Advances of presurgical evaluation of drug-resistant epilepsy in children / 中华实用儿科临床杂志

Epilepsy mostly starts in childhood and can cause severe mental disorders.Treatment with antiepileptic drugs is effective in most patients, but 20%-30% of the patients continue to have uncontrolled seizures despite medical therapy, these are called drug-resistant epilepsy and need surgical treatment.Critical to discussion of surgical therapy are detailed presurgical evaluation and the lateralization and localization of epileptogenic zone.With deepening of the knowledge of epilepsy and progress of imaging technology, the evaluation of epilepsy surgery is changing gradually.Now, some methods and advances of surgical evaluation for children with drug-resistant epilepsy are reviewed.

Verification of dipole fit source localization in patients with epilepsy using postoperative MRI

@#Objective: Dipole fit source (DFS) localisation is a non-invasive imaging process used to identify the epileptogenic zone (EZ) in the brain. The purpose of the present study was to verify the use of DFS localisation for identifying the EZ in patients with and without lesions using magnetic resonance imaging (MRI). Methods: In this study, DFS localisation was used in 16 patients, of whom 7 had no lesions and 9 had lesions on MRI post-surgery, with at least 3 years of follow-up data. For DFS localisation, different scalp electroencephalogram (EEG) ictal activity was assessed (ictal spikes, rhythmic, paroxysmal fast, and obscured activity). DFSs were superimposed with postoperative MRIs to confirm the accuracy of the determined EZs. Results: The DFS correctly identified EZ localization within the resection area in 14 of the 16 patients. These 14 patients were all seizure free after surgery. The two remaining patients, in whom the DFS was adjacent to the resected area, had a decreased seizure frequency following surgery.Conclusions: DFSs determined during preoperative evaluations can provide information on EZ lateralisation and localisation and contribute to the presurgical decision process. Thus, the accurate identification of EZ boundaries is important and can be achieved more reliably with the use of multiple quantitative EEG analysis methods.

EEG Source Imaging in Partial Epilepsy in Comparison with Presurgical Evaluation and Magnetoencephalography

BACKGROUND AND PURPOSE: The aim of this study was to determine the usefulness of three-dimensional (3D) scalp EEG source imaging (ESI) in partial epilepsy in comparison with the results of presurgical evaluation, magnetoencephalography (MEG), and electrocorticography (ECoG). METHODS: The epilepsy syndrome of 27 partial epilepsy patients was determined by presurgical evaluations. EEG recordings were made using 70 scalp electrodes, and the 3D coordinates of the electrodes were digitized. ESI images of individual and averaged spikes were analyzed by Curry software with a boundary element method. MEG and ECoG were performed in 23 and 9 patients, respectively. RESULTS: ESI and MEG source imaging (MSI) results were well concordant with the results of presurgical evaluations (in 96.3% and 100% cases for ESI and MSI, respectively) at the lobar level. However, there were no spikes in the MEG recordings of three patients. The ESI results were well concordant with MSI results in 90.0% of cases. Compared to ECoG, the ESI results tended to be localized deeper than the cortex, whereas the MSI results were generally localized on the cortical surface. ESI was well concordant with ECoG in 8 of 9 (88.9%) cases, and MSI was also well concordant with ECoG in 4 of 5 (80.0%) cases. The EEG single dipoles in one patient with mesial temporal lobe epilepsy were tightly clustered with the averaged dipole when a 3 Hz high-pass filter was used. CONCLUSIONS: The ESI results were well concordant with the results of the presurgical evaluation, MSI, and ECoG. The ESI analysis was found to be useful for localizing the seizure focus and is recommended for the presurgical evaluation of intractable epilepsy patients.

Clinical study of functional hemispherectomy for pediatric intractable epilepsy with hemisphere lesions / 实用医学杂志

Objective To study the results of functional hemispherectomy for pediatric intractable epilepsy with hemisphere lesions , and to explore the indications of functional hemispherectomy , as well as the prognosis. Methods Twenty-four children with intractable epilepsy caused by hemisphere lesions were included , who underwent functional hemispherectomy. All patients were followed up for 3 ~ 48 months. Results All 24 cases obtained improvement of abnormal behavior , and no significant exacerbation of neurological deficits was observed. During the follow-up, 18 cases were in EngelⅠ(75%), 5 in Engel Ⅱ(21%), and 1 in Engel Ⅰ(4%) respectively. No long-term complication was observed. Conclusion Comprehensive presurgical evaluation is a prerequisite for the surgical treatment of pediatric intractable epilepsy caused by hemisphere lesions. Functional hemispherectomy can effectively control seizures and obviously improve the prognosis.

Localization Value of Magnetoencephalography Interictal Spikes in Adult Nonlesional Neocortical Epilepsy

Few studies have included magnetoencephalography (MEG) when assessing the diagnostic value of presurgical modalities in a nonlesional epilepsy population. Here, we compare single photon emission computed tomography (SPECT), positron emission tomography (PET), video-EEG (VEEG), and MEG, with intracranial EEG (iEEG) to determine the value of individual modalities to surgical decisions. We analyzed 23 adult epilepsy patients with no abnormal MRI findings who had undergone surgical resection. Localization of individual presurgical tests was determined for hemispheric and lobar locations based on visual analysis. Each localization result was compared with the ictal onset zone (IOZ) defined by using iEEG. The highest to the lowest hemispheric concordance rates were MEG (83%) > ictal VEEG (78%) > PET (70%) > ictal SPECT (57%). The highest to lowest lobar concordance rates were ictal VEEG = MEG (65%) > PET (57%) > ictal SPECT (52%). Statistical analysis showed MEG to have a higher hemispheric concordance than that of ictal SPECT (P = 0.031). We analyzed the effects of MEG clustered-area resection on surgical outcome. Patients who had resection of MEG clusters showed a better surgical outcome than those without such resection (P = 0.038). It is suggested that MEG-based localization had the highest concordance with the iEEG-defined IOZ. Furthermore, MEG cluster resection has prognostic significance in predicting surgical outcome.

Localization Value of Magnetoencephalography Interictal Spikes in Adult Nonlesional Neocortical Epilepsy

Few studies have included magnetoencephalography (MEG) when assessing the diagnostic value of presurgical modalities in a nonlesional epilepsy population. Here, we compare single photon emission computed tomography (SPECT), positron emission tomography (PET), video-EEG (VEEG), and MEG, with intracranial EEG (iEEG) to determine the value of individual modalities to surgical decisions. We analyzed 23 adult epilepsy patients with no abnormal MRI findings who had undergone surgical resection. Localization of individual presurgical tests was determined for hemispheric and lobar locations based on visual analysis. Each localization result was compared with the ictal onset zone (IOZ) defined by using iEEG. The highest to the lowest hemispheric concordance rates were MEG (83%) > ictal VEEG (78%) > PET (70%) > ictal SPECT (57%). The highest to lowest lobar concordance rates were ictal VEEG = MEG (65%) > PET (57%) > ictal SPECT (52%). Statistical analysis showed MEG to have a higher hemispheric concordance than that of ictal SPECT (P = 0.031). We analyzed the effects of MEG clustered-area resection on surgical outcome. Patients who had resection of MEG clusters showed a better surgical outcome than those without such resection (P = 0.038). It is suggested that MEG-based localization had the highest concordance with the iEEG-defined IOZ. Furthermore, MEG cluster resection has prognostic significance in predicting surgical outcome.

Positron emission tomography (PET) scan in epilepsy.

Positron Emission Tomography (PET) has an advantage in localizing epileptogenic zones for successful surgery in several epileptic syndromes. Among the most radiopharmaceutical used in PET studies in epilepsy are [18F] fluorodeoxyglucose (FDG) and [11C]flumazenil (FMZ). Unilateral temporal hypometabolism (UTH) seen in FDGPET was shown to correlate well with ictal EEG origins in 60-90 % of temporal lobe epilepsy (TLE) patients. PET aids in surgical decision-making in TLE patients with discordant data from initial presurgical evaluation, in bitemporal disease and in nonlesional TLE. However, PET adds little in lesional TLE with congruent data. The extent of glucose hypometabolic area was shown to correlate with post-operative outcomes. PET may reduce the need for invasive EEG in bitemporal epilepsy. Abnormal FMZ binding has been proposed to guide the location of subdural electrode placement in extratemporal epilepsy (ETE). FMZ-PET and FDG-PET were shown to be sensitive in visualizing areas of cortical dysgenesis. Focal FDG-PET abnormality was demonstrated in 20 % of children with West’s syndrome and has provided a revolutionary approach for surgical treatment. Resection of the focal hypometabolism has rendered good control of infantile spasms and restoration of developmental delay. PET use of alpha-[11C] methyl-L-tryptophan (AMT), a serotonin precursor, has been shown to selectively localize epileptogenic tuber in the tuberous sclerosis complex as well as in identifying epileptic residual tissue following surgical failure. PET has potential in determining eloquent brain areas and in studying mechanisms of epilepsy. In epilepsy surgery, PET can be used with worthwhile cost-benefit even in a country with limited resources.

Epilepsy Surgery I

Epilepsy is a chronic neurological disorder manifesting recurrent unprovoked epileptic seizures. About 20~30% of epilepsy patients are resistant to antiepileptic medications. These patients suffer from high risk of physical injury, unemployment, marital problem, and psychological stress. Epilepsy surgery is the firstly recommended treatment modality for the patients with medically intractable epilepsy. Presurgical evaluation is the most important process for performing epilepsy surgery. The ultimate goal of the presurgical evaluation in patients with medically refractory partial seizures is the localization of the epileptogenic zone and the resection of which is also both necessary and sufficient to render the patient seizure-free. The localization of the epileptogenic zone derives from a hierarchical synthesis of localizing data independently obtained from clinical, electrographic, neuroimaging, and neuropsychological examination. In addition, closely related to the goal of localizing the epileptogenic zone is the significant need for anticipating the risks of functional deficits that could derive from the surgical resection. Mesial temporal lobe epilepsy (TLE) is the best candidate for epilepsy surgery. Anterior temporal lobectomy with amygdalohippocampectomy is a surgical treatment method for mesial TLE and its seizure-free rate (SFR) is 60~90%, whereas one-year SFR of antiepileptic drug treatment for mesial TLE is 10~20%. Cortisectomy is a surgical method for extratemporal epilepsy and its SFR is about 40~70%. Corpus callosotomy is a partial or complete division of corpus callosum for preventing seizure propagations between right and left hemispheres and is effective for controlling atonic seizures. The variation of postsurgical seizure outcomes is related to the qualities of epilepsy surgery program, presurgical evaluation and surgical techniques. For the good surgical outcome, the epilepsy surgery program should include neurologist, neurosurgeon, neuropsychologist, neuro-radiologist and neuro-nuclear medicine specialist for a comprehensive team approach.