Lesional Temporal Lobe Epilepsy Research Articles

SHORT-TERM SURGICAL OUTCOMES IN PATIENTS WITH DRUG-RESISTANT EPILEPSY DUE TO LESIONAL TEMPORA

Objectives: To describe the outcome of 35 cases of drug-resistant epilepsy due to the lesional temporal lobe surgery at Vietduc University Hospital from May 2018 to September 2022. Methods: A prospective description combined with retrospective, longitudinal follow-up of all patients diagnosed with drug resistance due to lesional temporal lobe epilepsy undergoing surgery at Vietduc University Hospital was conducted. Results: 35 cases of intractable lesional temporal lobe epilepsy surgery, male/female 1.5/1, partial seizures with loss of consciousness accounted for 99%, and 2/3 of cases occurred without aura. Seizure-free (post-operation 1 month) (Engel I) accounted for 74.3%, and the remaining (25.7%) had improved seizures (Engel 2, 3). Complications after surgery accounted for 17.1%, and there were no cases of death. Conclusion: Surgical treatment for drug resistance due to lesional temporal lobe epilepsy is safe and very effective, with a low complication rate.

Lateralization of interictal temporal lobe hypoperfusion in lesional and non-lesional temporal lobe epilepsy using arterial spin labeling MRI

PurposeNon-invasive imaging studies play a critical role in the presurgical evaluation of patients with drug-resistant temporal lobe epilepsy (TLE), particularly in helping to lateralize the seizure focus. Arterial Spin Labeling (ASL) MRI has been widely used to non-invasively study cerebral blood flow (CBF), with somewhat variable interictal alterations reported in TLE. Here, we compare temporal lobe subregional interictal perfusion and symmetry in lesional (MRI+) and non-lesional (MRI-) TLE compared to healthy volunteers (HVs). MethodsTwenty TLE patients (9 MRI+, 11 MRI-) and 14 HVs under went 3 T Pseudo-Continuous ASL MRI through an epilepsy imaging research protocol at the NIH Clinical Center. We compared normalized CBF and absolute asymmetry indices in multiple temporal lobe subregions. ResultsCompared to HVs, both MRI+ and MRI- TLE groups demonstrated significant ipsilateral mesial and lateral temporal hypoperfusion, specifically in the hippocampal and anterior temporal neocortical subregions, with additional hypoperfusion in the ipsilateral parahippocampal gyrus in the MRI+ and contralateral hippocampus in the MRI- TLE groups. Contralateral to the seizure focus, there was significant relative hypoperfusion in multiple subregions in the MRI- compared to the MRI+ TLE groups. The MRI+ group therefore had significantly greater asymmetry across multiple temporal subregions compared to the MRI- TLE and HV groups. No significant differences in asymmetry were found between the MRI- TLE and HV groups. ConclusionWe found a similar extent of interictal ipsilateral temporal hypoperfusion in MRI+ and MRI- TLE. However, significantly increased asymmetries were found only in the MRI+ group due to differences in perfusion contralateral to the seizure focus between the patient groups. The lack of asymmetry in the MRI- group may negatively impact the utility of interictal ASL for seizure focus lateralization in this patient population.

Long-term Remission and Resolution of Epilepsy following Surgery for Drug Resistant Lesional Temporal Lobe Epilepsy. (P2-1.001)

<h3>Objective:</h3> To determine the long-term seizure freedom and resolution of epilepsy in patients with drug resistant Temporal Lobe Epilepsy (TLE) and a clear-cut MRI lesion. <h3>Background:</h3> The long-term seizure free outcomes following surgery for TLE varied widely from 41% – 80% following surgery for TLE. <h3>Design/Methods:</h3> In a retrospective, longitudinal cohort study, we analysed the presurgical, surgical and post-surgical parameters to determine the seizure freedom and resolution of epilepsy in patients with ‘drug resistant lesional TLE with at least 10 years or more of post-surgery follow-up. The Study period was from June 2001 to 2012 <h3>Results:</h3> Of the 259 patients who formed the study population, 46% were women. The duration of follow-up ranged from 10 to 21 years. The average age at surgery was 25.80 ± 11.32 yrs; 49% had an aura, 61% had only hypomotor seizures and 38% had psychiatric comorbidity. The commonest pathology was hippocampal sclerosis(70%) followed by tumoral lesions and focal cortical dysplasia; 9.8% had acute post-operative seizures. At latest follow-up 75.6% were seizure free of which 52% had resolution of epilepsy. Presence of an aura , hippocampal sclerosis and longer time to first post-operative seizure were strong predictors for resolution of epilepsy while acute post-operative seizures and an abnormal post-surgery EEG at 1 year were predictors of persistent seizures. On survival analysis, the time to first seizure was significantly early in patients with persistent seizures. Seizure freedom both at three and five years predicted seizure freedom at 10 years. <h3>Conclusions:</h3> Resective surgery for drug resistant lesional TLE was associated with higher rate of seizure-freedom in ~75% and resolution of epilepsy in 52.15% even at long term follow-up. Longer time to first seizure, presence of aura at presentation and hippocampal sclerosis are strong predictors for resolution of epilepsy. APOS and abnormal Post-Surgery inter-ictal EEG are predictors of unfavourable outcome. <b>Disclosure:</b> Dr. Sattaluri has nothing to disclose. Dr. Patil has nothing to disclose. Dr. Choudhary has nothing to disclose. Dr. Vooturi has nothing to disclose.

Association of ictal aphasia with hypoperfusion in language areas in temporal lobe epilepsy patients

Ictal clinical phenomenology, including aphasia, is usually associated with increased regional cerebral perfusion. We present an unusual pattern of ictal cerebral perfusion in three patients with pharmacoresistant, lesional temporal lobe epilepsy and ictal/postictal aphasia studied with prolonged video-EEG, ictal, and interictal SPECT and MRI for pre-surgical evaluation. Subtraction of ictal-interictal SPECT images co-registered with MRI (SISCOM) showed ictal hyperperfusion in the temporal epileptogenic area in all patients. In addition, hypoperfusion of Broca's area in one case, Wernicke's area in other patient, and both areas in the remaining one were observed. Ictal aphasia in these patients may be explained by functional inhibition of a primary language area, driven by the epileptogenic network. This pattern can contribute to understand the pathophysiology of some ictal signs, with an impact on the evaluation of individual surgical risks.

Role of resective surgery in patients older than 60 years with therapy-resistant epilepsy.

Epilepsy surgery for older adults is controversial owing to their longer duration of epilepsy and perceived higher surgical risk. However, because of an aging population and documented benefit of epilepsy surgery, surgery is considered more frequently for these patients. The authors' objective was to analyze the role of resective surgery in patients older than 60 years and to assess outcomes and safety. The authors conducted a retrospective analysis of 595 patients who underwent resective epilepsy surgery at their center from 1999 to 2018. Thirty-one patients aged 60 years or older were identified. Sixty patients younger than 60 years were randomly selected as controls. Population characteristics, results of presurgical evaluations, outcomes, and complications were analyzed. No significant differences were found between the groups in terms of hemisphere dominance, side of surgery, presence of a lesion, and incidence of temporal lobe epilepsy. Epilepsy duration was greater in the older cohort (p = 0.019), and invasive EEG was more commonly employed in younger patients (p = 0.030). The rates of Engel class I outcome at 6 months, 1 year, and 2 years were 89.7%, 96.2%, and 94.7% for the older group and 75% (p = 0.159), 67.3% (p = 0.004), and 75.8% (p = 0.130) for the younger group, respectively. The proportion of seizure-free patients was greatest among those with temporal lobe epilepsy, particularly in the older group. Neurological complication rates did not differ significantly between groups, however medical and other minor complications occurred more frequently in the older group. Patients older than 60 years had equal or better outcomes at 1 year after epilepsy surgery than younger patients. A trend toward a greater proportion of patients with lesional temporal lobe epilepsy was found in the older group. These results suggest that good seizure outcomes can be obtained in older patients despite longer duration of epilepsy.

Seizure Duration and Spread Dynamics in MRI-Defined Subtypes of Temporal Lobe Epilepsy.

MRI and PET imaging enables subgroups of temporal lobe epilepsy (TLE) to be defined on the basis of structural pathology. Few studies have examined the variation in electroclinical seizure spread patterns based on imaging findings. We performed a retrospective cohort study to investigate the electroclinical differences among 3 specific groups of TLE: MRI-negative PET-positive TLE (MRI-negative TLE), temporal lobe lesion TLE (lesional TLE), and unilateral hippocampal sclerosis TLE (HS-TLE). Patients with an electroclinical diagnosis of TLE who had video-scalp EEG recordings of seizures were identified from the retrospective database of the Austin Comprehensive Epilepsy Program between 2005 and 2019. The cohort was further selected into the 3 defined groups based on imaging findings, using MRI and FDG-PET. Timings of clinical and electrographic seizure progression were measured, considering the onset, ipsilateral lobar spread, contralateral spread, and termination. Durations were compared between groups using linear mixed models with inclusion of demographic and clinical covariates. A total of 105 patients (137 seizures) were included, comprising 36 with MRI-negative TLE (54 seizures), 36 with lesional TLE (18 lateral vs 16 mesial lesions; 44 seizures), and 33 with HS-TLE (39 seizures). Seizure duration was similar between MRI-negative TLE and lesional TLE (mean 75.9 vs 71.7 seconds; p = 0.91). Further dividing lesional TLE into medial vs lateral temporal revealed no timing difference. However, the HS-TLE group had longer total seizure duration (114 seconds) compared with both MRI-negative TLE (p < 0.001) and lesional TLE (p < 0.001). Progression of electrographic spread also reflected this pattern, with involvement of extratemporal regions and then the contralateral hemisphere each taking significantly longer in HS-TLE. MRI-negative TLE appears electrographically similar to lesional TLE, whether mesial or lateral, in the duration of seizures and the timing of electrographic spread. Both appear electrographically different from HS-TLE, where propagation is slower, suggesting engagement of different epileptogenic networks or seizure suppression mechanisms. This study provides Class II evidence that the electroclinical features of seizures in HS-TLE are different than MRI-negative TLE and lesional TLE.

Imaging visuospatial memory in temporal lobe epilepsy-Results of an fMRI study.

PurposeImpairment of cognitive functions is commonly observed in temporal lobe epilepsy (TLE). The aim of this study was to assess visuospatial memory functions and memory-related networks using an adapted version of Roland’s Hometown Walking (RHWT) functional MRI (fMRI) task in patients with TLE.MethodsWe used fMRI to study activation patterns based on a visuospatial memory paradigm in 32 TLE patients (9 right; 23 left) and also within subgroups of lesional and non-lesional TLE. To test for performance, a correlational analysis of fMRI activation patterns and out-of-scanner neuropsychological visuospatial memory testing was performed. Additionally, we assessed memory-related networks using functional connectivity (FC).ResultsGreater contralateral than ipsilateral mesiotemporal (parahippocampal gyrus/hippocampus) activation was observed in left (n = 23)/right (n = 9) TLE. In lesional left TLE (n = 17), significant activations were seen in right more than left mesiotemporal areas (parahippocampal gyrus), while non-lesional left TLE patients (n = 6) showed significant bilateral (left>right) activations in mesiotemporal structures (parahippocampal gyrus). In left TLE, visuospatial cognitive testing correlated with fMRI activations in left (parahippocampal gyrus) and right mesiotemporal structures (hippocampus), characterized by greater fMRI activation being associated with better memory scores. In right TLE, higher scores in visuospatial memory testing were associated with greater fMRI activations in left and right insular regions. FC patterns of memory-related networks differ in right and left TLE.ConclusionWhile TLE in general leads to asymmetrical mesiotemporal activation, lesion-induced and non-lesional TLE patients reveal different memory fMRI activation patterns. In right TLE, insular regions try to compensate for impaired right mesiotemporal structures during the performance of visuospatial tasks. Underlying functional visuospatial memory networks differ in right and left TLE.

Lesional Temporal Lobe Epilepsy: Does the “Uncommon” Differ from the Common?

Abstract Objectives This study aims to evaluate the subgroup consisting of uncommon pathological entities presenting with temporal lobe epilepsy (TLE). Methodology Twenty-four consecutively operated patients of lesional temporal lobe epilepsy were included in the study. Eleven cases were identified that had pathologies implicated as “uncommon” in previously done studies on the pathology of TLE. A subgroup analysis consisting of these uncommon lesions was done for clinical presentation and seizure outcome. The seizure outcome was assessed in terms of Engel and International League Against Epilepsy (ILAE) classification. Results Nine different pathological entities were identified within the study group. The mean age at surgery was 18.6 years (range 2–30 years). The mean duration of epilepsy was 48.3 months and the average duration of follow-up was 39.2months. All patients had seizures as the only complaint except three. Three patients had focal-aware seizures, two had focal motor onset, and the rest all had focal-unaware seizures. Seven patients were seizure free and the average age at diagnosis for these patients was 15.4 years (range 2–24 years.). The duration of seizure in the postoperative seizure-free group was 29.7 months and it was 81 months for the other group. All the patients with persistent postoperative seizures had focal-unaware seizures preoperatively. Conclusion Despite the small and heterogeneous nature of this subgroup of uncommon lesions causing temporal lobe epilepsy, the clinical presentation, prognostic factors, and seizure outcome are similar to the cohort of common pathologies, including mesial temporal sclerosis.

Shape description and volumetry of hippocampus and amygdala in temporal lobe epilepsy – A beneficial combination with a clinical perspective

Shape-based markers have entered the field of morphometric neuroimaging analysis as a second mainstay alongside conventional volumetric approaches. We aimed to assess the added value of shape description for the analysis of lesional and autoimmune temporal lobe epilepsy (TLE) focusing on hippocampus and amygdala.We retrospectively investigated MRI and clinical data from 65 patients with lesional TLE (hippocampal sclerosis (HS) and astrogliosis) and from 62 patients with limbic encephalitis (LE) with serologically proven autoantibodies. Surface reconstruction and volumetric segmentation were performed with FreeSurfer. For the shape analysis, we used BrainPrint, a tool that utilizes eigenvalues of the Laplace–Beltrami operator on triangular meshes to calculate intra-subject asymmetry. Psychometric tests of memory performance were ascertained, to evaluate clinical relevance of the shape descriptor. The potential benefit of shape in addition to volumetric information for classification was assessed by five-fold repeated cross validation and logistic regression.For the LE group, the best performing classification model consisted of a combination of volume and shape asymmetry (mean AUC = 0.728), the logistic regression model was significantly improved considering both modalities instead of just volume asymmetry. For lesional TLE, the best model only considered volumetric information (mean AUC = 0.867). Shape asymmetry of the hippocampus was largely associated with verbal memory performance only in LE patients (OR = 1.07, p = 0.02).For lesional TLE, shape description is robust, but redundant when compared to volumetric approaches. For LE, in contrast, shape asymmetry as a complementary modality significantly improves the detection of subtle morphometric changes and is further associated with memory performance, which underscores the clinical relevance of shape asymmetry as a novel imaging biomarker.

The role of the temporal pole in temporal lobe epilepsy: A diffusion kurtosis imaging study

This study aimed to evaluate the use of diffusion kurtosis imaging (DKI) to detect microstructural abnormalities within the temporal pole (TP) and its temporopolar cortex in temporal lobe epilepsy (TLE) patients. DKI quantitative maps were obtained from fourteen lesional TLE and ten non-lesional TLE patients, along with twenty-three healthy controls. Data collected included mean (MK); radial (RK) and axial kurtosis (AK); mean diffusivity (MD) and axonal water fraction (AWF). Automated fiber quantification (AFQ) was used to quantify DKI measurements along the inferior longitudinal (ILF) and uncinate fasciculus (Unc). ILF and Unc tract profiles were compared between groups and tested for correlation with disease duration. To characterize temporopolar cortex microstructure, DKI maps were sampled at varying depths from superficial white matter (WM) towards the pial surface. Patients were separated according to the temporal lobe ipsilateral to seizure onset and their AFQ results were used as input for statistical analyses. Significant differences were observed between lesional TLE and controls, towards the most temporopolar segment of ILF and Unc proximal to the TP within the ipsilateral temporal lobe in left TLE patients for MK, RK, AWF and MD. No significant changes were observed with DKI maps in the non-lesional TLE group. DKI measurements correlated with disease duration, mostly towards the temporopolar segments of the WM bundles. Stronger differences in MK, RK and AWF within the temporopolar cortex were observed in the lesional TLE and noticeable differences (except for MD) in non-lesional TLE groups compared to controls. This study demonstrates that DKI has potential to detect subtle microstructural alterations within the temporopolar segments of the ILF and Unc and the connected temporopolar cortex in TLE patients including non-lesional TLE subjects. This could aid our understanding of the extrahippocampal areas, more specifically the temporal pole role in seizure generation in TLE and might inform surgical planning, leading to better seizure outcomes.

Skull-base temporal encephalocele: Hidden cause of temporal lobe epilepsy

Among patients with Temporal lobe epilepsy (TLE), up to 30% can have normal (non-lesional) MRI scans. With increased use of high resolution MRI (3 T) scans, many of the MRI‐negative TLE cases turn out to be lesional TLE. Skull-base temporal encephalocele (TE), has to be suspected and specifically searched for among patients with apparent MRI negative TLE. The study aims to analyse patients with TLE for temporal lobe encephalocoele.

Dynamic tractography-based localization of spike sources and animation of spike propagations.

This study was undertaken to build and validate a novel dynamic tractography-based model for localizing interictal spike sources and visualizing monosynaptic spike propagations through the white matter. This cross-sectional study investigated 1900spike events recorded in 19 patients with drug-resistant temporal lobe epilepsy (TLE) who underwent extraoperative intracranial electroencephalography (iEEG) and resective surgery. Twelve patients had mesial TLE (mTLE) without a magnetic resonance imaging-visible mass lesion. The remaining seven had a mass lesion in the temporal lobe neocortex. We identified the leading and lagging sites, defined as those initially and subsequently (but within ≤50ms) showing spike-related augmentation of broadband iEEG activity. In each patient, we estimated the sources of 100spike discharges using the latencies at given electrode sites and diffusion-weighted imaging-based streamline length measures. We determined whether the spatial relationship between the estimated spike sources and resection was associated with postoperative seizure outcomes. We generated videos presenting the spatiotemporal change of spike-related fiber activation sites by estimating the propagation velocity using the streamline length and spike latency measures. The spike propagation velocity from the source was 1.03mm/ms on average (95% confidence interval = .91-1.15) across 133 tracts noted in the 19 patients. The estimated spike sources in mTLE patients with International League Against Epilepsy Class 1 outcome were more likely to be in the resected area (83.9% vs. 72.3%, φ=.137, p<.001) and in the medial temporal lobe region (80.5% vs. 72.5%, φ=.090, p=.002) than those associated with the Class ≥2 outcomes. The resulting video successfully animated spike propagations, which were confined within the temporal lobe in mTLE but involved extratemporal lobe areas in lesional TLE. We have, for the first time, provided dynamic tractography visualizing the spatiotemporal profiles of rapid propagations of interictal spikes through the white matter. Dynamic tractography has the potential to serve as a unique epilepsy biomarker.

TEMPORAL LOBE EPILEPSY (PAST, PRESENT, AND THE FUTURE)

Background: The temporal lobe is the most epileptogenic region of the human brain. There are two types of temporal lobe epilepsy (TLE), the medial involves the medial or internal structures, and neocortical involves the outer portion of the temporal lobe. It can be associated with a magnetic resonance imaging (MRI) lesion or be non-lesional. The main causes of lesional TLE are Herpes simplex, benign tumors, vascular malformations, cortical development malformations, and post-traumatic or post-infectious gliosis. Objective: To discuss temporal lobe epilepsy with all its different causes, evaluating different modalities of treatment, obstacles in applying all modalities in developing countries, and ways to overcome these obstacles with future scope of epilepsy treatment especially temporal lobe epilepsy. Patients and methods: The study performed on twenty patients admitted to Al-Hussein and Sayed Galal University hospitals, and Al-Ahrar teaching hospital. There were pre-surgical evaluations by a multidisciplinary team of neurologists, clinical neurophysiologists, neuroradiologist, epileptologists, psychologists, psychiatrists, and neurosurgeons. Most of cases were temporal lobe lesional epilepsy. Surgical management was carried out for the included patients according to present pathology. Results: Our patients' ages ranged from 7 to 55 years old with the mean age of 21.2 ± 13.79 years. 60% were in 2nd decade. 70% of patients were males and 30% were females, 90% were right handed and 10% left handed. The range of duration of the disease was 2-8 years with the mean 4.1 ± 2.125 years. As regard MRI pathological findings; 10% normal, 10% left temporal sclerosis, 10% right insular dysplasia, 5% right temporal encephalomalacia, 10% temporal covernoma, 10% temporal arachnoid cyst, 5% right temporal epidermoid cyst and 40% temporal neoplastic lesions of MRI findings. 55% Left temporal epileptic discharge, 25% right temporal epileptic discharge, 10% bilateral temporal epileptogenic activity with tendency to generalization and 10% normal of EEG. 65% lesional excision, 10% excision and fenestration of cyst to subarachnoid space, 15% amygdalohippocampectomy, and 15% temporal lobectomy. Among the patients surgically operated, 4 patients (20%) had temporarily complications. Conclusion: Temporal lobe epilepsy surgeries provided a good chance for seizure control when the clinical and radiological data were concordant with seizure semiology, in particular with tumor-related epilepsy. TLE surgery can be safe when performed by experienced surgeons.

Outcomes of hippocampus-sparing lesionectomy for temporal lobe epilepsy and the significance of intraoperative hippocampography

ObjectivesWe investigated hippocampal-sparing lesionectomy (HSL) outcomes in temporal lobe epilepsy (TLE) and the significance of high-frequency oscillations (HFOs) detected by hippocampography in HSL. MethodsWe retrospectively reviewed data from patients who underwent HSL for lesional TLE. Patients were included when MRI confirmed (i) a lesion limited to the temporal lobe with normal hippocampi preoperatively and (ii) hippocampal integrity postoperatively. Factors possibly related to outcomes were collected. Intraoperative hippocampography was reviewed, and spikes, ripples, and fast ripples were marked. Seizure outcomes were tracked ≥ 2 years. Postoperative neuropsychological tests were performed and analyzed. ResultsWe included 67 patients (35 males/32 females, median age at surgery 28 years, 57 seizure-free). Complete resection was significantly associated with being seizure-free without aura, an outcome achieved by 32 (69.6%) patients with complete resection vs 1 (12.5%) with incomplete resection (p = 0.004). Spikes/ripples/fast ripples appeared frequently in the hippocampus, occurring in 86.4%/82.4%/75.0% of cases before resection and 76.7%/78.1%/63.0% after resection. The presence and rate were unconnected to seizure outcome. Postoperative neuropsychological outcomes in intelligence and visual memory improved overall. ConclusionsHSL in lesional TLE can produce satisfactory seizure and cognitive outcomes. Intraoperative hippocampography-guided resection of apparently normal hippocampi should be performed cautiously and might not be necessary. SignificanceThis study provided evidence in decision making for patients with lesional TLE with a radiologically normal hippocampus.

Verbal memory in children with temporal lobe epilepsy: Exploring task-specificity

RationaleThis study explored the applicability of the adult model of task-specificity of memory to children with temporal lobe epilepsy (TLE). MethodRetrospective clinical audit; 38 children and adolescents (6–16 years) with lesional TLE (n = 22 mesial; n = 16 lateral) treated at tertiary pediatric hospitals completed two types of verbal memory paradigms: arbitrary associative (Verbal Paired Associates – Hard Pairs) and semantically related (Verbal Paired Associates – Easy Pairs; Stories). ResultsChildren with mesial TLE performed more poorly than their lateral TLE counterparts on both types of memory paradigms: arbitrary associative and semantically related (Stories only). Groups with left and right TLE performed comparably on all verbal memory measures. ConclusionsOur findings suggest that the adult model of task-specificity may not be completely applicable to children with TLE. Consideration of the developmental context is critical in research and clinical work with pediatric populations.

Diagnostic and prognostic value of noninvasive long-term video-electroencephalographic monitoring in epilepsy surgery: A systematic review and meta-analysis from the E-PILEPSY consortium.

The European Union-funded E-PILEPSY network (now continuing within the European Reference Network for rare and complex epilepsies [EpiCARE]) aims to harmonize and optimize presurgical diagnostic procedures by creating and implementing evidence-based guidelines across Europe. The present study evaluates the current evidence on the diagnostic accuracy of long-term video-electroencephalographic monitoring (LTM) in identifying the epileptogenic zone in epilepsy surgery candidates. MEDLINE, Embase, CENTRAL, and ClinicalTrials.gov were searched for relevant articles. First, we used random-effects meta-analytical models to calculate pooled estimates of sensitivity and specificity with respect to postsurgical seizure freedom. In a second phase, we analyzed individual patient data in an exploratory fashion, assessing diagnostic accuracy within lesional and nonlesional temporal lobe epilepsy (TLE) and extratemporal lobe epilepsy (ETLE) patients. We also evaluated seizure freedom rate in the presence of "localizing" or "nonlocalizing" LTM within each group. The quality of evidence was assessed using the QUADAS-2 tool and the GRADE approach. Ninety-four studies were eligible. Forty-four were included in sensitivity meta-analysis and 34 in specificity meta-analysis. Pooled sensitivity was 0.70 (95% confidence interval [CI] = 0.60-0.80) and specificity was 0.40 (95% CI = 0.27-0.54). Subgroup analysis was based on individual data of 534 patients (41% men). In lesional TLE patients, sensitivity was 0.85 (95% CI = 0.81-0.89) and specificity was -0.19 (95% CI = 0.13-0.28). In lesional ETLE patients, a sensitivity of 0.47 (95% CI = 0.36-0.58) and specificity of 0.35 (95% CI = 0.21-0.53) were observed. In lesional TLE, if LTM was localizing and concordant with resection site, the seizure freedom rate was 247 of 333 (74%), whereas in lesional ETLE it was 34 of 56 (61%). The quality of evidence was assigned as "very low." Long-term video-electroencephalographic monitoring is associated with moderate sensitivity and low specificity in identification of the epileptogenic zone. Sensitivity is remarkably higher in lesional TLE compared to lesional ETLE. Substantial heterogeneity across the studies indicates the need for improved design and quality of reporting.

Unilateral temporal interictal epileptiform discharges correctly predict the epileptogenic zone in lesional temporal lobe epilepsy.

To evaluate the necessity of recording ictal electroencephalography (EEG) in patients with temporal lobe epilepsy (TLE) considered for resective surgery who have unilateral temporal interictal epileptiform discharges (IEDs) and concordant ipsitemporal magnetic resonance imaging (MRI) pathology. To calculate the necessary number of recorded EEG seizure patterns (ESPs) to achieve adequate lateralization probability. In a retrospective analysis, the localization and lateralization of interictal and ictal EEG of 304 patients with lesional TLE were analyzed. The probability of further contralateral ESPs was calculated based on a total of 1967 recorded ESPs, using Bayes' theorem. Two hundred seventy-one patients had unilateral TLE, and in 98% of them (265 of 271), IEDs were recorded during video-EEG monitoring. Purely unilateral temporal IEDs were present in 61% (166 of 271 patients). Ipsilateral temporal MRI pathology was found in 83% (138 of 166). Ictal EEG was concordant with the clinical side of TLE in 99% (136 of 138) of these patients. Two patients had discordant ictal EEG with both ipsilateral and contralateral ESPs. Epilepsy surgery with resection in the lesioned temporal lobe was still performed, and both patients remain seizure-free. Probability calculations demonstrate that at least 6 recorded unilateral ESPs result in a >95% probability for a concordance of >0.9 of any further ESPs. The combination of purely unilateral temporal IED with ipsitemporal MRI pathology is sufficient to identify the epileptogenic zone, and the recording of ictal ESP did not add any surgically relevant information in these 138 patients. Rarely, discordant ESPs might be recorded, but the surgical outcome remains excellent after surgery on the lesioned side.

The impact of stereotactic laser ablation at a typical epilepsy center

PurposeStereotactic laser ablation (SLA) is a novel form of epilepsy surgery for patients with drug-resistant focal epilepsy. We evaluated one hundred consecutive surgeries performed for patients with epilepsy to address the impact of SLA on our therapeutic approach, as well as patient outcomes. MethodsA retrospective, single center analysis of the last one hundred neurosurgeries for epilepsy was performed from 2013 to 2015. Demographics, surgical procedures, and postoperative measures were assessed up to 5years to compare the effect of SLA on outcome. Confidence intervals (CI) and comparative tests of proportions compared outcomes for SLA and resective surgery. Procedural categorical comparison used Chi-square and Kaplan–Meier curves. Student t-test was utilized for single variables such as age at procedure and seizure onset. ResultsOne hundred surgeries for epilepsy yielded thirty-three SLAs and twenty-one resections with a mean of 21.7-month and 21.3-month follow-up, respectively. The temporal lobe was the most common target for SLA (92.6%) and resection (75%). A discrete lesion was present on brain magnetic resonance imaging (MRI) in 27/32 (84.4%) of SLA patients compared with 7/20 (35%) of resection patients with a normal MRI. Overall, 55–60% of patients became seizure-free (SF). Four of five patients with initial failure to SLA became SF with subsequent resection surgery. Complications were more frequent with resection although SF outcomes did not differ (Chi square; p=0.79). Stereotactic laser ablation patients were older than those with resections (47.0years vs. 35.4years, p=0.001). The mean length of hospitalization prior to discharge was shorter for SLA (1.18days) compared with open resection (3.43days; SD: 3.16 days) (p=0.0002). ConclusionWe now use SLA as a first line therapy at our center in patients with lesional temporal lobe epilepsy (TLE) before resection. Seizure-free outcome with SLA and resection was similar but with a shorter length of stay. Long-term follow-up is recommended to determine sustained SF status from SLA.

Electro-clinical criteria and surgical outcome: Is there a difference between mesial and lesional temporal lobe epilepsy?

Mesial temporal lobe epilepsy syndrome (MTLE) with specific electrophysiological and clinical characteristics and hippocampal sclerosis (HS) on MRI is considered the prototype of a syndrome with good surgical prognosis. Ictal onset zones in MTLE have been found to extend outside the hippocampus and neocortical seizures often involve mesial structures. It can, thus, be questioned whether MTLE with HS is different from lesional temporal epilepsies with respect to electro-clinical characteristics and surgical prognosis. We assessed whether MTLE with HS is distinguishable from lesional TLE and which criteria determine surgical outcome. People in a retrospective cohort of 389 individuals with MRI abnormalities who underwent temporal lobectomy, were divided into "HS only" or "lesional" TLEs. Twenty-six presented with dual pathology and were excluded from further analysis. We compared surgical outcome and electro-clinical characteristics. Over half (61%) had "HS only." Four electro-clinical characteristics (age at epilepsy onset, febrile seizures, memory dysfunction and contralateral dystonic posturing) distinguished "HS only" from "lesional" TLE, but there was considerable overlap. Seizure freedom 2years after surgery (Engel class 1) was similar: 67% ("HS only") vs 69% ("lesional" TLE). Neither presence of HS nor electro-clinical criteria was associated with surgical outcome. Despite small differences in electrophysiological and clinical characteristics between MTLE with HS and lesional TLE, surgical outcomes are similar, indicating that aetiology seems irrelevant in the referral for temporal surgery.

Seizure outcomes of temporal lobe epilepsy surgery in patients with normal MRI and without specific histopathology

BackgroundSeizure outcome following surgery in pharmacoresistant temporal lobe epilepsy patients with normal magnetic resonance imaging and normal or non-specific histopathology is not sufficiently presented in the literature.MethodsIn a retrospective design, we reviewed data of 263 patients who had undergone temporal lobe epilepsy surgery and identified 26 (9.9%) who met the inclusion criteria. Seizure outcomes were determined at 2-year follow-up. Potential predictors of Engel class I (satisfactory outcome) were identified by logistic regression analyses.ResultsEngel class I outcome was achieved in 61.5% of patients, 50% being completely seizure free (Engel class IA outcome). The strongest predictors of satisfactory outcome were typical ictal seizure semiology (p = 0.048) and localised ictal discharges on scalp EEG (p = 0.036).ConclusionSurgery might be an effective treatment choice for the majority of these patients, although outcomes are less favourable than in patients with magnetic resonance imaging-defined lesional temporal lobe epilepsy. Typical ictal seizure semiology and localised ictal discharges on scalp EEG were predictors of Engel class I outcome.