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Query: UMLS:C0036572 (seizures)
 80,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Dysembryoplastic neuroepithelial tumor (DNT) is a relatively newly described entity and is an important cause of intractable epilepsy. We report 32 cases of DNT who were operated and treated in our hospital over a period of 12 years. Immunostaining for various proliferative markers and tumor suppressor gene proteins was done to assess the proliferative potential of these tumors. The most common presentation was partial complex seizures followed by generalized tonic-clonic seizures, focal motor seizures, and myoclonus. The most common location was temporal lobe followed by frontal and in one patient lesion was multifocal. All patients were seizure free at the last postoperative follow-up which varies from 12 to 96 months with mean of 33.7 months. Microscopic examination showed classical histology comprising of intracortical multinodular microcystic lesions with floating neurons. Proliferative indices were very low (<1%) and tumor suppressor gene protein expression was not seen in the present study. Cortical dysplasia of the surrounding brain was observed in 37.3% of cases.
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PMID:Dysembryoplastic neuroepithelial tumor: a clinicopathological study of 32 cases. 1916 15

Recent findings on the clinical, electroencephalography (EEG), neuroimaging, and surgical outcomes are reviewed comparing patients with Palmini type I (mild) and type II (severe) cortical dysplasia. Resources include peer-reviewed studies on surgically treated patients and a subanalysis of the 2004 International League Against Epilepsy (ILAE) Survey of Pediatric Epilepsy Surgery. These sources were supplemented with data from University of California, Los Angeles (UCLA). Cortical dysplasia is the most frequent histopathologic substrate in children, and the second most common etiology in adult epilepsy surgery patients. Cortical dysplasia patients present with seizures at an earlier age than other surgically treated etiologies, and 33-50% have nonlocalized scalp EEG and normal magnetic resonance imaging (MRI) scans. 2-((18)F)Fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) is positive in 75-90% of cases. After complete resection, 80% of patients are seizure free compared with 20% with incomplete resections. Compared with type I, patients with type II cortical dysplasia present at younger ages, have higher seizure frequencies, and are extratemporal. Type I dysplasia is found more often in adult patients in the temporal lobe and is often MRI negative. These findings identify characteristics of patients with mild and severe cortical dysplasia that define surgically treated epilepsy syndromes. The authors discuss future challenges to identifying and treating medically refractory epilepsy patients with cortical dysplasia.
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PMID:Assessment and surgical outcomes for mild type I and severe type II cortical dysplasia: a critical review and the UCLA experience. 1917 85

Cortical dysplasia (CD) is the most common malformation of cortical development in epilepsy surgery patients. Patients with mild Palmini type I CD represent about 50% of the surgical cases, and these lesions tend to occur most often in the temporal lobe, often associated with hippocampal sclerosis. By comparison, patients with severe type II CD present at younger ages, often with multilobar extratemporal lesions, and more aggressive seizures. The presurgical evaluation in CD patients can be challenging, as no single test is 100% accurate. Based on retrospective cohort studies, the accuracy of investigations are: interictal scalp electroencephalography (EEG), 50%; ictal scalp EEG, 65%; magnetic resonance imaging (MRI), 66%; fluorodeoxyglucose-positron emission tomography (FDG-PET), 81%; and ictal single photon emission computed tomography (SPECT), 57%. Intracranial electrodes are used in about 50% of patients with CD. Contemporary series report that 62% of patients with CD are seizure free after resective neurosurgery, with higher rates for complete (77%) compared with incomplete (20%) removal of the lesion. Morbidity (<3%) and mortality (0.2%) are low for patients with CD undergoing epilepsy neurosurgery. Future challenges include the noninvasive identification of patients with CD with 100% accuracy, evaluation of long-term outcomes in surgical patients, and devising new treatments based on a better understanding of the neurobiology leading to seizures in CD tissue.
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PMID:Challenges in the surgical treatment of epilepsy patients with cortical dysplasia. 1976 53

A consecutive, retrospective analysis of seizure control and quality of life was performed among 83 pediatric patients undergoing epilepsy surgery at Children's Hospital of Wisconsin. Seizure outcomes were generally favorable, with 68.7% class I outcomes; class II, 12%; and class III, 19.3%. Seizure freedom was highest among temporal lobectomies (84.2%) and hemispherectomies (76.2%). Outcomes among hemispherectomies were substantially superior to those of multilobar resections. Cortical dysplasia was associated with lower seizure freedom, at 57.5%. Among age groups, seizure-free outcomes in infants were lowest, at 50%. The lower infant seizure-free rate was likely attributable to frequency of multilobar resections and type of pathology (cortical dysplasia). Quality-of-life measures generally paralleled seizure outcomes. These results indicate that epilepsy surgery in children with intractable epilepsy can result in significant improvements in seizure control, quality of life, and development. Anticipated type of surgery, presumed location of epileptogenic site, absence of a defined lesion on magnetic resonance imaging scan of the brain, and patient's age should not prevent surgical evaluations of children with intractable epilepsy.
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PMID:Epilepsy surgery outcomes: quality of life and seizure control. 2000 57

Kabuki syndrome is a rare multiple anomaly syndrome characterized by a peculiar face, skeletal and dermatoglyphic anomalies, postnatal growth retardation and mental retardation. We report a case of Kabuki syndrome with unilateral perisylvian cortical dysplasia. This two-year old boy was referred to our hospital at 3-months of age for his growth retardation and muscle hypotonia. Because of his peculiar face, brachydactyly V and fingertip pad, we diagnosed him as having Kabuki syndrome. His MRI revealed cortical dysplasia along the left sylvian fissure. However, neither epileptic seizures nor epileptiform discharges on electroencephalogram were observed. Cortical dysplasia is a relatively rare brain malformation among the central nervous system anomalies accompanying with this syndrome. We have to take into consideration the likely onset of epilepsy in this patient because it is one of the most frequent neurological consequences of cortical dysplasia.
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PMID:A Japanese patient with Kabuki syndrome and unilateral perisylvian cortical dysplasia. 2044 62

Cortical dysplasia is often associated with intractable seizures. Studies in animal models have described changes in inhibitory and excitatory synaptic function that contribute to hyperexcitability. The role of changes in intrinsic excitability and abnormal dendritic properties has received less attention. Changes in hyperpolarization-activated nonselective cation (HCN) channels have been implicated in several models of epilepsy. Herein we review evidence for alterations in HCN channels and dendritic morphology in the rat freeze-lesion model of cortical dysplasia. Immunocytochemical HCN1 staining, typically seen in the apical dendrites of layer V pyramidal cells in normal cortex, was greatly reduced in the region adjacent to the freeze-induced microgyrus. Although staining was preserved in layer I, fewer dendrites were stained in upper cortical layers. Deeper cortical layers were virtually devoid of immunoreactivity. Examination of biocytin-labeled pyramidal cells revealed markedly altered dendritic trees in the lesioned animals. In addition, resting membrane properties were altered and a subpopulation of neurons with abnormal dendritic arbors was present. These changes are likely to interact with the previously reported synaptic changes in this model of cortical dysplasia. HCN channel alterations are a potentially important cellular mechanism underlying hyperexcitability in cortical dysplasia.
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PMID:Abnormal pyramidal cell morphology and HCN channel expression in cortical dysplasia. 2061 1

Cortical dysplasia of various types, reflecting abnormalities of brain development, have been closely associated with epileptic activities. Yet, there remains considerable discussion about if/how these structural lesions give rise to seizure phenomenology. Animal models have been used to investigate the cause-effect relationships between aberrant cortical structure and epilepsy. In this article, we discuss three such models: (1) the Eker rat model of tuberous sclerosis, in which a gene mutation gives rise to cortical disorganization and cytologically abnormal cellular elements; (2) the p35 knockout mouse, in which the genetic dysfunction gives rise to compromised cortical organization and lamination, but in which the cellular elements appear normal; and (3) the methylazoxymethanol-exposed rat, in which time-specific chemical DNA disruption leads to abnormal patterns of cell formation and migration, resulting in heterotopic neuronal clusters. Integrating data from studies of these animal models with related clinical observations, we propose that the neuropathologic features of these cortical dysplastic lesions are insufficient to determine the seizure-initiating process. Rather, it is their interaction with a more subtly disrupted cortical "surround" that constitutes the circuitry underlying epileptiform activities as well as seizure propensity and ictogenesis.
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PMID:Are developmental dysplastic lesions epileptogenic? 2261 7

Cortical dysplasia is the most common etiology in children and the third most frequent finding in adults undergoing epilepsy neurosurgery. The new International League Against Epilepsy (ILAE) classification grades isolated cortical dysplasia into mild type I (cortical dyslamination), severe type II (dyslamination plus dysmorphic neurons and balloon cells), and dysplasia associated with other epileptogenic lesions (type III). Multilobar type II lesions present at an earlier age and with more severe epilepsy compared with focal type I abnormalities, often in the temporal lobe, and these findings are reflected in types and age of operations for cortical dysplasia. Presurgical evaluation of patients with epilepsy from cortical dysplasia can be challenging. Interictal and ictal scalp electroencephalography (EEG) accurately localizes cortical dysplasia with 50-66% accuracy. Structural magnetic resonance imaging (MRI) is negative in roughly 30% of cases, most often linked with mild type I cases. FDG-PET can be 80-90% accurate, but is not 100% sensitive. Chronic intracranial electrodes are used in about 50% of cases with cortical dysplasia, but often do not capture restricted ictal-onset zones. About 60% of patients with cortical dysplasia are seizure free after epilepsy neurosurgery, with much higher rates of becoming seizure free with complete (80%) compared with incomplete (20%) resections. The most common reason for incomplete resection is the risk of an unacceptable neurologic deficit. Future challenges include better tools in identifying subtle forms of type I cortical dysplasia, and development of adjunctive treatments from basic research for those undergoing incomplete resections.
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PMID:Surgical treatment of epilepsy associated with cortical dysplasia: 2012 update. 2294 27

Cortical dysplasia (CD) is one of the most important causes of intractable epilepsy. The precise mechanisms of epileptogenesis in CD are not known. Using CD animal models, we attempted to understand the mechanisms and efficacy of various antiepileptic drugs. In two separate studies, we assessed (1) the effects of levetiracetam (LEV) and vagus nerve stimulation (VNS) on pentylenetetrazol (PTZ)-kindled rats, and (2) the effects of LEV and topiramate (TPM) on rats with CD and hyperthermia (HT). In the HT-induced rats with CD study, LEV and TPM decreased both the intensity of seizures and the number of rats with seizure. In these studies, we used immunocytochemistry (occludin, glial fibrillary acidic protein [GFAP], and P-glycoprotein [Pgp antibodies] and electron microscopy (EM) (sodium fluorescein [NaFlu]) and horseradish peroxidase [HRP]) to assess blood-brain barrier (BBB) integrity. Both LEV and TPM protected BBB. In PTZ- kindled rats with CD, both LEV and VNS reduced the duration of seizures. Immunocytochemistry and EM revealed no BBB impairment in any of the treatment groups. In a second set of experiments, we assessed the relationship between disruption of vascular components and epileptogenesis. Astrocytic albumin uptake in focal epileptogenic lesions with vascular components suggested that dysfunction of the BBB contributes immediately to epileptogenesis, rather than simply resulting from seizure activity. Hemosiderin deposits were seen as potential epileptogenic triggers in vascular malformations (e.g., cavernomas [CA] or arteriovenous malformations [AVMs] with or without a dysplastic cortical component). However, we found strikingly high accumulation of astrocytic albumin deposits in surgically removed brain parenchyma in the vicinity of CAs and AVMs from patients with pharmacoresistant epilepsy, which suggests different pathophysiologic dispersion pathways for hemosiderin and albumin in vascular lesions.
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PMID:Blood-brain barrier, epileptogenesis, and treatment strategies in cortical dysplasia. 2313 93

Based on intracranial-video electroencephalography (EEG), histopathological features, and postoperative seizure outcome, we elucidated the epileptogenicity in patients with dysembryoplastic neuroepithelial tumor (DNT). Five patients (P1-P5) pathologically diagnosed with DNT underwent intracranial-video EEG to identify the ictal onset zone and irritative zone. We evaluated the correlations of ictal onset zone and irritative zone with the magnetic resonance imaging-visible lesion (MRI-lesion) and their histopathological features. Intracranial-video EEG located the ictal onset zone adjacent to the MRI-lesion margin in four patients with complex/simple forms of DNT subcategory, and on the MRI-lesion in P3 with a nonspecific DNT form. The irritative zone extended to surrounding regions of the ictal onset zone in all patients. Histopathologically, MRI-lesions were characterized by specific glioneuronal elements, whereas the ictal onset zone and irritative zone were represented with dysplastic cortex accompanying oligodendroglia-like cells in four (P1, P2, P4, and P5) of five patients. Cortical dysplasia was identified with typical histopathologic features in the irritative zone remote from the MRI-lesion in P5. P3, with a nonspecific form, indicated prominent component of dysplastic cortex with oligodendroglia-like cells scattered in the MRI-lesion. Lesionectomy of MRI-lesion with additional cortical resections (including the ictal onset zone and irritative zone) yielded postoperative seizure freedom (Engel Class I) in P3, P4, and P5, while P1 and P2 (with only lesionectomy) experienced postoperative residual seizure (Class II and III in each patient). Our results suggest the intrinsic epileptogenicity of DNT. The topographical correlation indicated that the dysplastic cortex accompanying oligodendroglia-like cells was more epileptogenic than the specific glioneuronal elements itself. Meticulous intracranial-video EEG analysis delineating the MRI nonvisible ictal onset zone and the irritative zone may yield better seizure outcome.
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PMID:Electrocorticographic-histopathologic correlations implying epileptogenicity of dysembryoplastic neuroepithelial tumor. 2407 79


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