Clinical Ictal Symptomatology and Anatomical Lesions: Their Relationships in Severe Partial Epilepsy (original) (raw)
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Seminar in Epileptology Concept of epilepsy surgery and presurgical evaluation
Epilepsy surgery is a well-accepted treatment for drug-resistant epilepsy. The success of the epilepsy surgery depends upon an appropriate presurgical evaluation process which should ensure the selection of suitable patients who are likely to become seizure-free following surgery without any unacceptable deficit. The two basic goals of the presurgical evaluation are the accurate localization and delineation of the extent of the epileptogenic zone, and its complete and safe resection. The process of the presurgical evaluation requires a multimodality approach wherein each modality provides unique and complimentary information which is combined with the information provided by other modalities to generate a hypothesis with regard to the likely epileptogenic zone. The basic modalities for the presurgical evaluation are clinical history, long-term video-EEG recording, high-resolution MRI, and neuropsychological evaluation. The additional modalities include functional imaging studies, electrical and magnetic source imaging, functional MRI, and intracranial monitoring. Each modality has its own limitations and the information provided by none of them is absolute. Hence, a concordance among the different modalities is the key to surgical success. The presurgical evaluation is a step-wise process starting form the most basic and most reliable tests and progressing to more complex and invasive modalities. The number of tests required varies according to the complexity involved and may include very basic minimum investigations in a given case, to the use of all the available investigations in more complex cases. The proper selection of various investigations and their accurate interpretation at each stage is required to ensure a successful outcome. In this article, we intend to review some of these basic concepts of presurgical evaluation and epilepsy surgery, and try to provide a frame work of the presurgical evaluation process.
Concept of epilepsy surgery and presurgical evaluation
Epileptic disorders : international epilepsy journal with videotape, 2015
Epilepsy surgery is a well-accepted treatment for drug-resistant epilepsy. The success of the epilepsy surgery depends upon an appropriate presurgical evaluation process which should ensure the selection of suitable patients who are likely to become seizure-free following surgery without any unacceptable deficit. The two basic goals of the presurgical evaluation are the accurate localization and delineation of the extent of the epileptogenic zone, and its complete and safe resection. The process of the presurgical evaluation requires a multimodality approach wherein each modality provides unique and complimentary information which is combined with the information provided by other modalities to generate a hypothesis with regard to the likely epileptogenic zone. The basic modalities for the presurgical evaluation are clinical history, long-term video-EEG recording, high-resolution MRI, and neuropsychological evaluation. The additional modalities include functional imaging studies, el...
Presurgical evaluation of epilepsy patients
Medicina, 2008
Epilepsy surgery has been established as an effective treatment in pharmacoresistant focal epilepsies. Most candidates for epilepsy surgery are patients with partial epilepsy syndromes refractory to medical treatment. The curative surgery procedure is resection of the epileptogenic zone; therefore, precise detection of the site responsible for seizure generation is necessary. Modern structural and functional imaging techniques have made presurgical evaluation less invasive and available for a higher number of patients. Video electroencephalography (EEG) monitoring, high-resolution structural and functional imaging techniques are used widely for presurgical evaluation. When noninvasive evaluation is not sufficient for the detection of the epileptogenic zone, invasive EEG monitoring and intracarotid amobarbital test are used. A classical example of a surgically curable epilepsy syndrome is mesial temporal lobe epilepsy with about 70–80% of patients becoming free of seizures after surg...
Epilepsy surgery: perioperative investigations of intractable epilepsy
Anatomy and Embryology, 2005
Recent advances in our understanding of the basic mechanisms of epilepsy have derived, to a large extent, from increasing ability to carry out detailed studies on patients surgically treated for intractable epilepsy. Clinical and experimental perioperative studies divide into three different phases: before the surgical intervention (preoperative studies), on the intervention itself (intraoperative studies), and on the period when the part of the brain that has to be removed is available for further investigations (postoperative studies). Before surgery, both structural and functional neuroimaging techniques, in addition to their diagnostic roles, could be used to investigate the pathophysiological mechanisms of seizure attacks in epileptic patients. During epilepsy surgery, it is possible to insert microdialysis catheters and electroencephalogram electrodes into the brain tissues in order to measure constituents of extracellular fluid and record the bioelectrical activity. Subsequent surgical resection provides tissue that can be used for electrophysiological, morphological, and molecular biological investigations. To take full advantage of these opportunities, carefully designed experimental protocols are necessary to compare the data from different phases and characterize abnormalities in the human epileptic brain.
Surgical Outcome of Epilepsy Patients Evaluated with a Noninvasive Protocol
Epilepsia, 2000
Surgery is now an accepted treatment for some medically intractable epilepsies. Presurgical evaluation is particularly important for the localization of the epileptogenic zone, which may necessitate sophisticated imaging techniques and intracranial electroencephalogram (EEG) recordings. If patients are carefully selected, however, successful results can be achieved with noninvasive evaluation methods. Seventy-seven patients were operated on for intractable seizures. All patients underwent EEG, neuropsychological, psychiatric, and magnetic resonance imaging investigations. Ictal EEG-video recording was performed in all nonlesional and in some lesional cases that had discordant data. Selective amygdalo-hippocampectomy was performed on patients with mesial temporal lobe epilepsy (MTLE), an extended or a limited lesionectomy was performed on patients with structural lesions, and a lesionectomy with deafferentation was performed on two patients with West syndrome. Electrocorticography was not used. Tem-
Epilepsia, 1996
Summary: Purpose and Methods: The aim of this study was to analyze clinical, radiologic, and histopathologic findings in 60 consecutive patients with medically intractable extratemporal epilepsy who were operated on between November 1987 and May 1993.Results: Histologically, there were distinct structural abnormalities in 50 (83%) of the surgical specimens. Signal abnormalities on magnetic resonance imaging (MRI) were present in all patients with neoplastic lesions (n = 17) and in 94% of patients with nonneoplastic focal lesions (n = 32). Overall, structural abnormalities were detected by MRI in 47 (96%) of 49 patients with focal lesions. During a mean follow-up of 4 years, 30 (54%) patients remained completely seizure free, 11 (20%) had ≤2 seizures per year, seven (12%) showed a seizure reduction of ≥75%, and eight (14%) had <75% reduction in seizure frequency. The fraction of seizure-free patients was 12 (80%) of 15 in patients with neoplastic lesions, 16 (52%) of 31 in patients with nonneoplastic focal lesions, and two (20%) of 10 for those without histopathologic abnormalities. The differences in seizure outcome between patients with and without focal lesions were statistically significant (p < 0.05), if seizure-free outcome was compared with persistent seizures.Conclusions: Focal lesions and particularly neoplasms are associated with improved postoperative seizure control compared with patients without histopathologic abnormalities. We advise caution in considering surgery to treat extratemporal epilepsy in patients who have normal MRI scans, because the outcome with the approach described in this study is poor in such cases.
Non-invasive Evaluation for Epilepsy Surgery
Neurologia Medico-chirurgica, 2016
Epilepsy surgery is aimed to remove the brain tissues that are indispensable for generating patient's epileptic seizures. There are two purposes in the pre-operative evaluation: localization of the epileptogenic zone and localization of function. Surgery is planned to remove possible epileptogenic zone while preserving functional area. Since no single diagnostic modality is superior to others in identifying and localizing the epileptogenic zone, multiple non-invasive evaluations are performed to estimate the location of the epileptogenic zone after concordance between evaluations. Essential components of non-invasive pre-surgical evaluation of epilepsy include detailed clinical history, long-term video-electroencephalography monitoring, epilepsy-protocol magnetic resonance imaging (MRI), and neuropsychological testing. However, a significant portion of drug-resistant epilepsy is associated with no or subtle MRI lesions or with ambiguous electro-clinical signs. Additional evaluations including fluoro-deoxy glucose positron emission tomography (FDG-PET), magnetoencephalography and ictal single photon emission computed tomography can play critical roles in planning surgery. FDG-PET should be registered on three-dimensional MRI for better detection of focal cortical dysplasia. All diagnostic tools are complementary to each other in defining the epileptogenic zone, so that it is always important to reassess the data based on other results to pick up or confirm subtle abnormalities.