Summary:Purpose: To study the efficacy of extensive coverage of the brain surface with subdural grids in defining extratemporal cortical areas amenable for resection in patients with refractory extratemporal epilepy (R-ExTE) and normal or nonlocalizing magnetic resonance imaging (MRI) scans.Methods: Sixteen patients with R-ExTE were studied. Eleven patients had simple partial, eight had complex partial, and three had supplementary motor area seizures. Seizure frequency ranged from three per month to daily episodes. Interictal EEG showed large focal spiking areas in 11 patients, secondary bilateral synchrony in four, and was normal in one patient. Surface ictal recordings were nonlocalizing in six patients, and in 10, they disclosed large ictal focal spiking areas. MRI was normal in 10 patients, and in six patients, focal nonlocalizing potentially epileptogenic lesions were found. All patients were given an extensive coverage of the cortical convexity with subdural electrodes through large unilateral (n ‫ס‬ 13) or bilateral (n ‫ס‬ 3) craniotomies. Bipolar cortical stimulation was carried out through the implanted electrodes.Results: Interictal invasive recording findings showed widespread spiking areas in 13 patients and secondary bilateral synchrony in three. Ictal invasive recordings showed focal seizure onset in all patients. There were six frontal, two parietal, one temporooccipital, four rolandic, and three posterior quadrant resections. Thirteen patients had been rendered seizure free after surgery, and three had ജ90% of seizure-frequency reduction. Pathologic findings included gliosis (n ‫ס‬ 10), cortical dysplasia (n ‫ס‬ 5), or no abnormalities (n ‫ס‬ 1). Six patients had transient postoperative neurologic morbidity.Conclusions: Extensive subdural electrodes coverage seems to be an effective way to investigate patients with R-ExTE and normal or nonlocalizing MRI findings.

-Purpose: To study the seizures outcome in patients with refractory epilepsy and normal MRI submitted to resections including the rolandic cortex. Methods: .our adult patients were studied. All patients had motor or somatosensory simple partial seizures and normal MRI and were submitted to subdural grids implantation with extensive coverage of the cortical convexity (1 in the non-dominant and 3 in the dominant hemisphere). Results: ECoG was able to define focal areas of seizures onset in every patient. All patients were submitted to resection of the face and tongue motor and sensitive cortex; two patients had resections including the perirolandic cortex and 2 had additional cortical removals. Three patients are seizures free and one had a greater then 90% reduction in seizure frequency. Conclusion: Resections including the face and tongue rolandic cortex can be safely performed even within the dominant hemisphere.KEY WORDS: epilepsy, surgery, outcome, subdural grids, rolandic cortex.Resultados cirúrgicos em pacientes portadores de epilepsia refratária e ressonância magnética normal submetidos a ressecções das áreas rolândicas da face e língua investigados por meio de eletrodos subdurais RESUMO -Objetivo: Estudar o efeito na frequência de crises epilépticas de ressecções de cortex rolândico em pacientes com epilepsia refratária e ressonância normal. Material: Quatro pacientes epilépticos adultos foram estudados. Todos possuíam crises parciais simples motoras ou sensitivas e ressonância normal, e foram submetidos ao implante de eletrodos subdurais cobrindo extensamente a convexidade hemisférica (1 no hemisfério não-dominante e 3 no hemisfério dominante). Resultados: O ECoG foi capaz de definir áreas ictais focais em todos os pacientes. Todos os pacientes foram submetidos à ressecção das áreas da face e língua do cortex rolândico motor e sensitivo; em dois, o cortex perirolândico foi incluído na ressecção e em dois pacientes, outras ressecções corticais foram adicionadas. Três pacientes estão livres de crises e um obteve melhora maior que 90% da frequência de crises. Conclusão: Ressecções corticais envolvendo o cortex rolândico da língua e face podem ser realizadas com segurança mesmo no hemisfério dominante.

-Purpose: The introduction of new technologies in the clinical practice have greatly decreased the number of patients submitted to invasive recordings. On the other hand, some patients with refractory temporal lobe epilepsy have normal MR scans or bilateral potentially epileptogenic lesions. This paper reports the results of invasive neurophysiology and surgical outcome in such patients. Method: Sixteen patients were studied. Eleven had normal MRI (Group I) and five had bilateral mesial temporal sclerosis (Group II). All patients had BITLS and non-localizatory seizures on video-EEG monitoring. All patients were implanted bilaterally with 32-contacts subdural grids. They were submitted to a cortico-amygdalo-total hippocampectomy at the side defined by chronic electrocorticography (ECoG). Results: In Group I, seizures came from a single side in nine patients. In nine patients, seizures started at one side, spread to the ipsolateral contacts and contralaterally afterwards. On the other hand, in two Group I patients seizures started in one mesial region and spread to the contralateral parahippocampus and neocortex before spreading to ipsolateral contacts. All patients in Group II had seizures starting unilaterally with focal EcoG onset in the mesial regions. Eight Group I patients are seizure-free and three are in Engel's class II. Eighty percent of Group II patients are seizure-free after surgery and one patient is in Engel's class II. Conclusion: Good surgical results can be obtained in patients with BITLS. Patients with normal MRI seem to have a worse prognosis when compared to patients with unilateral or even bilateral MTS. Extensive subdural coverage is essential in patients with normal MRI.KEY WORDS: bitemporal epilepsy, surgery, subdural grids, outcome, MRI. Resultados cirúrgicos em pacientes com descargas bilaterais independentes do lobo temporal (DBILT) e ressonância magnética normal ou com esclerose mesial bilateral investigados com implante bilateral de grades subdurais.RESUMO -Introdução: A introdução de novas tecnologias na prática clínica tem diminuído em muito a necessidade do estudo com eletrodos invasivos em pacientes epilépticos refratários. Por outro lado, alguns pacientes com epilepsia do lobo temporal ainda possuem exames de imagem normais ou com lesões potencialmente epileptogênicas bilaterais. Este estudo relata os resultados da neurofisiologia invasiva e da cirurgia neste grupo de pacientes. Métodos: Dezesseis pacientes foram estudados. Onze possuíam RM normal (grupo I) e 5 esclerose mesial bilateral (grupo II). Todos possuíam DBILT e crises não-localizatórias após vídeo-monitorização. Todos foram implantados bilateralmente com placas subdurais de 32 contatos cada. Eles foram submetidos a córtico-amigdalo-hipocampectomia do lado definido pela neurofisiologia invasiva. Resultado: No grupo I, as crises originaram-se em somente um lado em 9 pacientes. Em 9 pacientes, as crises iniciavam-se em um lado, espraiandose para os contatos ipsilaterais e a seguir contralateralmente. Por outro la...

Object The authors conducted a study to assess the efficacy of surgery in patients who underwent magnetic resonance (MR) imaging alone for localization of foci in temporal lobe epilepsy (TLE). Methods One hundred patients (43 men, 57 women) with a clinical diagnosis of TLE were prospectively studied (mean age 28 ± 9 years [± standard deviation {SD}]). All patients underwent high-resolution MR imaging, and in all unilateral mesial temporal sclerosis (MTS) was diagnosed by visual inspection. All patients underwent interictal pre-operative electroencephalography (EEG) and in 87 patients pre- and 1-year postoperative neuropsychological testing was performed. Both EEG and neuropsychological examinations were conducted in a blinded fashion, and these data were not taken into account during the surgery-related decision-making process. All patients underwent a corti-coamygdalohippocampectomy at the side of the MTS. Surgery-related outcome was rated as Class I (seizure free or simple partial seizures only) or Class II (⩾ 90% improvement). The follow-up period ranged from 18 to 48 months (mean 24 ± 5 months [±SD]). No patient underwent prolonged video-EEG monitoring, Wada testing, positron emission tomography, or single-photon emission computerized tomography. In eighty-nine patients Class I results were achieved, and 11 Class II results were achieved postoperatively. There was no mortality in this series. Except for in two patients who underwent surgery in the dominant temporal lobe, there was no postoperatively cognitive decline. In these two patients verbal memory decline occurred, which was associated with posterior temporal cortical damage, demonstrated postoperatively on MR imaging. Twenty-five percent of the patients experienced improved memory function related to the nonoperated side, and 54% experienced a 10% gain in general intelligence quotient status. Conclusions In patients with clinically suspected TLE, MR imaging alone is able to localize temporal lobe foci correctly. Ruling out pseudoseizures remains the only indication for prolonged video-EEG recordings in this group of patients.

-Rationale: The need for invasive monitoring in patients with refractory epilepsy has been greatly reduced by the introduction of new technologies such as PET, SPECT and MRI in the clinical practice. On the other hand, 10 to 30% of the patients with refractory epilepsy have non-localizatory non-invasive preoperative work-up results. This paper reports on the paradigms for subdural electrodes implantation in patients with different refractory epileptic syndromes. Methods: Twenty-nine adult refractory epileptic patients were studied. Patients were divided into five different epileptic syndromes that represented the majority of the patients who needed invasive recordings: bitemporal (Group I; n=16 ), bi-frontal-mesial (Group II, n=5), hemispheric (Group III; n=2), anterior quadrant (Group IV; n=3) and posterior quadrant (Group V; n=3). All of them were submitted to extensive subdural electrodes' implantation (from 64 to 160 contacts) covering all the cortical surface potentially involved in epileptogenesis under general anesthesia. Results: All patients tolerated well the procedure. There was no sign or symptom of intracranial hypertension except for headache in 22 patients. In all except one Group II patient, prolonged electrocorticographic monitoring using the described subdural cortical coverage patterns was able to define a focal area amenable for resection. In all Groups II-V patients cortical stimulation was able to adequately map the rolandic and speach areas as necessary. Conclusion: Despite recent technological advances invasive neurophysiological studies are still necessary in some patients with refractory epilepsy. The standardization of the paradigms for subdural implantation coupled to the study of homogeneous patients' populations as defined by MRI will certainly lead to a better understanding of the pathophysiology involved in such cases and an improved surgical outcome.KEY WORDS: epilepsy, surgery, subdural electrodes, outcome, standards. Paradigmas para implante de placas subdurais em pacientes com epilepsia refratáriaRESUMO -Introdução: O advento de novas tecnologias de imagem tais como o PET, SPECT e RM diminuíram em muito a necessidade da utilização de eletrodos invasivos na investigação pré-operatória de pacientes epilépticos. No entanto, 10 a 30% dos pacientes com epilepsias refratárias ainda possuem investigação não-invasiva inconclusiva. Este estudo relata nossos paradigmas para o implante de eletrodos subdurais nesta população de epilépticos refratários. Métodos: Vinte e nove pacientes portadores de epilepsias refratárias foram estudados. Eles foram divididos em 5 grupos de síndromes epilépticas que incluíam a maioria dos pacientes submetidos a implantes: bitemporais (grupo I; n=16), bifrontomesiais (grupo II; n=5), hemisféricos (grupo III; n=2), quadrante anterior (grupo IV; n=3) e quadrante posterior (grupo V; n=3). Todos foram submetidos a extensos implantes subdurais (de 64 a 160 contatos) cobrindo todo o córtex potencialmente epileptogênico, sob anestesia geral. Resultados: To...