Acute Encephalopathy with Biphasic Seizures and Late Reduced Diffusion Associated with Dengue Infection in a Child.

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is a clinico-radiological syndrome in children secondary to viral or bacterial infections. The causes include viral (influenza, human herpes virus-6, adenovirus, rota) as well as bacterial infections. However, AESD with dengue infection has not been reported earlier. Here, we present an infant with dengue infection and AESD which recovered completely following treatment with intravenous human immunoglobulin therapy. A 9-month-old girl presented with seizures following fever and loose stools. Seizures recurred after 2 days of seizure-free interval. Cerebrospinal fluid analysis was not contributory. Dengue infection was confirmed by lab tests. Magnetic resonance imaging brain after the second seizure revealed diffusion restriction involving the bilateral frontal and parietal white matter, both hemispheres with a typical central perisylvian sparing lesion suggestive of AESD. This case report expands the reported spectrum of neurological manifestations of dengue infection.

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.

Seizure characteristics of epilepsy in childhood after acute encephalopathy with biphasic seizures and late reduced diffusion.

OBJECTIVE: The aim of this study was to clarify characteristics of post-encephalopathic epilepsy (PEE) in children after acute encephalopathy with biphasic seizures and late reduced diffusion (AESD), paying particular attention to precise diagnosis of seizure types. METHODS: Among 262 children with acute encephalopathy/encephalitis registered in a database of the Tokai Pediatric Neurology Society between 2005 and 2012, 44 were diagnosed with AESD according to the clinical course and magnetic resonance imaging (MRI) findings and were included in this study. Medical records were reviewed to investigate clinical data, MRI findings, neurologic outcomes, and presence or absence of PEE. Seizure types of PEE were determined by both clinical observation by pediatric neurologists and ictal video-electroencephalography (EEG) recordings. RESULTS: Of the 44 patients after AESD, 10 (23%) had PEE. The period between the onset of encephalopathy and PEE ranged from 2 to 39 months (median 8.5 months). Cognitive impairment was more severe in patients with PEE than in those without. Biphasic seizures and status epilepticus during the acute phase of encephalopathy did not influence the risk of PEE. The most common seizure type of PEE on clinical observation was focal seizures (n = 5), followed by epileptic spasms (n = 4), myoclonic seizures (n = 3), and tonic seizures (n = 2). In six patients with PEE, seizures were induced by sudden unexpected sounds. Seizure types confirmed by ictal video-EEG recordings were epileptic spasms and focal seizures with frontal onset, and all focal seizures were startle seizures induced by sudden acoustic stimulation. Intractable daily seizures remain in six patients with PEE. SIGNIFICANCE: We demonstrate seizure characteristics of PEE in children after AESD. Epileptic spasms and startle focal seizures are common seizure types. The specific seizure types may be determined by the pattern of diffuse subcortical white matter injury in AESD and age-dependent reorganization of the brain network.

Disrupted glutamate-glutamine cycle in acute encephalopathy with biphasic seizures and late reduced diffusion.

INTRODUCTION: Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is the most common subtype of infectious pediatric encephalopathy in Japan. It is sometimes difficult to make an early diagnosis of AESD; excitotoxicity is postulated to be the pathogenesis based on elevated glutamine (Gln) and glutamate (Glu) complex (Glx = Glu + Gln) observed on MR spectroscopy. It is uncertain whether Gln or Glu contributes to the elevated Glx, or whether MR spectroscopy is useful for an early diagnosis. METHODS: Five Japanese patients with AESD (three boys and two girls, 1 year of age) were enrolled in this study. MR spectroscopy was acquired from the frontal white matter (repetition time (TR) of 5000 ms, echo time (TE) of 30 ms) with a 1.5- or 3.0-T scanner. MR spectroscopy was performed four times for two patients, three times for one patient, and two times for two patients. Quantification of Glu and Gln was performed using LCModel. RESULTS: Glu was elevated in three of four studies on days 1-4 and became normal or low afterward. Gln was normal in three studies on days 1-2, elevated in all seven studies on days 4-12, and became normal or low afterward. CONCLUSION: These findings suggest that MR spectroscopy may be useful for an early diagnosis. Acute Glu elevation changes to subacute Gln elevation, suggesting that a disrupted Glu-Gln cycle may play an important role.

Factors influencing the development of infantile traumatic brain injury with a biphasic clinical course and late reduced diffusion.

BACKGROUND: Infantile traumatic brain injury (TBI) with a biphasic clinical course and late reduced diffusion (TBIRD) has been reported as a type of TBI. However, it remains uncertain which pediatric patients with TBI develop TBIRD. METHODS: Patients with TBI who were admitted to our hospital and underwent magnetic resonance imaging (MRI) between December 2006 and October 2022 were included in this study. A diagnosis of TBIRD was made in patients with or suspected TBI, with initial symptoms being convulsions or disturbance of consciousness and late-onset subcortical reduced diffusion, the so-called bright tree appearance. Clinical features, neuroimaging (computed tomography (CT) and MRI) findings, laboratory data, and Tada score were retrospectively compared between TBIRD and non-TBIRD patients. Neurological prognosis was assessed using the Pediatric Cerebral Performance Category scale. RESULTS: Of 21 patients who met the inclusion criteria, a diagnosis of TBIRD was made in 7 patients (median age: 8 months). The factors contributing to TBIRD development were seizures lasting over 30 min as the initial symptom (5/7 in TBIRD vs. 0/14 in non-TBIRD), tracheal intubation during initial treatment (5/7 vs. 0/14), and brain parenchymal lesions on CT (3/7 vs. 0/14), suggesting that severe TBI may progress to TBIRD. The Tada score was more positive in patients with TBIRD (6/7) than in those without (0/14). CONCLUSIONS: It is important to monitor infant patients with severe TBI for the development of TBIRD. The Tada score can be a useful tool for TBIRD prediction.

Severe pediatric acute encephalopathy syndromes related to SARS-CoV-2.

Background and objectives: To clarify whether severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection cause acute encephalopathy in children and which are the most common syndromes that cause them and what are the outcomes. Methods: A nationwide web-based survey among all members of the Japanese Society of Child Neurology to identify pediatric patients aged < 18 years who developed acute encephalopathy in Japan between 1 January 2020 and 31 May 2022 associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection confirmed by polymerase chain reaction or antigen tests using pharyngeal swabs. Acute encephalopathy was defined as acute onset of impaired consciousness lasting > 24 h or an altered mental state; neurological symptoms arising within 2 weeks of onset of COVID-19 or multisystem inflammatory syndrome in children (MIS-C)/pediatric inflammatory multisystem syndrome (PIMS); evidence of SARS-CoV-2 infection; and reasonable exclusion of other diseases. Patients were divided into the known clinico-radiological acute encephalopathy syndrome group and unexplained or unclassifiable acute encephalopathy group. Outcomes were assessed by pediatric cerebral performance category (PCPC) score at hospital discharge. Results: Of the 3,802 society members, 217 representing institutions responded, and 39 patients with suspected acute encephalopathy were reported, of which 31 met inclusion criteria. Of these patients, 14 were diagnosed with known clinico-radiological acute encephalopathy syndromes, with acute encephalopathy with biphasic seizures and late reduced diffusion (five patients) being the most common. Five developed acute encephalopathy associated with MIS-C/PIMS. Among 31 patients, 9 (29.0%) had severe sequelae or died (PCPC ≥ 4). Two of three patients with encephalopathy with acute fulminant cerebral edema and two with hemorrhagic shock and encephalopathy syndrome died. The PCPC scores were higher in the known clinico-radiological acute encephalopathy syndrome group than in the unexplained or unclassifiable acute encephalopathy group (P < 0.01). Discussion: Acute encephalopathy related to SARS-CoV-2 infection was demonstrated to be more severe than that caused by other viruses in Japan. Acute encephalopathy syndromes characterized by specific neuroradiological findings was associated with poor clinical outcomes.

Refractory status epilepticus with fever due to mumps vaccine-induced encephalitis caused secondary encephalopathy mimicking acute encephalopathy with biphasic seizures and late reduced diffusion.

BACKGROUND: Encephalitis due to vaccination for mumps is a rare complication that occurs in 0.00004% of recipients, and there has been no report of serious neurological sequelae. Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) has been reported as the most frequent type among acute encephalopathy syndromes in the pediatric population in Japan. There has been no report of AESD caused by vaccinations. Case presentation We present the clinical course of a 1-year and 10-month-old boy who had no preexisting condition, and developed mumps vaccine-induced severe primary encephalitis. Refractory status epilepticus due to encephalitis persisted for 16 h and resulted in secondary encephalopathy as a form of AESD mimic. He had serious neurological sequelae, such as West syndrome, transient spastic tetraplegia, and intellectual disability, despite intensive treatments. DISCUSSION: The presented boy is the first patient to develop mumps vaccine-induced primary encephalitis with severe central nervous system (CNS) damage. Screening of the immunological background in the presented patient revealed no abnormalities; therefore, it is unclear why he developed such severe adverse events. In patients with acute encephalitis caused by the herpes simplex virus 1, inborn immune errors in CNS based on mutations in single genes are involved in its pathophysiology. Consequently, some immunogenetic alterations could be found by further analysis in the presented patient.

Association of IL-1B rs16944 Polymorphism With Acute Encephalopathy With Biphasic Seizures and Late Reduced Diffusion Is Opposite to That of Febrile Seizures.

Objective: Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is a severe neurologic complication of febrile infectious diseases in children. At the onset, AESD is clinically manifested as febrile status epilepticus. Subsequent damage to the cerebral cortex is ascribed to neurotoxicity. The incidence of AESD is remarkably high in Japan, suggesting the involvement of genetic factors. The expression of interleukin 1 beta (IL-1ß), a member of the cytokine family involved in the inflammatory response, is reportedly associated with rs16944, a polymorphism in the upstream region of the IL-1B gene, being higher in TT genotype. Previous association studies of rs16944 with febrile seizures (FS) have demonstrated a significant excess in the TT vs. CC + CT genotype in the Asian population. Here, we conducted a case-control association study of rs16944 in AESD. Methods: We genotyped rs16944 by Sanger sequencing on 283 patients with AESD. As controls, we used genotyping data of 104 Japanese individuals obtained from the 1,000 Genomes Project. Then, we performed a case-control association study using the chi-square test. Results: The ratio of individuals with TT vs. those with CC+CT genotype was significantly lower in AESD than in the controls [p-value 0.021, Odds Ratio (OR) 0.52]. This finding was opposite to that of a previously reported FS. Conclusion: The AESD has a genetic background distinct from FS and is not a severe type of FS.

Fever, Seizures and Encephalopathy: From Bush Fires to Firestorms.

Fever-associated seizures and febrile encephalopathy are common neurological problems in children. Infections of the nervous system are responsible for the majority of cases. However, there is a spectrum of infection-associated and inflammatory conditions associated with the triad of fever, seizures, and encephalopathy. Apart from complex febrile seizures and febrile status epilepticus, fever infection-related epilepsy syndrome of childhood (FIRES), infantile hemiconvulsion hemiplegia epilepsy syndrome (IHHE), acute encephalopathy with delayed diffusion restriction (AESD), acute necrotizing encephalopathy of childhood (ANE), and reversible splenial lesion syndrome (RESLES) are age-related clinical phenotypes of fever-related epilepsy and encephalopathy. Awareness of these entities is important for appropriate diagnosis and the prompt use of immunomodulatory/immunosuppressive therapies. In this review, we discuss the pathophysiology, clinical phenotypes, and management approaches of these fever-related seizure and encephalopathy states.

MRI findings at neurological onset predict neurological prognosis in hemorrhagic shock and encephalopathy syndrome.

BACKGROUND: Hemorrhagic shock and encephalopathy syndrome (HSES) is a devastating disease and has an uncertain pathogenesis. The aim of this study was to predict neurological outcomes for HSES using magnetic resonance imaging (MRI) findings at neurological onset and elucidate the pathophysiology of HSES in the acute phase from serial MRI changes. MATERIALS AND METHODS: We analyzed the MRI findings of 13 patients who underwent an initial MRI within 24 h of neurological onset. According to neurological prognosis, seven patients were included in the severe group and six in the non-severe group. All patients in the non-severe group had a follow-up MRI. We divided the whole brain into 14 regions and each region was scored according to diffusion-weighted imaging findings. We compared the total scores of each region between the two groups and between onset and follow-up MRI. RESULTS: At neurological onset, symmetrical lesions were found predominantly in the frontal, parietal, and occipital lobes in 12 of 13 patients (92%). In the severe group, the total score for onset MRI was significantly higher than those in the non-severe group (p = 0.003). The total score was significantly higher for follow-up than those of onset MRI (p = 0.036). White matter lesions that showed a bright tree appearance were observed in the follow-up MRIs of all patients. CONCLUSION: Total scores for onset MRIs are useful for predicting neurological prognosis in patients with HSES. In addition to widespread cortical involvement of predominantly watershed areas, white matter lesions may play a role in the progression of brain edema.

The spectrum of acute leukoencephalopathy with restricted diffusion (ALERD): A case series and review of literature.

INTRODUCTION: The clinico-etiological spectrum of Acute leukoencephalopathy with restricted diffusion (ALERD) is not well known in Indian population. This is likely to vary between populations and ethnicities. METHODS: We retrospectively reviewed the clinicoetiological spectrum of ALERD at a tertiary care pediatric center, and described the clinical, imaging, etiological spectrum and short-term outcomes. RESULTS: Eleven out of 78 children with non-traumatic encephalopathy presenting to our center had a final diagnosis of ALERD. The mean age at presentation was 34.9 months (6-80 months) and 63.6% were males. The monophasic course (72.7%) and the diffuse pattern (63.6%) on neuroimaging were predominant in these children. Dengue haemorrhagic fever was the commonest underlying/triggering infection (5 of 11 children). Ten children required mechanical ventilation in view of neurogenic respiratory failure, with mean duration of ventilation of 6.4 days (Range 2-10 days). The duration of hospital stay varied from 11 to 25 days (Mean - 15.3 days). One child (9 %) died, 6 children (54.5 %) had varying degrees of cognitive impairment and 4 (36.3 %) children had a normal outcome. Children with a shorter duration of ventilation seemed to have a better outcome. CONCLUSION: Dengue haemorrhagic fever was the commonest cause, and diffuse imaging pattern with monophasic course was the commonest presentation in Indian children with ALERD. The clinical presentation and factors influencing outcome are possibly different from previously described literature.

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

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

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.

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.

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.

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.

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.

Acute encephalopathy with biphasic seizures and late reduced diffusion associated with Streptococcus sanguinis sepsis.

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) develops in association with systemic as well as central nervous system (CNS) viral or bacterial infections. AESD is most often noted with influenza or human herpesvirus 6 infection in previously healthy infants. However, AESD has also been reported in an infant with developmental retardation and in a mentally and motor-disabled adolescent. Here, we report the case of a 4- year-old female with significant development delay due to spinal muscular atrophy, who developed AESD during Streptococcus sanguinis sepsis with no apparent CNS infection. Although the patient had extremely high serum procalcitonin (45.84 ng/mL, reference; <0.4) on admission indicating a poor prognosis, she was successfully managed for sepsis and 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.

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.