| Resumen: | Object. Epilepsy is an occurrence of repetitive crises in absence of toxicmetabolic disturb, causing from a brain abnormal electrical activity. It can be secondary, caused by cerebral structural lesion (tumors, gliosis areas, malformations etc), or from de genetic mutation with repercussion in neuronal excitability. The mayor part of epileptic crisis has a good response from medical treatment. However, 20-30% of epilepsy is refractory from medical treatment. Those patients are candidates to epilepsy surgery, who aim at resects areas where crisis start. When this resection is not possible like in eloquent area, an alternative is a surgical procedure called multiple subpial transection (MST), which interrupts the neuronal horizontal connections, getting down the intracortical propagation of ictal epileptic discharges. The goal in this study was valuate the efficacy of TSM in the control of crises in epilepsy focal experimental model. Methods. We used 25 Wistar male rats, with 60-150 days of life, from Instituto de Pesquisas Biomédicas da Pontifícia Universidade Católica do Rio Grande do Sul, who seved like focal epilepsy model. The animals were kept under controlled illumination and temperature. After anesthetic procedure the animals were fixed in the stereotaxic apparatus and left craniotomy and Dura-mater were take out, than five electrodes were fixed at the cerebral cortex and video-electroencephalogram (video-EEG) were registered for 10 min. At this point we injected penicillin G potassic crystalline subpial in the same local to the most anterior electrode who was always in the forelimb motor cortex, than we registered 10 min video-EEG. After that procedure we divided in two groups: experimental group who we did a Multiple Subpial Trasection(MST) and a Sham group who we did not do MST, in both of that we registered 10 min video-EEG. Results. The time to get seizures had the same median in a surgical group and in the control group (180s). The rats which stopped crisis in the surgical group was 10 (66,7%) and in control group no one. Two animals (11,1%) died in a surgical group and 4(57,1%) in a control group. In the channel 3 the median post- TSM was 7(1 to 16) and in the end of register of control group 20 (6 to 35), p=0,012. For the interictal discharges in a surgical group the median post-penicillin against post-TSM was 17 (p<0,001), in the control group was 14 post-penicillin and in the end of the register 20 (p=0,091). Median in the surgical group for the post-penicillin was 1(0 to 6) and 0(0 to 1) (p=0,003).For the ictal discharges in the surgical group the median post-penicillin was 1 and post-TSM was 0 (p=0,003). There was not motor deficit after procedure in any animals; also there was no significant histological alteration in the rats. Conclusion. These findings suggest a role of MST stop or decrease tremendously the electrical spreading of epilepsy crisis in brain cortical layer of rats. It demonstrates that it is a very effective surgical therapy for refractory epilepsy focused on cerebral eloquent areas.
Fundamentos: Epilepsia, por conceito, é a ocorrência de crises repetitivas na ausência de distúrbio tóxico-metabólico, decorrente de uma atividade elétrica anormal do encéfalo. Pode ser secundária, causada por lesão cerebral estrutural (tumores, áreas de gliose, malformações, etc. ), ou decorrente de mutação genética com repercussão na excitabilidade neuronal. A maior parte das crises epilépticas responde bem ao tratamento medicamentoso; entretanto, 20-30% das epilepsias são refratárias ao tratamento medicamentoso. Estes pacientes são candidatos à cirurgia da epilepsia, a qual visa à ressecção da área de início das crises. Quando essa ressecção não é possível, como em áreas cerebrais eloqüentes, uma alternativa é o procedimento cirúrgico denominado de transecção subpial múltipla (TSM), que interrompe as conexões neuronais horizontais, reduzindo a propagação intracortical das descargas epilépticas ictais. Objetivo geral: Avaliar a eficácia da TSM no controle das crises epiléticas num modelo de epilepsia focal experimental. Materiais e métodos: Foi realizado um estudo experimental com intervenção, no qual foram estudados 25 ratos machos da raça Wistar, com idade aproximadamente entre 60-150 dias, divididos em dois grupos e submetidos a implante de eletrodos de registro eletrencefalográfico e indução de foco epiléptico por injeção de penicilina G potássica cristalina subpial. No Grupo I (Experimental) os animais foram submetidos à craniectomia monitorados por vídeo-EEG por 10 minutos, induzidos ao foco epilético e videomonitorizados pelo mesmo período; após, foram submetidos à TSM e novamente videomonitorados por 10 minutos. No Grupo II (Sham), os animais foram submetidos à craniectomia, submetidos por 10 minutos a vídeo-EEG; após, o foco epilético foi induzido, mas não foi realizada a TSM, sendo novamente submetidos a 10 minutos de vídeo-EEG. Todos os animais foram submetidos a estudo histológico para avaliação da vascularização e da organização estrutural do córtex cerebral. |
