Displasias corticais associadas a epilepsia : delineamento de uma nova sindrome, revisão de conceitos localizacionais e proposta de uma nova classificação

AUTOR(ES)
DATA DE PUBLICAÇÃO

1996

RESUMO

Modemneuro:imagingtechniques current1y allows lin vivo I identification of cortical dysplastic lesions in patients previously thought to have cryptogenic epilepsies. These lesions constitute an heterogenous group of disorders from clinicall anatomical, histopathological, and pathogenetic standpoints. The fact that such heterogeneity is not readily realized often precludes a more detailed understanding of both the clinical manifestations and the natural history of specific types of cortical dysplastic lesions. With a view to determine whether anatomical and histopathological pictures are associated with particular clinico-electrographic presentations in patients with cortical dysplastic lesions; to identify specific epileptic syndromes; and to re-evaluate localizational concepts, we studied 99 patients with various types of cortical dysplastic lesions and 39 patients with refractory epilepsy associated with non-dysplastic, extra¬hippocampal epileptogenic lesions. Ali patients underwent detailed clinical, electrographic, and neuro:imaging evaluations. Fifty-three of the 78 patients (68%) with localized dysplastic lesions were operated and histopathologic diagnoses were confirmed. In the other 25, and also in the 21 patien~s with diffuse cortical dysplasia or the IIdouble cortex syndrome" (DCS), diagnosis was based on magnetic resonance (MR) :imaging studies. Ali 39 patients with non-dysplastic, extra-hippocampal epileptogenic lesions were operated and histopathological disgnoses were established. The 54 patients with Taylor type focal cortical dysplasia (DCFIT) or with hem:imegalencephaly (HMG) - whose histopathological picture was characterized by the presence of dysplastic neurons and ballon cells, and were thus considered to represent abnormalities of cortical cell development - had a significant1y higheroccurrence of a history of status epilepticus (p=0,008), of continuous epiletogenic discharges on EEG (DEC-EED)! (p=O,OOl), and of medical intractability (p=O,OOOl), in comparison with the 24 patients with polymicrogyria (PMG) or schizencephaly (SCH). These latter entities do not display the histopathological elements described above, and are thought to represent destructive insults to the developing telencephalon. Sixteen of the 78 patients (20%) with a variety of types of localized dysplastic lesions had episodes of epilepsia partialis continua (EPC). This observation was furthermore increased to 27% when on1y the 54 patients with DCrIT or HMG were analyzed in this regard. In contrast, on1y 3 of 39 patients (7,6%) with non-dysplastic neocorticallesions had episodes of EPC. When the 2 patients with Rasmussen s chronic encephalitis were excluded from the analysis, then on1y 1 of 37 patients with non¬dysplastic neocorticallesions had EPC (p=0,06). Patients with cortical dysplasia and EPC had a significant1y higher occurrence of other types of partial motor seizures (p=0,0021; and 0,0009), of unilateral pyramidal syndrome on neurologic examination (p=O,OOOl; and 0,0003), of involvement of the rolandic cortex by the structural lesion (p= 0,0001 ; andO,0005 ), and of DEC-EEG (p=0,0002 ; and 0,0001 ) than patients with cortical dysplasia but without a history of episodes of EPC, and also than patients with neocortical Ron-dysplastic lesions, respectively. Surgi cal results in relation to seizure control were considered satisfactory in 60% of the patients with cortical dysplasia and EPC, but motor defucits emerged or accentuated in50% of the cases. Fifteen of the 54 patients with DCFTT /HMG (27%), but only one of the 24 with PMG/SCH (4%) had episodes of EPC, suggesting an association between the histopathological type of dysplasia and the occurrence of EPC. From 60 to 75% of the 21 patients with the double cortex syndrome (SCD) had one or more features suggestive of focal or regional accentuation of the epileptogenic dysfunction, despite the diffuse nature of the structural abnormality: partial seizures (61 % ), focal epileptiform abnormalities on EEG (67%), or localized hypoperfusion on single photon emission computed tomography (SPEcr) studies ( 75%; 6 of 8 patients thus studied). The occurrence of partial seizuers and of focal epileptiform abnormalities on EEG were significant1y associated with one another. There was no relationship between the severity of the heterotopia and clinical, electrographic, or imagingevidences of focal accentuation of the epileptogenic picture. The observations in this series of 99 patients with a variety of types of cortical dysplasia suggest that specific anatomic, histopathologic, and pathogenetic patterns are associated with distinct clinical-eletrographic pictures. A dassification encompassing in a c1inically relevant fashion anatomic, histological and pathogenentic data was then proposed, allocating the various types of cortical dysplasia in 4 diagnostic categories: (i) primary disorders of neuronal migration; (ii) disorders of neuronal migration secondary to destructive insults to the lining of the telencephalon; . (üi) primary disorders of cortical celL development; and (iv) mixed types. In conclusion, patients with DCFTT or HMG are associated with c1inical~, electrographic indicators of higher severity of the epileptogenic picture, including the occurrence of EPC, when compared to patients with PMG or SCH. A syndrome of EPC associated with cortical dysplasia was delineated. It affects approximately 27% of patients with dysplastic lesions of the DCFIT OF HMG types, and! is cna{ aeterizedl by the occurrence in these patients of other types of partial motor seizures, of trnilateral pyramidal abnormalities, of structurallesions involving the rolandic cortex, and of DEC-EEG. A favorable surgical outcome can be expected in about 60% of the patients, despite the fact that post-operative motor deficits may occur. A review of localizational concepts is suggested for the diffuse dysplastic lesions like the SCD. Despite the usually bilateral aRd diffuse nature of the heterotopia, most patients with SCD display evidence suggesting focal accentuation of the epileptogenic picture

ASSUNTO(S)

epilepsia

ACESSO AO ARTIGO

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