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Patients with malformations of cortical development (MCD) present with a wide spectrum of clinical manifestations ranging from asymptomatic cases to those with epilepsy and neurodevelopmental problems. Thorough clinical delineation of patients with MCD may provide clues for future phenotype-genotype correlation studies. We studied clinical features of patients with MCD, including developmental risk factors and family history. We evaluated 10 patients with MCD at Hacettepe University Children's Hospital, Department of Pediatric Neurology. All patients underwent neurological evaluation with detailed medical and family history, and neuropsychological evaluation. Routine EEG and MRI were obtained. The patients were between 1 month and 19 years of age (mean: 6.1 +/- 4.4 years). Fifty-four patients were diagnosed with polymicrogyria (PMG), 23 patients with lissencephaly, 12 patients with schizencephaly, and 12 patients with heterotopia. Parents were relatives in 31.7% of the cases; consanguinity was most common in patients with lissencephaly and other MCDs with diffuse/bilateral involvement. Initial clinical presentation was seizures in 61.4% of the cases, developmental delays in 12.9%, and microcephaly in 9.9%. Neurological evaluation revealed most severe abnormalities in patients with lissencephaly, and relatively better outcome in patients with heterotopias. Cognitive functions were better in patients with heterotopias compared to other groups. Overall, 71.3% of patients ha epilepsy. In conclusion, initial presentation and clinical course of patients with MCD are variable and seem to be correlated with the extent of cortical involvement. Epilepsy and mental retardation are the most common problems. The most severe clinical outcome was seen in patients with lissencephaly.

Malformations of cortical development (MCD) form a spectrum of lesions produced by insult to the developing neocortex. Clinical presentation and electrophysiologic findings of MCD are variable and depend on the affected cortical area. We evaluated epilepsy, EEG, and response to antiepileptic treatment in patients with MCD with respect to the neuroimaging findings. We studied 101 patients, ranging between 1 month and 19 years of age. Fifty-four patients were diagnosed with polymicrogyria (PMG), 23 patients with lissencephaly, 12 patients with schizencephaly, and 12 patients with heterotopia. With regards to epilepsy and seizure type, 72/101 (71.3%) patients had epilepsy, and 62/101 (61.4%) patients presented with seizures. Overall, 32.7% of patients had generalized seizures, and 25.7% had complex partial seizures. Mean age at the onset of seizures was 2.7 +/- 3.4 years. The onset of epilepsy tended to be younger in patients with lissencephaly and older in patients with heterotopias. Of the cases, 79.2% had abnormal EEG (56.3% with epileptiform abnormality, 22.9% with non-epileptiform abnormality). EEG was abnormal in 44.9% (13/29) of the cases without epilepsy. EEG showed bilateral synchronous and diffuse epileptiform discharges in 90% of patients with lissencephaly. Patients with schizencephaly had mostly focal epileptiform discharges. Heterotopia cases had a high rate of EEG abnormalities (72.7%). Patients with PMG had epileptiform abnormality in 59.5% of the cases. Patients with heterotopias and PMG achieved better seizure control in comparison with the other groups. In conclusion, epilepsy is the most common problem in MCD. Epilepsy and EEG findings of patients with MCD are variable and seem to be correlated with the extent of cortical involvement.

Introduction: Malformations of the cerebral cortex are a frequent cause of pharmacoresistant epilepsies and developmental disorders., Epidemiology and Genetics: The incidence of cortical dysplasias in epilepsy surgical series varies from 12 to 40% and focal cortical dysplasias (FCD) are one of the most common neuropathological findings in resection specimens from pediatric patients undergoing cortical resections for the treatment of refractory epilepsy., Macroscopy and Histopathology: Surgical specimens in FCD may appear normal macroscopically, but in some cases, widening of the cortex with poor demarcation from the underlying white matter is noted. In milder dysplasias, the main pathological feature is disorganization of the cortical architecture ("dislamination") with less striking neuronal and glial cytopathology. Histopathology shows an excess of neurons in layer I, including Cajal-Retzius cells, clusters of neurons, marginal glioneuronal heterotopias, and a persistent subpial granule cell layer. The hallmarks of FCD are disorganization of the laminar architecture and of the cytology of individual neurons. In many cases, layer I remains hypocellular and distinct from deeper laminae, but lower cortical layers may be ill-defined or broken up by the presence of many large and randomly located abnormal and cytomegalic neurons; depending on their morphology, referred to as "giant neurons," "immature neurons," or "dysmorphic neurons." The other pathognomonic cell type associated with FCD is the "balloon cell." These cells were originally considered to be of astrocytic lineage; however, there is evidence that they are in effect "balloon neurons.", Immunohistochemistry and Structural Findings: Immunohistochemistry is not essential in making the diagnosis of FCD or microdysgenesis but allows further characterization of cell types.

Focal cortical dysplasias (FCD) are defined as circumscribed malformations of cortical development. They result from an impairment of neuronal proliferation, migration and differentiation. In the diagnosis of focal epilepsy FCD prevalence ranges between 5% and 25%, depending on patient collective and imaging techniques. Several 'cryptogenic' epilepsies may be caused by FCD but have not been diagnosed because of the lack of high-quality magnetic resonance imaging assessment. Retrospective analysis of patients who have undergone epilepsy surgery can be biased because of the fact that they represent a mere subset of potential FCD diagnoses. Epilepsy typically manifests within the first years of life, but has been documented up to the age of 60 years. Cognitive impairment commonly accompanies early onset. Epilepsy is often refractory to antiepileptic drug (AED) treatment. Clinical observations and pathophysiological findings illustrate intrinsic epileptogenicity. Upregulation of drug transporter proteins has been found in FCD tissue. There is no specific drug treatment in FCD, as any AED used in focal epilepsy could prove effective. A sequential AED therapy should be designed individually and take side effects as well as developmental progresses into consideration. Fifty to sixty-five percent of FCD patients are rendered seizure-free after surgery. Presurgical evaluation should be initiated after two unsuccessful AED trials. Both risks and potential benefits regarding seizure control and developmental impairment need to be considered on an individual basis when deciding between surgical intervention and conservative treatment. Current knowledge on epilepsy course and psychomotor development in FCD is limited in the absence of qualified long-term studies combining imaging with cognitive evaluation.

Polymicrogyria is a relatively common malformation of cortical development, characterised by multiple small gyri with abnormal cortical lamination. The different forms of polymicrogyria encompass a wide range of clinical, aetiological, and histological findings. Advances in imaging have improved the diagnosis and classification of the condition. The molecular basis of polymicrogyria is beginning to be elucidated with the identification of a gene, GPR56, for bilateral frontoparietal polymicrogyria. Functional studies of the GPR56 gene product will yield insights not only into the causes of polymicrogyria but also into the mechanisms of normal cortical development and the regional patterning of the cerebral cortex. Based on imaging studies, several other region specific patterns of polymicrogyria have been identified, and there is increasing evidence that these may also have a significant genetic component to their aetiology. This paper reviews current knowledge of the different polymicrogyria syndromes, with discussion of clinical and imaging features, patterns of inheritance, currently mapped loci, candidate genes, chromosomal abnormalities, and implications for genetic counselling.

Purpose: The main features of congenital bilateral perisylvian syndrome (CBPS) are pseudobulbar palsy, cognitive deficits, epilepsy, and perisylvian abnormalities on imaging studies, however, the clinical spectrum of this syndrome is much wider than previously believed and may vary from minor speech difficulties to severely disabled patients. The objective of this study was to present the different imaging and clinical findings of 17 patients with CBPS, their genetic background, and the occurrence of prenatal injury during their pregnancies., Methods: We evaluated 17 consecutive patients with CBPS and divided them into two groups according to the imaging findings: (a) diffuse polymicrogyria around the sylvian fissure and (b) posterior polymicrogyria at the posterior parietal regions. They were systematically interviewed regarding history of prenatal events during their pregnancies, family history of speech difficulties, epilepsy, or other neurologic abnormality., Results: There were seven women, ages ranging from 3 to 41 years (mean, 11.5; median, 7 years). Seven patients had bilateral posterior parietal polymicrogyria (BPPP), and 10 had diffuse bilateral perisylvian polymicrogyria. All seven patients with BPPP had only minor speech difficulties, none had epilepsy, and all but one had a family history of epilepsy or cortical dysgenesis. In contrast, 10 patients with diffuse bilateral perisylvian polymicrogyria had pseudobulbar palsy, four had epilepsy, eight had a history of a major prenatal event, and only four had a family history of epilepsy or developmental delay., Conclusions: These findings suggest that diffuse bilateral perisylvian polymicrogyria appears to be more related to injuries caused by environmental factors, whereas BPPP has a stronger genetic predisposition. In addition, BPPP appears to have a wider clinical spectrum than previously believed, and may represent a milder extreme within the spectrum of CBPS.

Objectives: Various genetic and acquired factors have been proposed as being etiologically important in cortical dysgenesis. It has been suggested that fetal, developmental abnormalities may be induced by transient, circulatory instability in monochorionic twinning due to feto-fetal transfusions. We report the discordant occurrence of a malformation of cortical development in monozygotic, monochorionic twins, and discuss the findings and possible pathogenetic mechanisms., Material and Methods: The twins were females, 30 years of age, one of them suffering from uncontrolled localization-related epilepsy. Neurological deficits or mental retardation were not present. Genetic analysis, brain MRI, and a neuropsychological test battery were carried out., Results: DNA analysis verified monozygocity. MRI showed a unilateral grey matter heterotopion and a contralateral temporal arachnoid cyst in the affected twin. Neuro-psychological assessment revealed no corresponding focal cognitive deficits, but an overall slightly lowered performance in the affected twin., Conclusion: Discordant affection of focal, cortical dysgenesis in monozygotic twins creates a particular opportunity to assess the consequences of such a disorder. The fact that only a mild generalized influence on cognitive functioning was demonstrated in this case, is possibly due to the plasticity of the fetal brain. According to current, obstetrical literature, the unique embryology of monochorionic twinning may predispose to vascular events in early fetal life. As ultrasound studies now indicate that a large proportion of pregnancies start out as twin products, we hypothesize that the "vanishing twin" syndrome and its potential hemodynamic hazard to the surviving fetus may be an etiological factor in malformations of cortical development, even in singletons.

Purpose: Polymicrogyria (PMG) is often associated with symptomatic focal epilepsy and neurologic dysfunction. We investigated the clinical and laboratory features of a group of children with congenital hemiparesis, unilateral polymicrogyria on magnetic resonance imaging (MRI), and a peculiar epileptic syndrome., Methods: Twelve patients (seven girls and five boys) with a mean age of 7.8 years (range, 5-13 years) were studied. All patients underwent clinical evaluation, computed tomography (CT) and MRI scanning, and neuropsychological assessment at initial examination. Patients were followed up from 1 to 7 years (mean, 4.5 years)., Results: Partial motor seizures with secondary generalization with onset between age 1 and 6 years (mean age, 2 years) were recorded in all patients. The course of epilepsy was similar in all patients with development of atypical absences, negative myoclonus, and gait difficulties. EEG recording demonstrated continuous spike-wave or bilateral abnormality throughout. Frequent relapses of the atonic and myoclonic seizures were seen in seven patients. However, during follow-up, seven patients were seizure free, and the others have not developed this particular seizure pattern. A single case underwent cortical resection 23 months ago and has had no seizures since then. Mental retardation was mild in nine and moderate in three patients., Conclusions: Children with unilateral polymicrogyria may develop a syndrome of negative myoclonus seizures that appears to be age specific and responsive to antiepileptic drug (AED) treatment. Despite limited follow-up time, a good outcome was observed in most cases.

The role of the glutamate receptor GluR3 in Rasmussen's encephalitis is actively under investigation. Autoimmune processes with this receptor as the target are currently theorized. We provide an additional case of pathologically proved Rasmussen's encephalitis (with concomitant cortical dysplasia) in the presence of antibodies against the GluR3 receptor.