Extratemporal Lobe Research Articles

Connectivity and tissue microstructural alterations in right and left temporal lobe epilepsy revealed by diffusion spectrum imaging.

Focal epilepsy is increasingly recognized as the result of an altered brain network, both on the structural and functional levels and the characterization of these widespread brain alterations is crucial for our understanding of the clinical manifestation of seizure and cognitive deficits as well as for the management of candidates to epilepsy surgery.Tractography based on Diffusion Tensor Imaging allows non-invasive mapping of white matter tracts in vivo. Recently, diffusion spectrum imaging (DSI), based on an increased number of diffusion directions and intensities, has improved the sensitivity of tractography, notably with respect to the problem of fiber crossing and recent developments allow acquisition times compatible with clinical application.We used DSI and parcellation of the gray matter in regions of interest to build whole-brain connectivity matrices describing the mutual connections between cortical and subcortical regions in patients with focal epilepsy and healthy controls. In addition, the high angular and radial resolution of DSI allowed us to evaluate also some of the biophysical compartment models, to better understand the cause of the changes in diffusion anisotropy.Global connectivity, hub architecture and regional connectivity patterns were altered in TLE patients and showed different characteristics in RTLE vs LTLE with stronger abnormalities in RTLE. The microstructural analysis suggested that disturbed axonal density contributed more than fiber orientation to the connectivity changes affecting the temporal lobes whereas fiber orientation changes were more involved in extratemporal lobe changes. Our study provides further structural evidence that RTLE and LTLE are not symmetrical entities and DSI-based imaging could help investigate the microstructural correlate of these imaging abnormalities.

Alteration of Interictal Brain Activity in Patients with Temporal Lobe Epilepsy in the Left Dominant Hemisphere: A Resting-State MEG Study

Resting MEG activities were compared between patients with left temporal lobe epilepsy (LTLE) and normal controls. Using SAMg2, the activities of MEG data were reconstructed and normalized. Significantly elevated SAMg2 signals were found in LTLE patients in the left temporal lobe and medial structures. Marked decreases of SAMg2 signals were found in the wide extratemporal lobe regions, such as the bilateral visual cortex. The study also demonstrated a positive correlation between the seizure frequency and brain activities of the abnormal regions after the multiple linear regression analysis. These results suggested that the aberrant brain activities not only were related to the epileptogenic zones, but also existed in other extratemporal regions in patients with LTLE. The activities of the aberrant regions could be further damaged with the increase of the seizure frequency. Our findings indicated that LTLE could be a multifocal disease, including complex epileptic networks and brain dysfunction networks.

The extratemporal lobe epilepsies in the epilepsy monitoring unit.

Extratemporal lobe epilepsies (ETLE) are characterized by the epileptogenic foci outside the temporal lobe. They have a wide spectrum of semiological presentation depending upon the site of origin. They can arise from frontal, parietal, occipital lobes and from hypothalamic hamartoma. We discuss in this review the semiology of different types of ETLE encountered in the epilepsy monitoring unit.

Invasive electroencephalography monitoring: Indications and presurgical planning.

Electroencephalography (EEG) remains a “gold standard” for defining seizures; hence identification of epileptogenic zone for surgical treatment of epilepsy requires precise electrographic localization of the seizures. Routine scalp EEG recording is not sufficient in many instances, such as extratemporal lobe epilepsy or non-lesional temporal lobe epilepsy. In these individuals EEG recording from proximity of the seizure focus is necessary, which can be achieved by placing electrodes on the surface or in the substance of the brain. As this process requires invasive procedures (usually necessitating surgical intervention) EEG obtained via these electrodes is defined as invasive electroencephalography (iEEG). As only limited areas of the brain can be covered by these electrodes in an individual, precise targeting of the presumed seizure onset location is crucial. The presurgical planning includes where to place electrodes, which type of the electrodes to choose and planned duration of the intracranial recording. Though there are general principles that guide such endeavor, each center does it slightly differently depending upon the various technologies available to them and expertise and preferences of the epilepsy surgery team. Here we describe our approach to iEEG recording. We briefly describe the background, types of iEEG recording and rationale for each, various electrode types, and scenarios where iEEG might be useful. We also describe planning of iEEG recording once the need has been established as well as our decision making process of deciding about location of electrode placement, type of electrodes to use, length of recording, choice of arrays, mapping of eloquent cortex and finally surgical planning and decisions.

Multimodal neuroimaging in presurgical evaluation of drug-resistant epilepsy

Intracranial EEG (icEEG) monitoring is critical in epilepsy surgical planning, but it has limitations. The advances of neuroimaging have made it possible to reveal epileptic abnormalities that could not be identified previously and improve the localization of the seizure focus and the vital cortex. A frequently asked question in the field is whether non-invasive neuroimaging could replace invasive icEEG or reduce the need for icEEG in presurgical evaluation. This review considers promising neuroimaging techniques in epilepsy presurgical assessment in order to address this question. In addition, due to large variations in the accuracies of neuroimaging across epilepsy centers, multicenter neuroimaging studies are reviewed, and there is much need for randomized controlled trials (RCTs) to better reveal the utility of presurgical neuroimaging. The results of multiple studies indicate that non-invasive neuroimaging could not replace invasive icEEG in surgical planning especially in non-lesional or extratemporal lobe epilepsies, but it could reduce the need for icEEG in certain cases. With technical advances, multimodal neuroimaging may play a greater role in presurgical evaluation to reduce the costs and risks of epilepsy surgery, and provide surgical options for more patients with drug-resistant epilepsy.

Long-term Outcomes After Nonlesional Extratemporal Lobe Epilepsy Surgery

A focal lesion detected by use of magnetic resonance imaging (MRI) is a favorable prognostic finding for epilepsy surgery. Patients with normal MRI findings and extratemporal lobe epilepsy have less favorable outcomes. Most studies investigating the outcomes of patients with normal MRI findings who underwent (nonlesional) extratemporal epilepsy surgery are confined to a highly select group of patients with limited follow-up. To evaluate noninvasive diagnostic test results and their association with excellent surgical outcomes (defined using Engel classes I-IIA of surgical outcomes) in a group of patients with medically resistant nonlesional extratemporal epilepsy. A retrospective study. Mayo Clinic, Rochester, Minnesota. From 1997 through 2002, we identified 85 patients with medically resistant extratemporal lobe epilepsy who had normal MRI findings. Based on a standardized presurgical evaluation and review at a multidisciplinary epilepsy surgery conference, some of these patients were selected for intracranial electroencephalographic (EEG) monitoring and epilepsy surgery. Nonlesional extratemporal lobe epilepsy surgery. The results of noninvasive diagnostic tests and the clinical variables potentially associated with excellent surgical outcome were examined in patients with a minimum follow-up of 1 year (mean follow-up, 9 years). Based on the noninvasive diagnostic test results, a clear hypothesis for seizure origin was possible for 47 of the 85 patients (55%), and 31 of these 47 patients (66%) proceeded to intracranial EEG monitoring. For 24 of these 31 patients undergoing long-term intracranial EEG (77%), a seizure focus was identified and surgically resected. Of these 24 patients, 9 (38%) had an excellent outcome after resective epilepsy surgery. All patients with an excellent surgical outcome had at least 10 years of follow-up. Univariate analysis showed that localized interictal epileptiform discharges on scalp EEGs were associated with an excellent surgical outcome. Scalp EEG was the most useful test for identifying patients with normal MRI findings and extratemporal lobe epilepsy who were likely to have excellent outcomes after epilepsy surgery. Extending outcome analysis beyond the resective surgery group to the entire group of patients who were evaluated further highlights the challenge that these patients pose. Although 9 of 24 patients undergoing resective surgery (38%) had excellent outcomes, only 9 of 31 patients undergoing intracranial EEG (29%) and only 9 of 85 patient with nonlesional extratemporal lobe epilepsy (11%) had long-term excellent outcomes.

Seizure outcomes after resective surgery for extra–temporal lobe epilepsy in pediatric patients

While temporal lobe epilepsy (TLE) is the most common epilepsy syndrome in adults, seizures in children are more often extratemporal in origin. Extra-temporal lobe epilepsy (ETLE) in pediatric patients is often medically refractory, leading to significantly diminished quality of life. Seizure outcomes after resective surgery for pediatric ETLE vary tremendously in the literature, given diverse patient and epilepsy characteristics and small sample sizes. The authors performed a systematic review and meta-analysis of studies including 10 or more pediatric patients (age ≤ 19 years) published over the last 20 years examining seizure outcomes after resective surgery for ETLE, excluding hemispherectomy. Thirty-six studies were examined. These 36 studies included 1259 pediatric patients who underwent resective surgery for ETLE. Seizure freedom (Engel Class I outcome) was achieved in 704 (56%) of these 1259 patients postoperatively, and 555 patients (44%) continued to have seizures (Engel Class II-IV outcome). Shorter epilepsy duration (≤ 7 years, the median value in this study) was more predictive of seizure freedom than longer (> 7 years) seizure history (odds ratio [OR] 1.52, 95% confidence interval [CI] 1.07-2.14), suggesting that earlier intervention may be beneficial. Also, lesional epilepsy was associated with better seizure outcomes than nonlesional epilepsy (OR 1.34, 95% CI 1.19-1.49). Other predictors of seizure freedom included an absence of generalized seizures (OR 1.61, 95% CI 1.18-2.35) and localizing ictal electroencephalographic findings (OR 1.55, 95% CI 1.24-1.93). In conclusion, seizure outcomes after resective surgery for pediatric ETLE are less favorable than those associated with temporal lobectomy, but seizure freedom may be more common with earlier intervention and lesional epilepsy etiology. Children with continued debilitating seizures despite failure of multiple medication trials should be referred to a comprehensive pediatric epilepsy center for further medical and surgical evaluation.

Correlation between magnetoencephalography-based “clusterectomy” and postoperative seizure freedom

During the presurgical evaluation of patients with medically intractable focal epilepsy, a variety of noninvasive studies are performed to localize the hypothetical epileptogenic zone and guide the resection. Magnetoencephalography (MEG) is becoming increasingly used in the clinical realm for this purpose. No investigators have previously reported on coregisteration of MEG clusters with postoperative resection cavities to evaluate whether complete "clusterectomy" (resection of the area associated with MEG clusters) was performed or to compare these findings with postoperative seizure-free outcomes. The authors retrospectively reviewed the charts and imaging studies of 65 patients undergoing MEG followed by resective epilepsy surgery from 2009 until 2012 at the Cleveland Clinic. Preoperative MEG studies were fused with postoperative MRI studies to evaluate whether clusters were within the resected area. These data were then correlated with postoperative seizure freedom. Sixty-five patients were included in this study. The average duration of follow-up was 13.9 months, the mean age at surgery was 23.1 years, and the mean duration of epilepsy was 13.7 years. In 30 patients, the main cluster was located completely within the resection cavity, in 28 it was completely outside the resection cavity, and in 7 it was partially within the resection cavity. Seventy-four percent of patients were seizure free at 12 months after surgery, and this rate decreased to 60% at 24 months. Improved likelihood of seizure freedom was seen with complete clusterectomy in patients with localization outside the temporal lobe (extra-temporal lobe epilepsy) (p = 0.04). In patients with preoperative MEG studies that show clusters in surgically accessible areas outside the temporal lobe, we suggest aggressive resection to improve the chances for seizure freedom. When the cluster is found within the temporal lobe, further diagnostic testing may be required to better localize the epileptogenic zone.

Statistical parametric mapping of interictal 123I-iomazenil SPECT in temporal lobe epilepsy surgery

Brain single photon emission computed tomography (SPECT) for epilepsy is divided into two types (using three radionuclide tracers)-perfusion SPECT (123I-IMP or 99 mTc-ECD), identifying epileptogenic foci by detecting abnormality in regional cerebral blood flow, and 123I-iomazenil SPECT, identifying epileptogenic foci based on distribution of central benzodiazepine receptors. This study aimed to statistically evaluate and compare the SPECT effectiveness for the three tracers. Statistical parametric mapping (SPM) analysis was performed on 30 mesial temporal lobe epilepsy (mTLE) patients. The radionuclide and patient data were categorized as follows: abnormality in the medial temporal lobe on the operated hemisphere (AAA), in the entire temporal lobe on the operated hemisphere (AA), in the dominantly affected temporal lobe on the operated hemisphere (A), in bilateral temporal lobes (B), with no abnormalities in bilateral temporal lobes (C), and with abnormality in the temporal lobe on the nonoperated hemisphere (D). For analyses of (AAA), (AA), and (A), examining the hemisphere containing epileptogenic foci, IMP-SPECT was significantly superior to ECD-SPECT (P<0.05). For (AAA), indicating localization, IMZ-SPECT was significantly superior to the other two (P<0.05). IMP-SPECT was superior for lateralizing and IMZ-SPECT was useful for localizing epileptogenic foci in mTLE patients though the applicability of the results in extratemporal lobe epilepsy is unknown.

Prognostic significance of acute postoperative seizures in extra-temporal lobe epilepsy surgery

ObjectiveThis study aims to assess the prognostic value of acute postoperative seizures (APOS) in patients surgically treated for drug-resistant extra-temporal lobe (ET) epilepsy. MethodsWe studied 77 consecutive patients with ET epilepsy who underwent epilepsy surgery and were followed up for at least 2years (mean duration of follow-up 6.2years, range 2–14). Medical charts were reviewed to identify APOS, defined as ictal events with the exception of auras occurring within the first 7days after surgery. Seizure outcome was determined at annual intervals. Patients who were in Engel Class I at the last contact were classified as having a favourable outcome. ResultsSeizure outcome was favourable in 47 patients (61%). The occurrence of APOS and incompleteness of resection were found to be independently associated with unfavourable outcome in a multiple regression model including all preoperative factors identified as outcome predictors in univariate analysis. Duration of illness was the only independent preoperative predictor of APOS. ConclusionsOur study suggests that APOS may predict long-term outcome in patients undergoing resective surgery for ET epilepsy. Given some study limitations, our findings should be regarded as preliminary and need confirmation from future larger, prospective, multicentre studies. SignificanceCaution may be required in the clinical management of patients experiencing APOS.

Interleukin-6, interleukin-1 beta and interleukin-1 receptor antagonist levels in epileptic seizures

PurposeData are accumulating to support the involvement of inflammatory mechanisms in the pathogenesis and course of epilepsy. MethodsThe aim of this study was to examine seizure-induced changes in plasma concentrations of interleukin-6 (IL-6), interleukin-1 receptor antagonist (IL-1Ra), and interleukin-1 beta (IL-1β) in 23 patients with epilepsy undergoing a video-electroencephalography (EEG) study. Patients were divided into groups based on epilepsy type as follows: temporal lobe epilepsy (TLE) (n=6), extra-temporal lobe epilepsy (XLE) (n=8) and idiopathic generalised epilepsy (IGE) (n=9). Serum levels of IL-1β, IL-1Ra and IL-6 were measured at baseline, immediately after the epileptic seizure, and at 3h, 6h, 12h and 24h after the seizure. ResultsWe demonstrated a significant increase in plasma levels of IL-6 and IL-1Ra that peaked at 12h into the post-ictal period (p<0.05). IL-1β levels did not differ from the baseline levels. We did not observe any differences in post-ictal cytokine release patterns between the TLE, XLE and IGE groups. ConclusionThe present study confirms the findings that epileptic seizures induce the production of IL-6 and IL-1Ra.

Do neuroimaging results impact prognosis of epilepsy surgery? A meta-analysis

The neuroimaging results of drug-resistant epilepsy patients play an important role in the surgery decision and prognosis. The aim of this study was to evaluate the impact of these results on the efficacy of epilepay surgery, and then to explore surgical benefit for epilepsy patients with negative magnetic resonance (MR) images. Twenty-four subgroups describing the outcomes of 1475 epilepsy patients with positive-neuroimaging results and 696 patients with negative-neuroimaging results were involved in the meta-analysis. Overall, the odds of postoperational seizure-free rate were 2.03 times higher in magnetic resonance imaging-positive (MRI-positive) patients than in MRI-negative patients [odds ratio (OR)=2.03, 95% CI (1.67, 2.47), P<0.00001]. For patients with temporal lobe epilepsy (TLE), the odds were 1.76 times higher in those with MRI-positive results than in those with MRI-negative results [OR=1.76, 95% CI (1.34, 2.32), P<0.0001]. For patients with extra-temporal lobe epilepsy (extra-TLE), the odds were 2.88 times higher in MRI-positive patients than in MRI-negative patients [OR=2.88, 95% CI (1.53, 5.43), P=0.001]. It was concluded that the seizure-free rate of MRI-positive patients after surgery was higher than that of MRI-negative patients. For patients with negative results, an appropriate surgery should be concerned for TLE.

Update on the surgical treatment of epilepsy

Using the most recent evidence, we provide an update about epilepsy surgery, focusing on the presurgical evaluation and surgical planning, epilepsy surgery outcomes, and utilization. Great strides are being achieved in the presurgical evaluation and planning for epilepsy surgery, including fundamental advances in imaging and neurophysiology. A recent randomized controlled trial demonstrates that early surgery for patients with mesial temporal lobe epilepsy (TLE) is superior to medical therapy. The enduring benefits of surgery continue to be demonstrated, particularly after TLE surgery. However, studies examining the long-term outcomes after extratemporal lobe epilepsy surgery are scarce. Surgery is generally associated with an improvement in depression, but mostly in those with good surgical outcome. Complications from invasive monitoring or after epilepsy surgery are generally temporary, or limited in their symptomatology. One area in need of prospective studies is the topic of antiepileptic drug withdrawal after epilepsy surgery (Who? When? How?). Despite its proven effectiveness, epilepsy surgery continues to be underutilized, but new tools for health professionals are emerging to guide appropriate surgical referrals. Important contributions to the field of epilepsy surgery are discussed, in particular emerging imaging (fMRI) and neurophysiological (high-frequency oscillations) techniques. Epilepsy surgery is effective, well tolerated but still underutilized.

Quantitative MRI of Pharmaco-Resistant Focal Epilepsy (PFE): Temporal and Extratemporal Lobe Epilepsy (P06.173)

Quantitative MRI of Pharmaco-Resistant Focal Epilepsy (PFE): Temporal and Extratemporal Lobe Epilepsy (P06.173)

High‐frequency oscillations, extent of surgical resection, and surgical outcome in drug‐resistant focal epilepsy

Removal of areas generating high-frequency oscillations (HFOs) recorded from the intracerebral electroencephalography (iEEG) of patients with medically intractable epilepsy has been found to be correlated with improved surgical outcome. However, whether differences exist according to the type of epilepsy is largely unknown. We performed a comparative assessment of the impact of removing HFO-generating tissue on surgical outcome between temporal lobe epilepsy (TLE) and extratemporal lobe epilepsy (ETLE). We also assessed the relationship between the extent of surgical resection and surgical outcome. We studied 30 patients with drug-resistant focal epilepsy, 21 with TLE and 9 with ETLE. Two thirds of the patients were included in a previous report and for these, clinical and imaging data were updated and follow-up was extended. All patients underwent iEEG investigations (500 Hz high-pass filter and 2,000 Hz sampling rate), surgical resection, and postoperative magnetic resonance imaging (MRI). HFOs (ripples, 80-250 Hz; fast ripples, >250 Hz) were identified visually on a 5-10 min interictal iEEG sample. HFO rates inside versus outside the seizure-onset zone (SOZ), in resected versus nonresected tissue, and their association with surgical outcome (ILAE classification) were assessed in the entire cohort, and in the TLE and ETLE subgroups. We also tested the correlation of resected brain hippocampal and amygdala volumes (as measured on postoperative MRIs) with surgical outcome. HFO rates were significantly higher inside the SOZ than outside in the entire cohort and TLE subgroup, but not in the ETLE subgroup. In all groups, HFO rates did not differ significantly between resected and nonresected tissue. Surgical outcome was better when higher HFO rates were included in the surgical resection in the entire cohort and TLE subgroup, but not in the ETLE subgroup. Resected brain hippocampal and amygdala volumes were not correlated with surgical outcome. In TLE, removal of HFO-generating areas may lead to improved surgical outcome. Less consistent findings emerge from ETLE, but these may be related to sample size limitations of this study. Size of resection, a factor that was ignored and that could have affected results of earlier studies did not influence results.

Presurgical EEG-fMRI in a complex clinical case with seizure recurrence after epilepsy surgery

Epilepsy surgery has improved over the last decade, but non-seizure-free outcome remains at 10%–40% in temporal lobe epilepsy (TLE) and 40%–60% in extratemporal lobe epilepsy (ETLE). This paper reports a complex multifocal case. With a normal magnetic resonance imaging (MRI) result and nonlocalizing electroencephalography (EEG) findings (bilateral TLE and ETLE, with more interictal epileptiform discharges [IEDs] in the right frontal and temporal regions), a presurgical EEG-functional MRI (fMRI) was performed before the intraoperative intracranial EEG (icEEG) monitoring (icEEG with right hemispheric coverage). Our previous EEG-fMRI analysis results (IEDs in the left hemisphere alone) were contradictory to the EEG and icEEG findings (IEDs in the right frontal and temporal regions). Thus, the EEG-fMRI data were reanalyzed with newly identified IED onsets and different fMRI model options. The reanalyzed EEG-fMRI findings were largely concordant with those of EEG and icEEG, and the failure of our previous EEG-fMRI analysis may lie in the inaccurate identification of IEDs and wrong usage of model options. The right frontal and temporal regions were resected in surgery, and dual pathology (hippocampus sclerosis and focal cortical dysplasia in the extrahippocampal region) was found. The patient became seizure-free for 3 months, but his seizures restarted after antiepileptic drugs (AEDs) were stopped. The seizures were not well controlled after resuming AEDs. Postsurgical EEGs indicated that ictal spikes in the right frontal and temporal regions reduced, while those in the left hemisphere became prominent. This case suggested that (1) EEG-fMRI is valuable in presurgical evaluation, but requires caution; and (2) the intact seizure focus in the remaining brain may cause the non-seizure-free outcome.

Identification of common predictors of surgical outcomes for epilepsy surgery.

Although epilepsy surgery is an effective treatment for patients with drug-resistant epilepsy, surgical outcomes vary across patient groups and studies. Identification of reliable prognostic factors for surgical outcome is important for outcome research. In this study, recent systematic reviews and meta-analyses on prediction of seizure outcome have been analyzed, and common predictors of seizure outcome or unrelated factors for temporal lobe epilepsy (TLE), lesional extratemporal lobe epilepsy (ETLE), and tuberous sclerosis complex have been identified. Clinical factors such as lesional epilepsy, abnormal magnetic resonance imaging, partial seizures, and complete resection were found to be common positive predictors, and factors such as nonlesional epilepsy, poorly defined and localized epileptic focus, generalized seizures, and incomplete resection are common negative predictors, while factors such as age at surgery and side of surgery are unrelated to seizure outcome for TLE and lesional ETLE. In addition, diagnostic neuroimaging and resection are among the most important predictors of seizure outcome. However, common predictors of seizure outcome could not be identified in nonlesional ETLE because no predictors were found to be significant in adult patients (by meta-analysis), and outcome prediction is difficult in this case. Meta-analysis of other outcomes, such as neuropsychologic outcomes, is rare due to lack of evaluation standards. Further studies on identification of reliable predictors of surgical outcomes are needed.

Encéphalites dysimmunitaires, données cliniques, radiologiques et immunologiques

IntroductionEncephalitis is an inflammatory or infectious disease with an acute or subacute presentation. Immunological abnormalities in serum can be found but may be underdiagnosed. In several cases, a paraneoplastic origin with anti-neuron antibodies is noted. In all cases, other auto-antibodies can be found with or without any neoplastic mechanism. ObjectivesThe aim of our study was to describe a clinical, radiological and immunological cohort of patients with autoimmune encephalitis and suggest a diagnostic and therapeutic algorithm. Patients and methodWe performed a retrospective study in an immunological unit of neurology. All patients with autoimmune encephalitis between March 2000 and October 2009 were included. The clinical, imaging and immunological evaluations were recorded for each patient. ResultsOur cohort included 16 patients (eight men and eight women), mean age 45.3±10years. All patients had acute or subacute neuropsychological or neuropsychiatric impairment and all patients but one had temporal lobe dysfunction confirmed by cerebral MRI, PET or SPECT. Epilepsy was observed in 56% of cases, extra-temporal lobe impairment in 50%, including sleep disturbances. A cancer was found in only 25% (two small-cell lung cancers, one testis seminoma, one non-small-cell lung cancer with Merckel cells cancer). Anti-neuron antibodies were noted in 56% of cases (two with anti-voltage gate potassium channel complex antibodies (ab), two with anti-NMDA-R ab, two with anti-glutamate acid decarboxylase ab, one with anti-Ma2, two with anti-Hu ab and two remained uncharacterized). Systemic antibodies were found in 50% (one anti-gangliosides, one anti-SSA and one anti-DNA and four antinuclear ab uncharacterized, two anti-TPO and two anti-phospholipids). All patients received immunomodulatory treatments, including intravenous immunoglobulins (IgIV) and cancer was treated. Five patients achieved complete recovery, partial improvement was observed in 10 patients and two patients died. DiscussionDespite clinical homogeneity at presentation, clinical outcome seems to be different between patients with antibodies against neuronal surface antigens and those with antibodies against intracellular antigens, which are more likely refractory to immunotherapy and paraneoplastic. The frequency of extra-temporal lobe impairment suggests that the term of limbic encephalitis should be changed to autoimmune encephalitis.

The need for clinical quantification of combined PET/MRI data in pediatric epilepsy

In the past, multimodality integrative analysis of image data has been used to obtain a better understanding of underlying mechanisms of seizure generation and propagation in children with extratemporal lobe epilepsy. However, despite important advances in the combined analysis of PET, MRI, DTI and EEG data, successful surgical outcome is only achieved in about 2/3 of patients undergoing resective surgery. The advent of simultaneous PET/MR data acquisition promises an important advance in neuroimaging through clinical quantification, which will finally translate the strength of PET (which is the ability to absolutely quantify physiological parameters such as metabolic rates and receptor densities) into clinical work. Taking advantage of recently developed integrated PET/MR devices, absolute physiological values will be available in clinical routine, replacing currently used visual assessment of relative tissue tracer uptake. This will allow assessment of global increases/decreases of brain function during critical phases of development and is likely to have a significant impact on patient management in pediatric epilepsy.

9. Clinical yield of electric source imaging in epilepsy

Objective In patients with drug-resistant epilepsy who are candidate for surgery, non-invasive functional imaging methods are helpful in guiding surgical resections. Our main aim was to determine localisation precision of the epileptogenic focus with electric source imaging (ESI) and to compare it to other well-established imaging tools. Methods One hundred fifty-two pharmaco-resistant epileptic patients with more than 1 year post-operative follow-up were included. Sensitivity (defined as % of seizure free patients with focus localization within the resected zone) and specificity (defined as % of patients with focus localization outside the operated area) of different techniques was assessed: ESI, magnetic resonance imaging (MRI), positron emission tomography (PET) and single-photon emission-computed tomography (SPECT). Results A total of 43 patients underwent all examinations. High-resolution ESI (>64 electrodes) using individual MRI as a head model rendered the highest sensitivity (80%) and, principally, specificity rate (88%), followed by MRI (71.4% and 50%), PET (62.9% and 37.5%) and SPECT (54.3% but a higher specificity as compared to MRI and PET of 62.5%). The sensitivity of ESI was high in both temporal and extratemporal lobe epilepsy (91% and 75%, resp). The chance to become seizure-free if the focus source maximum is resected is 97%. Conclusion From a clinical point of view, ESI is a very attractive non-invasive technique with a high localization yield which provides superior temporal resolution in the millisecond range, as compared to methods based on changes in metabolic or vascular correlates of neural activity. From a practical perspective, this type of examination does not require sedation, it can be performed at patient’s bedside and it is suitable in the pediatric population and cognitively impaired patients.