Does F-18 FDG-PET substantially alter the surgical decision-making in drug-resistant partial epilepsy?

ObjectiveThere is a dearth of information on the critical utility of positron emission tomography (PET) in choosing candidates for epilepsy surgery especially in resource-poor countries where it is not freely available. This study aimed to critically analyze the utility of FDG-PET in the presurgical evaluation and surgical selection of patients with DRE based on the results obtained through its use in our comprehensive epilepsy program.MethodsFrom 2008 to 2012, 117 patients with drug-resistant epilepsy underwent F-18 fluoro-deoxy-glucose (FDG) PET in our center. We utilized their data to audit the utility of PET in choosing/deferring patients for surgery.ResultsOf the 117 patients (age: 5–42 years) who underwent F-18 FDG-PET, 64 had normal MRI, and 53 had lesions. Electroclinical data favored temporal ictal onset in 48 (41%), extratemporal in 60 (51.3%), and uncertain lobar localization in 9 (7.7%). The topography of PET hypometabolism was localizing in 53 (45.3%), lateralizing in 12 (10.3%), and 52 (44.4%) had either normal or discordant results. In the nonlesional group, focal hypometabolism was concordant to the area of ictal onset in 27 (41.5%) versus 38 (58.5%) in the lesional group (p = 0.002). Greater concordance was noted in temporal lobe epilepsy (TLE) (78.0%) as compared to extratemporal epilepsy (ETPE) (28.6%) (p < 0.001). Positron emission tomography was more concordant in patients with mesial temporal sclerosis than in those with other lesions (82.8% versus 50%) (p = 0.033). Positron emission tomography helped in surgical decision-making in 68.8% of TLE and 23.3% of ETPE cases. Overall, 37 patients (31.6%) were directly selected for resective surgery based on PET results.ConclusionsPositron emission tomography, when utilized judiciously, remained an ancillary tool in the surgical selection of one-third of patients with drug-resistant partial epilepsy, although its utility as an independent tool is not very promising.     

Subtraction peri-ictal SPECT is predictive of extratemporal epilepsy surgery outcome

OBJECTIVES: To determine whether localization of extratemporal epilepsy with subtraction ictal SPECT coregistered with MRI (SISCOM) is predictive of outcome after resective epilepsy surgery, whether SISCOM images provide prognostically important information compared with standard tests, and whether blood flow change on SISCOM images is useful in determining site and extent of excision required. BACKGROUND: The value of SISCOM in predicting surgical outcome for extratemporal epilepsy is unknown, especially if MRI findings are nonlocalizing. METHODS: SISCOM images in 36 consecutive patients were classified by blinded reviewers as "localizing and concordant with site of surgery," "localizing but nonconcordant with site of surgery," or "nonlocalizing." SISCOM images were coregistered with postoperative MRI, and reviewers visually determined whether cerebral cortex underlying the SISCOM focus had been completely resected, partially resected, or not resected. RESULTS: Twenty-four patients (66.7%) had localizing SISCOM, including 13 (76.5%) of those without a focal MRI lesion. Eleven of 19 patients (57.9%) with localizing SISCOM concordant with the surgical site, compared with 3 of 17 (17.6%) with nonlocalizing or nonconcordant SISCOM, had an excellent outcome (p < 0.05). With logistic regression analysis, SISCOM findings were predictive of postsurgical outcome, independently of MRI or scalp ictal EEG findings (p < 0.05). The extent of resection of the cortical region of the SISCOM focus was significantly associated with the rate of excellent outcome (100% with complete resection, 60% with partial resection, and 20% with nonresection, p < 0.05). CONCLUSION: SISCOM images may be useful in guiding the location and extent of resection in extratemporal epilepsy surgery.     

Ictal SPECT in Nonlesional Extratemporal Epilepsy

Summary:  Purpose: Ictal single-photon emission computed tomography (SPECT) may be a reliable indicator of the ictal onset zone in patients with intractable partial epilepsy who are being considered for epilepsy surgery. The rationale for the illustrated case report is to evaluate the use of an innovation in SPECT imaging in a patient with nonlesional extratemporal epilepsy.
Methods: We investigated the presurgical evaluation and operative outcome in a patient with intractable partial epilepsy. The ictal semiology indicated a "hypermotor" seizure with bipedal automatism. The electroclinical correlation and magnetic resonance imaging (MRI) did not suggest the appropriate localization of the epileptogenic zone. A subtraction periictal SPECT coregistered to MRI (SISCOM) was peformed.
Results: SISCOM revealed a region of localized hyperperfusion in the right supplementary sensorimotor area. Chronic intracranial EEG monitoring confirmed the relationship between the localized SISCOM alteration and the ictal onset zone. The patient was rendered seizure free after surgical treatment.
Conclusions: SISCOM may be used to identify potential candidates for surgical treatment of nonlesional extratemporal epilepsy. Periictal imaging may also alter the strategy for intracranial EEG recordings and focal cortical resection.     

The usefulness of subtraction ictal SPECT coregistered to MRI in single- and dual-headed SPECT cameras in partial epilepsy

PURPOSE: To prove the clinical usefulness of SISCOM and compare SISCOM images derived from single- and dual-headed single-photon computed tomography (SPECT) cameras for localization of partial epileptic seizures. METHODS: We retrospectively studied 38 partial epilepsy patients, using subtraction SPECT coregistered to magnetic resonance imaging (MRI; SISCOM). SPECT imaging of the first 15 patients was performed by single-headed camera, and the next 23 patients by dual-headed camera. Side-by-side ictal-interictal SPECT evaluation and SISCOM images were blindly reviewed and classified as either localizing to one of 16 sites or nonlocalizing. A third reviewer evaluated cases of disagreement between primary reviewers. Results were compared with seizure localization by any of the following three traditional techniques: surgical outcome, invasive, and noninvasive video-EEG monitoring. The results from the single- and dual-headed SPECT cameras were compared. RESULTS: Reviewers localized areas of hyperperfusion with SISCOM images more often than with side-by-side SPECT evaluation (71.0 vs. 47.4%; p = 0.01). When we compared results of SPECT evaluation with traditional techniques, SISCOM showed greater concordance than side-by-side SPECT evaluation (60.53 vs. 36.84%; p = 0.006). There were no differences in localization between images derived from single- and dual-headed cameras. Concordance of seizure localization, compared with traditional techniques, also was not different between these groups [kappa = 0.38, 95% confidence interval (CI), 0.18-0.58] vs. kappa = 0.63, 95% CI (0.45-0.81)]. CONCLUSIONS: SISCOM is a worthwhile technique for preoperative evaluation in partial epilepsy patients and improves the sensitivity and specificity of seizure localization of SPECT images derived from both single- and dual-headed SPECT cameras.     

The Relative Contributions of MRI, SPECT, and PET Imaging in Epilepsy

Summary: Functional and structural neuroimaging techniques are increasingly indispensable in the evaluation of epileptic patients for localization of the epileptic area as well as for understanding pathophysiology, propagation, and neurochemical correlates of chronic epilepsy. Although interictal single photon emission computed tomography (SPECT) imaging of cerebral blood flow is only moderately sensitive, ictal SPECT markedly improves yield. Positron emission tomography (PET) imaging of interictal cerebral metabolism is more sensitive than measurement of blood flow in temporal lobe epilepsy. Furthermore, PET has greater spatial resolution and versatility in that multiple tracers can image various aspects of cerebral function. Interpretation of all types of functional imaging studies is difficult and requires knowledge of time of most recent seizure activity and structural correlates. Only magnetic resonance imaging (MRI) can image the structural changes associated with the underlying epileptic process, and quantitative evidence of hippocampal volume loss has been highly correlated with seizure onset in medial temporal structures. Improved resolution and interpretation have made quantitative MRI more sensitive in temporal lobe epilepsy, as judged by pathology. When judged by electroencephalography (EEG), ictal SPECT and interictal PET have the highest sensitivity and specificity for temporal lobe epilepsy; these neuroimaging techniques have lower sensitivity and higher specificity for extratemporal EEG abnormalities. Regardless of the presence of structural abnormalities, functional imaging by PET or SPECT provides complementary information. Ideally these techniques should be used and interpreted together to improve the localization and understanding of epileptic brain.     

The clinical spectrum of focal cortical dysplasia and epilepsy

Focal cortical dysplasia is an important pathologic substrate in patients with epilepsy, but its clinical spectrum has not yet been completely defined. We retrospectively studied 30 epilepsy surgery patients with focal abnormalities of neuronal migration as the only histopathologic finding in resected tissue. Patients comprised two clinical groups. Seventeen patients with extratemporal epilepsy had early (median age, 7.0 years) extratemporal resection or hemispherectomy for severe epilepsy (47% of patients with > 10 partial seizures a day) that began in infancy or early childhood (median age, 1.0 year), usually in the setting of mental retardation or developmental delay (59% of patients), and often with magnetic resonance imaging (MRI) evidence of focal neuronal migration abnormality (44% of patients). In contrast, 13 patients with temporal lobe epilepsy were significantly older at age of seizure onset (median, 8.0 years; p = 0.001) and surgery (median, 22.0 years; p = 0.001), with less severe epilepsy (no patients with an average of > 10 seizures a day; p = 0.004), and without mental retardation or MRI evidence of neuronal migration abnormality (p = 0.001). In both groups, positron emission tomography (PET) was more sensitive than MRI and showed focal hypometabolism in seven patients with normal MRI. Seizure-free outcome tended to be more common after temporal lobectomy (77%) than after extratemporal resection or hemispherectomy (53%). Pathologic abnormalities were more severe in patients with extratemporal epilepsy than in patients with temporal lobe epilepsy. The clinical spectrum of focal cortical dysplasia included not only infants and children with severe extratemporal epilepsy and mental retardation, but also older patients with temporal lobe epilepsy and at least boderline IQ. Preoperative diagnosis may be difficult in cases with less severe pathologic abnormality, but high-resolution MRI and PET can increase the yield.     

Quantitative MRI in Outpatient Childhood Epilepsy

Summary: Purpose: In adult studies, MRI volumetrics is a proven technique in presurgical assessment of epilepsy. Hippocampal volume loss is maximal in the syndrome of mesial temporal lobe epilepsy. We aimed (a) to validate this methodology in a pediatric outpatient epilepsy population (b) to determine the relationship of hippocampal asymmetry (HA) to epileptic syndromes and risk factors. Methods: Two neurologists classified the epileptic syndrome in 79 pediatric outpatients, according to the International Classification of Epilepsies and Epileptic Syndromes (ILAE). Hippocampal volumetrics were performed in all patients. HA was defined according to adult control values. Results: Inter-rater variability on measurement of HA was very small (Correlation of test retest of 0.97 on 17 children <3 years old). The rate of HA was 44/79 (57%). In 21 patients, (27%) potentially epileptogenic lesions (other than HA) were identified (cerebral dysgenesis n = 11). HA was present in 9/15 (60%) of temporal lobe epilepsy and in 15/28 (54%) extratemporal onset epilepsy and 5/11 (46%) of generalized symptomatic epilepsy. Analysis confined to <13 years also showed HA was not specific for epileptic syndrome. There was no significant association of febrile convulsions (13%) with HA or temporal lobe epilepsy. Conclusions: There is a high incidence of HA in childhood epilepsy. HA was not confined to clinically defined temporal lobe epilepsy. The poor correlation of epileptic syndrome to quantitative MRI findings may be due to the inadequacies of epilepsy classification in the younger child, with the clinical semiology providing misleading localizing information. Normative childhood data for hippocampal volumes and symmetry is needed.     

MRI与PET在颞叶癫癎中定位价值的比较

目的 比较ＭＲＩ及ＦＤＧ－ＰＥＴ在颞叶癫癎致癎灶定位中的价值,探讨癫癎外科术前定位的方法以及手术预后的判断。方法 以手术后癫癎控制状况为标准,对３０例颞叶癫癎患者的术前ＭＲＩ和ＦＤＧ－ＰＥＴ的结果进行比较,分析ＭＲＩ及ＰＥＴ各自在癫癎致癎灶定位中的价值。结果ＭＲＩ有良好的脑结构分辨能力,对于症状性癫癎的定位价值高,当ＭＲＩ显示海马硬化时,对致癎灶定位的意义大,术后癫癎发作完全控制的可能性大。发作间期ＰＥＴ对于颞叶癫癎定位的敏感性高于ＭＲＩ,但ＰＥＴ低代谢的范围往往超过致癎灶。与ＰＥＴ的目测方法比较,ＰＥＴ半定量分析并不能提高致癎灶定位的准确性及对手术效果的预测。结论　ＭＲＩ与ＰＥＴ检查结合可以提高致癎灶定位的准确性及对手术效果的预测,减少颅内记录的应用。     

Outcome of surgical treatment in non-lesional intractable childhood epilepsy

PurposeThe aim of this study is to investigate seizure outcomes following epilepsy surgery in non-lesional neocortical pediatric epilepsy.MethodsWe performed a retrospective study on 27 patients with intractable childhood epilepsy who received epilepsy surgery between 1999 and 2006 at Sang-gye Paik Hospital and Severance Children's Hospital. None of the patients had any detectable lesions on MRI. Surgical outcome was assessed at least 2 years postoperatively; clinical characteristics, surgical outcome, pathologic findings, types of surgery, localizing features on SPECT, FDG-PET, and long-term video-EEG were reviewed.ResultsEighteen patients (67%) demonstrated an Engel class I outcome postoperatively. The mean follow-up duration was 4.3 years (range, 2.2–9 years). Eighteen out of 27 cases (67%) showed focal localizing features on ictal SPECT, and 21 of 27 cases (78%) showed abnormal findings on PET. Single lobectomy was the most common procedure, and was performed in 20 patients (74%). Multilobar resection was performed in seven patients (26%). Cortical dysplasia was the most common finding during pathological examination, and was observed in 15 (56%) cases. In addition, gliosis was found in two patients (7%) and non-specific pathological findings were described in 10 patients (37%).ConclusionsIn children with intractable epilepsy and a MRI demonstrating no abnormal lesions, epileptic surgery should be strongly considered when cortical pathology can be identified from other studies.     

Multimodality imaging for focus localization in pediatric pharmacoresistant epilepsy.

Multiple structural and functional imaging modalities are available to localize the epileptogenic focus. In pre-surgical evaluation of children with pharmacoresistant epilepsy, investigations with the maximum yield should be considered in order to reduce the complexity of the workup. OBJECTIVE: To determine the extent to which PET, ictal/interictal SPECT and its co-registration with the patient's MRI contributes to correct localization of the epileptogenic focus, surgical intervention and to the post surgical outcome in paediatric patients. METHODS: The study population included children and adolescents with pharmacoresistant epilepsy (n = 50) who underwent preoperative evaluation, surgery and had postoperative follow-up for at least 12 months. Outcome was measured by postoperative seizure frequency using Engel's classification. RESULTS: Thirty-nine patients (78%) became completely seizure free after surgical intervention. The likelihood to benefit from surgical treatment was significantly higher if localization with more imaging modalities (MRI, PET, SPECT) were concordant with respect to the resected brain area (p < 0.01). Preoperative PET examination provided better localizing information in patients with extratemporal epilepsy and/or dysplastic lesions, whereas SPECT was found to be superior to PET in patients with temporal lobe epilepsy and/or tumors (p < 0.05). No significant difference was noted in the surgical outcome in younger or older age group, in children with or without special education needs. CONCLUSION: In paediatric epilepsy pre-surgical evaluation, the combined use of multiple functional imaging modalities for a precise localisation of the epileptogenic focus is worthwhile for both extratemporal and temporal lobe epilepsy, also when EEG and MRI alone are non-contributive, given the potential benefit of complete postoperative seizure control.     

发作间期颞叶癫痫的18F-FDG PET 显像研究

目的：采用诊断试验评价方法评估发作间期^18F-FDG PET显像对颞叶癫痫定性和病业定位的诊断价值，探讨其外科治疗的意义。方法：26例CT或MRI检查正常，经临床及脑电图诊断的颞叶癫痫患者在同期进行发作间期^18F-FDG PET脑显像，图像通过目测和半定量的方法进行分析，PET显示的低代谢区行皮层脑电图（EcoG）或深部脑电图（DEEG）描记以评估^18F-FDG PET检测癫痫灶的特异性，17例定位明确的单侧颞叶癫痫行前颞叶切除术，术手进行随访。2例PET未检出癫痫灶，7例DEEG定位双侧病灶未行手术治疗。结果：26例颞叶癫痫中，发现^18F-FDG PET对癫痫灶检出的灵敏度为92%（24/26），特异度为87%(21/24)。结论：从颞叶癫痫的定性定位诊断来看，发作间期^18F-FDG PET脑显像对癫痫灶的检出率较高，但^18F-FDG PET显示的低代谢区与癫痫灶的位置并非完全重叠，尚需要其他的诊断措施加以肯定，^18F-FDG PET和皮层脑电图或深部脑电图对癫痫病灶定位的一致性是手术成功的关键。     

EEG source imaging in pediatric epilepsy surgery: a new perspective in presurgical workup

PURPOSE: Epilepsy is a relatively frequent disease in children, with considerable impact on cognitive and social life. Successful epilepsy surgery depends on unambiguous focus identification and requires a comprehensive presurgical workup, including several neuroimaging techniques [magnetic resonance imaging, positron emission tomography (PET), and single-photon emission computed tomography (SPECT)]. These may be difficult to apply in younger or developmentally delayed children or both, requiring sedation, and hence, a significant workforce. Modern electric source imaging (ESI) provides accurate epileptic source-localization information in most patients, with minimal patient discomfort or need for cooperation. The purpose of the present study was to determine the usefulness of ESI in pediatric EEG recordings performed with routine electrode arrays. METHODS: Preoperative EEGs recorded from 19 to 29 scalp electrodes were reviewed, and interictal epileptiform activity was analyzed by using a linear source-imaging procedure (depth-weighted minimum norm) in combination with statistical parametric mapping. RESULTS: In 27 (90%) of 30 patients, the ESI correctly localized the epileptogenic region. These numbers compare favorably with the results from other imaging techniques in the same patients (PET, 82%; ictal SPECT, 70%). In extratemporal epilepsy, ESI was correct in all cases, and in temporal lobe epilepsy, in 10 of 13 cases. In two temporal lobe patients showing less-accurate ESI results, 128-electrode data could be analyzed, and in both cases, the 128-electrode ESI was correct. CONCLUSIONS: ESI with standard clinical EEG recordings provides excellent localizing information in pediatric patients, in particular in extratemporal lobe epilepsy. The lower yield in temporal lobe epilepsy seems to be due to undersampling of basal temporal areas with routine scalp recordings.     

Neuroimaging in Partial Epilepsy: Structural Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) is a noninvasive technique that has been shown to be the structural neuroimaging procedure of choice in evaluating patients with partial or localization-related epilepsy. The diagnostic yield of MRI has been confirmed in patients with partial epilepsy related to mesial temporal sclerosis (MTS) or foreign-tissue lesions. Magnetic resonance imaging may be used preoperatively to identify patients with intractable partial epilepsy who have surgically remediable epileptic syndromes. Preoperative MRI studies are predictive of long-term seizure outcome in patients receiving surgical treatment. Analysis of hippocampal formation size has also been shown to correlate with the neurocognitive outcome following temporal lobe surgery. A recent development involving subtraction ictal single photon emission computed tomography (SPECT) coregistered with structural MRI (SISCOM) has important clinical applications. SISCOM studies are more sensitive and specific than visual side-by-side interpretation of interictal and ictal SPECT scans. Also, SISCOM images have been shown to have prognostic importance in patients undergoing surgical treatment for epilepsy.     

Comprehensive preoperative work-up and surgical treatment of low grade tumor/benign lesion related temporal lobe epilepsy

ObjectiveGenerally low-grade tumor/benign lesion related temporal lobe epilepsy (LGT/BL-TLE) is considered easier to treat and has better prognosis when compared to non-lesional TLE. However, multiple disputes exist in surgical management of this epilepsy entity. This study aims to discuss comprehensive preoperative work-up, surgical strategies and outcome of it.MethodsA retrospective review of sixty LGT/BL-TLE cases which underwent comprehensive preoperative work-up and then resective surgeries was conducted. Surgical strategies were categorized into limited and expanded resections. Surgical efficacy was evaluated using Engel grading after telephone or clinic follow-up and compared statistically.ResultsPreoperative work-up includes magnetic resonance imaging (MRI), conventional electroencephalography, semiology evaluation, positron emission tomography (PET) and 256-channel dense-array electroencephalography source imaging (256-ch dESI). In aspect of concordance with epileptic lesions demonstrated on MRI, 256-ch dESI was more accurate than PET (72.7% vs. 39.4%) (p < 0.05). Limited resections were performed in 28 cases while expanded resections in 32 cases. Altogether the surgical efficacy was: Engel grade I 86.7%, I + II 95.0%. Comparison of surgical outcome showed neither the outcome between limited and expanded resection nor the outcome between mesial and neocortical TLE (mTLE & nTLE) undergoing limited resections was significantly different (p > 0.05).ConclusionsFor LGT/BL-TLE, most surgical strategies can be made preoperatively after comprehensive work-up rather than intraoperatively. Limited and expanded strategies yield similar surgical outcome in either nTLE or mTLE as long as comprehensive work-up supports the strategy and the epileptic lesion is totally removed. 256-ch dESI which can visualize both structural and electrophysiological lesions may be contributable to surgical planning of this entity.     

Subtraction SPECT coregistered to MRI in focal malformations of cortical development: localization of the epileptogenic zone in epilepsy surgery candidates

PURPOSE: To determine the extent to which periictal subtraction single-photon emission computed tomography (SPECT) may improve detection and definition of the epileptogenic zone in patients with focal malformations of cortical development (MCDs). METHODS: Subtraction SPECT coregistered to magnetic resonance (MR) images (SISCOM) were constructed for 22 consecutive patients with focal MCDs who underwent periictal SPECT injection (18 ictal and four postictal). In the 17 patients who had epilepsy surgery, concordance between the site of SISCOM localization and site of surgical resection was determined by coregistration of SISCOM images with postoperative MRIs. RESULTS: SISCOM images were localizing in 19 (86%) patients, including eight of the 10 with nonlocalizing MRI. Concordance of SISCOM localization was 91% with MRI localization, 93% with scalp ictal EEG localization, and 100% with intracranial EEG localization. Eight patients whose SISCOM localization was concordant with the surgical resection site had lower postoperative seizure frequency scores (SFSs; p = 0.04) and greater postoperative improvement in SFSs (p = 0.05) than the nine patients whose SISCOM was either nonconcordant or nonlocalizing. On multiple regression analysis, a model combining SISCOM concordance with surgical resection site and extent of MRI lesion resection was predictive of postoperative SFS (R2 = 0.47; p = 0.03). CONCLUSIONS: Periictal subtraction SPECT using the SISCOM technique provides useful information for seizure localization in patients with focal MCDs, even when MRI is nonlocalizing.     

Comparison of voxel-based 3-D MRI analysis and subtraction ictal SPECT coregistered to MRI in focal epilepsy

While voxel-based 3-D MRI analysis methods as well as assessment of subtracted ictal versus interictal perfusion studies (SISCOM) have proven their potential in the detection of lesions in focal epilepsy, a combined approach has not yet been reported. The present study investigates if individual automated voxel-based 3-D MRI analyses combined with SISCOM studies contribute to an enhanced detection of mesiotemporal epileptogenic foci. Seven consecutive patients with refractory complex partial epilepsy were prospectively evaluated by SISCOM and voxel-based 3-D MRI analysis. The functional perfusion maps and voxel-based statistical maps were coregistered in 3-D space. In five patients with temporal lobe epilepsy (TLE), the area of ictal hyperperfusion and corresponding structural abnormalities detected by 3-D MRI analysis were identified within the same temporal lobe. In two patients, additional structural and functional abnormalities were detected beyond the mesial temporal lobe. Five patients with TLE underwent epileptic surgery with favourable postoperative outcome (Engel class Ia and Ib) after 3-5 years of follow-up, while two patients remained on conservative treatment. In summary, multimodal assessment of structural abnormalities by voxel-based analysis and SISCOM may contribute to advanced observer-independent preoperative assessment of seizure origin.     

Functional neuroimaging in the preoperative evaluation of children with drug-resistant epilepsy

Functional neuroimaging Although the primary imaging modality in the management of epilepsy is magnetic resonance imaging MRI, functional neuroimaging with positron-emission tomography (PET) and single photon emission computed tomography (SPECT) often provides complementary information and, in a number of situations, provides unique information that cannot be obtained with MRI. The most commonly used PET tracers used for epilepsy evaluation are 2-deoxy-2-[¹⁸F]fluoro-d-glucose (FDG) and [¹¹C]flumazenil (FMZ). Recently, interictal PET with alpha-[¹¹C]methyl-l-tryptophan was found to be highly specific for the epileptic focus and can differentiate between epileptogenic and nonepileptogenic lesions in the same patient (e.g., in patients with tuberous sclerosis).Discussion In this review, we discuss clinical applications of these three PET tracers in drug-resistant temporal and extratemporal lobe epilepsy, selected epilepsy syndromes of childhood, lesional and nonlesional epilepsy, and the challenges of imaging secondary epileptic foci. A brief discussion of SPECT applications in epilepsy is also included. With further development of new tracers highly sensitive and specific for epileptogenic brain regions, the presurgical evaluation of refractory epilepsy will be greatly facilitated. Approximately 0.5 to 1.0% of the population suffer from epilepsy, of which 15–20% are intractable. Infants and children, whose seizures have a focal onset are refractory to anticonvulsants and are prolonged, tend to have the worst cognitive outcome [Meador KJ, Neurology 58 (Suppl 5):S21–S26, 2002]. Seizures themselves affect the developing brain and contribute to an adverse neurologic outcome (Holmes, Pediatric Neurology 33:1–110, 2005).Conclusion Therefore, in treating children with intractable epilepsy, it is important to consider seizure control and to give allowance for normal cognitive development.     

Ictal Single-Photon Emission Computed Tomography Imaging in Extra Temporal Lobe Epilepsy Using Statistical Parametric Mapping

PURPOSE: To examine the application of statistical parametric mapping (SPM) to analyze ictal single-photon emission computed tomography (SPECT) scans in surgical candidates with extratemporal lobe epilepsy. METHODS: The authors selected patients who underwent successful ictal SPECT acquisition in the process of surgical treatment of intractable partial epilepsy. Thirteen patients were identified who met inclusion criteria for confident seizure localization from either intracranial electroencephalogram recordings or epilepsy surgery outcome. In these cases, ictal scans were registered to an in-house-developed normal SPECT atlas composed of 14 spatially normalized brains of normal subjects. SPM96 was used to test on a voxel-by-voxel basis for statistically significant increases in blood flow associated with each patient's ictal scan. The results were then mapped back onto the patient's magnetic resonance image (MRI) for final interpretation. Statistical parametric mapping (SPM) analysis of ictal SPECT scans was compared to both conventional visual interpretation and the analysis of subtraction ictal SPECT co-registered to MRI (SISCOM). RESULTS: Ten of 13 patient scans showed localizing focal ictal increases in regional cerebral blood flow, all of which were concordant with ultimate epilepsy localization. Of the 3 cases not localized with SPM, 1 was localized by conventional visual interpretation and another, not localized by visual interpretation, was correctly localized with SISCOM. Two cases not localized by SISCOM were localized by both visual and SPM analysis. CONCLUSIONS: This work provides supportive evidence for proof of principle that SPM can be used to provide objective, accurate analysis of ictal SPECT scans in patients with extratemporal lobe epilepsy.     

Increasing volume and complexity of pediatric epilepsy surgery with stable seizure outcome between 2008 and 2014: A nationwide multicenter study

ObjectiveThe objective of the study was to assess common practice in pediatric epilepsy surgery in Italy between 2008 and 2014.MethodsA survey was conducted among nine Italian epilepsy surgery centers to collect information on presurgical and postsurgical evaluation protocols, volumes and types of surgical interventions, and etiologies and seizure outcomes in pediatric epilepsy surgery between 2008 and 2014.ResultsRetrospective data on 527 surgical procedures were collected. The most frequent surgical approaches were temporal lobe resections and disconnections (133, 25.2%) and extratemporal lesionectomies (128, 24.3%); the most frequent etiologies were FCD II (107, 20.3%) and glioneuronal tumors (105, 19.9%). Volumes of surgeries increased over time independently from the age at surgery and the epilepsy surgery center. Engel class I was achieved in 73.6% of patients (range: 54.8 to 91.7%), with no significant changes between 2008 and 2014. Univariate analyses showed a decrease in the proportion of temporal resections and tumors and an increase in the proportion of FCDII, while multivariate analyses revealed an increase in the proportion of extratemporal surgeries over time. A higher proportion of temporal surgeries and tumors and a lower proportion of extratemporal and multilobar surgeries and of FCD were observed in low (< 50 surgeries/year) versus high-volume centers.There was a high variability across centers concerning pre- and postsurgical evaluation protocols, depending on local expertise and facilities.SignificanceThis survey reveals an increase in volume and complexity of pediatric epilepsy surgery in Italy between 2008 and 2014, associated with a stable seizure outcome.     

What is needed for resective epilepsy surgery from a neurosurgical point of view?

Invasive versus non-invasive epileptogenic zone definition was analyzed in a series of 89 patients operated on for drug-resistant epilepsy. In the group of 69 cortical resections, 26% needed invasive recordings, 13.5% when foreign-tissue lesions had been detected by MRI and 32% when were absent. In this last group temporal resections had invasive EEG recordings in 23.5% versus 54.5% when the epileptogenic zone was extratemporal. In a group of 43 temporal resections with more than one year follow-up MRI has detected some abnormality in 84%. Excluding focal lesions, MRI detected hippocampal/temporal lobe atrophy in 66% of the cases in agreement with other noninvasive tests and in 4% contralateral to the epileptogenic zone located by subdural strips. The outcome analysis showed that 85% of the patients with MRI-EEG agreement were seizure free in contrast to only 43% when MRI was non-lateralizing. Future studies has to be oriented to better understand the epileptic process of patients without MRI abnormalities.