Diffusion MRI abnormalities after prolonged febrile seizures with encephalopathy

Transient cortical diffusion restriction in children immediately after prolonged febrile seizures

AIM

Little is known about acute febrile status epilepticus-induced injury of extrahippocampal structures. To clarify the presence and clinical significance of acute extrahippocampal injuries, we performed diffusion-weighted imaging (DWI) in children immediately after prolonged febrile seizure (PFS).

METHOD

We performed a retrospective cohort study in children younger than 6 years old who visited one of two hospitals due to PFSs between January 2013 and October 2018. PFS was defined as a febrile seizure that persisted for 15 min or longer. We collected brain DWI data within 6 h of the end of PFS. When the initial DWI detected an abnormality, a follow-up DWI was performed a few days later.

RESULTS

The study population consisted of 101 patients with PFSs. DWI was performed within 6 h in 51 patients, while the remaining 50 patients did not undergo imaging because of good recovery of consciousness. Restricted cortical diffusion was evident in 9 (18%) patients on initial DWI. All of them underwent DWI within 100 min after PFS. Restricted cortical diffusion was associated with male sex, asymmetrical PFS symptoms, and a shorter duration between the end of the seizure and DWI, but was not associated with seizure duration. All cortical abnormalities had resolved on follow-up DWI of these patients within 72 h after the initial imaging, but ipsilateral hippocampal hyperintensity appeared in one patient. All 9 patients with restricted cortical diffusion were finally diagnosed with PFS and discharged without sequelae.

CONCLUSIONS

Some children with PFSs exhibit transient restricted diffusion in the regional cortex on DWI performed immediately after the end of PFS. These transient diffusion changes were not associated with unfavorable epileptic sequelae or neuroimaging in the short-term.

Determinants of outcomes for acute encephalopathy with reduced subcortical diffusion

Acute encephalopathy with reduced subcortical diffusion (AED), characterised by seizure onset and widespread reduced apparent diffusion coefficient in the cortex/subcortical white matter, is one of the most common acute encephalopathies in children in East Asia. This 14-year single-centre retrospective study on 34 patients with AED showed that therapeutic hypothermia was used for patients with more severe consciousness disturbance after the first seizure or second phase initiation, extrapolating from neonatal hypoxic encephalopathy and adult post-cardiac arrest syndrome. The basal ganglia/thalamus lesions and the Tada score were the poor outcome determinants in the multivariate analysis. The correlation between the worse outcomes and the duration from the first seizure to the initiation of therapeutic hypothermia was observed only in the patients with AED cooled before the second phase. This correlation was not observed in the overall AED population. There was a moderate negative association between the worse outcomes and the duration between the first seizure and the second phase. Therefore, the basal ganglia/thalamus lesions and the Tada score were the outcome determinants for patients with AED. Further investigation is required to examine the efficacy of therapeutic hypothermia in this population while considering the timing of the therapeutic hypothermia initiation and the second phase.

A case of CLCN2-related leukoencephalopathy with bright tree appearance during aseptic meningitis

CLCN2-related leukoencephalopathy (CC2L) is a rare autosomal recessive disorder caused by variants in CLCN2. We report a boy whose brain MRI during an episode of aseptic meningitis at the age of 6 years revealed wide areas of restriction on diffusion-weighted images (DWI) in the cerebral subcortical white matter called bright tree appearance (BTA). In addition to the BTA, high intensity signals were also observed bilaterally in the posterior limbs of the internal capsules, cerebral peduncles, middle cerebellar peduncles, cerebellar white matter, and brain stem (longitudinal pontine bundle) along with low apparent diffusion coefficient values in the same areas. The BTA was transient, seen only during the acute phase of the aseptic meningitis. With the resolution of the infection, his meningitis symptoms completely resolved, but abnormal brain MRI findings remained, other than BTA, which disappeared. At age 13 years, whole exome sequencing revealed a homozygous variant (c.61dupC, p.(Leu21Profs*27)) of CLCN2. He had no intellectual disability or neurological abnormalities. The transient DWI high-intensity signals in the subcortical white matter and the T2 high-intensity signals in the white matter could reflect varying degrees of water imbalance in the extracellular space in myelin sheaths in CC2L.

DWI scoring system for prognosis of acute encephalopathy with biphasic seizures and late reduced diffusion

PURPOSE

The aim of this study was to predict neurological outcomes for acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) using diffusion-weighted imaging (DWI), and assess relationships between anatomical sites of lesions and their outcomes.

MATERIALS AND METHODS

We assessed DWI abnormalities and neurological outcomes in 30 patients with AESD, and classified patients into severe and non-severe groups according to their neurological outcomes. We also established a DWI scoring system as follows: zero for normal, and one for lesion at each location. Differences between the severe and non-severe groups were examined, and receiver operating characteristic (ROC) curve analysis was performed.

RESULTS

Nine (30%) patients were classified into the severe group. On DWI, patients in the severe group were more likely to have temporal lobe (P = 0.014), perirolandic (P = 0.008), and corpus callosum (P = 0.0008) lesions than those in the non-severe group. The total DWI scores were significantly higher in the severe group than those in the non-severe group (P = 0.0002). ROC curve showed an area under the curve of 0.929, with a cutoff value of five, sensitivity of 88.9%, and specificity of 81.0%.

CONCLUSION

Patients with severe AESD had more extensive DWI abnormalities than those with non-severe AESD. Our DWI scoring system may be useful for the prediction of outcomes of AESD. Widespread lesions seemed to have stronger influence on outcomes than each lesion location.

Vitamin B6 in acute encephalopathy with biphasic seizures and late reduced diffusion

BACKGROUND

The initial presentation of acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is indistinguishable from that of complex febrile seizures (FS), which poses a great diagnostic challenge for clinicians. Excitotoxicity is speculated to be the pathogenesis of AESD. Vitamin B6 (VB6) is essential for the biosynthesis of gamma-aminobutyric acid, an inhibitory neurotransmitter. The aim of this study is to investigate our hypothesis that VB6 deficiency in the brain may play a role in AESD.

METHODS

We obtained cerebrospinal fluid (CSF) samples from pediatric patients with AESD after early seizures and those with FS. We measured pyridoxal 5'-phosphate (PLP) and pyridoxal (PL) concentrations in the CSF samples using high-performance liquid chromatography with fluorescence detection.

RESULTS

The subjects were 5 patients with AESD and 17 patients with FS. Age did not differ significantly between AESD and FS. In AESD, CSF PLP concentration was marginally lower (p = 0.0999) and the PLP-to-PL ratio was significantly (p = 0.0417) reduced compared to those in FS.

CONCLUSIONS

Although it is impossible to conclude that low PLP concentration and PLP-to-PL ratio are causative of AESD, this may be a risk factor for developing AESD. When combined with other markers, this finding may be useful in distinguishing AESD from FS upon initial presentation.

Granzyme A Participates in the Pathogenesis of Infection-Associated Acute Encephalopathy

OBJECTIVE

The present study aimed to determine whether granzymes are implicated in the pathogenesis of infection-associated acute encephalopathy (AE).

METHODS

We investigated granzyme and cytokine levels in the cerebrospinal fluid of patients with acute encephalopathy or complex febrile seizures (cFS). A total of 24 acute encephalopathy patients and 22 complex febrile seizures patients were included in the present study. Levels of granzymes A and B were measured using enzyme-linked immunosorbent assay, and levels of tumor necrosis factor α (TNF-α), interferon-γ (IFN-γ), interleukin 1β (IL-1β), IL-1 receptor antagonist (IL-1RA), IL-4, IL-6, IL-8, and IL-10 were assessed using the Bio-Plex suspension array system.

RESULTS

Cerebrospinal fluid levels of granzyme A were significantly higher, and those of TNF-α and IL-1RA were significantly lower in the AE group than in the cFS group; however, no significant differences in the levels of granzyme B, IFN-γ, IL-1β, IL-4, IL-6, IL-8, and IL-10 were observed between the 2 groups. In addition, no significant differences in granzyme A, granzyme B, or cytokine levels were observed between acute encephalopathy patients with and those without neurologic sequelae.

CONCLUSIONS

Our findings indicate the involvement of granzyme A in the pathogenesis of acute encephalopathy.

Human Herpesvirus 7-Related Acute Encephalopathy with Biphasic Seizures and Late Reduced Diffusion

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is a recently described entity so far exclusively in East Asian children. AESD diagnosis is based on clinicoradiologic criteria, often without pleocytic CSF and characterized by hyperglycemia and transaminasemia. Here, we present the first case of human herpesvirus 7-related AESD in an immunocompetent child >2 years old and of Caucasian origin.

Serum and cerebrospinal fluid cytokines in children with acute encephalopathy

BACKGROUND

The pathogenesis of acute encephalopathy (AE) remains unclear, and a biomarker has not been identified.

METHODS

Levels of 49 cytokines and chemokines, including osteopontin (OPN), were measured in serum and cerebrospinal fluid (CSF) of children with AE (n = 17) or febrile convulsion (FC; n = 8; control group). The AE group included acute necrotizing encephalopathy (n = 1), acute encephalopathy with biphasic seizures and late reduced diffusion (AESD; n = 3), clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS; n = 4), and unclassified acute encephalopathy (UCAE; n = 9) that does not meet the criteria of syndrome classification. Five individuals with AE had neurological sequelae or death (poor prognosis), whereas 12 were alive without neurological sequelae (good prognosis).

RESULTS

The CSF:serum ratios of OPN, CC chemokine ligand (CCL)4, and interleukin (IL)-10 were significantly higher in AE than in FC. The CSF levels of macrophage inhibitory factor (MIF) and leukemia inhibitory factor (LIF) were significantly higher in the poor-prognosis group than in the good-prognosis group. The CSF:serum ratios of OPN were significantly higher in AESD and in MERS than in FC. The CSF:serum ratios of MIF and OPN were higher in MERS than in UCAE or FC.

CONCLUSION

Our results suggest that microglia-related cytokines and chemokines such as OPN, MIF, and LIF could be novel biomarkers of AE, in addition to the previously reported IL-10 and CCL4, and that MIF and LIF may be markers of poor prognosis.

Detailed characteristics of acute encephalopathy with biphasic seizures and late reduced diffusion: 18-year data of a single-center consecutive cohort

OBJECTIVE

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is a syndrome characterized by biphasic seizures with impaired consciousness. AESD is rare outside Asia, and consecutive cohort studies are therefore scarce. Herein, we aimed to describe the detailed characteristics of AESD, including clinical course, electroencephalogram data, laboratory data, imaging findings, treatment, and outcomes.

METHODS

We reviewed the clinical database and medical charts of 43 consecutive pediatric patients (<18 years old) who developed AESD between October 1, 2002, and September 30, 2019.

RESULTS

We found that AESD occurred even though patients did not develop prolonged seizures. A comparison between the two groups (first seizure duration <30 min and first seizure duration ≥30 min) revealed three main findings: first, patients with AESD who had shorter seizures had better prognosis than those with prolonged seizures; second, patients with AESD who had shorter seizures tended to have earlier occurrence of a second seizure; and third, high signal intensity on diffusion-weighted magnetic resonance imaging was observed mainly in frontal areas, not diffusely, in patients with shorter seizures, and in a broader area in patients with prolonged seizures.

CONCLUSIONS

Our description of the detailed clinical picture of AESD may add new insight into its pathophysiology.

Perfusion abnormality on three-dimensional arterial spin labeling in patients with acute encephalopathy with biphasic seizures and late reduced diffusion

PURPOSE

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is the most common encephalopathy subtype in Japanese children. Few case reports have shown perfusion abnormality on arterial spin labeling (ASL) in patients with AESD. The present study aimed to review the chronological change of cerebral perfusion on three-dimensional (3D) ASL in patients with AESD.

METHODS

Twenty consecutive patients with AESD were enrolled; the patients underwent MRI including 3D ASL. The clinical course of AESD was divided into four phases according to the time from occurrence of seizures to MRI. Two neuroradiologists independently assessed presence or absence, distribution, and severity of perfusion abnormality using ASL and qualitatively scored perfusion abnormality using a five-point grading system. The level of interobserver agreement in the evaluation was analyzed using weighted κ statistics. Additionally, the signal ratio of abnormal perfusion region and peri-central sulcus region on ASL was semi-quantitatively evaluated. Moreover, we qualitatively compared the distribution between perfusion abnormality on ASL and bright tree appearance (BTA) on diffusion-weighted image (DWI).

RESULTS

ASL showed hypoperfusion from 8.5 to 22 h after early seizures (ESs) and hyperperfusion within 24 h after late seizures (LSs). Various perfusions were found >3 days after LSs. Interobserver agreement for qualitative scored perfusion abnormality was good (κ = 0.77). The distribution of abnormal perfusion was relatively consistent with BTA.

CONCLUSION

In AESD, cerebral perfusion changes with time. ASL showed hypoperfusion from 8.5 to 22 h after ESs, hyperperfusion within 24 h after LSs in patients with AESD.

A case of respiratory syncytial virus-associated encephalopathy in which the virus was detected in cerebrospinal fluid and intratracheal aspiration despite negative rapid test results

We report a first case of respiratory syncytial virus (RSV) infection-associated encephalopathy in which RS virus was detected in the patient's intratracheal aspiration and cerebrospinal fluid despite negative rapid test results of the nasal swab. The patient's findings and clinical course coincided with those of acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) with severe subsequent sequelae. Our case indicates that clinicians should consider RSV infection when patients have AESD with unknown etiology.

Prognostic value of MR spectroscopy in patients with acute excitotoxic encephalopathy

PURPOSE

Acute excitotoxic encephalopathy is the most common encephalopathy syndrome in Japan, and consists of acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) and mild encephalopathy associated with excitotoxicity (MEEX). Neurological sequelae remain in approximately 70% of patients with AESD, however, it is difficult to predict the prognosis early in the course. We evaluated the brain metabolites observed on MRS as to whether they can predict the neurological outcome.

METHODS

16 previously healthy Japanese patients with excitotoxic encephalopathy (8 with AESD and 8 with MEEX) were included in this study. MR spectroscopy (MRS) was acquired from the fronto-parietal white matter (TR/TE = 5000/30 msec) with a 3.0 T scanner. Quantification of metabolites was performed using an LCModel. Neurological outcome was assessed with the Pediatric Cerebral Performance Category score, score 1 being classified as G1 (normal), scores 2 and 3 as G2 (mild to moderate), and scores 4-6 as G3 (severe).

RESULTS

MRS data which predict a poor neurological outcome (G2 and 3) include the following: decreased N-acetyl aspartate (NAA) (sensitivity 88%, specificity 100%), decreased creatine (47%, 100%), increased lactate (47%, 100%), and decreased glutamate (sensitivity 35%, specificity 100%). Limited to the acute stage within seven days of onset, those for a poor prognosis are as follows, decreased NAA (88%, 100%), decreased creatine (38%, 100%), and increased lactate (38%, 100%).

CONCLUSION

MRS is useful for prognosis prediction of acute excitotoxic encephalopathy. Decreased NAA will be the most effective metabolite for neurological prognosis prediction.

Three Cases of Hemiconvulsion-Hemiplegia-Epilepsy Syndrome With Focal Cortical Dysplasia Type IIId

Hemiconvulsion-hemiplegia-epilepsy syndrome (HHES) is a subset of acute encephalopathy characterized by infantile-onset with acute hemiconvulsive febrile status and subsequent unilateral cerebral atrophy and hemiparesis. In the chronic phase, patients with HHES develop epilepsy, typically displayed as intractable focal seizures. The patients are often intractable with antiepileptic drugs and need surgical treatment. Although viral encephalitis and genetic abnormalities are presumed to be the underlying etiology, the pathogenesis remains mostly unknown. We describe three cases of successful functional hemispherotomy for intractable epilepsy in HHES. Patients developed acute asymmetrical convulsive status following viral infections during the ages of 17–30 months. Their seizures were intractable with antiepileptic drugs and required hemispherotomy. On the basis of the pathological findings, all cases were diagnosed as focal cortical dysplasia (FCD) type IIId. The epileptogenic mild cortical malformations may be the cause of HHES.

Acute encephalopathy with biphasic seizures and late reduced diffusion (central sparing type)—MRI and MR spectroscopy findings

Acute encephalopathy with biphasic seizure and late reduced diffusion (AESD) is a clinico-radiologic syndrome of acute encephalopathy characterized by biphasic seizure and altered consciousness in acute phase followed by restricted diffusion in bilateral cerebral parenchyma on magnetic resonance imaging (MRI) in the subacute stage. Here, we present the MRI and magnetic resonance spectroscopy (MRS) findings in a case of AESD presenting in 4-year child and diagnosed based on clinico-radiological correlation.

Early administration of vitamins B1 and B6 and l-carnitine prevents a second attack of acute encephalopathy with biphasic seizures and late reduced diffusion: A case control study

BACKGROUND

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is the most prevalent encephalopathy in Japanese children. AESD is characterized by a prolonged febrile seizure on day 1 followed by secondary seizures and MRI abnormality on days 4-6, resulting in high incidence of neurological sequelae. We aimed to clarify whether early administration of vitamins (vitamin B1, vitamin B6, and l-carnitine) would improve the clinical course of AESD.

METHODS

We retrospectively reviewed 34 patients with acute encephalopathy who were admitted to our hospital between January 2009 and August 2016. Of the retrospectively registered 34 patients, 22 (65%) since 2011 were treated with the drug cocktail (prescription group) within 24 h of onset, whereas 12 (35%) before 2011 were not (non-prescription group). We compared clinical course, laboratory data, and MRI findings historically in both groups.

RESULTS

The two groups did not differ in terms of laboratory findings except for blood lactate values. There were no differences between the two groups regarding duration of ICU admission, intubation, or the duration of seizures. Among the prescription group, two patients developed AESD while 20 had mild encephalopathy (single phasic). In contrast, seven patients inthe non-prescription group developed AESD while five did not. The incidence of AESD was lower in the prescription group (P = 0.004). As for outcomes, the rate of developmental delay and epilepsy was significantly lower in the prescription group.

CONCLUSIONS

Our data suggested that early administration of vitamins would improve the clinical course of acute encephalopathy. Mitochondrial rescue and neuroprotection are thought to be responsible for the favorable results.

An acute encephalopathy with reduced diffusion in BRAF-associated cardio-facio-cutaneous syndrome

BACKGROUND

Cardio-facio-cutaneous syndrome (CFCS) is a rare genetic disorder characterized by cardiovascular anomalies, dysmorphic faces, ectodermal abnormalities and developmental delays. Mutations in BRAF and other RAS-MAPK pathway-associated genes are commonly identified in patients with CFCS. While this molecular pathway is known to be associated with neuro-inflammatory conditions, only one case with CFCS has been reported thus far to develop acute encephalopathy in childhood.

CASE REPORT

A 3-year-old boy with dysmorphic features and mild psychomotor delay developed acute encephalopathy. After a 45-min long, generalized seizure, the magnetic resonance imaging revealed that the restricted diffusion signals spread to the bilateral subcortical white matters on day 1 of illness. Despite the 14 days of intensive care, the acute symptoms of encephalopathy left him intractable epilepsy and severe neurocognitive impairments. The whole-exome sequencing analysis identified a de novo heterozygous mutation of BRAF (NM_004333:p.Thr241Met) in this case.

CONCLUSION

The present case suggests that the hyperactive condition of ERK signals might augment the development of acute encephalopathy and post-encephalopathic epilepsy in childhood.

A nationwide survey of norovirus-associated encephalitis/encephalopathy in Japan

BACKGROUND

Norovirus is a major pathogen of gastroenteritis and is known to cause encephalitis/encephalopathy. The aim of this national survey was to clarify the clinical features of norovirus-associated encephalitis/encephalopathy (NoVE) among children in Japan.

METHODS

A nationwide survey of children with NoVE was conducted using a structured research form. The initial survey asked pediatricians about children with NoVE treated between January 2011 and March 2016. The second survey obtained patient information from two sources: hospitals that responded to the initial survey and those identified as having treated cases from a literature search.

RESULTS

Clinical information was available for 29 children. Their median age was 2 y 8 m. The outcome was good in 13 patients and poor in 15. The interval between the onset of gastrointestinal symptoms and that of encephalitis/encephalopathy was significantly shorter in those with a poor outcome. At the onset of an elevated serum creatinine level and an abnormal blood glucose level were correlated with a poor outcome. Regarding the subtypes of encephalitis/encephalopathy, acute encephalopathy with biphasic seizures and late reduced diffusion and hemorrhagic shock and encephalopathy syndrome were frequent.

CONCLUSION

The outcome of children with NoVE was poor. Early onset of neurological symptoms, an elevated serum creatinine level, and an abnormal blood glucose level were associated with a poor outcome. No effective treatment was identified and this should be the subject of future studies.

Acute Encephalopathy With Biphasic Seizures and Late Reduced Diffusion Associated With Adenoviral Pneumonia

Acute encephalopathy with biphasic seizures and late reduced diffusion is a subtype of acute encephalopathy described in a cohort of Japanese children. Few cases have been reported in countries other than Japan. It is characterized clinically by biphasic seizures and late reduced subcortical diffusion on magnetic resonance imaging (MRI). We report the case of a 3-year-old Korean girl with acute encephalopathy with biphasic seizures and late reduced diffusion who presented with status epilepticus associated with fever and pneumonia. Human adenovirus was detected from a respiratory specimen using multiplex real-time reverse transcriptase polymerase chain reaction. After 5 days, she developed a second cluster of seizures followed by altered consciousness, aphasia, stereotypic movement, and developmental regression. Her brain MRI showed symmetrical and extensive restricted diffusion in the subcortical white matter, which finally resulted in global brain atrophy, consistent with acute encephalopathy with biphasic seizures and late reduced diffusion. Here, we report a case of acute encephalopathy with biphasic seizures and late reduced diffusion associated with preceding adenoviral pneumonia.

Early Intervention With Adrenocorticotropin for Acute Encephalopathy-Associated Epileptic Spasms: Report of Two Cases

PURPOSE

Acute encephalopathy with biphasic seizures and reduced diffusion (AESD) is a leading cause of childhood-onset encephalopathy in Japan. Children with AESD frequently develop intractable epilepsy, whereas their treatment options remain to be determined.

METHOD

We present 2 unrelated girls, who developed AESD at 25 months (case 1) and 12 months of age (case 2). Both cases underwent intensive cares from the first day of illness, whereas severe neurological impairments were left on discharge. They showed repeated signs of epileptic spasms at 2 months (case 1) and 8 months (case 2) after the onset of AESD. Video-monitoring electroencephalograms (EEG) detected the recurrent attacks accompanying slow-wave bursts and transient suppressions of the precedent epileptiform discharges, as typically observed in epileptic spasms.

RESULTS

Intramuscular injection of adrenocorticotropic hormone (ACTH, 0.0125 mg/kg/d) was introduced within 1 month from the onset of epileptic spasms and continued for 2 weeks. The ACTH treatment disrupted the paroxysmal activity in EEG, and it has relieved these patients from epileptic seizures for more than 1 year.

CONCLUSION

This report illustrates the potential efficacy of ACTH for a group of children with epileptic spasms after AESD.

Subcortical axonal loss with glial reactions following partial status epilepticus with neuroradiological findings of reduced subcortical diffusion

Hyperintensity in the subcortical white matter on the diffusion-weighted magnetic resonance image has been described recently, in association with partial status epilepticus. Although this reduced subcortical diffusion is typically seen in patients with acute encephalopathy with biphasic seizures and late reduced diffusion (AESD), the exact pathophysiological mechanism is unclear. We report the case of a 3-month-old boy who underwent surgery for intractable epilepsy associated with cortical dysplasia in the left peri-Rolandic area, coincident with the appearance of reduced subcortical diffusion. Neurohistological findings revealed that the most prominent finding was axonal loss with marked astroglial and microglial reactions in the white matter. Neither degenerated neurons nor neurophagocytic microglial accumulation was evident in the cortex. These findings confirm that white matter can be secondarily damaged in patients with partial status epilepticus, and possible pathomechanism of reduced subcortical diffusion is discussed.

Loss of myelinated axons and astrocytosis in an autopsy case of acute encephalopathy with biphasic seizures and late reduced diffusion

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is the most common pediatric encephalopathy in Japan, however, the exact neuropathology remains uncertain. The postmortem neuropathology in a patient with AESD revealed reduction of myelinated axons with early stage of astrocytosis in the absence of neuronal loss, which suggests the primary pathological damage in AESD involves myelinated axons and astrocytes rather than cortical neurons. An increased number of gemistocytic astrocytes at the corticomedullary junction may cause reduced diffusion, leading to the so-called bright tree appearance on magnetic resonance imaging, characteristic to AESD.

Vascular pathomechanism in acute encephalopathy with biphasic seizures and late reduced diffusion

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is a childhood-onset encephalopathy, but the precise pathophysiology remains unclear. We encountered a child with Moyamoya syndrome and AESD. He exhibited left-predominant stenosis of the middle cerebral artery (MCA), and later developed broad lesions in the left hemisphere, raising the possibility that insufficient blood supply relates to formation of the lesions. To test the hypothesis, we investigated the relationship between MCA volume and lesion extent in seven AESD children without preexisting diseases. The MCA volume and lesion extent were quantified with time of flight images for construction of magnetic resonance angiography and apparent diffusion coefficient maps, respectively. Lateralization indices ([right - left]/[right + left]) of the MCA volume and lesion extent were calculated. We found that the lateralization indices were negatively correlated (r = -0.786, p = .036), that is, when the MCA volume was smaller in one side than the other side, the lesions were likely to develop more extensively in the ipsilateral side than the contralateral side. This indicates the association of insufficient blood supply with the lesions. The present study provides the first observation to suggest the involvement of vascular mechanism in AESD and has potential implications for novel therapeutic approach.

Clinical characteristics of acute encephalopathy with acute brain swelling: A peculiar type of acute encephalopathy

OBJECTIVES

Acute encephalopathy has been observed with acute brain swelling (ABS) that is characterized by rapid progression to whole-brain swelling. The objective of this study was to describe the clinical characteristics of ABS.

METHODS

We encountered four patients with ABS and retrospectively investigated their clinical data with a medical chart review.

RESULTS

Three patients had seizure clustering or status epilepticus in the clinical course. Signs of elevated intracranial pressure (ICP) appeared 3-9 h after the first convulsive attack in three patients. In all patients, signs of brainstem involvement appeared 1-8 h after signs of elevated ICP. Mild hyponatremia that progressed after signs of elevated ICP appeared was noted in three patients. Brain CT revealed mild brain swelling in the initial phase, which rapidly progressed to whole-brain swelling. No focal abnormalities were detected on brain MRI in one patient. Continuous electroencephalography was initially normal, but in two patients, high-amplitude slow waves appeared with rapid changes before signs of brainstem involvement. Although recovery was achieved without sequelae in two patients, outcome was fatal for the other two.

CONCLUSIONS

The pathogenesis of ABS has yet to be clarified, but clinical features in our patients are not consistent with any established subtypes of acute encephalopathy. Therefore, we believe that ABS should be recognized as a new type of acute encephalopathy.

Differential diagnosis of nonepileptic twilight state with convulsive manifestations after febrile seizures

BACKGROUND

Nonepileptic twilight state with convulsive manifestations (NETC) is a nonepileptic state following a febrile seizure (FS), which may be misdiagnosed as a prolonged seizure and result in overtreatment. We aimed to describe clinical manifestations of NETC and to determine characteristics that are helpful to distinguish NETC from other pathological conditions.

METHODS

We conducted a retrospective chart review from January 2010 to December 2016 and selected the patients who presented with symptoms resembling status epilepticus with fever and a confirmed diagnosis using an electroencephalogram (EEG). We compared the NETC clinical features and venous blood gas analysis results with those of other conditions that mimic NETC. We also compared the characteristics of NETC with past reports.

RESULTS

Our NETC patients presented with short durations of the preceding generalized convulsions followed by tonic posturing, closed eyes, no cyanosis, responsiveness to painful stimulation, and no accumulation of CO₂ in the venous blood gas. Most of these characteristics were consistent with past reports. Prolonged FS or acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) showed several of these features, but all the characteristics were not consistent with our study.

CONCLUSIONS

Prolonged FS and AESD need to be differentiated from NETC, and close clinical observation makes it possible to partially distinguish NETC from the other conditions. EEG is recommended for patients with symptoms that are inconsistent with these features.

An episode of acute encephalopathy with biphasic seizures and late reduced diffusion followed by hemiplegia and intractable epilepsy observed in a patient with a novel frameshift mutation in HNRNPU

Microdeletions in the 1q44 region encompassing the HNRNPU gene have been associated with infantile spasms and hemiconvulsion-hemiplegia-epilepsy syndrome. Recent studies have revealed that heterozygous HNRNPU variants resulted in early onset epilepsy and severe intellectual disability. A de novo frameshift mutation in HNRNPU was identified in a 5-year-old boy with developmental delay associated with Rett-like features including stereotypic hand movements and respiratory abnormalities with episode of apnea and hyperpnea followed by falling. He also showed an episode of acute encephalopathy with biphasic seizures and late reduced diffusion followed by hemiplegia and intractable epilepsy. Unique and variable clinical features are related to loss-of-function or haploinsufficiency of HNRNPU.

Long-term outcomes in motor and cognitive impairment with acute encephalopathy

BACKGROUND

Acute encephalopathy causes various sequelae, including motor disabilities and intellectual delays. Previous studies reported that cognitive impairments can also occur after acute encephalitis. Although the incidence of acute encephalopathy is high in Japan, there have been few reports on its sequelae.

OBJECTIVE

To characterize the neurological outcomes of pediatric patients who sought motor rehabilitation for motor dysfunction after acute encephalopathy.

METHOD

Subjects were 26 children who were healthy before suffering from motor dysfunction following acute encephalopathy and were referred to our pediatric rehabilitation institute during a 9-year period (August 2007-April 2017). We examined subjects' neurological status and followed sequelae for at least 8 months.

RESULTS

Of 26 individuals, 21 became ambulatory after several months or years during the observation period. Patients who could sit without support within 5 months after the onset of acute encephalopathy were able to walk within several months or years. Patients showing high intensity on T2-weighted sequences or "bright tree appearance" in the frontal region took an average of 7 months to develop walking, which was longer than other patients. Among ambulatory subjects, 16(76%) exhibited mild to moderate intellectual delay with a developmental quotient (DQ) under 70, and 20 (95%) exhibited cognitive impairment. There was a significant correlation between DQ scores and motor disability (p = 0.013, r = -0.481).

CONCLUSIONS

Although 80% of patients who had motor dysfunction caused by acute encephalopathy and visited out motor rehabilitation outpatient clinic were eventually able to walk, the time taken to develop walking ability depended on which region exhibited magnetic resonance imaging abnormalities. DQ scores and motor disability were significantly correlated.

Early prognostic factors for acute encephalopathy with reduced subcortical diffusion

OBJECTIVE

The aim of this study was to determine the prognostic factors for acute encephalopathy with reduced diffusion (AED) during the acute phase through retrospective case evaluation.

METHODS

The participants included 23 patients with AED. The diagnosis of AED was based on their clinical course and radiological findings. We divided the patients into severe and non-severe groups based on the neurodevelopmental outcome. The severe group included seven patients (median age, 21 months; range, 6-87 months) and the non-severe group included 16 patients (19 months, 9-58 months). Clinical symptoms, laboratory data and electroencephalogram (EEG) findings within 48 h from the initial seizure onset were compared between the two groups to identify neurological outcome predictors.

RESULTS

The incidence of coma 12-24 h after onset, serum creatinine (Cr) levels within 2 h after onset, maximum aspartate aminotransferase (AST) levels within 24 h after onset, and the rate of electrographic seizures in EEG were significantly higher in the severe group (Coma, 80%; Cr, 0.40 mg/dl, 0.37-0.73; AST, 363 IU/L, 104-662; electrographic seizures, 80%) than the non-severe group (Coma, 0%; Cr, 0.29 mg/dL, 0.19-0.45; AST, 58.5 IU/L, 30-386; electrographic seizures, 0%).

CONCLUSIONS

Coma 12-24 h after onset, elevation of Cr levels within 2 h after onset, elevation of AST levels within 24 h after onset, and non-convulsive status epileptics (NCSE) in comatose patients were early predictors of severe AED. Patients in a coma after a febrile seizure should be checked for NCSE signs in EEG to terminate NCSE without delay.

Acute focal bacterial nephritis characterized by acute encephalopathy with biphasic seizures and late reduced diffusion

Acute focal bacterial nephritis (AFBN) is a localized bacterial infection of the kidney presenting as an inflammatory mass, and some patients show deterioration of clinical condition with neurological symptoms. Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is a syndrome that is characterized by biphasic seizures and impaired consciousness with reduced diffusion in the subcortical white matter on magnetic resonance imaging, typically observed between days 3 and 9 after clinical onset. Although AFBN sometimes causes neurological symptoms, no cases of AFBN with AESD have been reported, and no studies have presented the cytokine profiles of patients with a severe form of acute encephalopathy with AFBN. We report here a very rare case involving a 6-month-old boy who developed AFBN due to Enterococcus faecalis with both the clinical and radiological features of AESD. In our patient, serum interleukin (IL)-6, IL-10, and interferon (IFN)-γ levels markedly increased on admission, and on day 4, only IL-6 levels significantly increased in the cerebrospinal fluid (CSF). These results suggest that high serum cytokines are produced locally in response to AFBN and elevated IL-6 levels in CSF may have neuroprotective roles.

Predictive indicators for the development of epilepsy after acute encephalopathy with biphasic seizures and late reduced diffusion

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is a newly defined clinicoradiologic syndrome characterized by biphasic seizures and altered consciousness followed by restricted diffusion in the white matter on magnetic resonance imaging in acute phase. Intractable epilepsy commonly occurs as the late complication. This study aimed to search predisposing factors to the development of epilepsy after AESD. Consecutively treated 22 patients with AESD in our institution from 2006 to 2016 were grouped into those with post-encephalopathic epilepsy (PEE, n = 10) or without PEE (n = 12). There was no difference between two groups in age at the onset of AESD, duration of the initial seizures, or the follow-up periods after discharge. PEE group patients more frequently showed coma or involuntary movements during the course of AESD than non-PEE group patients (36% vs. 8%, p = 0.008). The quantitative analysis of apparent diffusion coefficient (ADC) map revealed that PEE group showed broader areas with reduced diffusion in the posterior lobes at the onsets of AESD than non-PEE group (0.113 vs. 0.013, p = 0.035). On the other hand, the atrophy on day 30-ADC map did not correlate with the development or control of epilepsy. These results suggest that the clinical severity and ADC profiles in acute phase, rather than the brain atrophy in convalescent phase, may predict the development of post-AESD epilepsy.

Excitotoxicity in encephalopathy associated with STEC O-157 infection

Cytokines play an important role in the pathogenesis of the severe complications of Shiga toxin-producing Escherichia coli (STEC) infection, such as hemolytic uremic syndrome (HUS) and acute encephalopathy. A 3-year-old boy with acute encephalopathy associated with STEC O-157 HUS showed increased levels of IL-6 and IL-10, which normalized after methylprednisolone pulse therapy, and additionally exhibited a transient increase of glutamine on MR spectroscopy. This finding suggests that excitotoxicity, in addition to hypercytokinemia, may play an important role in the pathogenesis of HUS encephalopathy.

Prognostic factors in the early phase of acute encephalopathy

BACKGROUND

Neurological sequelae occur in 40% of patients with acute encephalopathy (AE). The early prediction of poor outcomes is critical to the initiation of appropriate treatment. The aim of the present study was therefore to elucidate prognostic factors that can be quickly and feasibly evaluated on hospital admission in patients with AE.

METHODS

We analyzed data from 51 AE patients admitted to Hirakata City Hospital between January 2005 and December 2014. Age at onset, sex, underlying disease, status epilepticus (SE), presence of benzodiazepine-resistant SE (BZD-resistant SE), and basic blood serum parameters on admission were evaluated in relation to each patient's outcome.

RESULTS

On univariate analysis age at onset, BZD-resistant SE, and serum aspartate aminotransferase (AST), alanine aminotransferase, lactate dehydrogenase, and platelet count varied significantly according to outcome. On multivariate analysis age at onset (≤21 months), presence of BZD-resistant SE, and AST (≥46 IU/L) were identified as independent variables associated with poor outcome.

CONCLUSION

Age at onset, presence of BZD-resistant SE, and AST are associated with a poor prognosis in AE.

Cause of acute encephalitis/encephalopathy in Japanese children diagnosed by a rapid and comprehensive virological detection system and differences in their clinical presentations

BACKGROUND

Acute encephalitis/encephalopathy (AE/E) is a rare and severe complication of common childhood infections; however, a treatment strategy based on clinical and pathological evidence has not been established.

METHODS

The clinical data and aetiological results using a rapid and comprehensive virological detection system of 62 Japanese children diagnosed with AE/E from 2010 to 2014 were collected. We assessed clinical differences between causes and effectiveness of our multiplex PCR system to establish a pathogen-based treatment strategy for AE/E.

RESULTS

Suspected causes were detected in 84% of patients, and our multiplex PCR system contributed to diagnosing 38% of the patients. Furthermore, a negative virus PCR might be important for inferring underlying disease. Most cases were triggered by human herpes virus (HHV) 6/7 (32%) and influenza virus (24%). The causes of AE/E depended on age (p=0.00089) but not on sex (p=0.94). The median age of HHV6/7-associated AE/E was 2.3years, which is lower than the median ages of AE/E associated with other viruses. Major initial treatments were pulse steroid therapy (83.9%) and acyclovir (71%). Most of the patients in this study had good prognoses: 77% recovered without neurological sequalae.

CONCLUSIONS

Our virological detection system was useful for detecting the cause of AE/E, and may also contribute to construction of pathogen-based treatment strategies for AE/E. Our data indicated the possibility that early intervention with pulse steroid therapy could be effective for treating AE/E. Further investigation for selection of antiepileptic drugs and additional therapies might be required to prevent progression of AE/E.

Use of high b value diffusion-weighted magnetic resonance imaging in acute encephalopathy/encephalitis during childhood

AIM

To determine the use of high b value diffusion-weighted imaging (DWI) in the diagnosis and assessment of acute febrile encephalopathy/encephalitis in childhood.

SUBJECTS AND METHODS

We enrolled 22 children, for whom we examined DWI with b=1000s/mm², DWI with b=3000s/mm², and apparent diffusion coefficient (ADC) map with b=1000 during the acute phase of febrile encephalopathy/encephalitis. Clinical diagnoses included acute encephalopathy with biphasic seizures and late reduced diffusion (AESD; n=6), clinically mild encephalopathy/encephalitis with a reversible splenial lesion (MERS; n=6), and herpes simplex virus encephalitis (HSE; n=3), unclassified acute encephalopathy/acute encephalitis (n=2); acute encephalitis with refractory, repetitive partial seizures (AERRPS; n=1); other encephalopathy (n=1); infarction (n=1); head injury (n=1); or mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (n=1). The diagnostic quality of brain lesions was compared between b=1000 and b=3000 DWI images by visual inspection. In addition, we attempted a quantitative assessment using apparent diffusion coefficient (ADC) value and an index of signal intensity (SI) ratio, defined as the mean SI at the affected lesion divided by the mean SI at the pons.

RESULTS

High intensity lesions were either visible only on b=3000 DWI (n=5; 2 AESD, 1 MERS, 1 HSE, and 1 unclassifiable encephalopathy) or more effectively identified on b=3000 DWI than on b=1000 DWI (n=17). The outcome of the former five subjects was favorable, without motor or intellectual sequelae. The mean SI ratio of b=3000 was significantly greater than that of b=1000 in AESD and MERS subgroups as well as in all 22 subjects. Mean ADC values were lower in the AESD and MERS than that in the HSE subgroups.

CONCLUSION

We concluded that b=3000 DWI was superior to b=1000 DWI in detecting abnormal lesions in acute encephalopathy/encephalitis during childhood.

Acute Leukoencephalopathy with Restricted Diffusion

Treatment and outcome of children with acute encephalopathy depend on the cause, prompt treatment of the underlying cause, and use of adequate supportive measures. Many novel causes of acute encephalopathy are emerging where lumbar puncture, computed tomography of the head, and routine biochemical testing can be normal such as acute disseminated encephalomyelitis and febrile infection-related refractory epilepsy syndrome. Magnetic resonance imaging (MRI) plays an important role in the workup of children with acute leukoencephalopathy. Despite this in few cases, a correct diagnosis is not possible and novel conditions have been described in the last decade. One such condition is acute encephalopathy with biphasic seizures and restricted diffusion also called as acute leukoencephalopathy with restricted diffusion. Here, the routine MRI sequences such as T1, T2, and fluid-attenuated inversion recovery sequences can be normal. Here, we have reviewed the etiology, types, clinicoradiological features, and treatment of this condition.

A case of mumps-related acute encephalopathy with biphasic seizures and late reduced diffusion

BACKGROUND

Mumps is a common childhood viral disease characterized by fever and swelling of the parotid gland. The prognosis is generally good, although some complications, such as encephalitis (0.1%), exist. Acute encephalopathy with biphasic seizures and late reduced diffusion is the most common type of acute encephalopathy. However, this type of encephalopathy has not been reported in association with mumps infection.

PATIENT

A previously healthy 3-year-old Japanese boy had a brief convulsion after fever for 3days, and then had conscious disturbance and parotitis. After several days, he had a second brief convulsion and was admitted. Increased serum amylase levels and presence of anti-mumps immunoglobulin M antibody confirmed mumps parotitis. The patient had another brief seizure later the day of admission. He did not have status or cluster seizures, although the biphasic nature of his seizures, conscious disturbance between the seizures, no pleocytosis in cerebrospinal fluid, and brain magnetic resonance images were consistent with acute encephalopathy with biphasic seizures and late reduced diffusion.

DISCUSSION

In Japan, the mumps vaccine is not administered as a part of routine immunizations. It thus has low coverage (30-40%), and as a result, mumps infections are still common. However, this is the first case of mumps-related acute encephalopathy with biphasic seizures and late reduced diffusion. This case may be representative of only a minority of patients with mumps-associated central nervous system involvement. Nevertheless, this diagnostic possibility may be considered. In order to prevent mumps-related complications, routine mumps vaccination might be warranted.

Transient dysautonomia in an acute phase of encephalopathy with biphasic seizures and late reduced diffusion

Paroxysmal sympathetic hyperactivity (PSH) is a dysautonomic condition that is associated with various types of acquired brain injuries. Traumatic brain lesions have been documented as the leading cause of PSH. However, detailed clinical features of pediatric PSH caused by intrinsic brain lesions remain to be elusive. We present a 3-year-old boy, who had been diagnosed as having cerebral palsy, developmental delay and epilepsy after perinatal hypoxia-induced brain injury. He developed status epilepticus with fever on the third day of respiratory infection. Whereas the seizure was terminated by systemic infusion of midazolam, consciousness remained disturbed for the next 48h. Serial magnetic resonance imaging studies revealed that acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) evolved on 3days after the seizure. Therapeutic hypothermia was immediately introduced, however, the brain lesion extended to the whole subcortical white matters on day 8. The intermittent bilateral dilation of pupils with increased blood pressure and tachycardia were observed until day 12. Real-time monitoring of electroencephalograms ruled out the recurrent attacks of seizures. The abnormal signs of autonomic nervous system gradually ceased and never relapsed after recovery from the hypothermia. PSH or a transient condition of dysautonomia may emerge and persist during the acute phase of AESD.

Febrile status epilepticus due to respiratory syncytial virus infection

BACKGROUND

Febrile status epilepticus can have neurological sequelae. The type of sequelae, however, depend on the etiology, including infection due to viral agents such as the influenza virus. Respiratory syncytial virus (RSV) infection in childhood may also contribute to this. The aim of this study was therefore to characterize febrile status epilepticus associated with RSV infection, and to determine whether this type of infection is a risk factor for neurological sequelae in febrile status epilepticus.

METHODS

We reviewed the medical records of children aged ≤3 years with febrile status epilepticus who were admitted to a tertiary hospital between January 2007 and December 2011. The differences between the RSV-positive and RSV-negative groups were evaluated according to the demographic and clinical data.

RESULTS

A total of 99 patients with febrile status epilepticus who had been tested for RSV infection were identified. Three patients in the RSV-positive group (n = 19) and four in the RSV-negative group (n = 80) presented with bronchiolitis. The incidence of intubation and anti-seizure drug treatment in the RSV-positive group was significantly higher than in the -negative group. While all of the patients in the RSV-negative group recovered completely, six patients in the RSV-positive group developed encephalopathy and profound neurological sequelae. In five of the six patients, diffusion-weighted magnetic resonance imaging showed subcortical white matter lesions.

CONCLUSIONS

RSV infection in the absence of bronchiolitis can initially present as febrile status epilepticus and subsequently develop into acute encephalopathy with profound neurological sequelae.

A new infectious encephalopathy syndrome, clinically mild encephalopathy associated with excitotoxicity (MEEX)

Acute infectious encephalopathy is often observed in children in East Asia including Japan. More than 40% of the patients remain unclassified into specific syndromes. To investigate the underlying pathomechanisms in those with unclassified encephalopathy, we evaluated brain metabolism by MR spectroscopy. Among seven patients with acute encephalopathy admitted to our hospital from June 2016 to May 2017, three were classified into acute encephalopathy with biphasic seizures and late reduced diffusion (AESD). The other four showed consciousness disturbance lasting more than three days with no parenchymal lesion visible on MRI, which led to a diagnosis of unclassified encephalopathy. MR spectroscopy in these four patients, however, revealed an increase of glutamine with a normal N-acetyl aspartate level on days 5 to 8, which had normalized by follow-up studies on days 11 to 16. The four patients clinically recovered completely. Among 27 patients with encephalopathy, including the present seven patients, admitted to our hospital from January 2015 to March 2017, seven (26%) were classified into this type, which we propose is a new encephalopathy syndrome, clinically mild encephalopathy associated with excitotoxicity (MEEX). MEEX is the second most common subtype, following AESD (30%). This study suggests that excitotoxicity may be a common underlying pathomechanism of acute infectious encephalopathy, and prompt astrocytic neuroprotection from excitotoxicity may prevent progression of MEEX into AESD.

Clinically mild encephalitis/encephalopathy with a reversible splenial lesion of corpus callosum in Chinese children

OBJECTIVE

To investigate the characteristics and etiology of mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) in Chinese children.

METHODS

We collected ten pediatric MERS patients from local hospital and enrolled another nineteen patients by reviewing the available literatures. The information of enrolled patients about clinical features, laboratory data, treatment strategies and prognoses were collected for further analysis.

RESULTS

A total of 29 children, the median age of twenty-nine patients was (4.09±3.64) years old. The male-to-female ratio was 1.42:1.0. The major cause of MERS was viral infection. 18 patients had consciousness disturbance which was the most prominent syndrome. 18 patients had transient seizures and only one needed anticonvulsant treatment for long. 9 patients were observed serum sodium levels <135mEq/L. The cells and protein of cerebral spinal fluid (CSF) were increased in 3 patients. In all patients, brain MRI evaluation revealed typical lesion in splenium of the corpus callosum (SCC). 5 patients had additional lesions involving the periventricular white matter or bilateral centrum semiovale diagnosed. 3 patients were treated with antivirus treatment because of virus infection. 7 patients received corticosteroid. 2 patients received intravenous IVIG. As a result, all patients had fully recovered without neurological residual.

CONCLUSIONS

The result of present study suggests that Chinese children with MERS might have favorable prognosis, although there is still no guideline for treatment.

New guidelines for management of febrile seizures in Japan

In 2015, the Japanese Society of Child Neurology released new guidelines for the management of febrile seizures, the first update of such guidelines since 1996. In 1988, the Conference on Febrile Convulsions in Japan published "Guidelines for the Treatment of Febrile Seizures." The Task Committee of the Conference proposed a revised version of the guidelines in 1996; that version released in 1996 was used for the next 19years in Japan for the clinical management of children with febrile seizures. Although the guidelines were very helpful for many clinicians, new guidelines were needed to reflect changes in public health and the dissemination of new medical evidence. The Japanese Society of Child Neurology formed a working group in 2012, and published the new guidelines in March 2015. The guidelines include emergency care, application of electroencephalography, neuroimaging, prophylactic diazepam, antipyretics, drugs needing special attention, and vaccines. While the new guidelines contain updated clinical recommendations, many unsolved questions remain. These questions should be clarified by future clinical research.

A case of acute encephalopathy with biphasic seizures and late reduced diffusion: Utility of arterial spin labeling sequence

A 1-year-old boy was admitted because of febrile status epilepticus (FSE). A secondary cluster of seizures was seen on day 5 after onset, and the patient eventually displayed developmental delay. Conventional magnetic resonance imaging (MRI) showed no abnormal findings on day 1 after onset, but showed reduced diffusion in the subcortical regions of bilateral frontal lobes on day 5 after onset. Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) was diagnosed. Arterial spin labeling (ASL) revealed reduced cerebral blood flow (CBF) in bilateral frontal lobes on day 1 after onset and showed increased CBF in the corresponding region in the subacute phase. Outcomes after prolonged febrile seizures are usually good, but mental deficit and/or epilepsy often remain in AESD. Discriminating between these syndromes is difficult, because no useful biomarkers have been identified. Reduced CBF in bilateral frontal lobes was observed on ASL on day 1 of FSE in the present case, and this finding may be predictive of developing AESD.

Clinically mild infantile encephalopathy associated with excitotoxicity

Acute infectious encephalopathy is very frequently observed in children in East Asia including Japan. Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is the most common subtype in Japan; however, more than 40% of the patients remain unclassified into specific syndromes. To investigate the underlying pathomechanism in those with unclassified acute encephalopathy, we evaluated brain metabolism by MR spectroscopy. Among 20 patients with acute encephalopathy admitted to our hospital during January 2015 to May 2016, 12 could not be classified into specific syndromes. MR spectroscopy was performed in 8 of these 12 patients with unclassified encephalopathy. MR spectroscopy showed an increase of glutamine with a normal N-acetyl aspartate level on days 3 to 8 in three of the 8 patients, which had normalized by follow-up studies. The three patients clinically recovered completely. This study suggests that excitotoxicity may be the underlying pathomechanism in some patients with unclassified mild encephalopathy.