Heterotopia associated with hippocampal sclerosis: an under-recognized cause of early onset epilepsy in children operated on for temporal lobe epilepsy.

Purpose: The aim of this study is to report on 52 children operated on for pharmacoresistant temporal lobe epilepsy, with special emphasis on histopathology and correlation with clinical features.

Methods: Charts were retrospectively analyzed. All children underwent comprehensive clinical, electrophysiological and radiological investigations before surgery.

Pontoneocerebellar hypoplasia: definition of MR features.

We report five patients with pontoneocerebellar hypoplasia. Because the issue of cerebellar malformations is a difficult subject, we tried to define criteria for diagnosis on MRI: a thin flat pons with disappearance of the anterior curve, a small cerebellum with predominant flattening of the hemispheres and shortened cerebellar fissures, in contrast to atrophy. The posterior fossa is not enlarged.

Immunocytochemical characterization of long-term persistent immune activation in human brain after herpes simplex encephalitis.

The clinical, virological and immunocytochemical features of three children who recovered from acute herpes simplex encephalitis (HSE) before the age of 2 years, and who developed secondary severe focal epilepsy after a symptom-free period, leading to neurosurgery 3-10 years later are described. In one child, relapse of HSE occurred immediately after surgery. In all three patients, brain sample biopsies showed abundant CD3-positive T lymphocytes with a majority of CD8 cells, and abundant activated macrophage-microglial cells, a pattern similar to that found in acute HSE.

Increased density of oligodendrocytes in childhood ataxia with diffuse central hypomyelination (CACH) syndrome: neuropathological and biochemical study of two cases.

We report neuropathological, biochemical and molecular studies on two patients with childhood ataxia with diffuse central nervous system hypomyelination (CACH) syndrome, a leukodystrophy recently defined according to clinical and radiological criteria. Both had severe cavitating orthochromatic leukodystrophy without atrophy, predominating in hemispheric white matter, whereas U-fibers, internal capsule, corpus callosum, anterior commissure and cerebellar white matter were relatively spared. The severity of white matter lesions contrasted with the rarity of myelin breakdown products and astroglial and microglial reactions.

[Cortical heterotopias: animal models and human disease].

Cortical heterotopia is defined as the misplacement of a group of neurons displaced to a precise localization in the neocortex and results from perturbed migration along the glial guide, either because of glial destruction or molecular anomalies. Heterotopic neurons are rarely dispersed but are rather grouped in nodules or bands. Heterotopic masses may lie in an ependymal or subcortical localization depending on whether they result from lack of migration or an arrested migration.

Focal cortical dysplasia and hemimegalencephaly: histological and neuroimaging correlations.

Background: The classification of cerebral cortical dysplasia is difficult and there are histological similarities between focal cortical dysplasia (FCD) and hemimegalencephaly. Objectives. To correlate the MR features and histological data of cortical dysplasias.

Early hemispherectomy in a case of hemimegalencephaly.

We report a case with hemimegalencephaly and catastrophic epilepsy treated early at 4 months by functional hemispherectomy. The boy had intractable continuous epilepsy, with seizures every 10 min, hemiparesis and absence of psychomotor acquisition. Three years after hemispherectomy, the boy is seizure free and has a mild psychomotor delay.

Distribution and submicroscopic immunogold localization of cellular prion protein (PrPc) in extracerebral tissues.

In transmissible spongiform encephalopathies (TSE), such as scrapie in animals and Creutzfeldt-Jakob disease in humans, the central event is the conversion of a host-encoded amyloidogenic protein (PrPc) into an abnormal isoform (PrPsc) that accumulates as amyloid in TSE brain. PrPc is a membrane sialoglycoprotein synthesized in the central nervous system and elsewhere. We have examined the ultrastructural localization of PrPc in numerous hamster and some human extracerebral tissues, by means of a post-embedding electron-microscopic method combined with immunogold labeling.

Antenatal thalamic lesions in the newborn: two anatomoclinical cases.

We report two cases of antenatal bilateral thalamic lesions constituted by neuronal loss, gliosis and mineralized glial or neuronal cells. No etiology could be found. Neuroradiological findings were poorly correlated with histological changes.

Transmission of the BSE agent to mice in the absence of detectable abnormal prion protein.

The agent responsible for transmissible spongiform encephalopathies (TSEs) is thought to be a malfolded, protease-resistant version (PrPres) of the normal cellular prion protein (PrP). The interspecies transmission of bovine spongiform encephalopathy (BSE) to mice was studied. Although all of the mice injected with homogenate from BSE-infected cattle brain exhibited neurological symptoms and neuronal death, more than 55 percent had no detectable PrPres.

Expression of the adrenoleukodystrophy protein in the human and mouse central nervous system.

The gene mutated in X-linked adrenoleukodystrophy (ALD), a progressive demyelinating disease, codes for a protein (ALDP) involved in very-long-chain fatty acid (VLCFA) transport. The expression of ALDP and of two peroxisomal enzymes involved in beta-oxidation of VLCFA, acyl-CoA oxidase, and catalase was studied in human and mouse brain. The pattern of expression was similar in both species.

[Corpus callosum agenesis and parasagittal interhemispheric cyst].

We report the association of a corpus callosum agenesis with a parasagittal interhemispheric cyst, without cortical malformation. This rare malformation is related to an early disorder in embryogenesis. The importance of the anatomic abnormalities compared with the good clinical status is remarkable.

Opercular malformations: clinical and MRI features in 11 children.

Opercular malformations are rare and complex brain malformations for which only very fragmented neuropathological descriptions have been reported. They are related to an abnormal development of both sylvian fissure and frontoparietal operculum. We report a retrospective clinical and MRI study of 11 patients presenting with opercular malformations.

Migrating partial seizures in infancy: a malignant disorder with developmental arrest.

Fourteen infants of both sexes had a previously unreported epileptic condition characterized by nearly continuous multifocal seizures. The first seizures occurred at a mean age of 3 months, without antecedent risk factors. At 1 to 10 months, the seizures became very frequent.

An unusual presentation of focal cortical dysplasia.

In a case of histologically proved focal cortical dysplasia, there was an absence of cortex-white matter delineation in the right parietooccipital area only on the T2-weighted images. This pattern correlated with the gross and histologic findings obtained on the resected cerebral tissue.

Ultrastructural localization of cellular prion protein (PrPc) in synaptic boutons of normal hamster hippocampus.

The cellular prion protein (PrPc) is a membrane sialoglycoprotein synthesized in the central nervous system and extraneural tissues. Its post-translational modification produces an accumulation of abnormal isoform PrPsc found in brains of transmissible neurodegenerative disorders in animals (scrapie and bovine spongiform encephalopathy) and humans (Kuru, Creutzfeldt-Jakob disease, Gerstmann-Sträussler-Scheinker syndrome). One major unanswered question relative to PrPc concerns its physiological role in brain neurons, depending largely on the limited knowledge of its subcellular localization.

Clinical, biochemical, and molecular analysis of a maternally inherited case of Leigh syndrome (MILS) associated with the mtDNA T8993G point mutation.

We report a new case of Leigh disease (subacute necrotizing encephalomyelopathy) in a girl with mitochondrial DNA (mtDNA) mutation in the ATPase6 gene at nucleotide position 8993. Sequence analysis of mtDNA revealed a T-to-G transversion at nucleotide position 8993 in the ATPase6 gene. Southern blot restriction analysis of patient muscle mtDNA showed only a mutant pattern for the mutation 8993.

Dysembryoplastic neuroepithelial tumors in two children with neurofibromatosis type 1.

Dysembryoplastic neuroepithelial tumors (DNT) occur mainly in children and are always clinically associated with intractable complex partial seizures. In the first report, which included 39 cases, the patients had no neurological deficit and no stigmata of phacomatosis. In contrast, we observed a DNT in 2 children with a neurofibromatosis type 1.

Infantile spasms: a pathophysiological hypothesis.

Clinical and electroencephalogram (EEG) observations permit a hypothesis for the pathophysiology of infantile spasms. The triggering area(s) for spasms is probably cortical. Diffuse hyperexcitability of the immature cortex and/or diffusion of the epileptic process from a focal abnormality would allow development of hypsarrhythmia.

Reappraisal of Rasmussen's syndrome with special emphasis on treatment with high doses of steroids.

Eight patients with Rasmussen's syndrome and epilepsia partialis continua were treated with high doses of steroids, including pulses of methylprednisolone and prednisone in decreasing doses. Three patients exhibited clinical, radiological, or histological evidence of bilateral involvement. Epilepsy and focal deficit decreased within six months in seven patients.

Kainate-induced apoptotic cell death in hippocampal neurons.

We have examined the role apoptosis plays in epileptic brain damage using intra-amygdaloid injection of kainate. With the silver staining technique of Gallyas, argyrophylic (dying) neurons were observed, a few hours after the injection, in the amygdala and in the vulnerable pyramidal neurons of the hippocampal CA3 region. In both areas, cell death has apoptotic features, including: (i) nuclear chromatin condensation and marginalization with light and electron microscopy; (ii) DNA fragmentation with a typical ladder pattern on agarose gel electrophoresis; (iii) positive nuclear labelling with a selective in situ DNA fragmentation staining method.

Cardiac rhabdomyoma and tuberous sclerosis in three fetuses: a neuropathological study.

In spite of the development of modern imaging, most lesions of tuberous sclerosis (TS) remain difficult to detect before birth. Particularly, brain involvement at a fetal stage of development is poorly documented. We report three cases of fetuses examined after pregnancy was interrupted because of the detection of cardiac rhabdomyoma.

Development of mossy fiber synapses in hippocampal slice culture.

The mossy fiber synaptogenesis has been studied in hippocampal slice cultures. In vivo mossy fiber terminals contact the thorny excrescences of CA3 pyramidal neurons over a restricted portion, i.e.