Early Thalamic Injury After Resuscitation From Severe Asphyxial Cardiac Arrest in Developing Rats

Children who survive cardiac arrest often develop debilitating sensorimotor and cognitive deficits. In animal models of cardiac arrest, delayed neuronal death in the hippocampal CA1 region has served as a fruitful paradigm for investigating mechanisms of injury and neuroprotection. Cardiac arrest in humans, however, is more prolonged than in most experimental models. Consequently, neurologic deficits in cardiac arrest survivors arise from injury not solely to CA1 but to multiple vulnerable brain structures. Here, we develop a rat model of prolonged pediatric asphyxial cardiac arrest and resuscitation, which better approximates arrest characteristics and injury severity in children. Using this model, we characterize features of microglial activation and neuronal degeneration in the thalamus 24 h after resuscitation from 11 and 12 min long cardiac arrest. In addition, we test the effect of mild hypothermia to 34°C for 8 h after 12.5 min of arrest. Microglial activation and neuronal degeneration are most prominent in the thalamic Reticular Nucleus (nRT). The severity of injury increases with increasing arrest duration, leading to frank loss of nRT neurons at longer arrest times. Hypothermia does not prevent nRT injury. Interestingly, injury occurs selectively in intermediate and posterior nRT segments while sparing the anterior segment. Since all nRT segments consist exclusively of GABA-ergic neurons, we asked if GABA-ergic neurons in general are more susceptible to hypoxic-ischemic injury. Surprisingly, cortical GABA-ergic neurons, like their counterparts in the anterior nRT segment, do not degenerate in this model. Hence, we propose that GABA-ergic identity alone is not sufficient to explain selective vulnerability of intermediate and posterior nRT neurons to hypoxic-ischemic injury after cardiac arrest and resuscitation. Our current findings align the animal model of pediatric cardiac arrest with human data and suggest novel mechanisms of selective vulnerability to hypoxic-ischemic injury among thalamic GABA-ergic neurons.

Abstract 13824: Computerized Tomography vs Ultrasound Imaging for Detecting Hypoxic-Ischemic Brain Injury

Introduction: After an out-of-hospital cardiac arrest (OHCA), the resulting hypoxic-ischemic injury (HII) to the brain remains the main cause of mortality. Standardized approaches for measuring the extent of injury and monitoring of changes are lacking and continue to be a critical barrier to progress in improving neurological survival. Objective: We sought to characterize the prevalence of HII detected on computerized tomography of the brain and its correlation to point-of-care optic nerve sheath diameter (ONSD) measurements as an alternative modality for detecting brain injury. Methods: Adult OHCA patients at an urban academic ED were included in this study on a convenience sample basis from 2018-2019. The patients were grouped by findings of hypoxic-ischemic injury (HII) on both initial and subsequent CT brain imaging performed after ROSC in respective groups. CT Brain findings were compared to ONSD measurements as performed with point-of-care ultrasound by fellowship-trained emergency physicians within one hour of hospital arrival and at 6 hours, after return of spontaneous circulation (ROSC) and to cerebral performance category (CPC) at hospital discharge. Results: 76 patients enrolled in the study had a median age was 59, 49% were female, and 37% survived to hospital discharge. 58 patients had CT head performed, 40 had ONSD measured within one hour, and 27 patients had both. Of that 27, 9 (33%) had evidence of HII on initial imaging and 15 (55%) had evidence of HII on subsequent imaging for a total of 20 unique patients. The average ONSD within 1 hour of ROSC for those with no HII on any imaging was 0.59 cm, and for those without HII on initial imaging but with HII on subsequent imaging was 0.67 cm, and this difference was statistically significant (p< 0.05). Of the 20 patients with HI, 14 (70%) patients died and 6 (30%) survived with a CPC of 4. The average time to first CT head was 4 hours and 45 mins and the average time to subsequent imaging was 97 hours and 45 mins. Conclusion: After an OHCA, early time point ONSD measurements can potentially indicate brain injury within 1 hour of ROSC even in those without initial evidence of HII on CT imaging.

Scutellarin ameliorates neonatal hypoxic-ischemic encephalopathy associated with GAP43-dependent signaling pathway

Background Neonatal hypoxic-ischemic encephalopathy (HIE) refers to the perinatal asphyxia caused by the cerebral hypoxic-ischemic injury. The current study was aimed at investigating the therapeutic efficacy of Scutellarin (Scu) administration on neurological impairments induced by hypoxic-ischemic injury and exploring the underlying mechanisms. Methods Primary cortical neurons were cultured and subjected to oxygen–glucose deprivation (OGD), and then treated with Scu administration. The growth status of neurons was observed by immunofluorescence staining of TUJ1 and TUNEL. Besides, the mRNA level of growth-associated protein 43 (GAP43) in OGD neurons with Scu treatment was detected by quantitative real-time polymerase chain reaction (qRT-PCR). To further verify the role of GAP43 in Scu treatment, GAP43 siRNA and knockout were applied in vitro and in vivo. Moreover, behavioral evaluations were performed to elucidate the function of GAP43 in the Scu-ameliorated long-term neurological impairments caused by HI insult. The underlying biological mechanism of Scu treatment was further elucidated via network pharmacological analysis. Finally, the interactive genes with GAP43 were identified by Gene MANIA and further validated by qRT-PCR. Results Our data demonstrated that Scu treatment increased the number of neurons and axon growth, and suppressed cell apoptosis in vitro. And the expression of GAP43 was downregulated after OGD, but reversed by Scu administration. Besides, GAP43 silencing aggravated the Scu-ameliorated neuronal death and axonal damage. Meanwhile, GAP43 knockout enlarged brain infarct area and deteriorated the cognitive and motor dysfunctions of HI rats. Further, network pharmacological analysis revealed the drug targets of Scu participated in such biological processes as neuronal death and regulation of neuronal death, and apoptosis-related pathways. GAP43 exhibited close relationship with PTN, JAK2 and STAT3, and GAP43 silencing upregulated the levels of PTN, JAK2 and STAT3. Conclusions Collectively, our findings revealed Scu treatment attenuated long-term neurological impairments after HI by suppressing neuronal death and enhancing neurite elongation through GAP43-dependent pathway. The crucial role of Scutellarin in neuroprotection provided a novel possible therapeutic agent for the treatment of neonatal HIE. Graphic abstract

Hypoxic-Ischemic Injury of Basal Ganglia Associated with the COVID-19 Infection: Case Report

There is emerging evidence of a broad spectrum of neurological manifestations in COVID-19 patients. We report a case of a patient diagnosed with COVID-19 who presented bilateral lesions of the basal ganglia related to a severe acute respiratory distress syndrome. This observation allows expanding the neurological spectrum of COVID-19 particularly in patients with a more severe clinical course.

Voxel-based map of the inter-arterial watershed zones in children

Purpose To create a voxel-based map of the inter-arterial watershed derived from children who have sustained a hypoxic-ischemic injury involving this region at term. Materials and methods Patients 0–18 years of age diagnosed with a hypoxic-ischemic injury of the watershed on magnetic resonance imaging (MRI) were included. Two pediatric neuroradiologists segmented the lesions as visualized on the T2-weighted sequence. All lesion maps were normalized to a brain template and overlapped to create a frequency map in order to highlight the frequency of involvement of portions of the cortical watershed. Results A total of 47 patients (35 boys) were included in the final sample. Their mean age was 7.6 ± 3.6 years. The cortical watershed was successfully mapped. Three watershed regions were defined: the anterior, peri-Sylvian, and posterior watershed zones. The anterior and peri-Sylvian watershed zones are connected through the involvement of the middle frontal gyrus. The peri-Sylvian and the posterior watershed zones are connected through the involvement of the inferior parietal lobule, the posterior aspect of the superior temporal gyrus, and the angular gyrus with the occipital lobe. The temporal lobe and orbital part of the frontal lobe are largely spared in all patients. Conclusion A voxel-based lesion map of children with watershed hypoxic ischemic injury at term was created and three inter-arterial watershed zones defined: anterior, peri-Sylvian, and posterior watersheds.