Biphasic clinical course and early white matter abnormalities may be indicators of neurological sequelae after status epilepticus in children

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.

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.

Long-term white matter tract reorganization following prolonged febrile seizures

Objective

Diffusion magnetic resonance imaging (MRI) studies have demonstrated acute white matter changes following prolonged febrile seizures (PFS), but their longer‐term evolution is unknown. We investigated a population‐based cohort to determine white matter diffusion properties 8 years after PFS.

Methods

We used diffusion tensor imaging (DTI) and applied Tract‐Based Spatial Statistics for voxel‐wise comparison of white matter microstructure between 26 children with PFS and 27 age‐matched healthy controls. Age, gender, handedness, and hippocampal volumes were entered as covariates for voxel‐wise analysis.

Results

Mean duration between the episode of PFS and follow‐up was 8.2 years (range 6.7–9.6). All children were neurologically normal, and had normal conventional neuroimaging. On voxel‐wise analysis, compared to controls, the PFS group had (1) increased fractional anisotropy in early maturing central white matter tracts, (2) increased mean and axial diffusivity in several peripheral white matter tracts and late‐maturing central white matter tracts, and (3) increased radial diffusivity in peripheral white matter tracts. None of the tracts had reduced fractional anisotropy or diffusivity indices in the PFS group.

Significance

In this homogeneous, population‐based sample, we found increased fractional anisotropy in early maturing central white matter tracts and increased mean and axial diffusivity with/without increased radial diffusivity in several late‐maturing peripheral white matter tracts 8 years post‐PFS. We propose disruption in white matter maturation secondary to seizure‐induced axonal injury, with subsequent neuroplasticity and microstructural reorganization as a plausible explanation.

Inflammatory mediators in human epilepsy: A systematic review and meta-analysis

BACKGROUND

Accumulating evidence suggests a role for inflammation in the pathophysiology of epilepsy.

METHODS

We performed a systematic review and meta-analysis of studies that investigated inflammatory mediators in human epilepsy. Studies reporting on inflammatory mediators in serum, cerebrospinal fluid or brain tissue of epilepsy patients were included. Studies comparing patients to controls were included in a meta-analysis.

RESULTS

66 articles reporting on 1934 patients were included. IL-1ra, IL-1β, IL-6, IL-10, IFN-γ and TNF-α were the most extensively investigated proteins. Elevated levels for IL-1ra, IL-1β, IL-6 and CXCL8/IL-8 were reported in several different epilepsy etiologies and media, while other proteins were specifically increased for one etiology. IL-1α, IL-7 and IL-13, as well as the chemokines CCL2-5, -19 and -22, were increased exclusively in brain tissue. In an aggregate meta-analysis, we found significantly different protein levels for serum IL-6, IL-17 and CSF IL-1β and IL-10.

CONCLUSION

Inflammatory pathways are involved in epilepsy. Future studies may further clarify their role, and prove potential of targeted anti-inflammatory treatment.

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.

Prolonged febrile seizures cause reversible reductions in white matter integrity

Prolonged febrile seizures (PFS) are the commonest cause of childhood status epilepticus and are believed to carry a risk of neuronal damage, in particular to the mesial temporal lobe. This study was designed to determine: i) the effect of prolonged febrile seizures on white matter and ii) the temporal evolution of any changes seen.

33 children were recruited 1 month following PFS and underwent diffusion tensor imaging (DTI) with repeat imaging at 6 and 12 months after the original episode of PFS. 18 age-matched healthy control subjects underwent similar investigations at a single time point. Tract-based spatial statistics (TBSS) was used to compare fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) between patients and controls on a voxel-wise basis within the white matter skeleton.

Widespread reductions in FA along multiple white matter tracts were found at 1 and 6 months post-PFS, but these had resolved at 12 months. At one month post-PFS the main changes seen were reductions in AD but at 6 months these had predominantly changed to increases in RD.

These widespread white matter changes have not previously been noted following PFS. There are many possible explanations, but one plausible hypothesis is that this represents a temporary halting of normal white matter development caused by the seizure, that then resumes and normalises in the majority of children.

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Widespread reductions in FA occur in children after prolonged febrile seizures.

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These reductions persist up to 6 months post-PFS but resolve by 1 year.

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This may represent a seizure-related disruption of white matter development.

Seizures in 204 comatose children: incidence and outcome

Purpose

Seizures are common in comatose children, but may be clinically subtle or only manifest on continuous electroencephalographic monitoring (cEEG); any association with outcome remains uncertain.

Methods

cEEG (one to three channels) was performed for a median 42 h (range 2–630 h) in 204 unventilated and ventilated children aged ≤15 years (18 neonates, 61 infants) in coma with different aetiologies. Outcome at 1 month was independently determined and dichotomized for survivors into favourable (normal or moderate neurological handicap) and unfavourable (severe handicap or vegetative state).

Results

Of the 204 patients, 110 had clinical seizures (CS) before cEEG commenced. During cEEG, 74 patients (36 %, 95 % confidence interval, 95 % CI, 32–41 %) had electroencephalographic seizures (ES), the majority without clinical accompaniment (non-convulsive seizures, NCS). CS occurred before NCS in 69 of the 204 patients; 5 ventilated with NCS had no CS observed. Death (93/204; 46 %) was independently predicted by admission Paediatric Index of Mortality (PIM; adjusted odds ratio, aOR, 1.027, 95 % CI 1.012–1.042; p < 0.0005), Adelaide coma score (aOR 0.813, 95 % CI 0.700–0.943; p = 0.006), and EEG grade on admission (excess slow with >3 % fast, aOR 5.43, 95 % CI 1.90–15.6; excess slow with <3 % fast, aOR 8.71, 95 % CI 2.58–29.4; low amplitude, 10th centile <9 µV, aOR 3.78, 95 % CI 1.23–11.7; and burst suppression, aOR 10.68, 95 % CI 2.31–49.4) compared with normal cEEG, as well as absence of CS at any time (aOR 2.38, 95 % CI 1.18–4.81). Unfavourable outcome (29/111 survivors; 26 %) was independently predicted by the presence of ES (aOR 15.4, 95 % CI 4.7–49.7) and PIM (aOR 1.036, 95 % CI 1.013–1.059).

Conclusion

Seizures are common in comatose children, and are associated with an unfavourable outcome in survivors. cEEG allows the detection of subtle CS and NCS and is a prognostic tool.

Cortical gray matter lesions in acute encephalopathy with febrile convulsive status epilepticus

In acute encephalopathy with febrile convulsive status epilepticus (AEFCSE), subcortical white matter lesions on diffusion-weighted images are sometimes encountered on magnetic resonance imaging (MRI), such as in acute encephalopathy with biphasic seizures and late reduced diffusion (AESD). We report here a severe case of AEFCSE following respiratory syncytial virus infection, with emphasis on the cranial MRI findings. MRI in this patient showed widespread T2-hyperintensity along the cerebral cortical gray matter from day 3 to day 22. Lesions with reduced diffusion were noted on day 3 in the deep zone of gray matter of the left occipito-temporo-parietal cortex, but on day 7 they shifted to the subcortical white matter of both the cerebral hemispheres. These MRI findings provide radiologic evidence for damage to the cortical gray matter in AEFCSE. The serial change of diffusion-weighted images suggests that the cortical gray matter may be injured prior to the involvement of the subcortical white matter.

The spectrum of acute encephalopathy with reduced diffusion in the unilateral hemisphere

We describe the clinical, EEG, and MRI features of children with reduced diffusion in the unilateral hemispheres. Seven patients with reduced diffusion in the subcortical white matter of the unilateral hemisphere alone were identified. Their median age was 32 months. Human herpesvirus 6 infection was virologically proven in 2 patients and human herpesvirus 7 in 1. The initial neurological symptom was a prolonged seizure in 4, a brief seizure in 2, and delirious behavior in 1. Three patients had biphasic clinical course. Laboratory tests were unremarkable in most patients. MRI showed no abnormal findings during the acute phase, whereas reduced diffusivity in the unilateral hemisphere was seen during the subacute phase. EEG during the acute phase demonstrated marked slowing in the affected hemisphere in 1 patient, mild slowing in 4, and relatively low voltage in 1. No patients died, but 6 patients had various degrees of neurological sequelae. Acute encephalopathy with reduced diffusion in the unilateral hemisphere may be one of the representative phenotypes of acute encephalopathy.

Differences of clinical manifestations according to the patterns of brain lesions in acute encephalopathy with reduced diffusion in the bilateral hemispheres

BACKGROUND AND PURPOSE

The precise clinical characteristics of acute encephalopathy with bilateral reduced diffusion are not fully understood. We compared clinical, laboratory, and neuroimaging findings according to the patterns of brain lesions among children with reduced diffusion in the bilateral hemispheres.

MATERIALS AND METHODS

Nine patients were analyzed. The patterns of brain lesions were divided into diffuse lesions and central-sparing lesions. Diffuse lesions were defined as reduced diffusion in the whole cortex and/or subcortical white matter. Central-sparing lesions were defined as the lack of reduced diffusion in the areas around the bilateral Sylvian fissures. Clinical, laboratory, and neuroimaging findings were compared between groups.

RESULTS

Five patients showed diffuse lesions and 4 showed central-sparing lesions. Coma was significantly more common in patients with diffuse lesions, whereas a biphasic clinical course was more common in those with central-sparing lesions. Outcome was worse in patients with diffuse lesions. Maximal aspartate aminotransferase, alanine aminotransferase, and kinase levels were also significantly higher in patients with diffuse lesions. In 2 patients with diffuse lesions, diffusion-weighted images during the acute phase revealed reduced diffusion in the bilateral frontal and occipital areas, followed by diffuse lesions. No patient with central-sparing lesions showed MR imaging abnormalities during the acute phase.

CONCLUSIONS

Clinical manifestations in patients with diffuse lesions were severe, whereas those in patients with central-sparing lesions were relatively mild.

Sepsis associated encephalopathy in an infant with biliary atresia

We describe a girl with sepsis-associated encephalopathy complicating biliary atresia. At 4 months of age, decreased consciousness and repetitive seizures of the left upper and lower extremities occurred in association with fever. Pseudomonas aeruginosa was cultured from blood, while bacterial culture was negative and cell counts were normal in cerebrospinal fluid. The interleukin-6 level in the cerebrospinal fluid was markedly elevated. MRI revealed unilateral subcortical white matter lesions in the right hemisphere. She was diagnosed as having sepsis-associated encephalopathy and was treated with dexamethasone and midazolam. She achieved normal psychomotor development until the last follow-up at 19 months of age, whereas mild atrophic changes were observed in the right hemisphere.

Transient encephalopathy with reversible white matter lesions: a case report

We report on a boy with bilateral optic nerve hypoplasia and mild psychomotor retardation. At 1 year and 9 months of age, he was admitted to hospital with a cluster of febrile convulsions and unconsciousness. Magnetic resonance imaging (MRI) revealed widespread areas of high signal intensity on diffusion-weighted imaging of the deep cerebral white matter and corpus callosum. This imaging disappeared at five days of illness. No atrophy or abnormalities were noted on the 6-month follow-up MRI. Despite full recovery after the acute episode, the patient showed retarded developmental progress. We discuss the differential diagnosis for this case.

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.

Acute encephalopathy associated with influenza and other viral infections

Acute encephalopathy is the most serious complication of pediatric viral infections, such as influenza and exanthem subitum. It occurs worldwide, but is most prevalent in East Asia, and every year several hundreds of Japanese children are affected by influenza-associated encephalopathy. Mortality has recently declined, but is still high. Many survivors are left with motor and intellectual disabilities, and some with epilepsy. This article reviews various syndromes of acute encephalopathy by classifying them into three major categories. The first group caused by metabolic derangement consists of various inherited metabolic disorders and the classical Reye syndrome. Salicylate is a risk factor of the latter condition. The second group, characterized by a systemic cytokine storm and vasogenic brain edema, includes Reye-like syndrome, hemorrhagic shock and encephalopathy syndrome, and acute necrotizing encephalopathy. Non-steroidal anti-inflammatory drugs, such as diclofenac sodium and mephenamic acid, may aggravate these syndromes. Severe cases are complicated by multiple organ failure and disseminated intravascular coagulation. Mortality is high, although methylprednisolone pulse therapy may be beneficial in some cases. The third group, characterized by localized edema of the cerebral cortex, has recently been termed acute encephalopathy with febrile convulsive status epilepticus, and includes hemiconvulsion-hemiplegia syndrome and acute infantile encephalopathy predominantly affecting the frontal lobes. Theophylline is a risk factor of these syndromes. The pathogenesis is yet to be clarified, but an increasing body of evidence points to excitotoxicity and delayed neuronal death.