ABSTRACT
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.
Subject(s)
Cerebral Cortex/physiopathology , Epilepsies, Partial/physiopathology , Adolescent , Adult , Cerebral Cortex/surgery , Child , Child, Preschool , Electroencephalography , Epilepsies, Partial/surgery , Female , Humans , Infant , Male , Treatment OutcomeABSTRACT
Cortical dysplastic lesions (CDLs) are usually identified by magnetic resonance imaging (MRI). Clinical, electrographic and histologic findings suggest that focal CDLs (FCDLs) are highly epileptogenic, often involve the rolandic cortex, and can present variable degrees of histopathologic abnormalities. An ictal or "ictal-like" bursting pattern of electrographic activity was recorded over dysplastic cortex in 65% of our patients. Resective surgery can eliminate or significantly reduce seizure frequency in many medically intractable patients, depending on lesion location, degree, and extent of histopathologic abnormalities. Best results are achieved when complete or major excision of both the MRI-visible lesion and the cortical areas displaying ictal electrographic activity can be performed. This is more likely when the degree of histopathologic abnormality is mild to moderate or when the lesion is in a temporal lobe. More severe histopathologic abnormalities and central insular or multilobar lesions usually lead to less favorable results: either major excision of the visualized lesion is impractical or the lesion is microscopically more extensive than shown by MRI. Multilobar resection or hemispherectomy for patients with infantile spasms associated with CDLs and for patients with hemimegalencephaly are often associated with dramatic improvement in seizure control. Callosotomy can be performed in selected patients with diffuse CDLs who have intractable drop attacks.
Subject(s)
Cerebral Cortex/abnormalities , Cerebral Cortex/surgery , Epilepsy/surgery , Neural Tube Defects/surgery , Adolescent , Adult , Cerebral Cortex/pathology , Child, Preschool , Electroencephalography , Epilepsies, Partial/congenital , Epilepsies, Partial/diagnosis , Epilepsies, Partial/surgery , Epilepsy/congenital , Epilepsy/pathology , Female , Humans , Infant, Newborn , Magnetic Resonance Imaging , Neural Tube Defects/diagnosis , Neural Tube Defects/pathologyABSTRACT
Lesöes displásicas corticais (LDC) estäo frequentemente associadas a epilepsias de difícil controle. Nós descrevemos os correlatos eletrográficos deste alto grau de epileptogenicidade, caracterizado por descargas epileptógenas rítmicas, contínuas ou quase-contínuas, registradas diretamente das LDC durante eletrocorticografia trans-operatória. Esta atividade ictal ou descargas epileptogênicas contínuas (AI/DEC) manifestava-se por um de três padröes: (a) crises eletrográficas repetidas; (b) surtos de polipontas recorrentes; ou (c) espículas rítmicas contínuas ou quase-contínuas. Um ou mais destes padröes estava presente em 23 de 34 pacientes (67 por cento ) com epilepsia partial de difícil controle associada a LDC. Esta AI/DEC era geralmente mais localizada, assim contrastando com a atividade interictal ao eletrocorticograma, que era mais difusa. Nós concluimos que LDC säo altamente e intrinsicamente epileptogênicas e discutimos mecanismos possivelmente relacionados a esta epileptogenicidade intrínsica