, both brain regions displayed high densities of activated IBA1-positive cells and CD68-positive macrophages, which showed CHIT1 co-localization in the striate cortex. Furthermore, enlarged GFAP- and S100β-positive astroglia emerged in both regions around 9-10 d post-HIBI, i.e., along with clearance of dead neurons from the neuropil, although GFAP-/S100β-positive gemistocytic astrocytes that co-expressed CHI3L1 were found only in the striate cortex. Thus, only GFAP-/S100β-positive astrocytes in the striate cortex, but not cerebellar Bergmann glia, differentiated into CHI3L1-positive gemistocytes. CHIT1 was co-expressed almost entirely in macrophages in the striate cortex and not cerebellum of long-term survivors, thereby indicating that CHIT1 and CHI3L1 could be valuable biomarkers for monitoring the outcome of global HIBI.

The MRI of Jahi McMath and Its Implications for the Global Ischemic Penumbra Hypothesis

Jahi McMath was diagnosed brain dead on 12/12/2013 in strict accordance with both the pediatric and adult Guidelines, reinforced by 4 isoelectric electroencephalograms and a radionuclide scan showing intracranial circulatory arrest. Her magnetic resonance imaging scan 9 1/2 months later surprisingly showed gross integrity of cortex, basal ganglia, thalamus, and upper brainstem. The greatest damage was in the white matter, which was extensively demyelinated and cystic, and in the lower brainstem, most likely from partial herniation that resolved. The apparent integrity of gray matter and the ascending reticular activating system may have provided a potential structural basis for the reemergence of some limited brain functions, while the white matter and lower brainstem lesions would have caused severe motor disability, brainstem areflexia and apnea. The findings indicate that there could never have been a period of sustained intracranial circulatory arrest. Rather, at the time of brain death diagnosis, low blood flow below the detection threshold of the radionuclide scan was sufficient to maintain widespread neuronal viability, though insufficient to support synaptic function. Her case represents the first indirect confirmation of the reality and clinical relevance of global ischemic penumbra, hypothesized in 1999 as a generally unacknowledged and possibly common brain death mimic.

Thiamine-responsive, life-threatening, pulmonary hypertensive crisis with encephalopathy in young infants: A case series

OBJECTIVE

Thiamine (Vitamin B1) deficiency (TD), although reduced in incidence, is still seen in infants. We describe a rarely reported form of infantile TD with life-threatening pulmonary hypertensive crisis and severe encephalopathy, with dramatic response to thiamine supplementation.

METHODS

Study design: Descriptive case series. Six young infants with mean age 76 days (range 1-3 months), manifesting rapidly progressive encephalopathy and cardio-pulmonary arrest were included. All infants underwent cardiac, neuroimaging and metabolic evaluations.

RESULTS

All six infants had similar presentation with severe pulmonary arterial hypertension (PAH), hypotensive shock, metabolic acidosis and severe encephalopathy. All infants were exclusively breast-fed. Thiamine treatmwnt resulted in dramatic improvement in haemodynamic and neurological function in all the infants. There were no major neurological deficits on follow up.

CONCLUSION

A high index of suspicion is warranted for this rarely described form of TD, as early identification helps in preventing mortality and morbidity.

18F-fluorodeoxyglucose positron-emitted tomography for predicting neurological outcome in hypoxic-ischemic encephalopathy

Background: ¹⁸F-fluorodeoxyglucose positron-emitted tomography (FDG-PET) is a promising yet unexplored functional neuroimaging tool in the study and prognosis of hypoxic-ischemic encephalopathy (HIE) after cardiac arrest or respiratory failure. The present study aimed to correlate clinical data and FDG-PET scans for both analysis and prognostic use. Methods: 24 patients from an intensive rehabilitation ward were retrospectively evaluated. Data collected included age, gender, cause of anoxic event, length of stay in acute and rehabilitation units, discharge destination, and evaluation at admission and discharge using three clinical scales to assess cognitive function, independence and disability. Subjects were identified as good and bad performers on the basis of quantitative analysis of FDG-PET scans with the Cortex ID software. The relation between glucose uptake reduction and neurological outcome was evaluated. Results: good and bad performers presented no statistically significant difference regarding demographical data and in-hospital length of stay. The two categories significantly differed for impairment and disability levels both at admission and at discharge from the inpatient rehabilitation unit. Conclusions: FDG-PET considerably facilitates the early identification of patients with HIE who will have poor neurological outcome and could inform planning for their rehabilitation and care.

Neuroimaging of central diabetes insipidus

Central diabetes insipidus (CDI) occurs secondary to deficient synthesis or secretion of arginine vasopressin peptide from the hypothalamo-neurohypophyseal system (HNS). It is characterized by polydipsia and polyuria (urine output >30mL/kg/day in adults and >2l/m²/24h in children) of dilute urine (<250mOsm/L). It can result from any pathology affecting one or more components of the HNS including the hypothalamic osmoreceptors, supraoptic or paraventricular nuclei, and median eminence of the hypothalamus, infundibulum, stalk or the posterior pituitary gland. MRI is the imaging modality of choice for evaluation of the hypothalamic-pituitary axis (HPA), and a dedicated pituitary or sella protocol is essential. CT can provide complimentary diagnostic information and is also of value when MRI is contraindicated. The most common causes are benign or malignant neoplasia of the HPA (25%), surgery (20%), and head trauma (16%). No cause is identified in up to 30% of cases, classified as idiopathic CDI. Knowledge of the anatomy and physiology of the HNS is crucial when evaluating a patient with CDI. Establishing the etiology of CDI with MRI in combination with clinical and biochemical assessment facilitates appropriate targeted treatment. This chapter illustrates the wide variety of causes and imaging correlates of CDI on neuroimaging, discusses the optimal imaging protocols, and revises the detailed neuroanatomy required to interpret these studies.

Cerebellar Hippocampal and Basal Nuclei Transient Edema with Restricted diffusion (CHANTER) Syndrome

Background

Abnormal restricted diffusion on magnetic resonance imaging is often associated with ischemic stroke or anoxic injury, but other conditions can present similarly. We present six cases of an unusual but consistent pattern of restricted diffusion in bilateral hippocampi and cerebellar cortices. This pattern of injury is distinct from typical imaging findings in ischemic, anoxic, or toxic injury, suggesting it may represent an under-recognized clinicoradiographic syndrome. Despite initial presentation with stupor or coma in the context of obstructive hydrocephalus, patients may have acceptable outcomes if offered early intervention.

Methods

We identified an ad hoc series of patients at our two institutions between years 2014 and 2017 who presented to the neurocritical care unit with severe, otherwise unexplained cerebellar edema and retrospectively identified several commonalities in history, presentation, and imaging.

Results

Between two institutions, we identified six patients—ages 33–59 years, four male—with similar presentations of decreased level of consciousness in the context of intoxicant exposure, with acute cytotoxic edema of the cerebellar cortex, hippocampi, and aspects of the basal nuclei. All patients presented with severe cerebellar edema which led to obstructive hydrocephalus requiring aggressive medical and/or surgical management. The five patients who survived to discharge demonstrated variable degrees of physical and memory impairment on discharge and at follow-up.

Conclusions

We present findings of a potentially novel syndrome involving a distinct pattern of cerebellar and hippocampal restricted diffusion, with imaging and clinical characteristics distinct from ischemic stroke, hypoxic injury, and known toxidromes and leukoencephalopathies. Given the potential for favorable outcome despite early obstructive hydrocephalus, early identification and treatment of this syndrome are critical.

The Perirolandic Sign: A Unique Imaging Finding Observed in Association with Polymerase γ-Related Disorders

Pathogenic variants in the polymerase γ gene (POLG) cause a diverse group of pathologies known as POLG-related disorders. In this report, we describe brain MR imaging findings and electroencephalogram correlates of 13 children with POLG-related disorders at diagnosis and follow-up. At diagnosis, all patients had seizures and 12 had abnormal MR imaging findings. The most common imaging findings were unilateral or bilateral perirolandic (54%) and unilateral or bilateral thalamic signal changes (77%). Association of epilepsia partialis continua with perirolandic and thalamic signal changes was present in 86% and 70% of the patients, respectively. The occipital lobe was affected in 2 patients. On follow-up, 92% of the patients had disease progression or fatal outcome. Rapid volume loss was seen in 77% of the patients. The occipital lobe (61%) and thalamus (61%) were the most affected brain regions. Perirolandic signal changes and seizures may represent a brain imaging biomarker of early-onset pediatric POLG-related disorders.

Methadone-induced Toxic Encephalopathy In Pediatric Patients: Two Case Reports

Toxic encephalopathy is a wide spectrum of encephalopathy secondary to insult from toxic substances, with variable clinical presentations from minor cognitive impairment to severe neurological dysfunction and death. Methadone-induced toxic encephalopathy is an extremely rare form of toxic encephalopathy which typically demonstrates abnormal imaging findings in the dentate nuclei or cerebellum. This is a report of methadone-induced toxic encephalopathy in two toddlers secondary to accidental ingestion. They were brought in unconscious to the emergency department of a tertiary hospital and were found to be cyanotic and pulseless, requiring cardiopulmonary resuscitation and mechanical ventilation. Magnetic resonance imaging (MRI) of the brain of both patients showed similar findings of symmetrical hyperintense foci in bilateral cerebellar hemispheres on T2-weighted and fluid-attenuated inversion recovery (FLAIR) sequences. These areas also demonstrated diffusion restriction on diffusion weighted imaging (DWI). Blood and urine toxicology results confirmed the presence of methadone in both patients. As the exact substance of accidental ingestion may not be known at the time of presentation, early radiological diagnosis of methadone-induced encephalopathy may prompt early initiation of treatment to prevent further life-threatening complications, particularly in vulnerable pediatric population.

Investigation of Brain Impairment Using Diffusion-Weighted and Diffusion Tensor Magnetic Resonance Imaging in Experienced Healthy Divers

Background

The aim of this study was to understand the changes of decompression illness in healthy divers by comparing diffusion-weighted (DWI) and diffusion tensor MRI findings among healthy professional divers and healthy non-divers with no history of diving.

Material/Methods

A total of 26 people were recruited in this prospective study: 11 experienced divers with no history of neurological decompression disease (cohort) and 15 healthy non-divers (control). In all study subjects, we evaluated apparent diffusion coefficient (ADC) and type of diffusion tensor metric fractional anisotropy (FA) values of different brain locations (e.g., frontal and parieto-occipital white matter, hippocampus, globus pallidus, putamen, internal capsule, thalamus, cerebral peduncle, pons, cerebellum, and corpus callosum).

Results

ADC values of hippocampus were high in divers but low in the control group; FA values of globus pallidus and putamen were lower in divers compared to the control group. DWI depicted possible changes due to hypoxia in different regions of the brain. Statistically significant differences in ADC values were found in hypoxia, particularly in the hippocampus (p=0.0002), while FA values in the globus pallidus and putamen were statistically significant (p=0.015 and p=0.031, respectively). We detected forgetfulness in 6 divers and deterioration in fine-motor skills in 2 divers (p=0.002 and p=0.17, respectively). All of them were examined using neuro-psychometric tests.

Conclusions

Repeated hyperbaric exposure increases the risk of white matter damage in experienced healthy divers without neurological decompression illness. The hippocampus, globus pallidus, and putamen are the brain areas responsible for memory, learning, navigation, and fine-motor skills and are sensitive to repeated hyperbaric exposure.

Febrile status epilepticus due to respiratory syncytial virus infection

BACKGROUND

Febrile status epilepticus can have neurological sequelae. The type of sequelae, however, depend on the etiology, including infection due to viral agents such as the influenza virus. Respiratory syncytial virus (RSV) infection in childhood may also contribute to this. The aim of this study was therefore to characterize febrile status epilepticus associated with RSV infection, and to determine whether this type of infection is a risk factor for neurological sequelae in febrile status epilepticus.

METHODS

We reviewed the medical records of children aged ≤3 years with febrile status epilepticus who were admitted to a tertiary hospital between January 2007 and December 2011. The differences between the RSV-positive and RSV-negative groups were evaluated according to the demographic and clinical data.

RESULTS

A total of 99 patients with febrile status epilepticus who had been tested for RSV infection were identified. Three patients in the RSV-positive group (n = 19) and four in the RSV-negative group (n = 80) presented with bronchiolitis. The incidence of intubation and anti-seizure drug treatment in the RSV-positive group was significantly higher than in the -negative group. While all of the patients in the RSV-negative group recovered completely, six patients in the RSV-positive group developed encephalopathy and profound neurological sequelae. In five of the six patients, diffusion-weighted magnetic resonance imaging showed subcortical white matter lesions.

CONCLUSIONS

RSV infection in the absence of bronchiolitis can initially present as febrile status epilepticus and subsequently develop into acute encephalopathy with profound neurological sequelae.

Assessment and Management of Toxidromes in the Critical Care Unit

The most important diagnostic factor in uncovering a toxic etiology for delirium or critical illness is the clinician's openness to the possibility of its existence. Therefore, a consulting psychiatrist, already prepared to perform the detail-oriented work of sorting out behavioral manifestations of disease, can be a vital asset at the bedside if also attuned to the role of purposeful, accidental, and iatrogenic exposures in the intensive care unit. This article summarizes the presentation, evaluation, and treatment of toxidromes relevant to the work of acute psychosomatic medicine.

Global and Regional Derangements of Cerebral Blood Flow and Diffusion Magnetic Resonance Imaging after Pediatric Cardiac Arrest

OBJECTIVE

To quantify and examine the relationship between global and regional cerebral blood flow (CBF) and water diffusion on brain magnetic resonance imaging (MRI) in children after cardiac arrest.

STUDY DESIGN

Children admitted to a tertiary care children's hospital from July 2011 to April 2013 who received a brain MRI within 2 weeks after cardiac arrest that included arterial spin labeling and apparent diffusion coefficient (ADC) sequences were studied. CBF and ADC values were calculated globally and in 19 regions of interest. Outcome variables included survival and favorable neurologic outcome, which was defined as Pediatric Cerebral Performance Category ≤3 at 6 months. We examined global and regional relationships between CBF and ADC and their association with outcome.

RESULTS

This sample included 14 pediatric patients (mean time to MRI 6 ± 4 days), 9 of whom survived and 6 who survived with favorable outcome. Global ADC was significantly decreased in patients with unfavorable outcome (P = .02). Increased CBF and decreased ADC often were colocalized in the same region, especially in children who had unfavorable outcomes.

CONCLUSIONS

In this exploratory study, global restricted water diffusion on ADC after pediatric cardiac arrest was associated with unfavorable outcome. MRI assessments of perfusion and diffusion may have prognostic value after pediatric cardiac arrest.

Hypoxic preconditioning differentially affects GABAergic and glutamatergic neuronal cells in the injured cerebellum of the neonatal rat

In this study we examined cerebellar alterations in a neonatal rat model of hypoxic-ischemic brain injury with or without hypoxic preconditioning (Pc). Between postnatal days 7 and 15, the cerebellum is still undergoing intense cellular proliferation, differentiation and migration, dendritogenesis and synaptogenesis. The expression of glutamate decarboxylase 1 (GAD67) and the differentiation factor NeuroD1 were examined as markers of Purkinje and granule cells, respectively. We applied quantitative immunohistochemistry to sagittal cerebellar slices, and Western blot analysis of whole cerebella obtained from control (C) rats and rats submitted to Pc, hypoxia-ischemia (L) and a combination of both treatments (PcL). We found that either hypoxia-ischemia or Pc perturbed the granule cells in the posterior lobes, affecting their migration and final placement in the internal granular layer. These effects were partially attenuated when the Pc was delivered prior to the hypoxia-ischemia. Interestingly, whole nuclear NeuroD1 levels in Pc animals were comparable to those in the C rats. However, a subset of Purkinje cells that were severely affected by the hypoxic-ischemic insult—showing signs of neuronal distress at the levels of the nucleus, cytoplasm and dendritic arborization—were not protected by Pc. A monoclonal antibody specific for GAD67 revealed a three-band pattern in cytoplasmic extracts from whole P15 cerebella. A ∼110 kDa band, interpreted as a potential homodimer of a truncated form of GAD67, was reduced in Pc and L groups while its levels were close to the control animals in PcL rats. Additionally we demonstrated differential glial responses depending on the treatment, including astrogliosis in hypoxiated cerebella and a selective effect of hypoxia-ischemia on the vimentin-immunolabeled intermediate filaments of the Bergmann glia. Thus, while both glutamatergic and GABAergic cerebellar neurons are compromised by the hypoxic-ischemic insult, the former are protected by a preconditioning hypoxia while the latter are not.