Imaging of central nervous system viral diseases

Case report: Fatal Borna virus encephalitis manifesting with basal brain and brainstem symptoms

Background

Since the first report of fatal Borna virus-1 (BoDV-1) encephalitis in 2018, cases gradually increased. There is a lack of diagnostic algorithm, and there is no effective treatment so far.

Case presentation

We report an acute BoDV-1 encephalitis in a 77-year-old female with flu-like onset, rapid progression to word-finding difficulties, personality changes, global disorientation, diffuse cognitive slowness, and gait ataxia and further deterioration with fever, meningism, severe hyponatremia, epileptic seizures, cognitive decline, and focal cortical and cerebellar symptoms/signs. The extensive diagnostic workup (cerebrovascular fluid, serum, and MRI) for (meningo-)encephalitis was negative for known causes. Our empirical common antiviral, antimicrobial, and immunosuppressive treatment efforts failed. The patient fell into coma 5 days after admission, lost all brainstem reflexes on day 18, remained fully dependent on invasive mechanical ventilation thereafter and died on day 42. Brain and spinal cord autopsy confirmed an extensive, diffuse, and severe non-purulent, lymphocytic sclerosing panencephalomyelitis due to BoDV-1, affecting neocortical, subcortical, cerebellar, neurohypophysis, and spinal cord areas. Along with our case, we critically reviewed all reported BoDV-1 encephalitis cases.

Conclusion

The diagnosis of acute BoDV-1 encephalitis is challenging and delayed, while it progresses to fatal. In this study, we list all tried and failed treatments so far for future reference and propose a diagnostic algorithm for prompt suspicion and diagnosis.

Dissociations in white matter tracts and neuropsychological findings in a 17 years old patient with Subacute sclerosing panencephalitis

The present multimodal diffusion tensor imaging and neuropsychological study investigated the integrity of the white matter fascicles in a 17 years-old patient diagnosed with subacute sclerosing panencephalitis (SSPE). A brief neuropsychological testing showed that word and pseudoword repetition, naming, semantic and phonological fluency, long-term memory, working memory were impaired. A review of the literature on Diffusion weighted imaging (DWI) and Diffusion Tensor Imaging (DTI) evidenced that, studies investigating the integrity of white matter in this condition being a rare disease, are very few. Significant differences (p < 0.05) were found between the fractional anisotropy (FA) values of the controls and the patient in the Superior Longitudinal fasciculus, the Inferior Longitudinal Fasciculus, the Inferior Fronto-Occipital Fasciculus, the Uncinate Fasciculus, and the Arcuate Fasciculus with lower values in the patient. No differences were found for the corticospinal tract. The number of streamlines was significantly lower in the patient, compared to controls, for the left Superior Longitudinal fasciculus, and for the left Uncinate fasciculus while for all the other fascicles, the number did not significantly differ from controls. DTI results were consistent with the patient's cognitive profile showing impairments at repetition, at tasks tapping lexical-semantics and long-term memory / retrieval. Diffusion tensor imaging results indicate that there were diffuse alterations of the degree of anisotropic diffusion along the white matter tracts distributed in posterior-anterior direction. Differently, a selective sparing of this measure was observed along the white matter tract distributed in inferior-superior direction (the corticospinal fascicle).

Meningoencephalitis in primary antibody deficiency: Our experience from northwest India

BACKGROUND/OBJECTIVES

Patients with primary antibody deficiency (PAD) are predisposed to develop meningoencephalitis, often considered to be enteroviral. However, there is a paucity of literature on this subject, and there are no studies from developing countries.

METHODS

We analyzed our cohort of children with PAD who developed meningoencephalitis.

RESULTS

This complication was observed in 13/135 (10.4%) patients with PAD - 5 patients had X-linked agammaglobulinemia (XLA), 7 had common variable immunodeficiency (CVID) and 1 had suspected nuclear factor kappa B essential modulator (NEMO) defect. Mean age at onset of neurological illness was 9.3 years. Presenting features included seizures (n=8), neurodevelopmental delay (n=2), regression of milestones (n=2), and acute flaccid paralysis (n=1). Trough IgG levels were found to be low in 12/13 patients at the time of development of neurological symptoms. Herpes simplex virus (HSV), cytomegalovirus (CMV), and Streptococcus pneumoniae were isolated in 1 each. Eight (72.7%) patients had altered signal hyperintensities in gray matter and deep white matter on magnetic resonance imaging (MRI), while 4 patients showed global cerebral atrophy. All patients were treated with high-dose intravenous immunoglobulin (IVIg). Fluoxetine was given to 3 patients. Eight patients in the present series have died, 3 have recovered with varying degrees of neurological sequelae and 2 patients are showing gradual recovery.

CONCLUSIONS

To conclude, meningoencephalitis is an uncommon complication in patients with PAD and is associated with high morbidity and mortality. Early diagnosis of immune deficiency and initiation of replacement immunoglobulin therapy may prevent the development of neurological complications.

A systematic review of brain imaging findings in neurological infection with Japanese encephalitis virus compared with Dengue virus

OBJECTIVES

Japanese encephalitis virus (JEV) and dengue virus (DENV) represent important causes of encephalitis in Asia. Brain imaging may provide diagnostic clues about the etiology of infectious encephalitis. We performed a systematic review of brain imaging findings in Japanese encephalitis (JE) and DENV neurological infection (dengue) to identify characteristic lesions.

METHODOLOGY

Five databases were searched. We included all study types and imaging techniques. Laboratory methods were categorized using diagnostic confidence levels. Imaging data were synthesized, and focal findings are presented as proportions for JE and dengue and for subgroups based on diagnostic confidence.

PRINCIPAL FINDINGS

Thalamic lesions were the most reported magnetic resonance imaging finding in both diseases but appeared to occur more often in JE (74% in 23 studies) than dengue (29.4% in 58 studies). In cases diagnosed with antigen or nucleic acid tests, thalamic lesions were reported frequently in both JE (76.5% in 17 studies) and dengue (65.2% in 23 studies).

SIGNIFICANCE

The results suggest that thalamic lesions frequently occur in both JE and dengue encephalitis. No radiological findings were found to be pathognomonic of either disease. Although brain imaging may support a diagnosis, laboratory confirmation with highly specific tests remains crucial.

Early detection of cerebrovascular pathology and protective antiviral immunity by MRI

Central nervous system (CNS) infections are a major cause of human morbidity and mortality worldwide. Even patients that survive CNS infections can have lasting neurological dysfunction resulting from immune and pathogen induced pathology. Developing approaches to noninvasively track pathology and immunity in the infected CNS is crucial for patient management and development of new therapeutics. Here, we develop novel MRI-based approaches to monitor virus-specific CD8+ T cells and their relationship to cerebrovascular pathology in the living brain. We studied a relevant murine model in which a neurotropic virus (vesicular stomatitis virus) was introduced intranasally and then entered the brain via olfactory sensory neurons - a route exploited by many pathogens in humans. Using T2*-weighted high-resolution MRI, we identified small cerebral microbleeds as an early form of pathology associated with viral entry into the brain. Mechanistically, these microbleeds occurred in the absence of peripheral immune cells and were associated with infection of vascular endothelial cells. We monitored the adaptive response to this infection by developing methods to iron label and track individual virus specific CD8+ T cells by MRI. Transferred antiviral T cells were detected in the brain within a day of infection and were able to reduce cerebral microbleeds. These data demonstrate the utility of MRI in detecting the earliest pathological events in the virally infected CNS as well as the therapeutic potential of antiviral T cells in mitigating this pathology.

Dengue Infection: Not Just Fever—A Rare Presentation with Literature Review

Dengue fever is a common viral infection in the tropical areas, especially in India. However, dengue infection presenting as hemorrhagic encephalitis is rare. A 10-year-old girl presented with fever, headache, vomiting, and seizures followed by altered sensorium. Her blood serum was positive for antidengue immunoglobulin M enzyme-linked immunosorbent assay (ELISA) and NS1Ag, and cerebrospinal fluid study showed lymphocytic pleocytosis. Magnetic resonance imaging T2-weighted and fluid-attenuated inversion recovery (FLAIR) images showed hyperintensities involving the bilateral thalami, pons, and midbrain with patchy hemorrhage. Despite all supportive measures, she expired 3 days after admission. Our case highlights that dengue encephalitis may present even in the absence of other classical signs.

Meta-analysis of brain metabolite differences in HIV infection

BACKGROUND

Numerous studies have used magnetic resonance spectroscopy (MRS) neurometabolite measurements to study HIV infection effects. While many have reported differences in total N-Acetylaspartate (tNAA), myo-Inositol (mI), and total Choline (tCho), there have been no meta-analyses performed to evaluate concordance across studies.

PURPOSE

To evaluate the consistency of HIV serostatus effects on brain metabolites.

STUDY SELECTION

The sample included studies conducted between 1993 and 2019 reporting HIV infection effects measured using proton MRS. tNAA/tCr ratios (21 papers), tCho/tCr ratios (21 papers), mI/tCr ratios (17 papers) and quantitative tCr (9 papers), sampling from basal ganglia (BG), gray matter (GM), and white matter (WM) were included.

DATA ANALYSIS

Random effects meta-analysis using inverse variance weighting and bias corrected standardized mean differences (SMDs) was used. Meta-regression examined effects of publication year and data acquisition technique differences.

DATA SYNTHESIS

BG SMDs related to positive serostatus were -0.10 [-0.39; 0.18] tNAA/tCr, 0.27 [0.05; 0.49] tCho/tCr, 0.60 [0.31; 0.90] mI/tCr, and -0.26 [-0.59; 0.06] tCr. GM SMDs related to serostatus were -0.29 [-0.49; -0.09] tNAA/tCr, 0.37 [0.19; 0.54] tCho/tCr, 0.41 [0.15; 0.68] mI/tCr, and -0.24 [-0.45; -0.03] tCr. WM SMDs related to serostatus were -0.52 [-0.79; -0.25] tNAA/tCr, 0.41 [0.21; 0.61] tCho/tCr, 0.59 [0.24; 0.94] mI/tCr, and -0.03 [-0.25; 0.19] tCr. WM regions showed larger serostatus effect sizes than BG and GM. I² ranged from 52 to 88% for the metabolite ratios. Both GM and WM tNAA/tCr SMDs were lower with increasing calendar year.

LIMITATIONS

Many studies pooled participants with varying treatment, infection, and comorbidity durations.

CONCLUSIONS

HIV neurometabolite studies showed consistently lower tNAA/tCr, higher tCho/tCr and higher mI/tCr ratios associated with chronic HIV infection. Substantial between-study variation may have resulted from measurement technique variations, study population differences and HIV treatment changes over time. Higher WM tCho/tCr and mI/tCr may reflect reactive gliosis or myelin turnover. Neurometabolite measurements can reliably detect chronic HIV infection effects and may be useful in understanding the pathophysiology of cognitive and sensorimotor decline following HIV infection.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence of neurometabolite differences in chronic HIV infection.

Magnetic Resonance Imaging Findings in Viral Encephalitis: A Pictorial Essay

Viral encephalitis by definition is the result of human virus affecting the brain and sparing the meninges. The other nervous system manifestations are meningitis, meningoencephalitis, encephalomyelitis, and encephalomyeloradiculitis. Encephalitis can involve any age group from children to old people. The severity of the disease depends on the viral agent and the host immune system. The patient can present with fever, headache, seizure, neurological deficit, or altered sensorium. Laboratory investigations, imaging, and cerebrospinal fluid analysis are crucial in the diagnosis of encephalitis. Magnetic resonance imaging (MRI) findings may be nonspecific or specific and plays a major role in the diagnosis of encephalitis and predicting the possible cause. This pictorial essay reviews the MRI findings of common types of viral encephalitis.

Diphtheric encephalitis and brain neuroimaging features

We report a rare case of paediatric diphtheria complicated with encephalitis. A 6-year-old boy who did not receive his scheduled diptheria-tetanus-pertusis vaccination presented with one episode of generalised convulsive seizure. His illness was preceded by a 3day history of fever associated with enlarged exudative tonsils with a pseudomembrane. He was commenced on intravenous penicillin and oral erythromycin. However, he developed progressive encephalopathy with focal neurological deficit which required intubation on day 5 of illness. Throat swab polymerase chain reaction for diphtheria toxin A and B were positive and diphtheria antitoxin was given. Magnetic resonance imaging (MRI) of brain showed T2-weighted hyperintensities over the anterior cingulate gyri, insular cortex and cerebellum. This is the first reported MRI finding of diphtheric encephalitis. Our report highlights the importance of neuroimaging in diagnosing diphtheric encephalitis particularly in cases with unremarkable cerebrospinal findings.

Diffusion-weighted MRI abnormalities in an outbreak of Streptococcus agalactiae Serotype III, multilocus sequence type 283 meningitis

PURPOSE

In 2015, an outbreak of group B streptococcal (GBS) infection caused by Streptococcus agalactiae Serotype III, multilocus sequence type 283, related to consuming infected raw freshwater fish, affected more than 200 patients in Singapore. We describe the clinical, laboratory, and neuroimaging features of a subgroup of adults with central nervous system (CNS) infections caused by GBS.

MATERIALS AND METHODS

The database of the Singapore Neurologic Infections Program (SNIP), a national multicenter study for surveillance of infectious neurologic disease, was reviewed to select patients with GBS CNS infection during the outbreak. Cases were diagnosed on the basis of clinical features, cerebrospinal fluid (CSF) findings and identification or isolation of Streptococcus agalactiae in the blood or CSF. Demographic, clinical and neuroradiological information was obtained prospectively and retrospectively abstracted.

RESULTS

Fourteen patients (6 male, 8 female; median age, 58 years) presented with fever, meningism, headache, encephalopathy, focal neurological deficits, and/or seizures. All except two were previously healthy. Diffusion-weighted imaging (DWI) on admission was abnormal in 13 patients, showing tiny hyperintensities in the subarachnoid space (7 patients), ventricles (6 patients) and brain parenchyma (8 patients); 5 patients had cerebellar abnormalities.

CONCLUSION

Among healthy non-pregnant adults infected with Serotype III, multilocus sequence type 283 GBS meningitis linked to eating infected raw freshwater fish, DWI detected small pus collections and unusual cerebellar involvement. A collaborative national surveillance system that includes MRI can be helpful during unusual food-borne zoonotic infectious disease outbreaks.

LEVEL OF EVIDENCE

4 J. Magn. Reson. Imaging 2017;45:507-514.

CNS infections in patients with hematological disorders (including allogeneic stem-cell transplantation)-Guidelines of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO)

Diagnosis of CNS infections remains a great challenge in patients with hematological disorders since symptoms might both be masked and be mimicked by other conditions such as metabolic disturbances or consequences from antineoplastic treatment. Thus, awareness of this complication is crucial and any suspicion of a CNS infection should lead to timely and adequate diagnostics and treatment to improve the outcome in this population.

Infections of the central nervous system (CNS) are infrequently diagnosed in immunocompetent patients, but they do occur in a significant proportion of patients with hematological disorders. In particular, patients undergoing allogeneic hematopoietic stem-cell transplantation carry a high risk for CNS infections of up to 15%. Fungi and Toxoplasma gondii are the predominant causative agents. The diagnosis of CNS infections is based on neuroimaging, cerebrospinal fluid examination and biopsy of suspicious lesions in selected patients. However, identification of CNS infections in immunocompromised patients could represent a major challenge since metabolic disturbances, side-effects of antineoplastic or immunosuppressive drugs and CNS involvement of the underlying hematological disorder may mimic symptoms of a CNS infection. The prognosis of CNS infections is generally poor in these patients, albeit the introduction of novel substances (e.g. voriconazole) has improved the outcome in distinct patient subgroups. This guideline has been developed by the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO) with the contribution of a panel of 14 experts certified in internal medicine, hematology/oncology, infectious diseases, intensive care, neurology and neuroradiology. Grades of recommendation and levels of evidence were categorized by using novel criteria, as recently published by the European Society of Clinical Microbiology and Infectious Diseases.

Proven Epstein-Barr encephalitis with negative EBV-DNA load in cerebrospinal fluid after allogeneic hematopoietic stem cell transplantation in a child with acute lymphoblastic leukemia

We report a case of EBV encephalitis in a seven-yr-old child with Ph+ ALL. Two months after an allogeneic HSCT from his HLA mismatched mother, the patient showed an altered sensorium, generalized seizures, and a left hemiparesis. Brain MRI demonstrated multiple lesions highly suggestive for viral encephalitis. Blood and CSF PCR analyses were negative for the most common viruses involved in immunocompromised patients including EBV. A cerebral biopsy was performed, which showed intense gliosis and perivascular lymphocytic cuffing. PCR analysis performed on brain tissue was positive only for the EBV genome, while extensive investigations for other viral infections were negative. The patient's neurological symptoms rapidly worsened and he died two months later. This case report suggests that in patients presenting neurological and radiological signs of encephalitis after an HSCT, an EBV involvement should be considered, even in the absence of CSF and blood PCR virus detection.

Eradication of human immunodeficiency virus from brain reservoirs

Isolated cases in which human immunodeficiency virus (HIV) infection was claimed to have been eradicated generated renewed interest in HIV reservoirs in the brain particularly since attempts to reproduce the findings using genetically engineered stem cells and immune- or myeloablation have failed. A clear understanding of the cell types in which the virus resides in the brain, the mechanism of viral persistence, restricted replication and latency, and the turnover rate of the infected cells is critical for us to develop ways to control or get rid of the virus in the brain. The brain has several unique features compared to other reservoirs. There are no resident T cells in the brain; the virus resides in macrophages and astrocytes where the viral infection is non-cytopathic. The virus evolves in the brain and since the turnover rate of these cells is low, the virus has the potential to reside in these cells for several decades and possibly for the life of the individual. This review discusses the HIV reservoirs in the brain, issues related to eradication of the virus from sanctuaries in the brain, and current challenges faced by neuroscientists in finding a cure.

Brain MRI of children with retinopathy-negative cerebral malaria

Our goals were to understand the brain magnetic resonance imaging (MRI) findings in children with retinopathy-negative cerebral malaria (CM) and investigate whether any findings on acute MRI were associated with adverse outcomes. We performed MRI scans on children admitted to the hospital in Blantyre, Malawi with clinically defined CM. Two hundred and seventeen children were imaged during the study period; 44 patients were malarial retinopathy-negative; and 173 patients were retinopathy-positive. We compared MRI findings in children with retinopathy-negative and retinopathy-positive CM. In children who were retinopathy-negative, we identified MRI variables that were associated with death and adverse neurologic outcomes. On multivariate analysis, cortical diffusion weighted imaging (DWI) abnormality and increased brain volume were strongly associated with neurologic morbidity in survivors. Investigations to explore the underlying pathophysiologic processes responsible for these MRI changes are warranted.

Implementation of the Cepheid Xpert EV assay for rapid detection of enteroviral meningitis: experience of a tertiary care center and a technical review

AIMS

Rapid molecular detection of enterovirus in cerebrospinal fluid (CSF) has revolutionized the diagnosis and treatment modalities of patients with meningitis and largely affected cost of unnecessary antibiotic use and length of stay in hospitals.

MATERIALS AND METHODS

Between January 2010 and July 2012, we tested 220 CSF samples on the GeneXpert DX real-time polymerase chain reaction system (by Cepheid) using the Xpert EV kit assays. In addition, we reported 14 sample results cross-validated with an external referral laboratory as well as the results of external proficiency testing.

RESULTS

Out of all tested samples, 19% were positive for enterovirus. Furthermore, all referred and proficiency testing specimens were concordant with the peer-reviewed and tested samples.

CONCLUSION

Implementation of the Cepheid Xpert EV assay for rapid detection of enteroviral meningitis has been successful in our laboratory. This molecular diagnostic test is currently utilized by our staff physicians as a major tool in assessment and management of patients with meningitis.

An update on diagnostic imaging studies for viral encephalitis

Viral encephalitis is still a life-threatening disease occurring at any age. It is critical to make a rapid and correct diagnosis for a better outcome of the disease. Accumulating evidence has suggested that MRI is a powerful tool for the detection of any lesion of the CNS caused by viral infections and helps to initiate the timely treatment. In this review, we summarize the current understanding of MRI findings of viral encephalitis, especially related to HSV, HIV, varicella zoster, Japanese encephalitis, John Cunningham, and influenza viruses. With these considerations, we learnt that the inclusion of diffusion-weighted image sequences on routine MRI examination would have a significant value in detecting the pathologic changes that occur following viral invasion of the CNS.