Cortical dysplastic lesions (CDyLs) are often associated with severe partial epilepsies. We describe the electrographic counterpart of this high degree of epileptogenicity, manifested by continuous or frequent rhythmic epileptogenic discharges recorded directly from CDyLs during intraoperative electrocorticography (ECoG). These ictal or continuous epileptogenic discharges (I/CEDs) assumed one of the following three patterns: (1) repetitive electrographic seizures, (2) repetitive bursting discharges, or (3) continuous or quasicontinuous rhythmic spiking. One or more of these patterns were present in 23 of 34 patients (67%) with intractable partial epilepsy associated with CDyLs, and in only 1 of 40 patients (2.5%) with intractable partial epilepsy associated with other types of structural lesions. I/CEDs were usually spatially restricted, thus contrasting with the more widespread interictal ECoG epileptic activity, and tended to colocalize with the magnetic resonance imaging-defined lesion. Completeness of excision of cortical tissue displaying I/CEDs correlated positively with surgical outcome in patients with medically intractable seizures; i.e., three-fourths of the patients in whom it was entirely excised had favorable surgical outcome; in contrast, uniformly poor outcome was observed in those patients in whom areas containing I/CEDs remained in situ. We conclude that CDyLs are highly and intrinsically epileptogenic, and that intraoperative ECoG identification of this intrinsically epileptogenic dysplastic cortical tissue is crucial to decide the extent of excision for best seizure control.

Resection can alleviate both the seizures and the behavioral and cognitive abnormalities of hypothalamic hamartomas, but complications are frequent.

Summary:Purpose: Malformations of cortical development (MCDs) are usually highly epileptogenic, and their hyperexcitability could facilitate the occurrence of reflex seizures. We sought to characterize reflex seizures in patients with MCDs and refractory epilepsy.Methods: Clinical, electrographic, and neuroimaging data were reviewed in eight patients with MCDs who had reflex seizures reproduced during presurgical evaluation.Results: All eight patients had both reflex and spontaneous seizures. In six, however, drop attacks or axial myoclonic seizures occurred only upon specific sensory stimulation. Reflex seizures were induced by more than one type of stimulus in most patients, but anatomofunctional correlations could usually be invoked. Six patients had significant intellectual impairment. Surgical resection controlled seizures in two patients.Conclusions: Reflex seizures in patients with MCDs may be medically refractory and may often manifest as drop attacks or axial myoclonus. Surgical resection of focal lesions can bring reflex seizures under control. Putative mechanisms related to the relatively low frequency of reflex seizures in MCDs are discussed. Key Words: Reflex seizures-Malformations of cortical development-High degrees of epileptogenicity.Reflex seizures most commonly occur in patients with genetically related epilepsy syndromes (1-6), in which triggering stimuli are related to photosensitivity or higherorder cognitive processing (7,8). Seizure provocation through other stimuli and in patients with symptomatic epilepsies is less common, although perirolandic lesions are known to induce reflex seizures.A common assumption regarding reflex seizures is that hyperexcitable intracortical or corticosubcortical sensory circuits lead to fast and uninhibited recruiting and synchronization of neuronal pools (9-11). Converging clinical and experimental evidence suggests that malformations of cortical development (MCDs) are among the most hyperexcitable epileptogenic lesions (12,13). In addition, these malformations are often intrinsically epileptogenic

RESUMO -Fazemos uma análise das alterações neuropatológicas encontradas em 300 casos consecutivos de cirurgia da epilepsia realizadas durante período de 6 anos. O material foi predominantemente de lobo temporal (70,33%), sendo a esclerose hipocampal o diagnóstico mais frequente (44%), seguido das neoplasias (15%) e dos distúrbios da migração neuronal (10%). Os tumores mais frequentes foram o ganglioglioma (42,22%) e tumor neuroepitelial disembrioplástico (20%). Segue revisão dos diagnósticos mais comuns em epilepsia baseados nessa série e relatados na literatura.PALAVRAS-CHAVE: epilepsia, cirurgia, neuropatologia, esclerose hipocampal, ganglioglioma, DNT. Neuropathology of epilepsy: experience with 300 casesABSTRACT -We report histopathological findings in 300 consecutive surgical specimens from epilepsy surgery during 6 years. Our material was mainly from temporal lobe epilepsy (70.33%). In 44% the diagnosis was hippocampal sclerosis. There were tumors in 15% of cases and neuronal migration disorders in 10%. The most common tumors were gangliogliomas (42.22%) and dysembryoplastic neuroepithelial tumors (20%). We review the more frequent diagnosis in epilepsy surgery based on this series and comparing with literature.

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