MR Imaging Patterns and Prognosis in Powassan Virus Encephalitis.

BACKGROUND: Powassan virus (POWV) encephalitis is an arbovirus infection and the only tick-borne encephalitis serogroup which is present in mainland North America. The magnetic resonance (MR) imaging described with POWV encephalitis is varied, nonspecific, and limited in number, and as such, imaging patterns and outcomes with this arbovirus infection are not well appreciated. METHODS: A case report and literature review of the MR imaging associated with POWV encephalitis and correlate of the MR pattern with outcome is considered. RESULTS: The cerebellar dominant MR imaging pattern was identified in 50% of POWV encephalitis cases and was associated with a 60% fatality rate. POWV encephalitis with prominent cerebellar involvement on MR imaging responded to intravenous steroid. CONCLUSIONS: A cerebellar dominant MR pattern in POWV encephalitis was common, associated with a poor prognosis, and recognition could change management from supportive to life-saving.

Risk factors of epilepsy secondary to viral encephalitis: A meta-analysis.

OBJECTIVE: To systematically evaluate the risk factors of post-encephalitis epilepsy (PEE). METHODS: Systematic computerized searches of databases such as Cochrane Library, PubMed and EMBASE were performed. The meta-analysis of pooled odds ratios and 95% confidence intervals for PEE risk were calculated. RESULTS: Sixteen studies with 2504 patients were included for meta-analysis. The results showed that PEE was associated with coma, seizure, status epilepticus, cranial MRI abnormality, focal EEG abnormality, and positive herpes simplex virus (HSV) in cerebrospinal fluid (CSF). CONCLUSION: Coma, seizures or status epilepticus, abnormal MRI and focal EEG, and HSV in CSF were the risk factors of PEE.

Structured Imaging Approach for Viral Encephalitis.

MR imaging is essential in diagnosing viral encephalitis. Clinical features, cerebrospinal fluid analysis and pathogen confirmation by polymerase chain reaction can be supported by assessing imaging features. MR imaging patterns with typical locations can identify pathogens such as temporal lobe for herpes simplex virus type 1; bilateral thalami for Japanese encephalitis and influenza virus ; and brainstem for enterovirus and rabies. In this article, we have reviewed representative viral encephalitis and its MR imaging patterns. In addition, we also presented acute viral encephalitis without typical MR imaging patterns, such as dengue and varicella-zoster virus encephalitis.

Initial Seronegative West Nile Virus Encephalitis in an Immunocompromised Child.

We present a case of initial seronegative West Nile virus encephalitis in an immunocompromised child due to B-cell acute lymphoblastic leukemia. Although diagnostic guidelines for West Nile virus infection exist, we highlight that these may not be met in immunocompromised patients who may have a delayed immune response.

Fatal case of simply influenza A (H3N2)-associated encephalitis in immunocompetent patient.

Influenza virus-associated encephalopathy/encephalitis is a rare entity in adults that can lead to severe neurological sequelae and even death. The clinical presentation can be quite diverse. This absence of a typical presentation along with the difficulty detecting the virus in the cerebrospinal fluid represents a diagnostic challenge. We present the case of a 79-year-old male with sudden onset of decreased consciousness and signs of right hemisphere damage. The presence of influenza A (H3N2) virus in respiratory sample along with compatible findings in cranial magnetic resonance led to the diagnosis. The patient died without responding to treatment with antivirals and immunomodulators and the anatomopathological study did not detect infectious agent. Early diagnostic suspicion is essential to establish adequate treatment and improve the prognosis.

COVID-19 Post-Infectious Encephalitis Presenting With Delirium as an Initial Manifestation.

We report the case of a 65-year-old man with COVID-19 (coronavirus disease-2019) post-infectious encephalitis who presented with delirium as an initial manifestation. He had severe COVID-19 pneumonia and recovered with dexamethasone and tocilizumab. One week after discharge, he developed abnormal behavior and delirium without fever and respiratory symptoms. Brain magnetic resonance imaging showed no abnormalities. Cerebrospinal fluid showed pleocytosis and elevated protein concentrations and was negative for severe acute respiratory syndrome-coronavirus-2 RNA. No anti-neuronal autoantibodies against intracellular and neuronal surface proteins were detected. The cerebrospinal fluid inflammatory changes compatible with post-infectious encephalitis, and the patient recovered with intravenous methylprednisolone and intravenous immunoglobulin therapy. Delirium could be an initial symptom of post-infectious encephalitis in older adults with COVID-19, and these patients may require immunosuppressive therapy.

Post-infectious rhombencephalitis after coronavirus-19 infection: A case report and literature review.

A wide number of neurological manifestations have been described in association with coronavirus disease 19 (COVID-19). We describe an unusual case of a young man who developed severe rhombencephalitis after COVID-19. He demonstrated clinical and radiological improvement with high dose corticosteroids, plasma exchange and intravenous immune globulin. Our findings, along with previously reported cases that we review here, support an autoimmune para- or post-infectious mechanism and highlight a possible role for immunotherapy in patients with rhombencephalitis after COVID-19.

Reduced impact of viral load of HHV-6 in liquor on severity of AESD due to exanthema subitum: A case report and literature review.

BACKGROUND: The most common causative pathogen of acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) was reported as HHV-6. Although excitotoxic injury with delayed neuronal death is considered to be a possible pathogenesis of AESD, the detailed pathophysiology remains unclear. CASE PRESENTATION: We present a twelve-month-old girl with AESD due to HHV-6 primary infection. She was successfully treated for AESD including targeted temperature management and the administration of vitamin B1, B6, and L-carnitine. Although the viral load of HHV-6 in her liquor was high (12,000 copies/mL), she fully recovered without antiviral agent use. DISCUSSION: There has been no study focusing on the HHV-6 viral load in patients with AESD, and only a few case reports have been published. We reviewed the clinical features and viral load in the liquor of our case and four reported infants with AESD due to HHV-6 primary infection who had real-time PCR tests results. Viral loads in the three patients with a poor prognosis were 31.5, negative, and 3,390 copies/mL, respectively. On the other hand, the copy numbers of HHV-6 DNA in the two patients with no sequelae were 12,000 and 106 copies/mL, respectively, and our case had the highest viral load among the five summarized patients.

HPeV3-associated acute encephalitis/encephalopathy among Japanese infants.

OBJECTIVE: The current study aimed to identify and compare the clinical characteristics of human parechovirus type 3 (HPeV3)-associated acute encephalitis/encephalopathy (HPeV3E/E) between infants with abnormal brain magnetic resonance imaging (MRI) findings (typical, or MRI-positive HPeV3E/E) and those with MRI-negative findings (MRI-negative HPeV3E/E). METHODS: This is a retrospective study on patients with HPeV3 infection, and a two-step questionnaire survey performed on 837 hospitals in Japan between 2014 and 2016. RESULTS: We identified 240 infants with HPeV3 infection, of which 34 had been clinically-diagnosed HPeV3E/E (cHPeV3E/E). However, detailed clinical data were provided by 32 of the 34 patients. Among these 32, 23 had undergone MRI and were categorized into two groups, MRI-positive (n = 17) and -negative (n = 6). There were no significant intergroup differences in clinical lab results or symptoms, except for gastrointestinal symptoms that were only present in the MRI-negative patients. The MRI-positive group showed white matter involvement on brain MRI during the acute phase, and 8 patients presented with lesions on follow-up MRI. Furthermore, 4 (50%) of the 8 patients had neurological sequelae. CONCLUSION: Clinical characteristics of cHPeV3E/E patients with and without lesions on brain MRI showed no significant differences. Therefore, considering the difficulty in distinguishing febrile infants with cHPeV3E/E from those with a sepsis-like illness, during an HPeV3 infection epidemic, it is imperative to frequently perform brain MRI in febrile infants presenting with severe disease for the early diagnosis of HPeV3E/E presenting with brain lesions.

Influenza B-associated encephalitis with rapid improvement with oseltamivir.

A 25-year-old female veterinarian presented with 1-week of flu-like symptoms followed by progressive encephalopathy. She was originally from Nicaragua and had been in the USA for 4 months. In the emergency department, she was confused and non-verbal with meningismus and facial myoclonus, but with an otherwise non-focal neurological exam. MRI brain abnormalities were consistent with viral encephalitides. Influenza B was detected via nasopharyngeal swab PCR. Mental status improved rapidly with oseltamivir. In such presentations, especially during flu season, influenza encephalitis must be considered, to facilitate early recognition of this entity and allow for targeted treatment.

Acute Childhood Viral Encephalitis in Southern Brazil.

BACKGROUND: Viral meningoencephalitis is highly heterogeneous, varying by geographic location. The aim of this study was to characterize the etiology and reporting the clinical findings and outcome of viral encephalitis in children in southern Brazil. METHODS: A cross-Sectional study was conducted at Hospital Pequeno Príncipe, Curitiba, Brazil, between January 2013 and December 2017. It included patients younger than 18 years, who fulfilled the criteria: altered mental status as a major criteria and 2 or more minor criteria (1) fever, (2) seizures, (3) focal neurologic findings, (4) central system fluid white cell count of ≥5 cells/mm, (5) abnormal brain imaging, and/or (6) electroencephalogram abnormalities. RESULTS: Viral meningoencephalitis was diagnosed in 270 children, with median age of 2 years (interquartile range: 0-4), The etiology of viral meningoencephalitis was confirmed in 47% of patients. Enterovirus (18%) was the major cause of encephalitis in Southern Brazilian children, and a high prevalence of Epstein-Barr virus (6%) was demonstrated. Most patients presented with fever (81%), followed by vomiting (50%), focal neurologic findings (46%), seizures (31%) and headache (30%). Few abnormalities were detected on electroencephalograms and brain magnetic resonance images. On discharge from hospital, symptoms resolved completely in 87% of children. Sequelae were mainly observed in patients with focal neurologic symptoms (P<0.001), presence of seizures (P<0.001) and electroencephalogram abnormalities (P=0.024). CONCLUSIONS: Enterovirus was the major cause of encephalitis. Etiologic agent of encephalitis seems to be influenced by the local virologic pattern. A poor outcome was identified in patients with seizures, focal neurologic findings and electroencephalogram abnormalities.

Acute viral encephalitis associated with human parvovirus B19 infection: unexpectedly diagnosed by metagenomic next-generation sequencing.

We report here a case of a 17-year-old boy with viral encephalitis associated with human parvovirus B19 who presented consciousness disturbance, left hemiparesis, and focal neurologic signs. The diagnosis was based on the specific sequence reads corresponding to human parvovirus B19 (PVB19) in a CSF sample as analyzed by metagenomic next-generation sequencing (mNGS). Thus, PVB19 should be considered in the differential diagnosis of encephalitis and encephalopathy of unknown etiology. The introduction of mNGS into the diagnostic protocol of neuropathies, especially for those undiagnosed, could interrogate all genetic information in a biologic sample and facilitate the identification of the etiological agent.

Disseminated cortical and subcortical lesions in neonatal enterovirus 71 encephalitis.

Enteroviruses are one of the most important causes of viral encephalitis in the neonatal period. However, the non-specificity of the symptoms presented renders its diagnosis challenging. Intracranial MRI has been reported to be a very useful imaging modality that can detect the characteristic white matter lesions around the periventricular regions. In this study, we report a case of a patient with neonatal encephalitis who presented with normal white blood cell counts in the initial cerebrospinal fluid analysis. A lumbar puncture retap identified pleocytosis, and polymerase chain reaction assays detected enterovirus 71 in the blood and stool samples. Furthermore, MRI revealed atypical disseminated cortical and subcortical white matter lesions on diffusion weighted images, and neuroradiological re-evaluation showed necrotic changes 2 weeks later. This unique case expands our knowledge of the spectrum of neurological disorders due to enterovirus 71 infection in neonatal period.

Surgical treatment in children with intractable epilepsy after viral encephalitis.

PURPOSE: To investigate the surgical outcome in children with epilepsy after viral encephalitis (VE), we studied the prognostic factors for surgery and summarized the surgical strategies of children with epilepsy secondary to VE. METHODS: We retrospectively analyzed 23 surgically treated children with VE. The subjects were divided into two groups according to their surgical outcome. All presurgical evaluation data were collected and analyzed. RESULTS: Among the 23 operated children, the mean age at surgery was 6.1 years. Surgeries were hemispherotomy (n = 12), temporal-parietal-occipital disconnection (n = 4), whole corpus callosotomy (n = 3), lobectomy (n = 3), and vagus nerve stimulation (n = 1). The mean patient follow-up time was 37.2 months, and 13 children had a good outcome (ILAE classification 1-3). Univariate analyses revealed that the latency from infection to the first unprovoked seizure, MRI laterality, concordance of PET and MRI abnormalities, and acute postoperative seizure (APOS) were prognostic factors of seizure outcomes (P < 0.05). No correlation was found between generalized seizures and poor outcome (P = 0.229). CONCLUSIONS: We concluded that the children who achieve favorable surgical outcomes are those with longer latency, unilateral abnormalities on MRI, consistency of PET and MRI abnormalities, and no APOS. Without invasive studies, epilepsy surgery may be successful for selected children with epilepsy after VE, despite diffuse interictal epileptiform discharges on scalp EEG. In addition, children with generalized seizures were not an absolute contraindication for surgery.

Non-congenital viral infections of the central nervous system: from the immunocompetent to the immunocompromised child.

Non-congenital viral infections of the central nervous system in children can represent a severe clinical condition that needs a prompt diagnosis and management. However, the aetiological diagnosis can be challenging because symptoms are often nonspecific and cerebrospinal fluid analysis is not always diagnostic. In this context, neuroimaging represents a helpful tool, even though radiologic patterns sometimes overlap. The purpose of this pictorial essay is to suggest a schematic representation of different radiologic patterns of non-congenital viral encephalomyelitis based on the predominant viral tropism and vulnerability of specific regions: cortical grey matter, deep grey matter, white matter, brainstem, cerebellum and spine.