Hemiconvulsion-hemiplegia syndrome and primary human herpesvirus 7 infection

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

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

Stroke-Like Presentation Following Febrile Seizure in a Patient with 1q43q44 Deletion Syndrome

Hemiconvulsion-hemiplegia-epilepsy syndrome (HHE) is a rare outcome of prolonged hemiconvulsion that is followed by diffuse unilateral hemispheric edema, hemiplegia, and ultimately hemiatrophy of the affected hemisphere and epilepsy. Here, we describe the case of a 3-year-old male with a 1;3 translocation leading to a terminal 1q43q44 deletion and a terminal 3p26.1p26.3 duplication that developed HHE after a prolonged febrile seizure and discuss the pathogenesis of HHE in the context of the patient's complex genetic background.

Focal Coxsackie virus B5 encephalitis with synchronous seizure cluster and eruption: Infantile case

Enterovirus focal encephalitis is a rare clinical entity that is characterized by focal neurological signs including seizure, hemiparesis, hemichorea, and headache, which are mainly followed by rapid spontaneous improvement. We herein describe the case of a 9-month-old boy who developed Coxsackie virus B5 (CVB5) focal encephalitis with seizure clusters in the eruption stage of roseola infantum-like illness, which were followed by rapid improvement and benign outcome. Lumbar puncture indicated pleocytosis, and CVB5 infection in the cerebrospinal fluid was subsequently identified on genome sequencing and virus isolation. Magnetic resonance imaging and electroencephalography showed no abnormal findings at the acute stage or on 2 month follow up. Although the pathogenesis of enterovirus focal encephalitis currently remains unclear, the pure synchronism of seizure cluster and eruption in this case suggests the involvement of local vascular impairment as the underlying pathogenesis.

Fatal outcome in hemiconvulsion-hemiplegia syndrome

Hemiplegia-hemiconvulsion-epilepsy syndrome is characterized by prolonged unilateral clonic seizures in a child followed by the development of hemiplegia. Focal status epilepticus results in unilateral cerebral edema of the epileptic hemisphere in the acute phase followed by cerebral hemiatrophy. Literature in the last 5 years does not describe malignant cerebral edema or resultant death. We report a case of a 3-year-old girl with hemiplegia-hemiconvulsion-epilepsy syndrome who died due to malignant cerebral edema and temporal lobe herniation. The first indication of worsening of clinical status after being seizure free was voltage suppression on continuous electroencephalography (EEG). We describe neuroimaging, EEG findings, and neuropathologic findings at autopsy and review pertinent literature. We also evaluate the evolving role of continuous EEG monitoring in the pediatric intensive care unit.

Hemiconvulsion-hemiplegia-epilepsy syndrome. Magnetic resonance findings in a 3-year-old boy

The term 'hemiconvulsion-hemiplegia-epilepsy syndrome' (HHE) was first used by Gastaut et al. to describe the se-quential combination of unilateral or predominantly unilateral clonic seizures (hemiconvulsion), occurring during the first 2 years of life, immediately followed by an ipsilateral flaccid hemiplegia lasting 7 or more days. In the following phase partial epileptic seizures occur. We report a case of HHE syndrome in a 3-year-old boy with partial seizures (hemiconvulsion lasting 15-30 minutes) followed by left hemiplegia and hyporeflexia. Magnetic resonance imaging showed diffuse and high signal hyperintensity of the whole right cerebral hemisphere. Diffusion-weighted images showed a reduction of the apparent diffusion coefficient in the subcortical region. Magnetic resonance arterio-graphy showed a narrow flow signal in the distal territory of the right middle cerebral artery. The authors emphasize the importance of neuroradiological findings in early diagnosis and in the follow-up of HHE syndrome.

Hemiconvulsion-hemiplegia-epilepsy syndrome: current understandings

Hemiconvulsion-Hemiplegia (HH) syndrome is an uncommon consequence of prolonged focal febrile convulsive seizures in infancy and early childhood. It is characterized by the occurrence of prolonged clonic seizures with unilateral predominance occurring in a child and followed by the development of hemiplegia. Neuroradiological studies showed unilateral edematous swelling of the epileptic hemisphere at the time of initial status epilepticus (SE). This acute phase is followed by characteristic cerebral hemiatrophy with subsequent appearance of epilepsy, so called Hemiconvulsion-Hemiplegia-Epilepsy (HHE) syndrome. The etiologies and the underlying mechanisms remain to be understood. Using a review of the literature, we summarized the data of the last 20 years. It appears that idiopathic HH/HHE syndrome is the most common reported form. The basic science data suggest that immature brain is relatively resistant to SE-induced cell injury. Several factors might contribute to the pathogenesis of HH/HHE syndrome: 1. prolonged febrile seizure in which inflammation may worsen the level of cell injury; 2. inflammation and prolonged ictal activity that act on blood-brain-barrier permeability; 3. predisposing factors facilitating prolonged seizure such as genetic factors or focal epileptogenic lesion. However, these factors cannot explain the elective involvement of an entire hemisphere. We draw new hypothesis that may explain the involvement of one hemisphere such as maturation of brain structure such as corpus callosum or genetic factors (CACNA1A gene) that are specifically discussed. An early diagnosis and a better understanding of the underlying mechanisms of HHE are needed to improve the outcome of this condition.

Hemiconvulsion-hemiplegia-epilepsy syndrome in South African children: insights from a retrospective case series

INTRODUCTION

Hemiconvulsion-hemiplegia-epilepsy (HHE) syndrome is a recognized sequel of febrile partial status in children younger than 4 years.

OBJECTIVE

To describe the clinical features, neuroradiology and outcome in 8 South African children with HHE syndrome.

METHOD

A retrospective descriptive study of 8 consecutive cases of HHE syndrome presenting to tertiary hospitals in the Western Cape over a 2 year period.

RESULTS

The median age of onset of convulsive status was 16 months (range: 9-36 months). Gender distribution was equal. The duration of the initial episode of status exceeded 2 h in all children. All children were reported to have been developmentally normal prior to the onset of the first seizure and none previously suffered seizures or had a family history of febrile seizures and epilepsy. In 7 of the 8 cases the initial seizure was not associated with fever or preceding illness. Imaging demonstrated cerebral hemiatrophy in all and additional crossed cerebellar atrophy in 2 children. Moderate to severe intellectual disability ensued in the majority of children. The severity of the intellectual disability correlated with the degree of the motor deficit and occurred irrespective of the cerebral hemisphere involved.

CONCLUSION

In contrast to developed countries, HHE syndrome is still prevalent in South Africa. The neurological morbidity in South African children is significant and highlights the need for improved emergency care of status epilepticus.

Hemiconvulsion-hemiplegia-epilepsy syndrome associated with CACNA1A S218L mutation

Hemiconvulsion-hemiplegia-epilepsy syndrome involves sudden and prolonged unilateral seizures, followed by transient or permanent hemiplegia and epilepsy during infancy or early childhood. Some patients with familial hemiplegic migraine and demonstrating the S218L mutation in CACNA1A experience severe attacks with unilateral cerebral edema after trivial head trauma. We report on a 5-year-old Japanese girl presenting with hemiconvulsion-hemiplegia-epilepsy syndrome after infection with parvovirus B19. Magnetic resonance imaging performed 2 days after admission revealed cerebellar atrophy and marked hyperintensity in the left hemisphere on T(2)-weighted and diffusion-weighted imaging. Magnetic resonance angiography performed 7 days after admission demonstrated obliteration of the left proximal middle cerebral artery in the acute phase. However, this finding was not evident on brain angiography performed 25 hours after magnetic resonance angiography. Genetic analysis of familial hemiplegic migraine revealed a heterozygous S218L mutation in CACNA1A. Taken together, these results suggest that vasospasms of cerebral vascular smooth muscle, with possible cortical spreading depression, may have caused the hemiconvulsions and hemiplegia in the left hemisphere. This case report is the first, to the best of our knowledge, to associate CACNA1A with hemiconvulsion-hemiplegia-epilepsy syndrome and familial hemiplegic migraine, and to suggest that similar pathogenic mechanisms may underlie these two disorders.

Multiplex real-time PCR for the simultaneous detection of herpes simplex virus, human herpesvirus 6, and human herpesvirus 7

A simultaneous detection system to quantify HSV, HHV-6, and HHV-7 DNA via multiplex real-time PCR using different fluorochromes was developed. The minimum quantitative level established via this multiplex assay was four copies per reaction for HSV type 1, four copies for HHV-6, and three copies for HHV-7, respectively. The dynamic range encompassed at least six orders of magnitude. The system was specific and reproducible even in the presence of large amounts of other viral DNA. We then applied this multiplex real-time PCR assay to 105 CSF specimens obtained from subjects less than 15 years old in whom a diagnosis of viral encephalitis/encephalopathy was suspected on clinical grounds. The detection rate for each viral DNA was 6.7% for HSV, 9.5% for HHV-6, and 1.9% for HHV-7. These results indicate that our system is reliable and may be useful for the rapid diagnosis of viral encephalitis/encephalopathy.

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.

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.

Isolated cortical signal increase on MR imaging as a frequent lesion pattern in sporadic Creutzfeldt-Jakob disease

BACKGROUND AND PURPOSE

Hyperintense basal ganglia on MR imaging support the diagnosis of sporadic Creutzfeldt-Jakob disease (CJD). Our aim was to study the frequency of patients with sporadic CJD presenting with and without characteristic basal ganglia lesions on MR imaging and to examine the corresponding patient characteristics.

MATERIALS AND METHODS

Fluid-attenuated inversion recovery (FLAIR) and diffusion-weighted images (DWI) of 55 patients with CJD were assessed for signal-intensity increase (FLAIR) or restricted diffusion (DWI) in 7 cortex regions and the basal ganglia, thalamus, and cerebellum. Patient characteristics as well as electroencephalography, CSF, and codon 129 genotype of the prion protein gene (PRNP) were correlated with the most frequent MR imaging lesion patterns.

RESULTS

Two major lesion patterns were identified by DWI: cortex and basal ganglia involvement (two thirds) and isolated cortex involvement (one third). In the latter patient group, the cortex involvement was widespread (at least 3 regions affected in 89% on DWI) and usually included the frontal and parietal lobes (78%). The length of the disease course was significantly prolonged (median, 12 versus 5 months). No significant differences were observed concerning electroencephalography and CSF findings and codon 129 genotype distributions. Of 4 patients with normal MR imaging findings, the CSF was positive for the 14-3-3 protein in 3.

CONCLUSION

A high number of patients with CJD present without basal ganglia lesions on MR imaging. Isolated cortex involvement on DWI and FLAIR should lead to suggestion of CJD, even if the disease course is only slowly progressive. Additional 14-3-3 protein analysis in the CSF may support the CJD diagnosis.

Decompressive hemicraniectomy in a space-occupying presentation of hemiconvulsion–hemiplegia–epilepsy syndrome

A case of an acute life-threatening presentation of hemiconvulsion-hemiplegia-epilepsy (HHE) syndrome requiring an urgent decompressive hemicraniectomy is described. A 9 month-old baby had a status epilepticus following a sustained fever, leading to a comatose state and a right pupillary dilatation associated with a left hemiplegia. The MRI showed a swelling right hemisphere with marked temporal herniation. The baby underwent a decompressive right hemicraniectomy with temporal cortical biopsies. The post-operative course was favourable. The histological findings were unspecific, showing a gliotic spongiosis with disseminated granular cells. The post-operative MRI depicted a right hemisphere atrophy. To our knowledge, a space-occupying presentation of HHE syndrome requiring surgical decompression has never been described before while only a few reports dealt with the neuropathological aspects of this syndrome.

Neuropathological and MRI findings in an acute presentation of hemiconvulsion-hemiplegia: a report with pathophysiological implications

The mechanisms underlying the hemiconvulsion-hemiplegia-epilepsy syndrome (HHE) remain unclear. The current proposed pathogenic mechanism is a neuronal injury induced by venous thrombosis and/or hypoxia. Previous abnormalities of the brain were suggested as underlying mechanism.

MATERIALS AND METHODS

We report a patient who presented acutely with hemiconvulsion-hemiplegia (HH) syndrome, but unfortunately died. We discuss the possible pathophysiology of the HH syndrome and possible therapeutic implications utilizing the data from neuroimaging and pathological studies. Post-mortem examination was performed including immunohistochemistry and electron microscopy of the brain tissue.

RESULTS

The abnormalities in diffusion-weighted imaging indicate cytotoxic edema of the epileptic hemisphere. The pathological studies confirmed a right homogenous hemispheric edema without evidence of any malformation, inflammatory, infectious or metabolic disease. We found axonal damages in the right thalamus confirmed by anti-neurofilament staining.

DISCUSSION

The pathological studies suggest that cytotoxic edema is responsible for neuronal damage. In HH syndrome, two mechanisms playing a role in the development of a later epilepsy could suggest delayed cell death induced by cytotoxic edema and/or thalamic dysfunction causing a disruption of thalamo-cortical circuit. In acute presentation, the use of anti-edema therapy should be discussed to prevent the cell injury.

Hemiconvulsion-hemiplegia-epilepsy syndrome: early magnetic resonance imaging findings and neuroradiological follow-up

We describe a case of hemiconvulsion-hemiplegia-epilepsy (HHE) syndrome documented by longitudinal magnetic resonance imaging (MRI). A two-year and nine-month-old boy had a prolonged hemiconvulsion during fever followed by right hemiparesis. Seven days later the imaging abnormality on T2 and diffusion-weighted images (DWI) was limited to the white matter of the left hemisphere. One month later severe gliosis and unilateral brain atrophy were already evident. MRI is useful in the early stages of prolonged seizures and T2 and DWI abnormalities appear to be well correlated with parenchymal damage that results from sustained ictal activity. The neuroradiological findings in our case and in the few HHE patients reported in the literature seem to be very characteristic and, if confirmed in larger series, could permit an early diagnosis.

HHV-6 encephalopathy with cluster of convulsions during eruptive stage

The features of a characteristic type of encephalopathy caused by human herpesvirus-6 are presented. All patients have clusters of brief convulsions during the stage of skin eruptions. Sometimes the encephalopathy resulted in hemiplegia or mental retardation. Because the clinical course is similar, we propose a subtype of encephalopathy "human herpesvirus-6 encephalopathy with cluster of convulsions in eruptive stage" for further studies of pathophysiology and treatment.

Serial diffusion-weighted MRI in hemorrhagic shock and encephalopathy syndrome

This report presents a case of hemorrhagic shock and encephalopathy syndrome. In the acute stage, brain magnetic resonance imaging demonstrated symmetrical hyperintensity on diffusion-weighted images and hypointensity on the apparent diffusion coefficient maps in the subcortical white matter. Whereas the abnormal diffusion-weighted imaging signals of the white matter resolved in the subacute stage, the adjacent gray matter became hyperintense on diffusion-weighted images and hypointense on apparent diffusion coefficient maps. The evolution of diffusion-weighted imaging signals is thus considered to be one of the early findings in hemorrhagic shock and encephalopathy syndrome.

Epilepsy syndromes in infancy

An increasing number of infantile epilepsy syndromes have been recognized. However, a significant number of infants (children aged 1-24 months) do not fit in any of the currently used subcategories. This article reviews the clinical presentation, electroencephalographic findings, evolution, and management of the following entities: early infantile epileptic encephalopathy, early myoclonic epilepsy, infantile spasms/West syndrome, severe myoclonic epilepsy of infancy, myoclonic-astatic epilepsy, generalized epilepsy with febrile seizures plus, malignant migrating partial seizures of infancy, hemiconvulsions-hemiplegia-epilepsy, benign myoclonic epilepsy, and benign familial/nonfamilial infantile seizures. Issues related to their classification are addressed.