Epileptic disorders : international epilepsy journal with videotape
-
Case Reports
Video-EEG evidence of lateralized clinical features in primary generalized epilepsy with tonic-clonic seizures.
Whether cortical or subcortical structures, specifically the thalamus, play the dominant role in generating primary generalized seizures has been the subject of long debate. Most experimental data implicate a hyperexcitable cortical generator of spike-and-wave activity, with the thalamus quickly recruited to sustain the generalized oscillations through a reverberating thalamocortical network. However, there is little clinical evidence to support the cortical generator hypothesis. We present video-EEG recordings of generalized tonic-clonic seizures in three patients with proven primary generalized epilepsy (PGE), all of whom showed a consistent pattern of lateralized seizure onset compatible with a focal frontal lobe generator. ⋯ Tonic-clonic seizures are presumed to be generalized from onset in patients with PGE. However, video-EEG monitoring in these patients is rarely performed and the actual clinical features of the seizures maybe underappreciated. The demonstration of sustained lateralization at onset in our patients, with features clinically indistinguishable from focal onset frontal lobe seizures, is compatible with the hypothesis of a focal region of cortical hyperexcitability situated in the frontal lobes of some patients with PGE. Whether this cortical generator is autonomous or "triggered" by ascending, possibly normal, thalamocortical volleys is unresolved.
-
Twelve patients suffering from intractable epilepsy and presenting with radiological evidence of diffuse hemispheric involvement of a dysplastic process, were treated by disconnective hemispherectomy, either functional hemispherectomy or peri-insular hemispherotomy. The median age at surgery was 4.5 years old and the interval between seizure onset and surgery, 3 years. All patients underwent a presurgical evaluation that led to the suggestion of disconnective hemispherectomy. ⋯ There was one unexplained death and one case of early hydrocephalus. Hemispherectomy offers the possibility to improve seizure control in the majority of patients undergoing surgery for extensive dysplastic pathology of the hemisphere. Disconnective techniques reduce the rate of complications in this specific pathology.
-
A brief survey of cortical development is presented, focusing on neuronal migration and its alterations. Corticogenesis is achieved through ordered temporospatial steps, via the formation of transient structures, and successive waves of cell proliferation and migration (followed by cell differentiation and maturation), and apoptotic cell death. The appearance of the proliferative ventricular zone and marginal zone, and of the superficial primordial plexiform layer, is followed by the formation of the prospective layer I, of the subplate, whose neurons are destined to die, and of the cortical plate that will give rise to layers II-VI. ⋯ Disorders of this complex process lead to a wide range of alterations, and focal derangements of cortical organization have been grouped under the term focal cortical dysplasia (FCD). As the result of a neuropathological revision of FCD cases with intractable epilepsy, a novel classification comprising three subgroups of FCD has been introduced, and is supported by electroclinical and neuroimaging data, as well as by the postsurgical outcome of patients: i). architectural dysplasia, characterized by altered cortical lamination; ii). cytoarchitectural dysplasia, with the occurrence of giant neurons besides cortical dyslamination; iii). Taylor-type cortical dysplasia, in which altered cortical lamination is consistently associated with the occurrence of giant, dysmorphic and ectopic neurons, and frequently with the so-called balloon cells.