Risk factors for post-encephalopathic epilepsy in patients with acute encephalopathy with biphasic seizures and late reduced diffusion

BACKGROUND

Post-encephalopathic epilepsy (PEE) is a serious complication of acute encephalopathy syndromes, and is more frequent in patients with acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) than in children with acute encephalopathy. However, a risk factor analysis using laboratory findings in the acute phase of AESD has not yet been performed. Therefore, the present study examined risk factors of AESD-related PEE using laboratory parameters in the acute phase of AESD.

METHODS

We retrospectively screened 27 pediatric patients with AESD for inclusion, and enrolled 20 ("the PEE group", n = 6; "the non-PEE group", n = 14) according to inclusion criteria.

RESULTS

The incidence of AESD-related PEE was 30 %, and the median duration from the onset of AESD to the development of PEE was 2.5 months (range, 1-32). The most common types of seizures were focal seizures, epileptic spasms, and startle seizures: 4 out of 6 patients (66.7 %) had intractable epilepsy. The median values of alanine aminotransferase (ALT) in the 1st and 2nd seizure phases of AESD and aspartate aminotransferase (AST) in the 2nd seizure phase were significantly higher in the PEE group than in the non-PEE group (p < 0.01).

CONCLUSIONS

This is the first study to report higher serum levels of ALT and AST at the onset of AESD as risk factors for AESD-related PEE. We also provided a detailed description on the clinical characteristics on AESD-related PEE, which are consistent with previous findings.

A serial analysis of serum aspartate aminotransferase levels in patients with acute encephalopathy with biphasic seizures and late reduced diffusion and prolonged febrile seizure

BACKGROUND

There are no established biomarkers for diagnosing acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) in the early acute phase, called "the 1st seizure phase". Based on our clinical experience, we hypothesized that serial examinations of blood levels of aspartate aminotransferase (AST) in children with febrile convulsive status epilepticus (FCSE) revealed higher levels in patients with AESD in the 1st seizure phase than in those with prolonged febrile seizures (PFs).

METHODS

To test our presented hypothesis, we retrospectively investigated changes in serum AST in patients with FCSE due to AESD (n = 11) or PFs (n = 27) who were serially examined within 48 h of the onset of convulsions.

RESULTS

The rate of increase in AST was significantly higher in patients with AESD than in those with PFs. The rate of increase in AST correlated with previously reported scoring systems, i.e., Yokochi and Tottori scores, for the prediction of AESD. A positive correlation between the rate of increase in AST and creatinine levels in the first examination were observed; however, creatinine levels did not significantly differ between the AESD and PFs groups in the first or second examination. Blood levels of pH, ammonia, and sugar in the first examination and C-reactive protein in the second examination were significantly higher in the AESD group than in the PFs group.

CONCLUSIONS

The present study revealed that the rate of increase in AST was significantly higher in patients with AESD than in those with PFs. A novel predictive scoring system needs to be established in combination with the rate of increase in AST and reported clinical parameters, which will improve the prognosis of patients with FCSE.

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.

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.

Effect of a novel prolonged febrile seizure model on GABA associated ion channels

Prolonged febrile seizures are usually modelled in animals using hyperthermia as an inducer. In this study, a modified simple febrile seizure model using a combination of lipopolysaccharide (LPS) and kainic acid (KA) was used to develop a prolonged febrile seizure animal model, which we used to assess effects on the expression of the sodium- potassium-chloride cotransporter 1 (NKCC1) and potassium-chloride cotransporter 2 (KCC2) and their possible role in seizure exacerbation. At post-natal day (PND) 14, rat pups were divided into a saline (S), simple febrile seizure (FSA-), prolonged febrile seizure (FSB-), saline A (SA+) and saline B (SB+) groups. SA+ and SB+ groups received different concentrations of KA (1.75 mg/kg, 1.83 μg/kg respectively) but no LPS. Changes in temperature, seizure activity and duration were recorded. Gene and protein expression of NKCC1, KCC2 and KCC2 phosphorylated serine (KCC2 ser) 940 were measured 1 h post seizure termination and on PND 15 using RT- PCR and western blot. There was an initial increase in temperature that was immediately followed by a temperature decrease and an increase in seizure severity and duration in the FSB- group. There was a decrease in KCC2 ser 940 protein expression. NKCC1 protein expression was increased in both FS groups suggesting decreased GABA receptor functionality. Therefore, the novel FSB- model resulted in more severe and sustained seizure activity by altering cotransporter gene and protein expression. This suggests that this model can be used to mimic prolonged febrile seizures and hence can be used to investigate the physiological changes accompanying this condition.

Prolonged febrile seizure history exacerbates seizure severity in a pentylenetetrazole rat model of epilepsy

Epilepsy is a debilitating neurological illness that affects all aspect of an individual life. Despite advancement in research there is little reduction in the incidence of this disease. Prolonged febrile seizure (PFS) has been linked to epilepsy however, the pathophysiology of this is still not clear. We therefore looked at the effect of PFS on the development of epilepsy in a pentylenetetrazole (PTZ) rat model of epilepsy. A total of 42 male Sprague-Dawley rats were used for the experiment. On post-natal day (PND) 14, PFS was induced in 14 rats. This was followed by the induction of epilepsy in the 14 PFS animal and 14 animals from the remaining 28 rats by an initial injection of PTZ at a dose of 60 mg/kg on day one followed by 35 mg/kg on alternate day until kindle. We looked at the effect of PFS on the onset and the stage of convulsion at kindle. We also observed it effect on the hippocampal glial fibrillary acidic protein (GFAP), synaptophysin and metabotropic glutamate receptor 3 (mGluR3) expression measured with immunofluorescence, LI Cor Tissue florescence and immunohistochemistry respectively. Our study showed that PFS reduced seizure threshold by decreasing the time it took animals to kindle and also increased the stage of convulsion. The hippocampal GFAP, synaptophysin and mGluR3 expressions where upregulated in PTZ rats with PFS history when compared to PTZ rats alone.These findings indicated that PFS may increase the severity of epilepsy and alter brain expression of GFAP, synaptophysin and mGluR3 proteins.

High incidence of status epilepticus and ongoing seizures on arrival to the hospital due to high prevalence of febrile seizures in Izumo, Japan: A questionnaire-based study

OBJECTIVES

To determine the incidence of prolonged febrile seizures and status epilepticus in the first three years of life.

METHODS

A questionnaire was sent to 1560 families between April 2016 and March 2017 before their child attended a routine health check at three years of age in Izumo, Shimane prefecture, Japan. The questionnaire included an overview of febrile seizures, including the age at which febrile seizures occurred, the duration, and how the condition was managed.

RESULTS

We received 1089 (69.8%) responses and these showed that 134 (12.3%) children had a history of febrile seizures. Fourteen children with febrile seizures (10.4%) had prolonged seizures lasting 10-30 min and six children (4.5%) had status epilepticus. Ongoing febrile seizures that did not terminate on arrival to the hospital were observed in 11 children (8.2%) with febrile seizures. The incidence rates of status epilepticus, prolonged febrile seizures including status epilepticus and ongoing febrile seizures were 184, 612 and 337 per 100,000 children aged 36 months or less, respectively.

CONCLUSIONS

There was a greater incidence of status epilepticus than previously thought, possibly due to the high prevalence of febrile seizures in Japan. Eight percent of children with febrile seizures were seizing on arrival to the hospital. These ongoing seizures requiring emergency interventions were almost twice more than status epilepticus. Thus, it is necessary to develop an early intervention for the termination of prolonged febrile seizures.

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.