Clinical characteristics of acute encephalopathy of obscure origin: a biphasic clinical course is a common feature

[FIRES Syndrome in a Preschool Child]

Severe epileptic syndromes of childhood are an urgent problem for pediatric neurologists and neuroresuscitators. The article presents a clinical observation of FIRES syndrome in a pediatric patient, which is a form of severe drug-resistant epilepsy in children of preschool and school age, the development of which is caused by hyperthermia, probably associated with herpesvirus (human herpesvirus type 6) infection. The features of the progressive course and the difficulties of diagnostic search are reflected. An empirical approach to etiotropic therapy is described, since the disease manifested itself with respiratory manifestations and fever. The tactic of pathogenetic treatment is described, in which drugs of polyfunctional action, such as Cytoflavin, have a priority, many years of experience in the use of which allows the authors to recommend it as a starting intensive therapy.

Acute encephalopathy with biphasic seizures and late reduced diffusion: Predictive EEG findings

BACKGROUND

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is a common type of acute encephalopathy in Japan; the condition is clinically characterized by prolonged seizures as the initial neurological symptom, followed by late seizures 4-6 days later. It is difficult to differentiate AESD from prolonged febrile seizures (PFSs). Here, we explored the use of electroencephalography to differentiate AESD from PFSs.

METHODS

We studied the electroencephalograms (EEGs) of children <6 years of age diagnosed with AESD or PFSs; all EEGs were recorded within 48 h of seizure onset (i.e., before the late seizures of AESD). Two pediatric neurologists evaluated all EEGs, focusing on the basic rhythm, slowing during wakefulness/arousal by stimuli, spindles, fast waves, and slowing during sleep.

RESULTS

The EEGs of 14 children with AESD and 31 children with PFSs were evaluated. Spindles were more commonly reduced or absent in children with AESD than in those with PFSs (71% vs. 31%, p = 0.021). Fast waves were also more commonly reduced or absent in children with AESD (21% vs. 0%, p = 0.030). The rates of all types of slowing did not differ between children with AESD and those with PFSs, but continuous or frequent slowing during sleep was more common in the former (50% vs. 17%, p = 0.035).

CONCLUSIONS

EEG findings may usefully differentiate AESD from PFSs. Reduced or absent spindles/fast waves and continuous or frequent slowing during sleep are suggestive of AESD in children with prolonged seizures associated with fever.

Infant with right hemiplegia due to acute encephalopathy with biphasic seizures and late reduced diffusion (AESD): A case report

RATIONALE

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is a condition characterized by biphasic convulsions and disturbance of consciousness. In Japan, the most common pediatric cases of acute encephalopathy are associated with infection. AESD usually occurs in early childhood, with the characteristic magnetic resonance imaging (MRI) appearance called "bright tree appearance." The disease often has neurological sequelae and interferes with the schooling of children and their activities of daily living; however, there are few clinical case reports of hemiplegia caused by AESD.

PATIENT CONCERNS

A case with right-sided hemiplegia due to AESD in an 11-month-old girl who was followed up to 30 mo of age.

DIAGNOSES

The patient was diagnosed with overlap AESD and hemiconvulsion-hemiplegia-epilepsy syndrome (HHE syndrome), based on the clinical course and imaging findings. DNA tests of her blood and cerebrospinal fluid revealed the presence of human herpesvirus 6.

INTERVENTIONS

Pharmacotherapy and rehabilitation therapy.

OUTCOME

Gross motor function has recovered considerably, but she had a mild developmental delay at 30 mo old.

LESSONS

Hemiplegia due to AESD was extremely rare, and appropriate rehabilitation treatment resulted in recovery of physical function. However, as mild developmental delay was observed, the patient was referred to a specialized facility before entering school.

Guidelines for the diagnosis and treatment of acute encephalopathy in childhood

The cardinal symptom of acute encephalopathy is impairment of consciousness of acute onset during the course of an infectious disease, with duration and severity meeting defined criteria. Acute encephalopathy consists of multiple syndromes such as acute necrotizing encephalopathy, acute encephalopathy with biphasic seizures and late reduced diffusion and clinically mild encephalitis/encephalopathy with reversible splenial lesion. Among these syndromes, there are both similarities and differences. In 2016, the Japanese Society of Child Neurology published 'Guidelines for the Diagnosis and Treatment of Acute Encephalopathy in Childhood', which made recommendations and comments on the general aspects of acute encephalopathy in the first half, and on individual syndromes in the latter half. Since the guidelines were written in Japanese, this review article describes extracts from the recommendations and comments in English, in order to introduce the essence of the guidelines to international clinicians and researchers.

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.

Detailed clinical course of fatal acute encephalopathy in children

OBJECTIVE

Although the mortality among previously healthy children with acute encephalopathy (AE) is approximately 5%, their detailed clinical course has not been clarified. The objective of the present study was to describe the detailed clinical course, in minutes, of fatal AE.

METHODS

We retrospectively reviewed the medical records of five patients (from 6 months to 14 years of age) who previously had no neurological disorders and were diagnosed with brain death due to AE between 2002 and 2018 at Kobe Children's Hospital.

RESULTS

The initial clinical symptoms were convulsion in three cases and impaired consciousness in two. The earliest noted brain imaging abnormality was 7.5 h after neurological symptom detection. Liver enzymes and creatinine levels increased at initial examination, and sodium elevated gradually. All patients met the criteria of systemic inflammatory response syndrome, disseminated intravascular coagulation, and shock within 14 h of symptom detection. High dose steroids and targeted temperature management were initiated 3.5-14 h after onset. Despite these therapies, patients were diagnosed with brain death from 16 h to 4 days after initial neurological symptoms. AE diagnoses were made between 4 h 29 min and 4 days after initial neurological symptoms and included hemorrhagic shock and encephalopathy syndromes, Reye-like syndrome, and acute necrotizing encephalopathy in two, two, and one patient(s), respectively.

CONCLUSIONS

We revealed the time series' of clinical events (e.g. SIRS, shock, DIC, AE diagnosis, brain death, and treatments) and laboratory findings relative to initial neurological symptom in fatal AE.

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 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 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.

Prediction of acute encephalopathy with biphasic seizures and late reduced diffusion in patients with febrile status epilepticus

INTRODUCTION

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is the most common subtype of acute encephalopathy among children in Japan. The pathogenesis of AESD is mostly delayed cerebral edema caused by excitotoxic injury. It is difficult to discriminate AESD and complex febrile seizure in the early phase. Many cases have neurologic sequelae because early intervention is difficult.

METHODS

To establish an early diagnostic method, we assessed 213 hospitalized cases of febrile status epilepticus (FSE) between January 2004 and August 2014. We categorized FSE cases into an AESD group and a non-AESD group and compared their clinical courses, laboratory data and cranial computed tomography (CT) findings.

RESULTS

Of 213 hospitalized FSE cases, 19 (9%) were AESD. Univariate analysis showed that the AESD group took a significantly longer time to wake after FSE, had a higher degree of respiratory acidemia, and higher levels of serum AST, ALT, LD, hyperglycemia and hyperammonemia than the non-AESD group. We developed a scoring model that predicts AESD based on multivariate analysis. Using cut-off points of 4 and more with this scoring model, we could identify the AESD cases with 93% sensitivity and 91% specificity. These scores also had a positive correlation with prognosis.

DISCUSSION

Our scoring model enables early diagnosis of AESD. Patients with high scores should be observed carefully and early intervention should be considered.

Early predictors of status epilepticus-associated mortality and morbidity in children

BACKGROUND

Early predictors of status epilepticus (SE)-associated mortality and morbidity have not been systematically studied in children, considerably impeding the identification of patients at risk.

OBJECTIVES

To determine reliable early predictors of SE-associated mortality and morbidity and identify the etiology of SE-associated sequelae in Japanese children.

METHODS

We conducted a prospective multicenter study of clinical findings and initial laboratory data acquired at SE onset, and assessed outcomes at the last follow-up examination. In-hospital death during the acute period and neurological sequelae were classified as poor outcomes.

RESULTS

Of the 201 children who experienced their first SE episode, 16 exhibited poor outcome that was most commonly associated with acute encephalopathy. Univariate analysis revealed that the following were associated with poor outcomes: young age (⩽24 months); seizure duration >90 min; seizure intractability (failure of the second anticonvulsive drug); biphasic seizures; abnormal blood glucose levels (<61 or >250 mg/dL); serum aspartate aminotransferase (AST) ⩾56 U/L; and C-reactive protein (CRP) levels >2.00 mg/dL. Multivariate analysis revealed that young age, seizure intractability, abnormal blood glucose levels, and elevated AST and CRP levels were statistically significant.

CONCLUSIONS

Young age and seizure intractability were highly predictive of poor outcomes in pediatric SE. Moreover, abnormal blood glucose levels and elevated AST and CRP levels were predictors that might be closely associated with the etiology, especially acute encephalopathy and severe bacterial infection (sepsis and meningitis) in Japanese children.

Midazolam fails to prevent neurological damage in children with convulsive refractory febrile status epilepticus

BACKGROUND

We conducted a retrospective study to compare the outcome of intravenous midazolam infusion without electroencephalography or targeted temperature management and barbiturate coma therapy with electroencephalography and targeted temperature management for treating convulsive refractory febrile status epilepticus.

PATIENTS

Of 49 consecutive convulsive refractory febrile status epilepticus patients admitted to the pediatric intensive care unit of our hospital, 29 were excluded because they received other treatments or because of various underlying illnesses. Thus, eight patients were treated with midazolam and 10 with barbiturate coma therapy using thiamylal. Midazolam-treated patients were intubated only when necessary, whereas barbiturate coma therapy patients were routinely intubated. Continuous electroencephalography monitoring was utilized only for the barbiturate coma group. The titration goal for anesthesia was clinical termination of status epilepticus in the midazolam group and suppression or burst-suppression patterns on electroencephalography in the barbiturate coma group. Normothermia was maintained using blankets and neuromuscular blockade in the barbiturate coma group and using antipyretics in the midazolam group. Prognoses were measured at 1 month after onset; children were classified into poor and good outcome groups.

RESULTS

Good outcome was achieved in all the barbiturate coma group patients and 50% of the midazolam group patients (P = 0.02, Fisher's exact test).

CONCLUSIONS

Although the sample size was small and our study could not determine which protocol element is essential for the neurological outcome, the findings suggest that clinical seizure control using midazolam without continuous electroencephalography monitoring or targeted temperature management is insufficient in preventing neurological damage in children with convulsive refractory febrile status epilepticus.

Therapeutic indicators of acute encephalopathy in patients with complex febrile seizures

BACKGROUND

The aim of this study was to identify predictors of neurologic damage in children with febrile seizures or altered consciousness within 6 h of seizure onset.

METHODS

The present study included 86 children (age range, 4-159 months old), who fulfilled the diagnostic criteria for complex febrile seizures on admission between October 2002 and November 2008. Using the Pediatric Cerebral Performance Category Scale (PCPC), the children were classified into two groups: poor outcome (PCPC = 2-6) and good outcome (PCPC = 1). Clinical profiles and laboratory findings were compared between the groups.

RESULTS

Of the 86 children, 17 fell into the poor outcome and 69 into the good outcome group. Using univariate analysis, three early risk factors for poor outcome were identified: (i) consciousness disturbance or hemiplegia at 6 h from onset; (ii) refractory status epilepticus; and (iii) elevation of aspartate aminotransferase to >90 IU/L within 6 h of onset. Using these criteria, children in the poor outcome group were identified with a 94% sensitivity and 67% specificity rate (odds ratio, 36.6; 95% confidence interval: 4.87-1560). During the study period, the inpatients who met the criteria for acute encephalopathy also fell into the poor outcome group.

CONCLUSIONS

The development of neurologic damage in children with complex febrile seizures can be predicted within 6 h of onset, using the identified risk factors. The authors propose an assumption of severe febrile seizures (SFS) in children who fulfill these risk factors. Using SFS as an inclusion criterion, an interventional study for acute encephalopathy can be designed.

Late-onset epilepsy in children with acute febrile encephalopathy with prolonged convulsions: A clinical and encephalographic study

The aim of this study is to analyze the characteristics of epilepsies as the sequelae of acute febrile encephalopathy with prolonged convulsions during childhood. Sixteen patients (M:F=9:7) aged 2-13years (mean 6.1years) with history of febrile acute encephalopathy were retrospectively reviewed. These patients experienced febrile encephalopathy at the age of 11months to 4years, with 11 individuals presenting with findings of a biphasic clinical course (n=5), frontal predominant (n=8) lesions, and/or reduced diffusivity in the cerebral white matter on magnetic resonance imaging (MRI; n=3). The remaining 5 patients had unilateral lesions that manifested the phenotype of hemiconvulsion-hemiplegia-epilepsy syndrome (HHES). Epilepsy emerged with a latent period of 2months to 2years after the acute phase of febrile encephalopathy. Head nodding or spasm with subsequent motion arrest and brief tonic seizures were the main seizure phenotypes. Ictal records of epileptic seizures were available in 9 patients. Epileptiform discharges with a focal or uneven distribution appeared at the seizure onset and lasted less than 1s in all patients; these were followed by either generalized attenuation or fast activity in 8 patients with head nodding, spasm, or brief tonic seizures, and by localized fast activity in 1 patient with versive tonic seizures. Notably, the seizure onset area was often located outside the severe lesions on MRI, i.e., in the parietal areas in patients with frontal predominant lesions, and in the spared hemisphere of HHES. Although phenobarbital, zonisamide, carbamazepine, clobazam, clonazepam, and clorazepate were partially effective in some patients, daily seizures persisted in 11 patients. Callosotomy was performed in 2 patients, and beneficial effects were observed in both. These characteristics suggested a broad distribution of augmented excitability in these patients, resulting in the rapid propagation of epileptic activity in the initial phase of ictal phenomena. Thus, this study investigates the most severe subgroup of epilepsy following febrile acute encephalopathy and provides the basis for further exploration of the pathogenesis and treatment of characteristic seizures in this population.

Acute infantile encephalopathy predominantly affecting the frontal lobe (AIEF): a European case

Acute infantile encephalopathy predominantly affecting the frontal lobes (AIEF) has been described as a new entity, based on MRI findings (acute abnormal diffusion-weighted imaging signals in the frontal lobes followed by atrophy) and exclusion of other acute encephalopathies. Patients present with acute onset of fever, status epilepticus, and coma. Different causal mechanisms have been suggested such as localized viral infection, toxic insult due to cytokines, or postictal damage. Only children of Japanese descent have been described. We report the case of a Caucasian girl whose history and MRI findings were similar to the Japanese cases. She had a massive regression with verbal apraxia, while cognitive development was less affected; she initially presented with a cluster of complex partial seizures (and not convulsive status epilepticus), making epileptic or post anoxic-ischemic sequelae highly unlikely. The place of this proposed entity among other recently described acute encephalopathies with abnormal diffusion on MRI is discussed.

Clustered subclinical seizures in a patient with acute encephalopathy with biphasic seizures and late reduced diffusion

Using single-channel amplitude-integrated electroencephalography (aEEG), we monitored clustered seizures in a 12-month-old boy suffering from acute encephalopathy with biphasic seizures and late reduced diffusion (AESD). He was admitted to our hospital after losing consciousness and experiencing repeated seizures in association with fever. Although the patient's state of consciousness improved the next day, it declined on the fifth day of illness, and clinical seizures were observed. Diffusion-weighted images revealed abnormal high intensities in the frontal area bilaterally. On the same day, aEEG monitoring revealed an unexpected cluster of subclinical seizures. Attending pediatricians, nurses, and other caregivers did not recognize the presence of these frequent subclinical seizures. The efficacy of antiepileptic drugs could also be objectively assessed from aEEG findings. aEEG is useful for continuous monitoring in children with acute encephalopathy, may disclose subclinical seizures, and can contribute to an objective evaluation of the efficacy of antiepileptic drugs.

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. Clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) is characterized by a reversible lesion with homogeneously reduced diffusion in the corpus callosum (at least involving the splenium), sometimes associated with symmetrical white matter lesions. The most common neurological symptom is delirious behavior, followed by consciousness disturbance, and seizures, all of which completely recover within a month. The reason for the transiently reduced diffusion within the lesions is unknown; possibilities that have been postulated include intramyelinic edema, interstitial edema in tightly packed fibers, and a transient inflammatory infiltrate.

Acute encephalopathy with biphasic seizures and late restricted diffusion on MRI in a Japanese child living in the USA

We report an 18-month-old Japanese female living in the USA whose clinical course and radiographic findings were consistent with acute encephalopathy with biphasic seizures and late reduced diffusion (AESD). She was initially diagnosed with complex febrile seizures. However, on day 3 of admission, she had a cluster of complex partial seizures and the onset of a global developmental regression. In contrast to the normal magnetic resonance image of the brain obtained on admission, subsequent imaging demonstrated transient subcortical diffusion-weighted abnormalities in the white matter of the bilateral posterosuperior frontal, parietal, temporal, and occipital regions, with sparing of the perirolandic area. One year later, her developmental delay, although improved, persisted and she continued to experience sporadic seizures while being treated with topiramate monotherapy. Repeat imaging showed diffuse, poorly defined, increased T2 signals in the white matter of the posterosuperior frontal, parietal, temporal and occipital regions and diffuse cerebral volume loss. Previous reports of AESD have been limited to children aged under 4 years living in Japan. With the identification of this case, it is important that all physicians, not only those in Japan, who care for children with febrile seizures be aware of AESD and its associated neurological morbidity.

Acute encephalitis with refractory, repetitive partial seizures

BACKGROUND

Acute encephalitis with refractory, repetitive partial seizures (AERRPS) is a new epileptic syndrome described by Sakuma in Japan in 2001. The clinical manifestations, neuroimaging findings and outcome of AERRPS in Taiwan have not been reported.

METHODS

From 2000 to 2006, we collected cases that fulfilled the diagnostic criteria of AERRPS and analyzed the clinical course, virology, medication, electroencephalographic findings, neuroimaging characters and prognosis retrospectively.

RESULTS

Fourteen children aged from 1 year and 2 months to 15 years and 6 months were enrolled. They presented with prodromic symptoms including fever (n=13, 92.9%), upper respiratory tract infection symptoms (n=12, 85.7%) and gastrointestinal tract discomfort (n=6, 42.9%). Seizures occurred 3-14 days after antecedent symptoms with patterns of generalized tonic-clonic seizures, focal seizures or myoclonic seizures. The seizures were refractory to combinations of antiepileptic drugs (AEDs). Prolonged fever (n=14, 100.0%), hypersensitivity to AEDs (n=11, 78.6%) and liver function impairment (n=8, 57.1%) were noted during the period of hospitalization. The follow-up EEG findings were similar to those of initial findings including epileptiform discharges and/or generalized background slow waves. Initial brain MRI scans were normal but later showed focal or multifocal abnormal signal intensity followed by generalized brain atrophy in more than 50% of cases. The general prognosis was poor with variable psychomotor retardation and persistence of refractory epileptic seizures.

CONCLUSIONS

The similarities of the clinical features support AERRPS as a new epileptic syndrome. More study is needed to specify the etiology of the syndrome as the first step for more effective treatment.

Subacute encephalopathy: clinical features, laboratory data, neuroimaging, and outcomes

We sought to clarify the clinical, laboratory, neuroradiologic, and neurophysiologic features of the "subacute" subtype of encephalopathy. We retrospectively identified nine patients with subacute encephalopathy out of 97 patients diagnosed as manifesting acute encephalopathy. Neurologic symptoms, clinical course, laboratory data, neuroradiologic and electroencephalographic findings, and outcomes were reviewed through medical records. The median age of patients was 44 months (range, 28-156 months). The initial neurologic sign was a brief seizure in 4, a prolonged seizure in 3, delirious behavior in 1, and a loss of consciousness in 1. Loss of consciousness the next day was subtle in 4, and mild in 5. However, a worsening of consciousness was observed 3-7 days after onset. Laboratory data were unremarkable, and electroencephalography during the early phase found abnormalities in 4 of 7 patients. Magnetic resonance imaging revealed no abnormalities during the early phase, and mild cortical atrophy during the late phase. All but one patient had various degrees of neurologic sequelae. Subacute encephalopathy was characterized by a delayed worsening of neurologic symptoms, mild cortical atrophy on late magnetic resonance imaging, and poor neurologic outcomes. Recognition of this type of acute encephalopathy is important, and a method to promote early diagnosis is desirable.