RESUMEN
RATIONALE: We describe seizure and neuropsychological outcome obtained after CAH in patients with TLE and normal MRI evaluated in the modern imaging era. METHODS: Forty-five adult consecutive patients with TLE and normal MRI were studied. All patients had neuropsychological testing, interictal and ictal EEG recordings and MRI. They were divided into two groups: Group 1 (n=18), included patients in whom non-invasive neurophysiological evaluation was lateralizing and Group 2 (n=27) included patients with non-lateralizing neurophysiological data who were submitted to invasive recordings. RESULTS: Seventy-seven percent of the Group 1 patients were rated as Engel I; 11% were rated as Engel II and 11% as Engel III. In Group 2, there were 57% of patients seizure-free, 26% in Engel II and 14% in Engel III. Pre-operatively, mean general IQ was 82 and 78 in Groups 1 and 2, respectively; post-operatively, mean general IQ was respectively 86 and 71. Some degree of verbal memory decline was noted in all patients submitted to dominant temporal lobe resection in both Groups 1 and 2. At last follow-up visit, 22% of Group 1 and 11% of Group 2 patients were receiving no antiepileptic drugs (AED). CONCLUSIONS: Our data showed that patients with TLE and normal MRI could get good surgical results after CAH although 60% of them would need invasive recordings and their results regarding seizure control and cognition were worse than those obtained in patients with MRI defined temporal lobe lesions. Caution should be taken in offering dominant temporal lobe resection to this subset of patients.
Asunto(s)
Amígdala del Cerebelo/cirugía , Corteza Cerebral/cirugía , Epilepsia del Lóbulo Temporal/cirugía , Hipocampo/cirugía , Adolescente , Adulto , Edad de Inicio , Amígdala del Cerebelo/patología , Corteza Cerebral/patología , Electroencefalografía , Epilepsia del Lóbulo Temporal/patología , Femenino , Estudios de Seguimiento , Lateralidad Funcional/fisiología , Hipocampo/patología , Humanos , Imagen por Resonancia Magnética , Masculino , Memoria/fisiología , Trastornos de la Memoria/etiología , Trastornos de la Memoria/psicología , Trastornos de la Memoria/terapia , Pruebas Neuropsicológicas , Convulsiones/etiología , Convulsiones/cirugía , Resultado del Tratamiento , Adulto JovenRESUMEN
INTRODUCTION: Although some degree of bilateral hippocampal involvement might be frequent in patients with temporal lobe epilepsy, severe bilateral mesial temporal sclerosis (MTS) is very rare. We present our experience while treating patients with severe bilateral MTS submitted to invasive recordings. METHODS: Nine adult patients were studied. All patients had simple and complex partial seizures. All patients had bilateral independent interictal temporal lobe spiking and non-lateralizing video-EEG findings. MRI showed severe bilateral MTS and no other brain lesion. All patients had severe verbal and non-verbal memory deficits. All patients were submitted to invasive recordings after bilateral subdural grids implantation. Cortico-amygdalo-hippocampectomy (CAH) was performed in all patients on the side suggested by invasive recording. Follow-up time ranged from 5 to 10 years. RESULTS: Invasive video-EEG showed exclusively unilateral seizure onset in seven patients; in two patients, seizures originating from both temporal lobes were found (80% of them originated from one side). Five patients were submitted to left and four to right CAH. Seven patients were rendered seizure-free after surgery (Engel I); the other two were rated as Engel II. There was no additional memory decline. There was no surgical morbidity or mortality. Pathological examination showed MTS in all patients. DISCUSSION: Good surgical outcome (77% seizure-free patients) could be obtained even in this apparently unsuitable group of patients. All patients benefit from the procedure. We did not see any cognitive decline in our patients with severe bilateral MTS. Patients with severe bilateral MTS would need invasive recordings despite any findings during surface video-EEG.
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Amígdala del Cerebelo/cirugía , Corteza Cerebral/cirugía , Hipocampo/cirugía , Esclerosis/patología , Lóbulo Temporal/fisiopatología , Adulto , Electroencefalografía , Epilepsia/complicaciones , Humanos , Imagen por Resonancia Magnética/métodos , Vías Nerviosas/cirugía , Pruebas Neuropsicológicas , Estudios Retrospectivos , Esclerosis/etiología , Resultado del Tratamiento , Adulto JovenRESUMEN
PURPOSE: To study the outcome after hemispherectomy (HP) in a homogeneous adult patient population with refractory hemispheric epilepsy. METHODS: Fourteen adult patients submitted to HP were studied. Patients had to be at least 18 years old, and have refractory epilepsy, clearly focal lateralized seizures and unilateral porencephalus consistent with early middle cerebral artery infarct on magnetic resonance imaging (MRI). All patients were submitted to functional hemispherectomy. We analyzed age of seizure onset, age by the time of surgery, gender, seizure type and frequency, interictal and ictal electroencephalography (EEG) findings, MRI and IQ scores preoperatively; seizure frequency, drug regimen, and IQ outcome were studied postoperatively. RESULTS: Mean follow-up was 64 months. All patients had frequent daily seizures preoperatively. All patients had unilateral simple partial motor seizures (SPS); 11 patients had secondarily generalized tonic-clonic (GTC) seizures and five patients had complex partial seizures (CPS), preoperatively. All patients had hemiplegia and hemianopsia. Twelve patients had unilateral EEG findings, and in two epileptic discharges were seen exclusively over the apparently normal hemisphere. Twelve patients were seizure-free after surgery and two patients had at least 90% improvement in seizure frequency. Pre- and postoperative mean general IQ was 84 and 88, respectively. Five of the twelve Engel I patients were receiving no drugs at last follow-up. There was no mortality or major morbidity. CONCLUSIONS: Our results suggest that well-selected adult patients might also get good results after HP. Although good results were obtained in our adult series, the same procedure yielded a much more striking result if performed earlier in life.
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Epilepsia/cirugía , Hemiplejía/cirugía , Hemisferectomía/métodos , Infarto de la Arteria Cerebral Media/cirugía , Adulto , Electroencefalografía/métodos , Epilepsia/complicaciones , Femenino , Estudios de Seguimiento , Hemiplejía/complicaciones , Humanos , Infarto de la Arteria Cerebral Media/complicaciones , Inteligencia , Imagen por Resonancia Magnética/métodos , Masculino , Examen Neurológico/métodos , Resultado del Tratamiento , Adulto JovenRESUMEN
PURPOSE: We report on the surgical outcome obtained in patients with refractory temporal lobe epilepsy with mesial temporal sclerosis (MTS) who were evaluated preoperatively without ictal recording and were submitted to corticoamygdalohippocampectomy. METHODS: Two hundred twelve patients with refractory temporal lobe epilepsy were evaluated by means of clinical history, neurological examination, interictal electroencephalography (EEG), magnetic resonance imaging (MRI), and neuropsychological testing. MRI disclosed unilateral MTS in all patients. All patients were submitted to corticoamygdalohippocampectomy at the side determined by MRI. RESULTS: Interictal EEG showed unilateral temporal lobe spiking in 176 patients; in 36 patients, bilateral discharges were found. Mean follow-up time was 2.7 years. One hundred ninety-four patients (92%) were classified as Engel's class I. Eighteen patients (8%) were rated as Engel's class II. Thirty-two out of 36 patients, in whom bilateral discharges were found, were in Engel's class I. Sixty percent of the patients had an improvement in memory function related to the nonoperated temporal lobe. Fifty-nine percent of the patients had a 10-point increase in general IQ postoperatively. Verbal memory decline was noted in three patients. Pathological examination showed MTS in all patients. CONCLUSIONS: It is possible to adequately select good surgical candidates for temporal lobe resection using MRI and interictal EEG alone. In patients with MRI-defined MTS, we should expect a 90% postoperative remission rate. Cognitive decline was very rarely seen in this patient population. The finding of MTS on MRI is the single most important prognostic factor for good outcome after temporal lobe surgery.
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Amígdala del Cerebelo/cirugía , Epilepsia del Lóbulo Temporal/cirugía , Hipocampo/cirugía , Procedimientos Neuroquirúrgicos/métodos , Lóbulo Temporal/cirugía , Adolescente , Adulto , Niño , Electroencefalografía/métodos , Epilepsia del Lóbulo Temporal/patología , Femenino , Humanos , Imagen por Resonancia Magnética/métodos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Esclerosis/patología , Esclerosis/cirugía , Resultado del Tratamiento , Adulto JovenRESUMEN
INTRODUCTION: Several pre-operative work-up protocols have been used while selecting epileptic patients for surgery among different centers. The relative value of the different available pre-operative tests is still under discussion. OBJECTIVE: We report on the surgical outcome obtained in patients with refractory temporal lobe epilepsy associated to mesial temporal sclerosis (MTS) and who were evaluated pre-operatively by interictal EEG and MRI alone. METHOD: Forty one patients with refractory unilateral temporal lobe epilepsy were evaluated using interictal EEG and MRI. MRI disclosed unilateral MTS in all patients. All patients had at least 4 interictal EEG recordings. All patients were submitted to cortico-amygdalo-hippocampectomy at the side determined by MRI. RESULTS: Interictal EEG showed unilateral epileptiform discharges compatible with MRI findings in 37 patients; in four out of the 41 patients, bilateral discharges were found. Mean follow-up time was 4.3+/-1.1 years. Thirty-nine patients (95.1%) were classified as Engels Class I (70.6% Engel I-A). Two patients (4.9%) were rated as Engel's Class II. All patients in whom bilateral discharges were found were in Engels Class I. Pathological examination showed MTS in all patients. CONCLUSION: It is possible to adequately select good surgical candidates for temporal lobe resection using MRI and interictal EEG alone. In patients with MRI-defined MTS we should expect a postoperative remission rate higher then 90%. The finding of MTS on MRI is the most important good prognostic factor after temporal lobe resection.
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Epilepsia del Lóbulo Temporal/cirugía , Hipocampo/cirugía , Lóbulo Temporal/cirugía , Adolescente , Adulto , Niño , Electroencefalografía , Epilepsia del Lóbulo Temporal/etiología , Femenino , Estudios de Seguimiento , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Esclerosis , Lóbulo Temporal/patología , Resultado del TratamientoRESUMEN
INTRODUÇÃO: Protocolos diferentes têm sido utilizados para a investigação pré-operatória de pacientes epilépticos nos diferentes centros. No entanto, o valor relativo de cada teste disponível ainda é controverso na literatura.OBJETIVO: Relatamos os resultados cirúrgicos de pacientes com epilepsia refratária do lobo temporal associada a esclerose hipocampal (EH), cuja investigação pré-operatória consistiu exclusivamente de estudo de eletrencefalograma (EEG) inter-crítico e ressonância magnética (RM). MÉTODO: Foram estudados 41 pacientes com epilepsia refratária do lobo temporal, avaliados pré-operatoriamente somente por meio de EEG interictal e RM encefálica. Foram incluídos somente pacientes em quem a RM mostrava apenas EH unilateral. Todos pacientes possuíam ao menos quatro EEG inter-ictais. Todos os pacientes foram submetidos a córtico-amígdalo-hipocampectomia no lado demonstrado pela RM.RESULTADOS: A análise do EEG interictal revelou atividade epileptiforme unilateral, compatível com os achados da RM em 37 pacientes. Nos outros quatro pacientes, o EEG evidenciou comprometimento bilateral. O tempo médio de seguimento pós-operatório dos pacientes foi 4,3±1,1 anos. No período pós-operatório, 95,1% dos pacientes encontravam-se em classe I de Engel (70,6% em Engel I-A) e 4.9% em classe II de Engel. Todos os pacientes com achados bilaterais ao EEG estavam em classe I de Engel. O estudo anátomo-patológico das amostras cirúrgicas revelou EH em todos os pacientes. CONCLUSÃO: É possível selecionar bons candidatos à ressecção temporal utilizando-se apenas dados de RM e EEG inter-ictal. Nos pacientes com EH unilateral na RM, espera-se um índice de remissão pós-operatória das crises superior a 90%. O achado de EH na RM é, isoladamente, o maior fator indicativo de bom prognóstico após ressecção temporal.
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Adolescente , Adulto , Niño , Femenino , Humanos , Masculino , Persona de Mediana Edad , Epilepsia del Lóbulo Temporal/cirugía , Hipocampo/cirugía , Lóbulo Temporal/cirugía , Electroencefalografía , Epilepsia del Lóbulo Temporal/etiología , Estudios de Seguimiento , Imagen por Resonancia Magnética , Esclerosis , Resultado del Tratamiento , Lóbulo Temporal/patologíaRESUMEN
Hemimegalencephaly (HME) is a rare congenital brain malformation of unknown etiology. Patients with HME can present with an early onset epileptic syndrome which is often refractory to medical treatment and associated to impaired neurological development. Functional hemispherectomy (FH) has proven to be a valuable treatment alternative in patients with refractory epilepsy in this setting. Very few children operated under the age of 6 months and bearing HME and catastrophic epilepsy (CE) have been described in the literature. This study reports on 2 kids younger than 6 months with HME and CE submitted to FH with good clinical outcome.
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Encéfalo/anomalías , Epilepsia/cirugía , Hemisferectomía , Encéfalo/cirugía , Electroencefalografía , Epilepsia/complicaciones , Epilepsia/diagnóstico , Humanos , Lactante , Imagen por Resonancia Magnética , Masculino , Tomografía Computarizada de Emisión de Fotón Único , Tomografía Computarizada por Rayos XRESUMEN
A hemimegalencefalia (HME) é malformação congênita cerebral rara de etiologia desconhecida que pode se apresentar com síndrome epiléptica de início precoce e resistente à terapia com anticonvulsivantes, associada a comprometimento significativo do desenvolvimento neuropsicomotor. A hemisferectomia funcional (HF) tem-se mostrado alternativa eficaz nos casos refratários à terapêutica medicamentosa. Em número diminuto, crianças foram operadas antes dos seis meses de idade. Esse estudo relata duas crianças com idade inferior a 6 meses com HME e síndrome epiléptica catastrófica submetidas a HF e com boa evolução clínica.
Asunto(s)
Lactante , Humanos , Masculino , Encéfalo/anomalías , Epilepsia/cirugía , Hemisferectomía , Encéfalo/cirugía , Electroencefalografía , Epilepsia/complicaciones , Epilepsia/diagnóstico , Imagen por Resonancia Magnética , Tomografía Computarizada de Emisión de Fotón Único , Tomografía Computarizada por Rayos XRESUMEN
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 preoperative 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 corticoamygdalohippocampectomy at the side of the MTS. Surgery-related outcome was rated as Class I (seizure free or simple partial seizures only) or Class II (> or = 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.
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Epilepsia del Lóbulo Temporal/diagnóstico , Epilepsia del Lóbulo Temporal/cirugía , Lóbulo Temporal/patología , Lóbulo Temporal/cirugía , Adulto , Amígdala del Cerebelo/cirugía , Corteza Cerebral/cirugía , Femenino , Hipocampo/cirugía , Humanos , Imagen por Resonancia Magnética/métodos , Masculino , Procedimientos Neuroquirúrgicos/métodos , Estudios Prospectivos , Esclerosis/diagnóstico , Esclerosis/cirugía , Convulsiones/diagnóstico , Convulsiones/cirugía , Resultado del TratamientoRESUMEN
PURPOSE: To study the seizure's outcome in patients with refractory epilepsy and normal MRI submitted to resections including the rolandic cortex. METHODS: Four 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 percent reduction in seizure frequency. CONCLUSION: Resections including the face and tongue rolandic cortex can be safely performed even within the dominant hemisphere
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Humanos , Masculino , Adulto , Corteza Cerebral/cirugía , Epilepsia/fisiopatología , Epilepsia/cirugía , Corteza Cerebral/fisiopatología , Electrodos Implantados , Cara/fisiopatología , Imagen por Resonancia Magnética , Corteza Motora/fisiopatología , Corteza Motora/cirugía , Espacio Subdural , Lóbulo Temporal/fisiopatología , Lóbulo Temporal/cirugía , Lengua/fisiopatología , Resultado del TratamientoRESUMEN
O presente estudo relata um paciente com foco epiléptico localizado nas áreas motoras e sensitivas da língua, investigado de maneira invasiva com eletrodos subdurais e, subseqüentemente, submetido à ressecção cortical. O paciente de 22 anos, sexo masculino, possuía crises com versãoconsciente da cabeça para a esquerda, evoluindo, eventualmente, para crises tônico-clônicas, diárias, ocorrendo em vigília e no sono, desde os 5 anos de idade, refratárias ao tratamento clínico. Monitorização videoeletroencefalográfica revelou surtos interictais de ondas lentas comprojeção na região frontocentral (C4-T4). O registro ictal sugeria início na mesma região. A ressonância magnética não revelou alterações. Foi submetido ao implante de grades de eletrodos. O registro eletrocorticográfico crônico com eletrodos subdurais mostrou início das descargas nas regiões motora e sensitiva da língua com espraiamento para a região da face. As descargas intercríticas estendiam-se anterior e posteriormente aos giros rolândicos, bem como ao giro temporal superior. A estimulação cortical da área sensitiva da língua reproduziu as crises clínicas. Foi realizada ressecção subpial do córtex pré-motor, motor e sensitivo da língua e face e póssensitiva da língua e face e porções do giro temporal superior, com especial atenção para a preservação do arcabouço vascular da região. Mantém-se sem crises a partir daí. O estudo anatomopatológico demonstrou apenas gliose intensa.O tratamento cirúrgico de pacientes com focos epilépticos em região da língua pode ser realizado com segurança desde que as relações entre as áreas eloqüentes e epileptogênicas sejam bem conhecidas, em casos selecionados.
We report the case of a 22 year-old male patient with an epileptic focus located at the sensorimotor area of the tongue who was evaluated with subdural electrodes and submitted to a subpial cortical resection. He had seizures characterized by head rotation to the left without impairment ofconsciousness. They occurred in a daily basis, either during sleep or awake, since the age of 5 years. Video-EEG monitoring showed interictal slow waves over the right fronto-central region. Ictal recording suggested the onset over the same area. MRI was normal. He was submitted to subdural electrodes implantation over the right frontoparietal region. ECoGobtained through the implanted electrodes showed ictal onset over the motor and sensitive areas of the tongue with early spreading to the face areas. Interictal spiking was more widespread including the premotor gyrus, the postcentral gyrus and the superior temporal gyrus. Corticalstimulation of the tongue areas reproduced the patient?s habitual seizures. A subpial resection of the premotor, motor, sensory and postsensory cortex related to the tongue and an additional superior temporal gyrus resection was performed. Special caution was dedicated to the preservation of the surrounding vascular structures. He has been seizure-free since surgery. Pathological examination showed severe gliosis.The surgical treatment of patients with foci at the tongue area can be performed safely as far as the relationship between the focus and the surrounding eloquent areas is well delimited.
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Humanos , Masculino , Adulto Joven , Epilepsias Parciales/cirugía , Lengua/fisiopatologíaRESUMEN
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
Asunto(s)
Humanos , Adulto , Epilepsia del Lóbulo Temporal/cirugía , Lóbulo Temporal/patología , Electrodos Implantados , Estudios de Seguimiento , Imagen por Resonancia Magnética , Cuidados Preoperatorios , Esclerosis , Resultado del TratamientoRESUMEN
Uma paciente de 16 anos apresentava epilepsia mioclônica causada pela doença de Lafora. A biopsia muscular mostrou padräo vacuolar nas fibras musculares com as reaçöes nicotinamida adenina tetrazolium redutase desidrogenase, hematoxilina-eosina e PAS. O aspecto morfológico permite o diagnóstico através da biopsia muscular. Este é um procedimento menos agressivo que a biopsia de fígado e de cérebro. A microscopia eletrônica deve ser reservada para casos nos quais as alteraçöes musculares à microscopia óptica säo muito discretas deixando dúvidas quanto ao diagnóstico
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Humanos , Femenino , Adolescente , Enfermedad de Lafora/patología , Músculos/patología , Biopsia , Coloración y Etiquetado/métodosRESUMEN
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 percent 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