Comparison of mild encephalopathy with reversible splenial lesion with and without acute focal bacterial nephritis

ObjectiveClinically mild encephalitis/encephalopathy with a reversible lesion (MERS) is characterized by reversible lesions with transiently-reduced diffusion in the splenium of the corpus callosum on magnetic resonance imaging. Recently, cases of MERS with accompanying acute focal bacterial nephritis (AFBN) have been reported in children. This study aimed to clarify the clinical features of MERS with AFBN.MethodsA retrospective study of patients with MERS was conducted at Nagano Children’s Hospital, Japan, from April 2013 to March 2018. The clinical signs and laboratory findings of MERS patients with AFBN (AFBN group) and without AFBN (non-AFBN group) were measured and compared.ResultsOf 12 patients diagnosed as having MERS, 3 were also found to have AFBN. Seven of the 9 patients without AFBN were associated with infectious agents, including rotavirus and influenza viruses. No patient received steroids or intravenous immunoglobulin therapy, and none displayed neurological sequelae. Serum C-reactive protein (CRP) levels were significantly higher in the AFBN group than in the non-AFBN group (14.7 mg/dL versus 0.8 mg/dL, P = 0.009). AFBN group patients were also significantly older (97 months versus 27 months, P = 0.018) and experienced significantly less frequent seizures (33% versus 100%, P = 0.045). The mean duration of neurological symptoms was significantly longer in the AFBN group than in the non-AFBN group (4 days versus 1.7 days, P = 0.013).ConclusionsPediatric patients with AFBN often present with non-specific findings, such as fever and abdominal pain. Pediatricians should be aware of the possibility of AFBN in the clinical setting of MERS, particularly when the patient exhibits inexplicably high CRP.     

The first pediatric case of mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) associated with Neisseria meningitidis

BackgroundMild encephalitis/encephalopathy with a reversible splenial lesion (MERS) is a clinic-radiological syndrome characterized by neurological deficiencies and reversible magnetic resonance imaging findings in the splenium of the corpus callosum. Usually, it has a good prognosis, and patients recover without any sequelae. A viral infection has caused most MERS cases, and bacterial agents have rarely been reported as a cause of MERS.Case reportA 5-month-old male was admitted to the hospital with fever, poor feeding, decreased activity and groaning. He had focal seizures and required mechanical ventilation. A lumbar puncture was performed, and nucleic acid amplification tests (NAATs) of cerebral spinal fluid was positive for non-typeable serogroup of Neisseria meningitidis. Cranial magnetic resonance imaging (MRI) performed on day 3 of admission showed T2 hyperintensity and diffusion restriction at the splenium of corpus callosum (SCC). Diffusion restriction in the occipital horn of the left ventricular compatible with empyema was also obvious. According to the findings on cranial MRI, this clinical course was diagnosed as MERS associated with meningitis. His fever resolved in one week, cefotaxime was discontinued after 14 days, and the patient completely recovered. A follow-up MRI performed after three weeks of admission showed complete resolution of the signal intensity changes in the SCC and the occipital horn of the left lateral ventricle.ConclusionTo the best of our knowledge, this is the first report of MERS associated with Neisseria meningitidis in children. Bacterial agents as a cause of MERS should be kept in mind, and we should avoid unnecessary treatment strategies due to the good prognosis of MERS in children.     

A case of clinically mild encephalitis with a reversible splenial lesion (MERS) after mumps vaccination

We describe for the first time an 8-year-old male patient who demonstrated clinically mild encephalitis with a reversible splenial lesion after mumps vaccination. He suffered from transient hallucinations, nuchal rigidity, and inappropriate antidiuretic hormone secretion syndrome. On the 5th day of admission, his head MRI showed symmetrical high-signal-intensity lesions on T2, FLAIR, and diffusion-weighted images in the splenium of the corpus callosum and in the periventricular white matter, while an apparent diffusion coefficient map showed reduced diffusion. The images were not enhanced by gadolinium. Follow-up MRI on the 16th day of admission revealed none of these abnormalities. His serum IgM and IgG antibodies against the mumps virus were positive according to an enzyme immunoassay. Mumps Torii vaccine strain was isolated from the patient’s cerebrospinal fluid. Previous reports demonstrated that transient delirious behavior, the syndrome of inappropriate antidiuretic hormone secretion, and good prognosis were the main clinical features of mild encephalitis with a reversible splenial lesion. This case shows that mild encephalitis with a reversible splenial lesion could occur after mumps vaccination.     

Two newly proposed infectious encephalitis/encephalopathy syndromes

Two newly proposed infectious encephalitis/encephalopathy syndromes, in which magnetic resonance imaging (MRI) is essential for the diagnosis, have been reviewed. Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is reported only in East Asian infants, characterized by a febrile seizure (usually >30 min) as the initial neurological symptom on day 1, followed by secondary seizures at day 4 to 6; affected children display variable levels of neurological sequelae. MRI shows no acute abnormality during the first two days; reduced diffusion appears in the frontal or fronto-parietal subcortical white matter during days 3 to 9, then disappears between days 9 and 25. Excitotoxic injury with delayed neuronal death is hypothesized as a possible mechanism based on MR spectroscopic findings.     

Marked elevation of interleukin-6 in mild encephalopathy with a reversible splenial lesion (MERS) associated with acute focal bacterial nephritis caused by Enterococcus faecalis

This report describes two cases of mild encephalitis/encephalopathy with reversible splenial lesion (MERS) associated with acute focal bacterial nephritis (AFBN). The patients, who presented with fever and delirious behavior, exhibited hyponatremia and markedly elevated interleukin (IL)-6 in cerebrospinal fluid (CSF) and serum. Enterococcus faecalis was detected in the urine culture. After ampicillin treatment, their consciousness improved without neurological sequelae. Moreover, a diffusion-weighted MRI abnormality, i.e., intensified signals in splenium of the corpus callosum, disappeared. MERS is a possible complication of AFBN. Elevated CSF IL-6 levels suggest that remote activation of intracerebral immune response through the immune–neuroendocrine pathway might play an important role in the pathophysiology of MERS.     

Surgery for intractable epilepsy after severe encephalopathy with reversible splenial lesion and new onset hippocampal lesion associated with parechovirus

We describe a case of severe encephalopathy with reversible splenial lesion associated with parechovirus, followed by intractable temporal lobe epilepsy (TLE), which was improved by epilepsy surgery. A 3-year-old girl was admitted because of fever, consciousness disturbance and generalized tonic clonic seizure. Her seizure lasted for four hours. Fluid-attenuated inversion recovery (FLAIR) showed a hyperintensity in the splenium of the corpus callosum. Electroencephalogram (EEG) demonstarated continuous diffuse epileptic activity represented by synchronous and rhythmic high-amplitude spikes and waves, which led to the diagnosis of status epilepticus. Her consciousness was improved with fosphenytoin, midazolam and methylprednisolone pulse after 3 days. Seven days later, FLAIR hyperintensity in the splenium of the corpus callosum was disappeared; however, a hyperintensity in the right hippocampus was detected. Since the stool examination was positive for parechovirus, her final diagnosis was reversible splenial lesion syndrome (RESLES) associated with parechovirus. At age 8, she experienced epigastric sensation and consciousness disturbance once a week. Based on the scalp EEG and radiological findings, she was diagnosed with intractable right TLE. We performed a right selective amygdalohippocampectomy and anterior temporal disconnection at 10 years of age. One year and 3 months after surgery, she was seizure free. To our knowledge, this is the first report of severe febrile epilepticus status.with RESLES associated with parechovirus, followed by intractable TLE, which was resolved by epilepsy surgery.     

Epidemiology of acute encephalopathy in Japan, with emphasis on the association of viruses and syndromes

A research committee supported by the Japanese government conducted a nationwide survey on the epidemiology of acute encephalopathy in Japan using a questionnaire. A total of 983 cases reportedly had acute encephalopathy during the past 3 years, 2007-2010. Among the pathogens of the preceding infection, influenza virus was the most common, followed by human herpesvirus-6 (HHV-6) and rotavirus. Among syndromes of acute encephalopathy, acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) was the most frequent, followed by clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS), acute necrotizing encephalopathy (ANE) and hemorrhagic shock and encephalopathy syndrome (HSES). Influenza virus was strongly associated with ANE and MERS, HHV-6 with AESD, and rotavirus with MERS. Mortality was high in ANE and HSES, but was low in AESD, MERS and HHV-6-associated encephalopathy. Neurologic sequelae were common in AESD and ANE, but were absent in MERS.     

伴有胼胝体压部可逆性病灶的临床症状轻微的脑炎/脑病1例报道并文献复习

目的探讨伴有胼胝体压部可逆性病灶的临床症状轻微的脑炎/脑病的临床特点、治疗及预后、发病机制。方法报道1例伴有胼胝体压部可逆性病灶的临床症状轻微的脑炎患者的诊治过程,总结其临床特征并复习相关文献。结果患者表现为发热、头痛、呕吐等非特异性脑膜炎症状,合并出现抗利尿激素分泌不当导致的低钠血症,头颅MRI检查发现胼胝体压部有可逆性的DWI高信号的孤立病灶,经抗病毒及对症治疗,临床痊愈。结论伴有胼胝体压部可逆性病灶的临床症状轻微的脑炎/脑病以头颅MRI上发现胼胝体压部可逆性病灶为特点,临床症状轻微,容易合并低钠血症,预后良好,病因及发病机制尚不清楚。     

Kawasaki disease-associated MERS: pathological insights from SPECT findings

We report for the first time the single photon emission computed tomography (SPECT) findings of a patient with clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) associated with Kawasaki disease, which showed hypoperfusion of the bilateral cingulate gyri, thalamus, basal ganglia, brainstem, and cortex of the frontal lobes. These findings indicate that the pathogenesis of MERS is based on cerebral hypoperfusion due to vasculitis or cerebrovascular dehydration.     

Usefulness of arterial spin labeling imaging,which contributed to the early detection of cerebellitis complicated by clinically mild encephalitis/encephalopathy with a reversible splenial lesion: Lessons from three cases

BackgroundCerebellitis is a rare complication of clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS); however, MERS with cerebellitis is associated with a higher risk of neurological sequelae in comparison to MERS alone. Although the disease is difficult to diagnose by conventional MRI in the early disease phase, arterial spin labeling (ASL), a noninvasive MRI perfusion technique using magnetically-labeled arterial blood water protons, is considered promising.Case reportWe experienced three cases of MERS with cerebellitis. Diffusion-weighted imaging showed a high-intensity lesion at the splenium of the corpus callosum. ASL showed increased blood flow in the cerebellum in all three cases, despite cerebellar symptoms being inapparent or difficult to notice in the early phase of disease in all cases. Patients received methylprednisolone pulse therapy and intravenous immunoglobulin from the early phase of the disease and recovered without neurological sequelae.DiscussionASL magnetic response imaging simultaneously showed an area of hyperperfusion in the cerebellum. At the same time, the apparent diffusion coefficient of the splenial lesion was decreased in all three cases. The successful diagnosis of cerebellitis in the acute phase led to early therapeutic intervention, which may be important for this condition. We report the usefulness of ASL and review the relevant literature on MERS with cerebellitis.     

Reversible splenial lesions during febrile illness with or without white matter lesions

ObjectiveReversible splenium lesions during febrile illness (RESLEF) are found in a spectrum. There are two types of corpus callosum (CC) lesions: CC-only type, with limited lesions and the CC (+) type, with extensive white-matter lesions. This retrospective study aimed to describe the differences in clinical findings between CC-only and CC (+) lesions and the association between onset age and clinico-radiological features in RESLEF.MethodsFifty-two episodes of CC-only or CC (+) lesions accompanied by neurological symptoms, e.g., seizures, delirious behavior (DB), and disturbance of consciousness (DC), from January 2008 to October 2019 were included. We analyzed the etiology (pathogen), clinical course, laboratory data, magnetic resonance imaging and electroencephalography findings, therapy, and prognosis.ResultsThe rate of DC in the CC (+) was significantly higher than that in the CC-only group (5/6 [83%] vs 7/46 [15%]; p = 0.0016). The median number of seizures in the CC (+) was also significantly higher than that in the CC-only group (4 [0–7] vs 0 [0–7]; p = 0.034). Further, in RESLEF, the median onset age (months) in the seizure was significantly lower than that in the no-seizure group (39 [12–74] vs 83 [28–174]; p = 0.0007). The median onset age (months) in the DB was significantly higher than that in the no-DB group (74.5 [26–174] vs 28 [12–139]; p = 0.003).ConclusionsIn RESLEF, CC (+) is a more severe neurological symptom than CC-only. Furthermore, the onset age is related to the type of neurological symptoms that appear.     

Thermolabile polymorphism of carnitine palmitoyltransferase 2: A genetic risk factor of overall acute encephalopathy

ObjectivesAcute encephalopathy is an acute brain dysfunction after preceding infection, consisting of multiple syndromes. Some syndromes, such as acute encephalopathy with biphasic seizures and late reduced diffusion (AESD), are severe with poor outcome, whereas others, such as clinically mild encephalitis/encephalopathy with reversible splenial lesion (MERS), are mild with favorable outcome. Previous study reported the association of the thermolabile polymorphism in Carnitine Palmitoyltransferase 2 (CPT2) gene and severe syndromes of acute encephalopathy. To further explore the pathogenetic role of CPT2 in acute encephalopathy, we conducted a case-control association study of a typical thermolabile CPT2 polymorphism, rs2229291, in 416 patients of acute encephalopathy, including both severe and mild syndromes.MethodsThe case cohort consisted of 416 patients, including AESD, MERS, and other syndromes. The control subjects were 100 healthy Japanese. rs2229291 was genotyped by Sanger sequencing. Genetic distribution was compared between the patients and controls using Cochran-Armitage trend test.ResultsMinor allele frequency of rs2229291 was significantly higher in AESD (p = 0.044), MERS (p = 0.015) and entire acute encephalopathy (p = 0.044) compared to the controls. The polymorphism showed no significant association with influenza virus, or with outcome.ConclusionsThis study provided evidence that CPT2 is a susceptibility gene for overall acute encephalopathy, including both severe and mild syndromes, and suggested that impairment of mitochondrial metabolism is common to various syndromes of acute encephalopathy.     

Cytotoxic lesions of the corpus callosum in children: Etiology,clinical and radiological features,and prognosis

ObjectivesCytotoxic lesions of the corpus callosum (CLOCCs) are secondary lesions associated with entities like infection manifested by restricted diffusion on diffusion-weighted cranial magnetic resonance imaging. Our objectives are to evaluate the clinic-radiological spectrum of pediatric patients with cytotoxic lesions of the corpus callosum (CC).MethodsChildren (0–18 years) admitted between February 2017 and May 2020 with splenial lesions showing diffusion restriction on MRI, either isolated or within involvement of other parts of the brain, were included retrospectively. The primary lesions of the CC (e.g. acute disseminated encephalomyelitis, acute ischemic infarction, and glioblastoma multiforme) were excluded. CLOCCs were divided into infection-associated, metabolic disorder–associated, and trauma-associated lesions, as well as CLOCCs involving other entities. Data were collected from the medical databases.ResultsForty-one patients were determined to have CLOCCs. Twenty-five (61%) were infection-associated, nine (22%) were trauma-associated, and three (7%) were metabolic disorder–associated cases, including 2 inherited disorders of metabolism. There were four (10%) patients with other entities, three with epilepsy, and one had an apparent life-threatening event. Six patients had a known etiology among the infection-associated group; one had multisystem inflammatory syndrome caused by COVID-19 and one had been infected by COVID-19 without any complications. All the infection-associated patients with isolated splenial lesions recovered totally, although six patients required intensive care hospitalization. Four trauma-associated patients had sequela lesions.ConclusionsCLOCCs are associated with a spectrum of diseases, including the new coronavirus, COVID-19 infection. Infection-associated CLOCCs has the best prognosis, although severe cases may occur. Sequelae are possible based on the etiology.     

Changes in the treatment of pediatric acute encephalopathy in Japan between 2015 and 2021: A national questionnaire-based survey

BackgroundAlthough acute encephalopathy (AE) is the most serious disorder associated with a viral infection in childhood and often causes death or neurological sequelae, standard treatments have not been established. In 2016, the Japanese Society of Child Neurology published the “Guidelines for the Diagnosis and Treatment of Acute Encephalopathy in Childhood 2016” (AE GL 2016). We conducted a questionnaire survey to evaluate the status of the treatment of pediatric AE in 2021 and the changes in treatment before and after the publication of the AE GL 2016.MethodsIn October 2021, questionnaires were mailed via the web to members of two mailing lists who were involved in the practice of pediatric neurological disorders.ResultsMost Japanese physicians (98 %) engaged in the treatment of pediatric AE used the AE GL 2016 as a clinical reference. From 2015 to 2021, the number of institutions that implemented targeted temperature management (TTM), vitamin administration, and continuous electroencephalographic monitoring increased significantly. Regarding the targeted temperature for TTM, the proportion of patients who were treated with normothermia (36.0–37.0 °C) increased from 2015 (55 %) to 2021 (79 %). The use of corticosteroids in patients with AE caused by a cytokine storm, which is recommended in the AE GL 2016, had already been implemented in most institutions by 2015.ConclusionThe AE GL 2016 could be used to disseminate the knowledge accumulated to date. Evidence of the efficacy and proper indication criteria for the treatment of AE is insufficient and must be further accumulated.