Despite scarcity of data, in recent years, human parvovirus B19 (PVB19) has been emerging as an important pathogen in acute encephalitis syndrome (AES). But, PVB19 virus is mostly looked for only after the exclusion of other common pathogens implicated in AES. Hence, this study was conducted to correlate clinical, radiological, and sequencing data to establish the crucial role of PVB19 in AES. Cerebrospinal fluid and/or serum samples were collected from AES patients as per WHO criteria and tested by ELISA, real-time PCR and bacterial culture sensitivity for various pathogens. PVB19 positive samples were subjected to sequencing. PVB19 attributed to 5% of total AES cases in the present study with fatalities in two of eight cases. Two isolates of PVB19 belonged to Genotype 1 A whereas one belonged to Genotype 3B. On multivariate analysis of predictive symptoms of PVB19 AES cases, blurring of vision (odds ratio [OR] 20.67; p = 0.001) was found to be significant independent predictor of PVB19 AES. Six of eight patients (two encephalitis specific and four nonspecific) had abnormal radiological findings. Hence, being an emerging viral pathogen, PVB19 should be included in the diagnostic algorithm of AES for prompt diagnosis and definitive management to prevent undesired neurological sequelae.

An increasing number of reports have described human parvovirus B19 infection in association with a variety of neurological manifestations, especially in children. This study assessed the clinical and laboratory outcomes found in a case series of immunocompetent children who tested positive for parvovirus B19 by qualitative polymerase chain reaction assays of cerebrospinal fluid, in a tertiary referral center in the western Brazilian Amazon. We screened 178 children with clinically diagnosed central nervous system infections (meningoencephalitis). Of these, five (2.8%) were positive for parvovirus B19. A literature review also presented herein identified a further 50 cases of parvovirus B19 with neurological manifestations. Thus, even if the classic signs of parvovirus B19 infection are absent, such as the well-known rash, children with signs of neurological infection should also be evaluated for parvovirus B19 infection.

To investigate the clinical features, imaging features, and prognosis of mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) in children METHODS: The clinical and imaging data of a cohort of 28 children diagnosed as MERS from January 2019 to October 2020 were retrospectively analyzed RESULTS: Of the 28 patients, 17 were males and 11 were females. The onset age ranged from 8 months to 12 years old, with an average age of 4 years and 2 months. All children developed normally before onset, and three of them had a history of febrile convulsion. More than half of the patients (62.9%) had preceding infections of gastrointestinal tract. All the cases developed seizures, and most (71.4%) had more than one time. Other neurological symptoms included dizziness/headache, consciousness disorder, limb weakness, blurred vision, and dysarthria. Cranial magnetic resonance imaging (MRI) showed lesions in the splenium of the corpus callosum in all, extending to other areas of the corpus callosum, bilateral semi-ovoid center, and adjacent periventricular in two cases. The clinical symptoms were relieved after steroids, intravenous immunogloblin, and symptomatic treatment, without abnormal neurodevelopment during the followed-up (2 months-2 years). Complete resolution of the lesions was observed 8-60 days after the initial MRI examinations CONCLUSION: MERS in children is related to prodromal infection mostly, with a wide spectrum of neurologic symptoms, characteristic MRI manifestations, and good prognosis.

Mild encephalitis/encephalopathy with a reversible isolated splenial lesion (MERS) is a rare and complex clinico-radiological condition that aggregates various diseases. From a geographical point of view, most cases have been reported in Asia, especially in Japan. However, a very limited number of studies have properly evaluated Chinese patients diagnosed with MERS.

Putative encephalitis/encephalopathy patients affected by a reversible isolated SCC lesion, as detected by magnetic resonance imaging (MRI), were retrospectively evaluated. Specifically, we reviewed extensive patient data, including prodromal and neurologic symptoms, neurologic examinations, MRI and electroencephalography (EEG) findings, laboratory results, treatments, and prognosis.

Six clinically mild encephalitis/encephalopathy patients, affected by a reversible isolated SCC lesion, were identified in a cohort of 22 patients. Six patients presented fever symptoms before the onset of neurological manifestations. Initial MRI data exhibited isolated SCC lesions with isointense or slightly hypointense on T1WI, hyperintense on T2WI, Flair, and DWI, as well as decreased ADC values, without contrast enhancement. EEG data indicated abnormalities (3/4), as well as elevated serum inflammatory markers (5/6) and hyponatremia (4/6). Cell content and protein yields were normal or slightly increased in the CSF of 6 patients, excluding one episode of significant increase in cell number. Patients were treated with corticosteroids, antivirals, and antibiotics, resulting in their full clinical recovery. SCC lesions mostly disappeared in all patients.

In our study, the clinical features identified in all affected patients were mostly identical, which consisted of relatively mild CNS manifestations with a promising prognostic status.

The presence of isolated, reversible lesions in the splenium of the corpus callosum (SCC) is essential to confirm the diagnosis of mild encephalitis/encephalopathy. The lesions usually heal within a month after the onset of neurological symptoms. Magnetic resonance imaging (MRI) has increasingly been used as a diagnostic tool, which has led to the publication of an increasing number of case reports. These have highlighted some inconsistencies about encephalitis/encephalopathy. First, the condition is not always mild and may be severe. Second, reversible lesions in the SCC have been identified in various diseases and conditions other than viral encephalitis/encephalopathy. Third, lesions in SCC are not always completely reversible. On this note, this review describes the specific clinical and radiological features of encephalitis/encephalopathy.

The reversible lesion in SCC is an MRI finding observable in a wide variety of diseases and conditions. Thus, it should be considered as a secondary change rather than a peculiar feature associated with mild encephalitis/encephalopathy. If reversible lesions are present in the SCC, the symptoms and prognosis are not necessarily favorable, with manifestations of encephalitis/encephalopathy varying from absent to severe. Neuroradiological features that appear as isolated high-intensity signals on diffusion-weighted images and a decreased apparent diffusion coefficient of the lesion might indicate a diagnosis of cytotoxic edema. Findings of previous studies suggest that cytokine-mediated cytotoxic edema of the SCC may be an important pathophysiological manifestation of this condition.

The reversible lesions in the SCC found on MRI are not exclusive to encephalitis/encephalopathy but may be secondary to other disorders.

We aimed to present clinical and radiologic characteristics of mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) in children.

Eight children (5 boys and 3 girls; median age, 5.9 years; age range, 8 months to 14.1 years) diagnosed with MERS between September 2015 and June 2017 were included in the study. We reviewed the patient's data, including demographic characteristics, prodromal and neurologic symptoms, neurologic examination, magnetic resonance imaging and electroencephalography findings, laboratory findings, treatment, and prognosis.

Prodromal symptoms were nausea and vomiting (n=6), diarrhea (n=6), and fever (n=3). Initial neurologic symptoms were seizures (n=4), delirious behavior (n=1), drowsiness (n=1), ataxia (n=1), transient blindness (n=2), abnormal speech (n=2), and headache (n=1). Two patients had a suspected infective agent: urinary tract infection caused by Escherichia coli and gastroenteritis caused by rotavirus. Seven patients had type I lesions, comprising characteristic symmetric ovoid (n=6) and band-shaped (n=1) T2-weighted hyperintense lesions at the spenium of corpus callosum, and one patient had type II lesion with additional symmetric posterior periventricular lesions. The lesions were isointense to mildly hypointense on T1-weighted imaging and did not show enhancement. All lesions displayed restricted diffusion. In all patients, neurologic symptoms completely normalized < 48 hours from the onset of symptoms without any sequelae.

MERS has characteristic imaging features and favorable outcome.

Transient restricted diffusion and increased T2 signal intensity within the splenium of the corpus callosum is an increasingly recognized albeit uncommon imaging feature in the setting of acute encephalitis and antecedent viral illness. This review will discuss three index cases obtained from an institutional databank. Additionally, the current understanding of the underlying neurophysiologic pathogenesis will be discussed together with differential clinical and imaging diagnostic considerations, treatment options, and outcome metrics.

Central nervous system involvement in hemophagocytic lymphohistiocytosis (HLH) is associated with a poor outcome. For such patients, it is unknown whether more aggressive therapies, such as intrathecal methotrexate or hydrocortisone, are inevitably required. We present a very rare case of 3-year-old Japanese girl who developed mild encephalitis/encephalopathy with a reversible splenial lesion, accompanied by Epstein-Barr virus-associated HLH, and review previous similar reports. Our case and previous reports suggest that mild encephalitis/encephalopathy with a reversible splenial lesion accompanied by Epstein-Barr virus-associated HLH has a relatively good prognosis, even in the absence of intrathecal treatments.

To describe clinical features of reversible splenial lesion syndrome (RESLES) in children.

Retrospectively analyzed clinical features of RESLES in children and compared differences between severe and non-severe group, classified by clinical global impression-scale; summarized clinical features of children with mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) from case series.

16 episodes of RESLES occurring in 15 Chinese children were analyzed, with 13 episodes having MERS and 3 episodes with epilepsy. 10 episodes were associated with various pathogens including rotavirus (n=5), adenovirus (n=1), influenza A (n=1), mycoplasma (n=2), and jejunum campylobacter (n=1). The common neurological symptoms included seizure, behavioral changes, altered consciousness and motor deterioration. The lesions of splenium of corpus callosum (SCC), extra-SCC (n=2) or extra-CC (n=1) showed T2-weight and FLAIR hyper-intensity, with the corresponding reduced diffusion. All had complete resolution of radiological changes except 1 episode with small residual. 8 episodes had EEG abnormalities, while elevated white blood count, increased hs-CRP, and hyponatremia were commonly revealed. 7 episodes were given steroid plus therapy, while 3 episodes were treated with antiepileptic drugs. Compared with non-severe group, the number of patients with altered consciousness, EEG abnormalities, motor deterioration, or extra-SCC lesions in severe group was significantly increased. The patients in severe group tended to need longer hospital stay interval. No case caused neurological sequelae, except 1 patient in severe group with recurrent episode and extra-CC lesions having intellectual disability (ID). Five pediatric MERS case series were summarized, including 67 episodes (40 male and 27 female; age ranging 10 m∼13y) from 65 patients, with 33 episodes in Japan, 27 in China, and 7 in Caucasian Australian children, and all patients have a good prognosis except 1 patient with ID (current study).

Although RESLES in children tend to be a good outcome, the prognosis of patient in severe group, especially with extra-CC lesions, might have neurological sequelae.

Reports of neurologic manifestations of human parvovirus B19 (B19) infection have been on the rise. Acute encephalitis and encephalopathy is the most common, accounting for 38.8% of total B19-associated neurological manifestations. To date, 34 children with B19 encephalitis and encephalopathy have been reported, which includes 21 encephalitis and 13 encephalopathy cases. Ten (29%) were immunocompromised and 17 (39%) had underlying diseases. Fever at the onset of disease and rash presented in 44.1% and 20.6% of patients, respectively. Neurological manifestations include alteration of consciousness occurred in all patients, seizures in 15 (44.1%) patients, and focal neurologic signs in 12 (35.3%) patients. Anemia and pleocytosis in cerebrospinal fluid (CSF) occurred in 56.3% and 48.1% of patients, respectively. Serum Anti-B19 IgM (82.6%) and CSF B19 DNA (90%) were positive in the majority of cases. Some patients were treated with intravenous immunoglobulins and/or steroids, although an accurate evaluation of the efficacy of these treatment modalities cannot be determined. Nineteen (57.6%) patients recovered completely, 11 (33.3%) patients had some neurological sequelae and 3 (8.8%) patients died. Although the precise pathogenesis underlying the development of B19 encephalitis and encephalopathy is unclear, direct B19 infection or NS1protein of B19 toxicity in the brain, and immune-mediated brain injuries have been proposed.