Acute Encephalopathies in SARS-CoV-2 Infection: A Clinical and Neuroimaging Perspective.

Neurological manifestations are frequent in patients with SARS-CoV-2 infection and can be correlated with different pathogenic mechanisms which can be divided into two categories: direct invasion of the central nervous system by the virus and indirect effects deriving from the severity of the systemic infection and by the inflammatory response correlated with cytokine storm. Among the neurological manifestations, acute encephalopathy is very frequent and its nomenclature has recently been updated. The occurrence of a condition of altered mental status, reduced consciousness, delirium up to coma represents an element associated with a greater severity of the infection and mortality both in an Intensive Care Unit setting and in an Emergency Department setting. The tissue damage mechanisms found in COVID-19 patients' encephalopathy and neuroimaging patterns, as well as histopathology, are similar to those described in sepsis-associated encephalopathy, further confirming the role of indirect mechanisms, with no CNS invasion by the virus. The available data have some limitations, notably the underuse of diagnostic neuroimaging techniques in severely affected patients, particularly in the first wave of the pandemic.

Clinical characteristics and prognosis of paediatric respiratory syncytial virus-related encephalopathy.

BACKGROUND: To understand the clinical characteristics and prognosis of respiratory syncytial virus (RSV)-related encephalopathy in children. METHODS: A retrospective analysis of the data of children who were diagnosed with RSV-related encephalopathy and admitted to the paediatric intensive care unit (PICU) of Beijing Children's Hospital between November 2016 and November 2023 was performed. RESULTS: Four hundred and sixty-four children with RSV infection were treated in the PICU, and eight of these patients (1.7%) were diagnosed with RSV-related encephalopathy. The mean age of the patients was 24.89 (5.92 ∼ 36.86) months. Two patients had underlying diseases. The time from the onset of illness to impaired consciousness was 3 (1.88-3.75) days. Five patients had convulsions, and three patients had an epileptic status. The serum procalcitonin (PCT) level was 1.63 (0.24, 39.85) ng/ml for the eight patients, and the cerebrospinal fluid (CSF) protein level was 232 (163 ∼ 848) g/L. Among the 8 patients, four patients underwent electroencephalogram (EEG) monitoring or examination. One patient showed continuous low-voltage, nonresponsive activity, and another patient displayed persistent slow waves, the remaining two patients had negative results. One patient had a combination of acute necrotizing encephalopathy (ANE) and acute encephalopathy with biphasic seizures and late reduced diffusion (AESD). Additionally, one patient had ANE, and another had acute brain swelling (ABS). One patient died in the hospital, and the other seven patients were discharged with improvement. Routine follow-up was conducted for 4.58(0.5 ∼ 6.50) years, and all patients fully recovered. CONCLUSIONS: RSV-related encephalopathy could have varying clinical manifestations, and some types, such as ANE and ABS, are dangerous and can lead to death.

A Pediatric Case of Encephalopathy With Hypoglycemia Induced by Coxsackievirus A4 Infection.

We report a pediatric case developing hypoglycemic encephalopathy during the acute phase of coxsackievirus (CV)-A4 infection. A part of the sequence of the virus detected from our patient was completely identical to that in other CV-A4 strain reported as a recombinant strain with lethal CV-A2, suggesting that the properties of CV-A4 might be associated with the severe hypoglycemic encephalopathy.

Clinical characteristics and outcomes of COVID-19-associated encephalopathy in children.

Apart from the typical respiratory symptoms, coronavirus disease 2019 (COVID-19) also affects the central nervous system, leading to central disorders such as encephalopathy and encephalitis. However, knowledge of pediatric COVID-19-associated encephalopathy is limited, particularly regarding specific subtypes of encephalopathy. This study aimed to assess the features of COVID-19-associated encephalopathy/encephalitis in children. We retrospectively analyzed a single cohort of 13 hospitalized children with COVID-19-associated encephalopathy. The primary outcome was the descriptive analysis of the clinical characteristics, magnetic resonance imaging and electroencephalography findings, treatment progression, and outcomes. Thirteen children among a total of 275 (5%) children with confirmed COVID-19 developed associated encephalopathy/encephalitis (median age, 35 months; range, 3-138 months). Autoimmune encephalitis was present in six patients, acute necrotizing encephalopathy in three, epilepsy in three, and central nervous system small-vessel vasculitis in one patient. Eight (62%) children presented with seizures. Six (46%) children exhibited elevated blood inflammatory indicators, cerebrospinal fluid inflammatory indicators, or both. Two (15%) critically ill children presented with multi-organ damage. The magnetic resonance imaging findings varied according to the type of encephalopathy/encephalitis. Electroencephalography revealed a slow background rhythm in all 13 children, often accompanied by epileptic discharges. Three (23%) children with acute necrotizing encephalopathy had poor prognoses despite immunotherapy and other treatments. Ten (77%) children demonstrated good functional recovery without relapse. This study highlights COVID-19 as a new trigger of encephalopathy/encephalitis in children. Autoimmune encephalitis is common, while acute necrotizing encephalopathy can induce poor outcomes. These findings provide valuable insights into the impact of COVID-19 on children's brains.

[A case of COVID-associated encephalopathy in a patient with multiple sclerosis]. / Klinicheskii sluchai COVID-assotsiirovannoi entsefalopatii u patsienta s rasseyannym sklerozom.

A case of acute encephalopathy manifested with impaired consciousness, hemichorrhea, speech and cognitive impairment in a female patient with COVID-19 and multiple sclerosis is presented. In the literature, there are isolated reports of such a combination of diseases, and therefore difficulties arise in carrying out differential diagnosis and prescribing therapy. Given the limited knowledge about the long-term consequences of COVID-19, systematic analysis of such cases and follow-up of such patients is necessary.

Severe A(H1N1)pdm09 influenza acute encephalopathy outbreak in children in Tuscany, Italy, December 2023 to January 2024.

A severe outbreak of influenza A(H1N1pdm09) infection in seven children (median age: 52 months) occurred between December 2023 and January 2024 in Tuscany, Italy. Clinical presentation ranged from milder encephalopathy to acute necrotizing encephalopathy (ANE) with coma and multiorgan failure; one child died. This report raises awareness for clinicians to identify and treat early acute encephalopathy caused by H1N1 influenza and serves as a reminder of severe presentations of influenza in young children and the importance of vaccination.

Viral entry and translation in brain endothelia provoke influenza-associated encephalopathy.

Influenza-associated encephalopathy (IAE) is extremely acute in onset, with high lethality and morbidity within a few days, while the direct pathogenesis by influenza virus in this acute phase in the brain is largely unknown. Here we show that influenza virus enters into the cerebral endothelium and thereby induces IAE. Three-weeks-old young mice were inoculated with influenza A virus (IAV). Physical and neurological scores were recorded and temporal-spatial analyses of histopathology and viral studies were performed up to 72 h post inoculation. Histopathological examinations were also performed using IAE human autopsy brains. Viral infection, proliferation and pathogenesis were analyzed in cell lines of endothelium and astrocyte. The effects of anti-influenza viral drugs were tested in the cell lines and animal models. Upon intravenous inoculation of IAV in mice, the mice developed encephalopathy with brain edema and pathological lesions represented by micro bleeding and injured astrocytic process (clasmatodendrosis) within 72 h. Histologically, massive deposits of viral nucleoprotein were observed as early as 24 h post infection in the brain endothelial cells of mouse models and the IAE patients. IAV inoculated endothelial cell lines showed deposition of viral proteins and provoked cell death, while IAV scarcely amplified. Inhibition of viral transcription and translation suppressed the endothelial cell death and the lethality of mouse models. These data suggest that the onset of encephalopathy should be induced by cerebral endothelial infection with IAV. Thus, IAV entry into the endothelium, and transcription and/or translation of viral RNA, but not viral proliferation, should be the key pathogenesis of IAE.

Genetic Comparison of Human Parainfluenza Virus Type 3 Detected in Respiratory Samples from Patients with Encephalopathy and Airway Inflammation in Aichi Prefecture, Japan.

Human parainfluenza virus type 3 (HPIV-3, human respirovirus 3) is the second most frequently detected virus in lower respiratory tract infections in children after human respiratory syncytial virus (HRSV). HPIV-3, similar to related respiratory viruses such as HRSV and influenza virus, may cause encephalopathy; however, the relevance of HPIV-3 as a pathogenic factor in encephalopathy is unknown. We attempted to detect HPIV-1, HPIV-2, HPIV-3, HPIV-4, HRSV, and human metapneumovirus (HMPV) in 136 patients with encephalitis/encephalopathy or suspected encephalitis/encephalopathy during a 6-year period from 2014 to 2019. HPIV-3 was detected in 6 patients, followed by HRSV in 3 patients. The HPIV-3 strains detected were closely related to those detected in a patient with respiratory disease during the same period. Although HPIV-3 is less widely recognized than HRSV as a triggering virus of encephalopathy, our results suggest that HPIV-3 is as important as HRSV. Surveillance of the causative viruses of encephalopathy, including HPIV-3, would help clarify the causes of encephalopathy in Japan, as the cause is currently reported in less than half of cases in Japan.

Myeloencephalitis as the only presentation of Omicron SARS-CoV-2 infection.

SARS-CoV-2 is now a major global health issue and manifests mainly as a respiratory disorder. Several other complications involving hypercoagulability, cardiovascular system and central nervous system have been described in the literature. Among these atypical presentations, encephalopathy associated with SARS-CoV-2 is a rare entity with heterogenous clinical and radiological findings. The direct presence of SARS-CoV-2 in cerebrospinal fluid (CSF) was rarely found in encephalopathy patients with acute SARS-Cov-2 infection.Here, we report a case of myeloencephalitis with positive real-time PCR for SARS-CoV-2 in CSF in a young woman presenting exclusively with neurological symptoms. Other differential diagnosis were extensively pursued by a comprehensive aetiological workup. To our knowledge, this is the first case report in the Omicron era. In the context of recent global explosion of SARS-Cov-2 infections, clinicians should consider this pathogen among other possible neurotropic agents and be familiar with its radiological and clinical presentations.

Delayed encephalopathy after COVID-19: A case series of six patients.

RATIONALE: Acute encephalopathy is a severe neurological complication of coronavirus disease 2019 (COVID-19). Most cases of acute encephalopathy associated with COVID-19 occur within several weeks of COVID-19 onset. We describe a case series of 6 patients who developed delayed encephalopathy (DE) after COVID-19. PATIENT CONCERNS AND DIAGNOSES: We evaluated patients who recovered from COVID-19 and showed acute disturbance of consciousness or focal neurological deficits without recurrence of pneumonitis. Six patients, 2 females and 4 males, with ages ranging from 65 to 83 years were included. Durations of hospitalization due to COVID-19 were between 25 and 44 days. The severity of COVID-19 was moderate in 5 and severe in 1 patient. Patients were rehospitalized for acute disturbance of consciousness concomitant with postural tremor and, abnormal behavior, hemiplegia, aphasia, or apraxia between 34 and 67 days after the onset of COVID-19. Chest computed tomography showed no exacerbation of pneumonitis. Brain magnetic resonance imaging showed no specific findings except in 1 patient with an acute lacunar infarction. Electroencephalogram demonstrated diffuse slowing in all patients. Repeat electroencephalogram after recovery from encephalopathy demonstrated normal in all patients. One of the 6 patients had cerebrospinal fluid (CSF) pleocytosis. CSF protein levels were elevated in all patients, ranging from 51 to 115 mg/dL. CSF interleukin-6 levels ranged from 2.9 to 10.9 pg/mL. The immunoglobulin index was 0.39 to 0.44. Qlim(alb) < QAlb indicating dysfunction of the blood-brain barrier was observed in all patients. Severe acute respiratory syndrome coronavirus 2 reverse transcription polymerase chain reaction of CSF was negative in all patients. Neuronal autoantibodies were absent in serum and CSF. INTERVENTIONS AND OUTCOMES: Immunotherapy including steroid pulses was administered to 3 patients; however, symptoms of encephalopathy resolved within several days in all patients, regardless of treatment with immunotherapy, and their consciousness levels were recovered fully. Notably, postural tremor remained for 2 weeks to 7 months. LESSONS: In our patients, DE after COVID-19 was characterized by symptoms of acute encephalopathy accompanied with tremor in the absence of worsening pneumonitis after the fourth week of COVID-19 onset. Our findings indicate blood-brain barrier dysfunction may contribute to the pathogenesis of DE after COVID-19.

Mechanisms of coronavirus infectious disease 2019-related neurologic diseases.

PURPOSE OF REVIEW: As of January 8, 2022, a global pandemic caused by infection with severe acute respiratory syndrome coronavirus (SARS-CoV)-2, a new RNA virus, has resulted in 304,896,785 cases in over 222 countries and regions, with over 5,500,683 deaths (www.worldometers.info/coronavirus/). Reports of neurological and psychiatric symptoms in the context of coronavirus infectious disease 2019 (COVID-19) range from headache, anosmia, and dysgeusia, to depression, fatigue, psychosis, seizures, delirium, suicide, meningitis, encephalitis, inflammatory demyelination, infarction, and acute hemorrhagic necrotizing encephalopathy. Moreover, 30-50% of COVID-19 survivors develop long-lasting neurologic symptoms, including a dysexecutive syndrome, with inattention and disorientation, and/or poor movement coordination. Detection of SARS-CoV-2 RNA within the central nervous system (CNS) of patients is rare, and mechanisms of neurological damage and ongoing neurologic diseases in COVID-19 patients are unknown. However, studies demonstrating viral glycoprotein effects on coagulation and cerebral vasculature, and hypoxia- and cytokine-mediated coagulopathy and CNS immunopathology suggest both virus-specific and neuroimmune responses may be involved. This review explores potential mechanistic insights that could contribute to COVID-19-related neurologic disease. RECENT FINDINGS: While the development of neurologic diseases during acute COVID-19 is rarely associated with evidence of viral neuroinvasion, new evidence suggests SARS-CoV-2 Spike (S) protein exhibits direct inflammatory and pro-coagulation effects. This, in conjunction with immune dysregulation resulting in cytokine release syndrome (CRS) may result in acute cerebrovascular or neuroinflammatory diseases. Additionally, CRS-mediated loss of blood-brain barrier integrity in specific brain regions may contribute to the expression of proinflammatory mediators by neural cells that may impact brain function long after resolution of acute infection. Importantly, host co-morbid diseases that affect vascular, pulmonary, or CNS function may contribute to the type of neurologic disease triggered by SARS-COV-2 infection. SUMMARY: Distinct effects of SARS-CoV-2 S protein and CNS compartment- and region-specific responses to CRS may underlie acute and chronic neuroinflammatory diseases associated with COVID-19.

Multimodal Investigation of Neuroinflammation in Aviremic Patients With HIV on Antiretroviral Therapy and HIV Elite Controllers.

BACKGROUND AND OBJECTIVES: The presence of HIV in the CNS has been related to chronic immune activation and cognitive dysfunction. The aim of this work was to investigate (1) the presence of neuroinflammation in aviremic people with HIV (PWH) on therapy and in nontreated aviremic PWH (elite controllers [ECs]) using a translocator protein 18 kDa radioligand; (2) the relationship between neuroinflammation and cognitive function in aviremic PWH; and (3) the relationship between [11C]-PBR28 signal and quantitative MRI (qMRI) measures of brain tissue integrity such as T1 and T2 relaxation times (rts). METHODS: [11C]-PBR28 (standard uptake value ratio, SUVR) images were generated in 36 participants (14 PWH, 6 ECs, and 16 healthy controls) using a statistically defined pseudoreference region. Group comparisons of [11C]-PBR28 SUVR were performed using region of interest-based and voxelwise analyses. The relationship between inflammation, qMRI measures, and cognitive function was studied. RESULTS: In region of interest analyses, ECs exhibited significantly lower [11C]-PBR28 signal in the thalamus, putamen, superior temporal gyrus, prefrontal cortex, and cerebellum compared with the PWH. In voxelwise analyses, differences were observed in the thalamus, precuneus cortex, inferior temporal gyrus, occipital cortex, cerebellum, and white matter (WM). [11C]-PBR28 signal in the WM and superior temporal gyrus was related to processing speed and selective attention in PWH. In a subset of PWH (n = 12), [11C]-PBR28 signal in the thalamus and WM regions was related to a decrease in T2 rt and to an increase in T1 rt suggesting a colocalization of increased glial metabolism, decrease in microstructural integrity, and iron accumulation. DISCUSSION: This study casts a new light onto the role of neuroinflammation and related microstructural alterations of HIV infection in the CNS and shows that ECs suppress neuroinflammation more effectively than PWH on therapy.

Neuroimaging Findings of Hospitalized Covid-19 Patients: A Canadian Retrospective Observational Study.

PURPOSE: Coronavirus disease (COVID-19) has been associated with neurologic sequelae and neuroimaging abnormalities in several case series previously. In this study, the neuroimaging findings and clinical course of adult patients admitted with COVID-19 to a tertiary care hospital network in Canada were characterized. METHODS: This is a retrospective observational study conducted at a tertiary hospital network in Ontario, Canada. All adult patients with PCR-confirmed COVID-19 admitted from February 1, 2020 to July 22, 2020 who received neuroimaging related to their COVID-19 admission were included. CT and MR images were reviewed and categorized by fellowship-trained neuroradiologists. Demographic and clinical data were collected and correlated with imaging findings. RESULTS: We identified 422 patients admitted with COVID-19 during the study period. 103 (24.4%) met the inclusion criteria and were included: 30 ICU patients (29.1%) and 73 non-ICU patients (70.9%). A total of 198 neuroimaging studies were performed: 177 CTs and 21 MRIs. 17 out of 103 imaged patients (16.8%) had acute abnormalities on neuroimaging: 10 had macrohemorrhages (58.8%), 9 had acute ischemia (52.9%), 4 had SWI abnormalities (23.5%), and 1 had asymmetric sulcal effacement suggesting possible focal encephalitis (5.8%). ICU patients were more likely to have positive neuroimaging findings, more specifically acute ischemia and macrohemorrhages (P < 0.05). Macrohemorrhages were associated with increased mortality (P < 0.05). CONCLUSION: Macrohemorrhages, acute ischemia and SWI abnormalities were the main neuroimaging abnormalities in our cohort of hospitalized COVID-19 patients. Acute ischemia and hemorrhage were associated with worse clinical status.

Influenza-associated Neurologic Complications in Hospitalized Pediatric Patients: A Multicenter Retrospective Study in Republic of Korea.

BACKGROUND: The rates of influenza-associated neurologic complications are variable among studies, and a difference has been observed between the Western and Asian countries. The study aims to evaluate the frequency and characteristics of influenza-associated neurologic complications. METHODS: We performed a retrospective review of hospitalized cases of influenza infection from October 2010 to April 2017 from 3 referral hospitals. RESULTS: A total of 1988 influenza cases were identified. Influenza-associated neurologic complications were 161 cases (8.1%); influenza virus A was detected in 113 (70.2%) cases, B in 47 (29.2%) cases and both A and B in 1 case (0.6%). Twenty-four patients (15%) had underlying neurologic diseases. The most common diagnosis was a simple febrile convulsion (44%), followed by complex febrile convulsion (29%), fever-provoked seizure under pre-existing neurologic disease or afebrile seizure (14%), encephalopathy/encephalitis (8%) and meningitis (5%). Most of the patients fully recovered (96%). Three patients (1.9%) died of myocarditis (n = 1), encephalopathy (n = 1), and simultaneous encephalitis and myocarditis (n = 1). Pre-existing neurologic disease, age groups of 6 months to 6 years and 6-12 years were a risk factor of influenza-associated neurologic complications with an adjusted odds ratio of 5.41 (95% confidence interval [CI] 3.23-9.06, P < 0.001), 12.99 (95% CI 1.77-95.19, P = 0.01) and 8.54 (95% CI 1.14-64.79, P = 0.04), respectively. There was no association between neuropsychiatric adverse events and oseltamivir prescription (P = 0.17). CONCLUSIONS: Influenza-associated neurologic complications are not uncommon, and most patients fully recovered. The frequency of influenza-associated neurologic complications in Korean children was not significantly different from that of children in Western countries.

Microglia and Perivascular Macrophages Act as Antigen Presenting Cells to Promote CD8 T Cell Infiltration of the Brain.

CD8 T cell infiltration of the central nervous system (CNS) is necessary for host protection but contributes to neuropathology. Antigen presenting cells (APCs) situated at CNS borders are thought to mediate T cell entry into the parenchyma during neuroinflammation. The identity of the CNS-resident APC that presents antigen via major histocompatibility complex (MHC) class I to CD8 T cells is unknown. Herein, we characterize MHC class I expression in the naïve and virally infected brain and identify microglia and macrophages (CNS-myeloid cells) as APCs that upregulate H-2Kb and H-2Db upon infection. Conditional ablation of H-2Kb and H-2Db from CNS-myeloid cells allowed us to determine that antigen presentation via H-2Db, but not H-2Kb, was required for CNS immune infiltration during Theiler's murine encephalomyelitis virus (TMEV) infection and drives brain atrophy as a consequence of infection. These results demonstrate that CNS-myeloid cells are key APCs mediating CD8 T cell brain infiltration.

Neuropathology and Inflammatory Cell Characterization in 10 Autoptic COVID-19 Brains.

COVID-19 presents with a wide range of clinical neurological manifestations. It has been recognized that SARS-CoV-2 infection affects both the central and peripheral nervous system, leading to smell and taste disturbances; acute ischemic and hemorrhagic cerebrovascular disease; encephalopathies and seizures; and causes most surviving patients to have long lasting neurological symptoms. Despite this, typical neuropathological features associated with the infection have still not been identified. Studies of post-mortem examinations of the cerebral cortex are obtained with difficulty due to laboratory safety concerns. In addition, they represent cases with different neurological symptoms, age or comorbidities, thus a larger number of brain autoptic data from multiple institutions would be crucial. Histopathological findings described here are aimed to increase the current knowledge on neuropathology of COVID-19 patients. We report post-mortem neuropathological findings of ten COVID-19 patients. A wide range of neuropathological lesions were seen. The cerebral cortex of all patients showed vascular changes, hyperemia of the meninges and perivascular inflammation in the cerebral parenchyma with hypoxic neuronal injury. Perivascular lymphocytic inflammation of predominantly CD8-positive T cells mixed with CD68-positive macrophages, targeting the disrupted vascular wall in the cerebral cortex, cerebellum and pons were seen. Our findings support recent reports highlighting a role of microvascular injury in COVID-19 neurological manifestations.